Home » Public Forums » GMCnet » You Want To See The Piston?
| You Want To See The Piston? [message #73001] |
Fri, 05 February 2010 22:01  |
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WD0AFQ
Messages: 7111
Registered: November 2004
Location: Dexter, Mo.
Karma: 207
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I just got the pictures up on our blog.
Dan
3 In Stainless Exhaust Headers
One Ton All Discs/Reaction Arm
355 FD/Quad Bag/Alum Radiator Manny Tran/New eng.
Holley EFI/10 Tire Air Monitoring System
Solarized Coach/Upgraded Windows
Satelite TV/On Demand Hot Water/3Way Refer
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| Re: You Want To See The Piston? [message #73002 is a reply to message #73001] |
Fri, 05 February 2010 22:13  |
Chr$
Messages: 2690
Registered: January 2004
Location: Scottsdale, AZ
Karma: 1
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Yowch!
You guys have any suggestions to what may cause that? I'm thinking the motor may have ingested something metal, smashed around the cylinder a bit, jammed in the corner, then finally blew out the exhaust port.
Is this possible?
On the Bright side, this event surely shows what this group is made of. Nothing but good.
-Chr$: Perpetual SmartAss
Scottsdale, AZ
77 Ex-Kingsley 455 SOLD!
2010 Nomad 24 Ft TT 390W PV W/MPPT, EV4010 and custom cargo door.
Photosite: Chrisc GMC:"It has Begun" TT: "The Other Woman"
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| Re: You Want To See The Piston? [message #73003 is a reply to message #73002] |
Fri, 05 February 2010 22:19 |
Carl S.
Messages: 4186
Registered: January 2009
Location: Tucson, AZ.
Karma: 13
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Steve, and all you engine experts,
Take a look at that #1 piston on Dan's blog and tell us what you think. 
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: You Want To See The Piston? [message #73007 is a reply to message #73006] |
Fri, 05 February 2010 23:14 |
Ron
Messages: 250
Registered: February 2004
Location: Conifer, Colorado
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Guy's..
I supose that the tight ring gap may be the cause.. But I don't believe that it would have gon the 30 to 40k they said it had..
I am sure Dan would have heard detonation that heavy..
Buit then again...
Ron
now a P.O.
Conifer, CO
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| Re: You Want To See The Piston? [message #73011 is a reply to message #73001] |
Sat, 06 February 2010 00:30 |
Ken Burton
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
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What do the valves look like on that cylinder?
That sure is not the guess we made in Quartzsite on a lifter problem. I'm still wondering about the valves. I do not see a valve impression on the top of the piston.
I usually equate piston destruction to detonation or something getting loose inside the cylinder. I have no idea on yours.
Please keep that piston if you can. I'd like to see it in person some day.
Side note. I replaced a broken top ring on my airplane last fall. It left no damage on the piston or cylinder wall. I had run it broken for almost a year. From this experience I do not think your problem started as a broken ring.
Ken
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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| Re: You Want To See The Piston? [message #73012 is a reply to message #73001] |
Sat, 06 February 2010 00:31 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Just wondering what oil and /or additives you had in her at the time this happened. Not saying that was the cause, just wondering. John.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: [GMCnet] You Want To See The Piston? [message #73014 is a reply to message #73013] |
Sat, 06 February 2010 00:56 |
peter bailey
Messages: 367
Registered: March 2009
Location: Gawler, South Australia
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Dan,
After all of these problems you have had this trip out your attitude is
still good and I guess this is mainly bought about by the great help you
have had from your friends of the GMC movement, the only souring points of
dissapointment will be the cost (there goes your trip to Australia) being
the tow and replacement motor cost.
Regards To you and Teri
from Kay and Peter
from Ozy (Aussie)
----- Original Message -----
From: "Dan Gregg" <gregg_dan@hotmail.com>
To: <gmclist@temp.gmcnet.org>
Sent: Saturday, February 06, 2010 5:14 PM
Subject: Re: [GMCnet] You Want To See The Piston?
>
>
> I am no mechanic. Miguel thought it was just something that happened. But,
> I am sure he will look at it closer tomorrow and may have something else
> to add. There are little dents in the top of the piston along with that
> broken out spot. The broken spot is not quite the size of a pencil eraser,
> on top. Something was on top of that piston. The valves looked good. I
> will get pictures of the head exhaust ports tomorrow for yall to look at.
> Sometimes S--- happens. While I hate that I am out all of this money I
> must say that Teri and I have made some new friends. And, I always wanted
> to visit this area. I can always get a job, to pay for all of this, but I
> can not always make memories like these.
> Dan
> --
> Dan & Teri Gregg
>
> danandteri.blogspot.com
>
>
>
> ///Halon Automatic Fire Extinguishers
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
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| Re: You Want To See The Piston? [message #73015 is a reply to message #73011] |
Sat, 06 February 2010 01:08 |
idrob
Messages: 645
Registered: January 2005
Location: Central Idaho
Karma: 0
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| Ken Burton wrote on Fri, 05 February 2010 22:30 |
Side note. I replaced a broken top ring on my airplane last fall. It left no damage on the piston or cylinder wall. I had run it broken for almost a year. From this experience I do not think your problem started as a broken ring.
