Home » Public Forums » GMCnet » [GMCnet] Reviving the Cad 500
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| Re: [GMCnet] Reviving the Cad 500 [message #163494 is a reply to message #163490] |
Mon, 19 March 2012 07:22   |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Anything's possible - but given the long term history of this particular engine in a Cadillac you'd think not. Unless something really heavy or really light got installed along with seven normal whatevers. It's easily proved - or disproved - by looking at the thrust faces and seeing if they're worn evenly or assymetrically. Even would mean a steady push on the shaft, uneven would be a twist, couple, or bent shaft. And regardless, multiple times out in few miles adds up to frustration with the whole thing. I feel bad for Ken, here he is breaking ground for the rest of us and it's giving him serious grief.
I wanna play with one of these '3D' printer thingies. One might be able to model the needed case and fittings to get a 440 in the coach.....
--johnny
'76 23' transmode
'76 palm beach
From: Rob Mueller <robmueller@iinet.net.au>
To: gmclist@temp.gmcnet.org
Sent: Monday, March 19, 2012 8:05 AM
Subject: Re: [GMCnet] Reviving the Cad 500
Johnny,
I was wondering if it is possible in a V-8 engine to have enough couple
imbalance in the crankshaft to cause it to move forward and aft?
For those of you who don't know what couple imbalance is:
http://www.azimadli.com/Vibman/coupleimbalance.htm
Regards,
Rob M.
-----Original Message-----
From: Johnny Bridges
Some days it's the elevator. Some days, it's the shaft. You may be down to
RF&RA (Rage, Frustration, and Random Actions). If the transmission isn't
pushing against the shaft, what are the other possibilities? Slightly bent
cionnecting rod? Out of line cam drive? The diety doesn't like you?
--johnny
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Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] Reviving the Cad 500 [message #163504 is a reply to message #163441] |
Mon, 19 March 2012 09:56 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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""I have no idea WHY. Nor WHAT to do. And I don't want to talk about
it or even think about it for a while. Y'All figure it out; I'm gonna
go pout. Too bad I'm not a drinking man -- I could really do it up
right tonight; me & Ken Murphy could really hang one on!
""
I'm sure a lot of folks here on the net are scratching their heads on this one. For that amount of wear to occur in such a short time, the forces had to be pretty big. The only thing I could think of that would do that goes back to the converter--just don't ask me how it could have.
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: [GMCnet] Reviving the Cad 500 [message #163506 is a reply to message #163490] |
Mon, 19 March 2012 10:01 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Rob, rocking couple imbalance is very common in V-twins and Vertical twins.
As a V-8 is just 4 of them, the condition also exists in them. I don't
think that the forces act outside of the rotational plane however, which
might rule our thrust forces. Something is either introducing a mammoth
amount of abrasive material to the thrust surfaces, or some force greater
than what would be applied by a manual clutch is putting end play loads on
the crankshaft that is displacing the lubricants present in the thrust
area. As this type of loading is difficult to imagine in an engine with a
torque converter, it makes me scratch my head & ponder WTF?
Could it be the lubricant that he is using that does not have enough anti
scuff/anti wear additives? Dare I mention ZddP? Probably not a great idea.
I kinda am leaning towards that arena with the information at hand.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Mon, Mar 19, 2012 at 5:05 AM, Rob Mueller <robmueller@iinet.net.au>wrote:
> Johnny,
>
> I was wondering if it is possible in a V-8 engine to have enough couple
> imbalance in the crankshaft to cause it to move forward and aft?
>
> For those of you who don't know what couple imbalance is:
>
> http://www.azimadli.com/Vibman/coupleimbalance.htm
>
>
> Regards,
> Rob M.
>
> -----Original Message-----
> From: Johnny Bridges
>
> Some days it's the elevator. Some days, it's the shaft. You may be down
> to
> RF&RA (Rage, Frustration, and Random Actions). If the transmission isn't
> pushing against the shaft, what are the other possibilities? Slightly bent
> cionnecting rod? Out of line cam drive? The diety doesn't like you?
