Home » Public Forums » GMCnet » Engine - found this
| Engine - found this [message #175360] |
Mon, 02 July 2012 20:20  |
midlf
Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)
Karma: 1
|
Senior Member |
|
|
started to open up the 455. Turkey tray and lifter valley were not very coked up but the intake manifold had been removed sometime earlier and cleaned up. The turkey tray had been cleaned up (wire brush marks) and reinstalled.
However this was a "bit" of a surprise:
http://www.gmcmhphotos.com/photos/engine-455/p44611-engine-disassembly-008.html
Bent pushrod on the #1 cylinder. This is the cylinder that only has 25# of compression and the one that leaks air into the crankcase when air tested. No leaks noticed on the intake or exhaust.
Any ideas what I'm gonna find when I pull the head tomorrow?
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
|
|
|
|
|
|
| Re: Engine - found this [message #175368 is a reply to message #175360] |
Mon, 02 July 2012 21:00  |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
|
Senior Member |
|
|
| midlf wrote on Mon, 02 July 2012 20:20 |
started to open up the 455. Turkey tray and lifter valley were not very coked up but the intake manifold had been removed sometime earlier and cleaned up. The turkey tray had been cleaned up (wire brush marks) and reinstalled.
However this was a "bit" of a surprise:
http://www.gmcmhphotos.com/photos/engine-455/p44611-engine-disassembly-008.html
Bent pushrod on the #1 cylinder. This is the cylinder that only has 25# of compression and the one that leaks air into the crankcase when air tested. No leaks noticed on the intake or exhaust.
Any ideas what I'm gonna find when I pull the head tomorrow?
|
Steve,
I would guess that you will find more of the valve pushrods bent. You may have to roll them on a glass surface to detect. #1 seems to be the most likely to be affected by a sticky valve stem.
Will be curious to hear.
Dennis
Dennis S
73 Painted Desert 230
Memphis TN Metro
[Updated on: Mon, 02 July 2012 22:30] Report message to a moderator |
|
|
|
|
|
| Re: Engine - found this [message #175372 is a reply to message #175371] |
Mon, 02 July 2012 21:12 |
Dennis S
Messages: 3046
Registered: November 2005
Karma: 2
|
Senior Member |
|
|
| winter wrote on Mon, 02 July 2012 21:08 |
why #1 for the sticky stem?
|
I should say that my comment is anecdotal -- in my experience I have witnessed #1 pushrods bend more often. Not sure exactly why that valve would be more likley to stick.
Dennis
Dennis S
73 Painted Desert 230
Memphis TN Metro
[Updated on: Mon, 02 July 2012 22:30] Report message to a moderator |
|
|
|
| Re: [GMCnet] Engine - found this [message #175374 is a reply to message #175360] |
Mon, 02 July 2012 21:41 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
|
Senior Member |
|
|
Steve,
Sorry to say, the air leaking into the crankcase makes me fear you'll find
that valve, or part of it, went through the piston head. Just hope it
didn't score the cylinder wall before leaving the top side.
The day after I bought my GMC, 875 of the 950 miles toward home, #4
swallowed the intake valve, destroying the 59,065 mile engine -- cracked
the cylinder wall. Apparently the recent installer of a high lift cam
didn't check clearances, or didn't seat a spring retainer properly. I got
to learn early about GMC engine changing -- in July in an
un-airconditioned building
in Panama City -- alone. :-(
Hope your luck is better.
Ken H.
On Mon, Jul 2, 2012 at 9:20 PM, Steve Southworth wrote:
>
>
> started to open up the 455. Turkey tray and lifter valley were not very
> coked up but the intake manifold had been removed sometime earlier and
> cleaned up. The turkey tray had been cleaned up (wire brush marks) and
> reinstalled.
>
> However this was a "bit" of a surprise:
>
>
> http://www.gmcmhphotos.com/photos/engine-455/p44611-engine-disassembly-008.html
>
> Bent pushrod on the #1 cylinder. This is the cylinder that only has 25#
> of compression and the one that leaks air into the crankcase when air
> tested. No leaks noticed on the intake or exhaust.
>
> Any ideas what I'm gonna find when I pull the head tomorrow?
> --
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
|
|
|
|
| Re: [GMCnet] Engine - found this [message #175375 is a reply to message #175374] |
Mon, 02 July 2012 21:54 |
midlf
Messages: 2212
Registered: July 2007
Location: SE Wisc. (Palmyra)
Karma: 1
|
Senior Member |
|
|
| Ken Henderson wrote on Mon, 02 July 2012 21:41 |
Steve,
Sorry to say, the air leaking into the crankcase makes me fear you'll find
that valve, or part of it, went through the piston head. Just hope it
didn't score the cylinder wall before leaving the top side.
Hope your luck is better.