Ken
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Ken, I also have had a broken piston (not rings) on a 1991 Audi 100. Drove it for probably 500 miles after it happened, didn't have the power it should have had, and ran a bit ragged, but when they took it out, there was no cylinder damage. They put a new piston and rings back in with no other work. I still have it, It still runs well. The shop specializes in Audi's and they said "this never happens to Audi's" but it did to mine. I can only say I was driving up a 10 mile long 6 to 8% grade at 100 F outside temp when it happened. The symptoms were just loss of power. No noise, no change in oil pressure or temps of oil or water.
So, just more grist for the mill.
Rob Allen
former owner of '76 x-PB
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| Re: [GMCnet] You Want To See The Piston? [message #73016 is a reply to message #73011] |
Sat, 06 February 2010 01:23 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Ken,
I think Dan should keep the piston and use it as an ashtray / conversation
piece in his GMC. Considering his and Teri's positive outlook on life, all
the help he has gotten from those close by; and those of us in the "peanut
gallery" cheering him on I'm sure the "badness" of the event will be well
and truly overshadowed by all the "goodness."
I have a tendency to agree with you vis-à-vis how the problem started. When
I tore down the Caddy 500 two pistons had broken top compression rings and
there was no piston or cylinder wall damage.
Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Ken Burton
Sent: Saturday, 6 February 2010 5:30 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] You Want To See The Piston?
What do the valves look like on that cylinder?
That sure is not the guess we made in Quartzsite on a lifter problem. I'm
still wondering about the valves. I do not see a valve impression on the
top of the piston.
I usually equate piston destruction to detonation or something getting loose
inside the cylinder. I have no idea on yours.
Please keep that piston if you can. I'd like to see it in person some day.
Side note. I replaced a broken top ring on my airplane last fall. It left
no damage on the piston or cylinder wall. I had run it broken for almost a
year. From this experience I do not think your problem started as a broken
ring.
Ken
-
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] You Want To See The Piston? [message #73017 is a reply to message #73014] |
Sat, 06 February 2010 01:27 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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Peter,
Crikey, did you invite those two out here? Didn't you realize he used to
work as a Prison Officer (or was it a Parole Officer?)! We'd better watch
out if he does show up here! He'll really feel at home and never want to
leave! ;-)
Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
-----Original Message-----
From: gmclist-bounces@temp.gmcnet.org
[mailto:gmclist-bounces@temp.gmcnet.org] On Behalf Of Peter Bailey
Sent: Saturday, 6 February 2010 5:57 PM
To: gmclist@temp.gmcnet.org
Subject: Re: [GMCnet] You Want To See The Piston?
Dan,
After all of these problems you have had this trip out your attitude is
still good and I guess this is mainly bought about by the great help you
have had from your friends of the GMC movement, the only souring points of
dissapointment will be the cost (there goes your trip to Australia) being
the tow and replacement motor cost.
Regards To you and Teri
from Kay and Peter
from Ozy (Aussie)
_______________________________________________
GMCnet mailing list
List Information and Subscription Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] You Want To See The Piston? [message #73018 is a reply to message #73011] |
Sat, 06 February 2010 05:59 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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Senior Member |
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something else going on here, none of this seems to explain the loss of oil
pressure, the two knocking episodes, and the vacuum fluctuation during the
knocking episodes. And what smacked the spark plug? (no one ever said,
who built this engine?)
when my rings broke (10 years ago) they turned sideways in the ring grove
and gouged out the cylinder. No knocking, no loss of power, just started
using lots of oil......
don't think we will ever hear the answer, no one has the time to do a
postmortem...
gene
On Fri, Feb 5, 2010 at 10:30 PM, Ken Burton <n9cv@comcast.net> wrote:
>
>
> What do the valves look like on that cylinder?
>
> That sure is not the guess we made in Quartzsite on a lifter problem. I'm
> still wondering about the valves. I do not see a valve impression on the
> top of the piston.
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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| Re: You Want To See The Piston? [message #73022 is a reply to message #73001] |
Sat, 06 February 2010 07:59 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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| WD0AFQ wrote on Fri, 05 February 2010 23:01 |
I just got the pictures up on our blog.
Dan
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Dan,
Thanks for the great pictures. This sort of thing is a bear for a remote diagnosis, but with the right pictures (you got me the two I really need) I can do this.
You didn't do anything wrong and you didn't stand a chance (please fill in the hackneyed phrase of choice).
It is not detonation damage. You would not have had any warning that would stir up any concern before the whole thing went bad.