>
> --johnny
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
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| Re: [GMCnet] Reviving the Cad 500 [message #163519 is a reply to message #162802] |
Mon, 19 March 2012 11:12 |
roy1
Messages: 2126
Registered: July 2004
Location: Minden nevada
Karma: 6
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Senior Member |
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Sorry I feel your pain Ken.I know you are a little older then I am and the thought of pulling the engine again is a real drag.
I remember in an earlier post you said you needed to shave the thrust bearing because you had no end play to speak of. Is it possible you were mistaken and shaved too much off because something gave you a false reading? My engine at 5000 miles had very dark oil and shiny swirls in it. the filter also had like you describe. I sent a sample to Blackstone before I pulled it again and they said it was normal? It has 11000 on it now and it is a lot cleaner and stronger. I'll send in another sample to Blackstone.
Roy Keen
Minden,NV
76 X Glenbrook
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| Re: [GMCnet] Reviving the Cad 500 [message #163521 is a reply to message #163519] |
Mon, 19 March 2012 11:30 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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Ken,
Hate to hear of your engine troubles...
perhaps the best suggestion was to park the coach and drive your car to Shawnee -- and with time away, along with the opportunity to talk first-hand to some others, you can define a plan-of-attack.
And let us know of any help you may need as you move ahead.
Dennis
Dennis S
73 Painted Desert 230
Memphis TN Metro
[Updated on: Mon, 19 March 2012 11:54] Report message to a moderator |
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| Re: [GMCnet] Reviving the Cad 500 [message #163524 is a reply to message #162802] |
Mon, 19 March 2012 11:45 |
Ed Jarmul
Messages: 16
Registered: March 2012
Karma: 0
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Junior Member |
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Rob, I feel your pain and have to weigh in on this one with a short excerpt
from a recent Internet search since I have a 500 in my 75 Cadillac and
"bullet proof" Turbo 400 as well.
1. You want the radiator heat exchanger to be the last thing in the
hydraulic circuit before the fluid is returned to the transmission. If you
add an external fluid cooler (a really good idea), place it before the heat
exchanger so that the radiator heat exchanger has the "last word".
2. Keep the restriction in any cooler low. Since a high volume of oil
flows in this circuit at times, you need low restriction to avoid having
pressure build up in the torque converter. That pressure buildup is bad for
a lot of things, including the engine's thrust bearing, the torque
converter, and the various bearings and washers in the transmission which
handle the axial thrust load. In a really bad case, excess converter
pressure can crack a transmission case.
3. Do not block the hydraulic lines in any manner. This includes
thermostats and shutoff valves. Blocking the fluid flow not only results in
very high converter and line pressures, it also causes a lack of lubrication
inside the transmission which will quickly lead to transmission failure.
This article deals mostly with adding an extra transmission cooler but the
pressure buildup due to a restriction/converter issue can be extreme causing
engine trust bearing failures.
Just a thought and I have the complete article if interested in ideas for
controlling fluid temperatures, the killer of any automatic transmission.
Ed J
73 & 77 GMC 26'
75 Deville
69 Vette
Schenectady, NY
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| Re: [GMCnet] Reviving the Cad 500 [message #163528 is a reply to message #163441] |
Mon, 19 March 2012 13:08 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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That really stinks, Ken. I'm adding my vote for having you attend the rally in a car and hotel. The whole daunting situation might look a little bit better when you get back home
Carl Stouffer
'75 ex Palm Beach
Tucson, AZ.
Chuck Aulgur Reaction Arm Disc Brakes, Quadrabags, 3.70 LSD final drive, Lenzi knuckles/hubs, Dodge Truck 16" X 8" front wheels, Rear American Eagles, Solar battery charging. GMCSJ and GMCMI member
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| Re: [GMCnet] Reviving the Cad 500 [message #163535 is a reply to message #163524] |
Mon, 19 March 2012 14:39 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI+ & EBL
www.gmcwipersetc.com
Ed,
Rob's not the one with the Cad500 problem -- I, Ken H., am the victim.