The top ring broke quite a while ago. (Evidence the heavy coking on the second ring lower land.) You would not have noticed as a driver as there was a very slight loss of power and an slight increase in fuel rate, oil consumption and blow-by (not things a normal (even GMC normal) human pays real close attention to or can determine).
As you ran with the broken ring things were degenerating slowly. Until the top ring groove got pounded out enough for the broken ring to move enough to beat the second ring's groove down to where it trapped the second ring, that put more differential gas pressure on the remains of the top ring and Whoa Katy - Bar the Door. That probably happened less than an hour before the loss of lube oil pressure (good catch - by the way.)
When the top ring grove got pounded wide enough so the ring was allowed to flex, the top ring started to break up. The short pieces quickly broke out the top land (the notch in the crown) and little pieces escaped into the combustion chamber. Hence, the piston ring tracks on the piston crown. By then, metallic debris was most certainly circulating in the engine lube oil. (Remember to very thoroughly clean or replace the lube oil cooler.) Some went around the piston - see the damage to the second ring lower land? When debris start circulating, where it ends up is anybody's bet, but one bet I will make is that the lube oil pump picked up some (sucker bet) and that both damaged the pump so it lost capacity/capability and at the same time, some pieces got stuck in the pump's relief valve. That held the valve open just exactly when you didn't want that to happen (actually, it didn't matter very much by then because you were already aware of the problem).
The ticking you did hear could easily have been ring pieces in the combustion chamber or valve last adjusters collapsing because they have been fouled by the debris. There is no way you could have isolated the failure with tools available in Quartzsite, and there was substantially nothing you could have done about it at that time and with the engine in place.
In My Personal Opinion, the only thing you could have done that might have mitigated the situation would have been to depart Quartzsite to the west and head for Manny's thus avoiding the additional tow.
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] You Want To See The Piston? [message #73023 is a reply to message #73003] |
Sat, 06 February 2010 08:00 |
Steven Ferguson
Messages: 3447
Registered: May 2006
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Carl, Dan,
Please post some pix of the cyl Dan. It is very hard to tell but I
would guess that for some reason the ring gaps butted and with no more
room for expansion, this is the result. Looks like the whole top of
the piston started separating and that's what beat the plug gap
closed.
Dan, are those hypereutectic pistons? Nearly all alum pistons have a
gap of .0045 per inch of bore, Silvolites, KB etc, all require .0065
per inch or something like what you see results. Pull the oil pump
top off and look at the gears to if there's any damage.
We can' t stop here, need a bit more of a teardown.
I bet you don't run synthetic oil in this motor.
On Fri, Feb 5, 2010 at 9:19 PM, Carl Stouffer <carljr3b@yahoo.com> wrote:
>
>
> Steve, and all you engine experts,
>
> Take a look at that #1 piston on Dan's blog and tell us what you think. :?
> --
> Carl S.
> '75 ex Palm Beach
> Tucson, AZ.
> _______________________________________________
> GMCnet mailing list
> List Information and Subscription Options:
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>
--
Steve Ferguson
'76 EII
Sierra Vista, AZ
Urethane bushing source
www.bdub.net/ferguson/
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| Re: [GMCnet] You Want To See The Piston? [message #73024 is a reply to message #73021] |
Sat, 06 February 2010 08:12 |
Surbo
Messages: 213
Registered: February 2004
Karma: 0
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| Robert Mueller wrote on Sat, 06 February 2010 07:21 |
Dan,
Did you clean off the top of this piston before you took the pictures? The
reason I ask is there is NO carbon build up! It's not easy to see but the
next piston back you can see carbon build up.
What does the bore of #1 look like? The reason I ask is I wonder how a whole
piston ring broke into small enough pieces to go out through that relatively
small half moon gap between the piston and the cylinder wall.
It may be an optical contusion but it looks like the side of the piston
we're looking at is "stretched" vertically. It could also be that the piston
ring "fluttered" and hammered the ring gap into that thin elongated football
shape.
Regards,
Rob Mueller
Sydney, Australia
AUS '75 Avion-The Blue Streak TZE365V100428
USA '75 Avion-Double Trouble TZE365V100426
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Howdy;
Not that it matters, but it is not #1 piston, it is the front one on the right bank, #2. One would have to take a good look at the cylinder wall and see what damage it done to that, to determine what caused all the piston damage. I would be quite sure in saying it is not normal damage that a broken top compression ring would do, most broken top rings will stay in the groove and just go along for the ride with little or no damage to the piston or cyl wall as there is no tension left in the ring.
With just the piston pic to look at and no pic of the cyl wall, it appears something, like a nut or small bolt got into the combustion chamber and knocked a hole into the piston top and got wedged alongside the piston and really done a job on it.
What type of piston, cast, forged or hyper utec?
Could it be ethanol damage?? (vbg) Thirty years ago this month our local co-op started selling 10% ethanol blend, have been using it ever since in all the gas engines we own, including lawn mowers and chain saws.
Good luck Dan, from Bob Drewes in SESD
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