Thanks for your input. Unfortunately, there's nothing new there to help
me. I'd read all that sort of information even before I rebuilt the Cad
11,000 miles ago. And studied it all again before this latest repair.
None of that is, per se, applicable: I have only a nearly-new aluminum
radiator with ATF cooler as external cooling. And that's connected with
3/8" lines rather than the OEM 5/16". Additional cooling comes from a
transmission pan having cooling tubes for air flow -- NO hydraulic
restriction there nor anywhere else in the system.
That's not to say the transmission hydraulic pressure isn't high. In fact,
my current, unsubstantiated, opinion is that it's exactly the problem.
IMHO, there's just no other possible source of sufficient force to cause
such a rapid failure.
My intention now is that, when I finally feel like getting greasy again,
I'll put gauges on the service port and the converter outlet. Then I'll
abuse the still well running engine a little longer to see what those
pressures are.
Thanks again,
Ken H.
On Mon, Mar 19, 2012 at 12:45 PM, Ed Jarmul wrote:
> Rob, I feel your pain and have to weigh in on this one with a short excerpt
> from a recent Internet search since I have a 500 in my 75 Cadillac and
> "bullet proof" Turbo 400 as well.
>
>
>
> 1. You want the radiator heat exchanger to be the last thing in the
> hydraulic circuit before the fluid is returned to the transmission. If you
> add an external fluid cooler (a really good idea), place it before the heat
> exchanger so that the radiator heat exchanger has the "last word".
>
> 2. Keep the restriction in any cooler low. Since a high volume of oil
> flows in this circuit at times, you need low restriction to avoid having
> pressure build up in the torque converter. That pressure buildup is bad for
> a lot of things, including the engine's thrust bearing, the torque
> converter, and the various bearings and washers in the transmission which
> handle the axial thrust load. In a really bad case, excess converter
> pressure can crack a transmission case.
>
> 3. Do not block the hydraulic lines in any manner. This includes
> thermostats and shutoff valves. Blocking the fluid flow not only results in
> very high converter and line pressures, it also causes a lack of
> lubrication
> inside the transmission which will quickly lead to transmission failure.
>
> This article deals mostly with adding an extra transmission cooler but the
> pressure buildup due to a restriction/converter issue can be extreme
> causing
> engine trust bearing failures.
>
> Just a thought and I have the complete article if interested in ideas for
> controlling fluid temperatures, the killer of any automatic transmission.
>
>
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Reviving the Cad 500 [message #163589 is a reply to message #163524] |
Mon, 19 March 2012 23:17 |
Adrien G.
Messages: 474
Registered: May 2008
Location: Burns Flat, OK 73624
Karma: 1
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Senior Member |
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>1. You want the radiator heat exchanger to be the last thing in the
hydraulic circuit before the fluid is returned to the transmission. If you
add an external fluid cooler (a really good idea), place it before the heat
exchanger so that the radiator heat exchanger has the "last word".
>2. Keep the restriction in any cooler low. Since a high volume of oil
flows in this circuit at times, you need low restriction to avoid having
pressure build up in the torque converter. That pressure buildup is bad for
a lot of things, including the engine's thrust bearing, the torque
converter, and the various bearings and washers in the transmission which
handle the axial thrust load. In a really bad case, excess converter
pressure can crack a transmission case.
>3. Do not block the hydraulic lines in any manner. This includes
thermostats and shutoff valves. Blocking the fluid flow not only results in
very high converter and line pressures, it also causes a lack of lubrication
inside the transmission which will quickly lead to transmission failure.
Ed,
I think that's a good point.
I wonder how much axial expansion a TC does per lbs of oil pressure. How much pressure would be required to balloon the TC?
If the TC has internal problems that normal internal pressures cause it to expand (balloon) picking up the axial free play plus (?). That could put pressure on the thrust bearing.
I wonder if oil pressure built up between the TC and the oil pump, may be thrusting the TC forward. Just thinking out loud.
If the thrust bearing is worn on the rear side (flex plate end side), I think it would make the TC a strong candidate to consider.
Ken,
I'm sorry to read that after all that work, it ended in a demoralizing disappointment. But from this challenge (and inputs), new knowledge will be gained for the good of our GMCMH interest.
IMHO, for what it's worth.
Adrien & Jenny Genesoto
75 Glenbrook (26-3) Mods LS3.70 FD / Reaction Sys / 80mm Front&Intermidiate / Hydroboost / 16" Tires / Frame Rebuild / Interior Rebuild
Yuba City,Ca. Text 530-nine-3-three-3-nine-nine-6
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| Re: [GMCnet] Reviving the Cad 500 [message #163606 is a reply to message #163506] |
Tue, 20 March 2012 07:16 |
Steven Ferguson
Messages: 3447
Registered: May 2006
Karma: 0
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Senior Member |
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I've seen this happen in BBC engines when the thrust was checked with the
leading or trailing edge of the main bearings up against one or more fillet
radius on the crank. It doesn't take much. I prefer to check thrust
twice. Once with the crank sitting in the block without the main caps
installed, then after the main caps are installed and torqued. During the
torque process I rock the crank back and forth to ensure that I'm torquing
in the center of the bearing surface on the crank. A lot of premium engine
remanufactures will chamfer the edges of the bearings as cheap insurance
against this. Another issue is how the fillet radius on the crank main
thrust bearing is addressed during the grinding process. A friend of mine
in San Diego built a device to measure thrust pressure during shift points.
With a stage one shift kit installed it was amazing how much pressure was
generated against the thrust bearing. Considerable more than normal.
I'm not saying your CS was not in good hands Ken, just 2 cents worth here.
On Mon, Mar 19, 2012 at 8:01 AM, James Hupy <jamesh1296@gmail.com> wrote:
> Rob, rocking couple imbalance is very common in V-twins and Vertical twins.
> As a V-8 is just 4 of them, the condition also exists in them. I don't
> think that the forces act outside of the rotational plane however, which
> might rule our thrust forces. Something is either introducing a mammoth
> amount of abrasive material to the thrust surfaces, or some force greater
> than what would be applied by a manual clutch is putting end play loads on
> the crankshaft that is displacing the lubricants present in the thrust
> area. As this type of loading is difficult to imagine in an engine with a
> torque converter, it makes me scratch my head & ponder WTF?
> Could it be the lubricant that he is using that does not have enough anti
> scuff/anti wear additives? Dare I mention ZddP? Probably not a great idea.
> I kinda am leaning towards that arena with the information at hand.
> Jim Hupy
> Salem, OR
> 78 GMC Royale 403
>
> On Mon, Mar 19, 2012 at 5:05 AM, Rob Mueller <robmueller@iinet.net.au
> >wrote:
>
> > Johnny,
> >
> > I was wondering if it is possible in a V-8 engine to have enough couple
> > imbalance in the crankshaft to cause it to move forward and aft?
> >
> > For those of you who don't know what couple imbalance is:
> >
> > http://www.azimadli.com/Vibman/coupleimbalance.htm
> >
> >
> > Regards,
> > Rob M.
> >
> > -----Original Message-----
> > From: Johnny Bridges
> >
> > Some days it's the elevator. Some days, it's the shaft. You may be down
> > to
> > RF&RA (Rage, Frustration, and Random Actions). If the transmission isn't
> > pushing against the shaft, what are the other possibilities? Slightly
> bent
> > cionnecting rod? Out of line cam drive? The diety doesn't like you?
> >
> > --johnny
> >
> > _______________________________________________
> > GMCnet mailing list
> > Unsubscribe or Change List Options:
> > http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
> >
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Fathom the hypocrisy of a nation where every citizen must prove they have
health insurance......but not everyone has to prove they're a citizen.
Steve Ferguson
Sierra Vista, AZ
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| Re: [GMCnet] Reviving the Cad 500 [message #163608 is a reply to message #163589] |
Tue, 20 March 2012 08:09 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Adrien,
You, like most, IMHO, misunderstand the term "ballooning the TC". I
struggled with the concept for a long time myself until I came to realize
that the only way "ballooning" can be considered a problem is to think of a
flying balloon, NOT a static one:
The pressure inside a torque converter does indeed cause its housing to
expand like a balloon. But that's a very small amount -- no where near
enough to cause the problems I, and so many others, have experienced. It's
probably only a few thousandths, and the TC should have about 0.125" free
play fore & aft -- as mine does.
Where the axial pressure on the crankshaft comes from is the different
areas of the front and back of the TC -- that is, the area of the opening
in the TC hub. According to numbers I've found recently, that amounts to
about 2 square inches -- about what I'd have guessed at a glance.
If we assume that the transmission pumps 100 psi ATF into the torque
converter, it matters not what the area of the front of the TC is, so call
it X. The forward force will be 100X. But that force will be balanced by
the rearward force of 100X-2. So only the 2 is left to worry about -- that
means 200 lbf forward force on the crankshaft through the flex plate.
According to one reference, the Chevy 454 is rated for only 210 lbf
forward crankshaft force -- the 455 and 500 are probably about the same.
Thus the cautions about not creating conditions that cause excessive
transmission pressure.
Both Manny and Bill Bramlett told me of pressure checks they've run and I
considered doing them myself as soon as I reassembled my engine. But after
finding the distorted flex plate and other symptoms, I thought I'd found my
problem. Of course, I hadn't, so now I'll have to do those tests because I
can think of NO reason, other than excessive ATF pressure, for the second
thrust bearing failure.
Ken H.
On Tue, Mar 20, 2012 at 12:17 AM, Adrien Genesoto wrote:
> ...
> I wonder how much axial expansion a TC does per lbs of oil pressure. How
> much pressure would be required to balloon the TC?
>
> If the TC has internal problems that normal internal pressures cause it to
> expand (balloon) picking up the axial free play plus (?). That could put
> pressure on the thrust bearing.
>
> I wonder if oil pressure built up between the TC and the oil pump, may be
> thrusting the TC forward. Just thinking out loud.
>
> If the thrust bearing is worn on the rear side (flex plate end side), I
> think it would make the TC a strong candidate to consider.
>
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Reviving the Cad 500 [message #163613 is a reply to message #163606] |
Tue, 20 March 2012 08:54 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Steve,
Thanks for the input. I'm as positive as I can be that the crank was done
correctly, that there was no interference, and that the bearings were
properly set up. I checked everything multiple times (OK, so CRS stopped
by now & then), then had John Beaver, a NASCAR "mechanic of the year" award
winner check everything. Then, his son, the instructor for the
"Competition Mechanics" course at the local technical college, stopped by
and checked it all again. We did check the journal/throw radii on all the
journals; they were still recessed below the journal diameters. I
Plastigaged every journal and found them all near the middle of the spec.
As I've said before, the thrust bearing clearance was lower than we liked,
so John increased it -- something he does very frequently on his racing
engines. Certainly we did ensure that the thrust bearing cap was proper
seated to the rear and that the bearings were modified with the parting
line bevel toward the rear.
As for the possibility of the machine work being faulty, we have to
remember that all this follows immediately after the identical failure of
the same seasoned factory-perfect crank. Something outside the engine
caused those failures. Not much out behind there except the transmission,
especially now that I've replaced the flex plate with one I KNOW runs true.
Y'All keep coming up with new ideas -- I'm desperate! No way I'm going to
put another engine, of any kind, ahead of that transmission until I'm
pretty darned sure I know what's caused the problems.
Ken H.
On Tue, Mar 20, 2012 at 8:16 AM, Steven Ferguson <botiemad11@gmail.com>wrote:
> I've seen this happen in BBC engines when the thrust was checked with the
> leading or trailing edge of the main bearings up against one or more fillet
> radius on the crank. It doesn't take much. I prefer to check thrust
> twice. Once with the crank sitting in the block without the main caps
> installed, then after the main caps are installed and torqued. During the
> torque process I rock the crank back and forth to ensure that I'm torquing
> in the center of the bearing surface on the crank. A lot of premium engine
> remanufactures will chamfer the edges of the bearings as cheap insurance
> against this. Another issue is how the fillet radius on the crank main
> thrust bearing is addressed during the grinding process. A friend of mine
> in San Diego built a device to measure thrust pressure during shift points.
> With a stage one shift kit installed it was amazing how much pressure was
> generated against the thrust bearing. Considerable more than normal.
> I'm not saying your CS was not in good hands Ken, just 2 cents worth here.
>
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Reviving the Cad 500 [message #163626 is a reply to message #163613] |
Tue, 20 March 2012 11:38 |
Bob de Kruyff
Messages: 4260
Registered: January 2004
Location: Chandler, AZ
Karma: 1
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Senior Member |
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""Y'All keep coming up with new ideas -- I'm desperate! No way I'm going to
put another engine, of any kind, ahead of that transmission until I'm
pretty darned sure I know what's caused the problems.
Ken H.
""
Ken, the process of eleimination sure points to the trans/converter. I've lost track of the history of that transmission. Did you ever have it behind a different engine or was it all mated at the same time? If it came from a different GMC, do you know any of that history?
Bob de Kruyff
78 Eleganza
Chandler, AZ
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| Re: [GMCnet] Reviving the Cad 500 [message #163628 is a reply to message #163626] |
Tue, 20 March 2012 12:29 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Bob,
The transmission was in the new front clip I installed a few years ago,
behind the 455 I replaced with the 500. It was rebuilt by a reputable shop
in Nashville -- before I put maybe 20,000 miles on it. The removed 455 is
still in my shop on an engine stand, so yesterday I checked end play on its
crank -- imperceptible without putting a gauge on it. So, IF the
transmission has a problem, it's probably arisen during the 11,000 miles
since I installed the 500. Which is not unreasonable, considering what
happened to the thrust bearing this time in <300 miles. If the situation
was as bad when I installed the 500, it certainly wouldn't have lasted as
long as it did before the first failure.
This morning I dug through my stuff and found a couple of 160 psi pressure
gauges. When I decide to get greasy again, I'll connect one of those to
the 425's service port and tee the other into the converter output to the
cooler. It's not going to do much more damage to the engine than is
already done while I check those pressures.
Ken H.
On Tue, Mar 20, 2012 at 12:38 PM, Bob de Kruyff wrote:
>
>
> ""Y'All keep coming up with new ideas -- I'm desperate! No way I'm going to
> put another engine, of any kind, ahead of that transmission until I'm
> pretty darned sure I know what's caused the problems.
>
> Ken H.
>
> ""
>
> Ken, the process of eleimination sure points to the trans/converter. I've
> lost track of the history of that transmission. Did you ever have it behind
> a different engine or was it all mated at the same time? If it came from a
> different GMC, do you know any of that history?
> --
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Reviving the Cad 500 [message #164047 is a reply to message #163628] |
Sat, 24 March 2012 11:09 |
GMC Cruse
Messages: 606
Registered: June 2009
Location: SE Michigan
Karma: 3
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Senior Member |
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| Ken Henderson wrote on Tue, 20 March 2012 13:29 |
Bob,
The transmission was in the new front clip I installed a few years ago,
behind the 455 I replaced with the 500. It was rebuilt by a reputable shop
in Nashville -- before I put maybe 20,000 miles on it. The removed 455 is
still in my shop on an engine stand, so yesterday I checked end play on its
crank -- imperceptible without putting a gauge on it. So, IF the
transmission has a problem, it's probably arisen during the 11,000 miles
since I installed the 500. Which is not unreasonable, considering what
happened to the thrust bearing this time in <300 miles. If the situation
was as bad when I installed the 500, it certainly wouldn't have lasted as
long as it did before the first failure.
This morning I dug through my stuff and found a couple of 160 psi pressure
gauges. When I decide to get greasy again, I'll connect one of those to
the 425's service port and tee the other into the converter output to the
cooler. It's not going to do much more damage to the engine than is
already done while I check those pressures.
Ken H.
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Ken:
You probably already saw this old service bulletin info by "wbryant" on the photo site, but in case you haven't:
http://www.gmcmhphotos.com/photos/showphoto.php?photo=42694&title=rear-main-thrust-failure&cat=5293
Mike K.
'75 PB
Southeast Michigan
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| Re: [GMCnet] Reviving the Cad 500 [message #164061 is a reply to message #164047] |
Sat, 24 March 2012 15:32 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
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Senior Member |
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Ken,
Another couple of links -- you may have seen --
Brent Covey's notes on transmission and thrust bearing failure..
http://www.gmcmotorhomeinfo.com/BASICTRAN.html
And an interesting article on cooler restriction and thrust bearing failure. They set up tests on a GM transmission.
http://www.automotix.net/autorepair/audi-v8-engine_repair_guide-720.html
And lastly, a summary on a tuner site -- and one unexpected cause mentioned, poor grounding of the engine, but no real explanation why but a suggested test for poor grounding.
http://www.dsmtuners.com/forums/articles-engine-fuel/342560-crankwalk-depth-explanation.html
Dennis
| GMC Cruse wrote on Sat, 24 March 2012 11:09 |
| Ken Henderson wrote on Tue, 20 March 2012 13:29 |
Bob,
The transmission was in the new front clip I installed a few years ago,
behind the 455 I replaced with the 500. It was rebuilt by a reputable shop
in Nashville -- before I put maybe 20,000 miles on it. The removed 455 is
still in my shop on an engine stand, so yesterday I checked end play on its
crank -- imperceptible without putting a gauge on it. So, IF the
transmission has a problem, it's probably arisen during the 11,000 miles
since I installed the 500. Which is not unreasonable, considering what
happened to the thrust bearing this time in <300 miles. If the situation
was as bad when I installed the 500, it certainly wouldn't have lasted as
long as it did before the first failure.
This morning I dug through my stuff and found a couple of 160 psi pressure
gauges. When I decide to get greasy again, I'll connect one of those to
the 425's service port and tee the other into the converter output to the
cooler. It's not going to do much more damage to the engine than is
already done while I check those pressures.
Ken H.
|
Ken:
You probably already saw this old service bulletin info by "wbryant" on the photo site, but in case you haven't:
http://www.gmcmhphotos.com/photos/showphoto.php?photo=42694&title=rear-main-thrust-failure&cat=5293
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Dennis S
73 Painted Desert 230
Memphis TN Metro
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| Re: [GMCnet] Reviving the Cad 500 [message #164071 is a reply to message #163441] |
Sat, 24 March 2012 18:05 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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Senior Member |
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| Ken Henderson wrote on Sun, 18 March 2012 18:31 |
Today was not a good day.
Baffled, desperate, sad, disgruntled, upset,..., all that stuff, I
started trying to figure what to do. Wound up pulling the starter,
flywheel lower cover, and inspection hole cover. Then disconnected
the torque converter from the new flex plate. Sure 'nuff, the TC
slides fore and aft easily about 1/8" -- just like it should, and did
when installed last Sunday -- it didn't push on the crankshaft. But
something did: With a pry bar I made sure the crank end play (0.008"
when assembled) was all taken up toward the rear to verify the TC free
travel. Then I pried from the rear to the front -- Kerplunk! With a
dial indicator on the flex plate, I found that the crankshaft now has
0.062" end play!  ( That's almost half of the 0.125" I accumulated
in the 11,000 miles before the oil analysis identified the problem
before. And this time it took only about 300 miles!!!
I have no idea WHY. Nor WHAT to do. And I don't want to talk about
it or even think about it for a while. Y'All figure it out; I'm gonna
go pout.
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Ken,
Terrible news.
The following is probably all wet, but we are grasping at straws here.
I don't know beans about these GMCs compared to some but this has to be a lot of force. Are we sure there is not something amiss with the upper chain/sprocket/bearing/case? I don't even know how that is all held in there, but could something be out of line that is driving the sprocket forward into the TC and then on to the flex plate and crank? I know the TC is supposed to slid on the shaft. I just wonder if the sprocket dropped (pulled toward the driven sprocket) even a tiny amount it would be shoved forward by the uneven chain pressure. The flex plate could be making up for the misalignment.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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