Ken H.
|
Yeah - that is what I'm suspecting. Although, with oil, the compression is #150 for the first stroke. My engine builder is still rebuilding his shop from a fire so I am using this delay time to start pulling my engine apart to determine if my cores are good or if I should start making arrangements for a replacement core.
I sure don't have to roll that pushrod on glass to determine if it is straight.
Steve Southworth
1974 Glacier TZE064V100150 (for workin on)
1975 Transmode TZE365V100394 (parts & spares)
Palmyra WI
|
|
|
|
|
|
|
|
| Re: [GMCnet] Engine - found this [message #175392 is a reply to message #175377] |
Tue, 03 July 2012 06:43 |
Jim Bounds
Messages: 842
Registered: January 2004
Karma: 0
|
Senior Member |
|
|
Would be difficuly for a used valley pan to get a good seal, it crushes to make the first seal which could not be reset a second time. a bent push rod either has to have a valve with higher friction or like another suggested a broken bridge or something that would allow the rocker to move sideways. If that problem is found, you can chk compression to see if it comes back. If so, bed down the intake (install blockoff plates on the exh. crossover) and use a Mr. Gasket # 404 fiber intake gaskets set and I bet that motor will rise again! Of course that is if everything else is OK. Going in deep to repair an ailing motor is not always a good thing to do. I have a rule that if I have to go deeper than the intake to fix motor problem I will do the complete motor. Do a top job and the bottom blows out-- do repairs to the bottom section and you are asking for troubles and spending that much to get to the problem usually ends up being good money
after bad! One week area in a motor lugging around 12,000 pound and you will screw yourself.
If all that's with this motor is a bent push rod and you can ID a rocker arm issue, I would try and fix that.
Good luck,
Jim Bounds
---------------------
________________________________
From: Bob Drewes <bmdrewes@iw.net>
To: gmclist@temp.gmcnet.org
Sent: Monday, July 2, 2012 11:17 PM
Subject: Re: [GMCnet] Engine - found this
midlf wrote on Mon, 02 July 2012 20:20
> started to open up the 455. Turkey tray and lifter valley were not very coked up but the intake manifold had been removed sometime earlier and cleaned up. The turkey tray had been cleaned up (wire brush marks) and reinstalled.
>
> However this was a "bit" of a surprise:
>
> http://www.gmcmhphotos.com/photos/engine-455/p44611-engine-disassembly-008.html
>
> Bent pushrod on the #1 cylinder. This is the cylinder that only has 25# of compression and the one that leaks air into the crankcase when air tested. No leaks noticed on the intake or exhaust.
>
> Any ideas what I'm gonna find when I pull the head tomorrow?
The bent pushrod if for #1 cyld intake valve. Pull the valve cover, you may have a broken valve rocker bridge. Hope that is all it is! The bent pushrod is not opening the intake valve, so you won't have much compression on #1 because the cylinder is not filling with air during the intake stroke.
Bob Drewes in SESD
_______________________________________________
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
|
|
|
|
| Re: Engine - found this [message #175402 is a reply to message #175360] |
Tue, 03 July 2012 08:48 |
 |
Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
|
Senior Member |
|
|
| midlf wrote on Mon, 02 July 2012 21:20 |
started to open up the 455. Turkey tray and lifter valley were not very coked up but the intake manifold had been removed sometime earlier and cleaned up. The turkey tray had been cleaned up (wire brush marks) and reinstalled.
However this was a "bit" of a surprise:
http://www.gmcmhphotos.com/photos/engine-455/p44611-engine-disassembly-008.html
Bent pushrod on the #1 cylinder. This is the cylinder that only has 25# of compression and the one that leaks air into the crankcase when air tested. No leaks noticed on the intake or exhaust.
Any ideas what I'm gonna find when I pull the head tomorrow?
|
Steve,
This is most curious...
- Most often exhaust valve gear is damaged by hydraulic lock - never the intake. This can crack pistons.
- Intake valves are often damaged by "valve toss" during over speed operation. That damage is usually limited to the valve and the piston.
I did see a warranty claim like this once and only once.
The only scenario that made any sense was that the intake valve stuck in the guide at least one cycle (in this case, there was visible scuff on the valve stem - very rare on intakes). This allowed the lash adjuster (lifter) to expand to its full travel. On the next cycle, the expanded lash adjuster rammed the valve into the piston. This resulted in damage to the piston causing the ring land area to be crushed and so trap the compression rings. It also caused damage to the valve gear directly related to overload. As in this case, the rocker arm was distorted, the pushrod was bent (not this badly), and there was damage to the roller follower and and the cam surface.
So, I bet you find a valve print on the piston crown. At least.
But, do let us know so that we can expand the knowledge base.
Matt (too long an engine lab rat)
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
|
|
|
|
| Re: [GMCnet] Engine - found this [message #175416 is a reply to message #175402] |
Tue, 03 July 2012 10:45 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
|
Senior Member |
|
|
Steve, if that engine has been open previously, all bets are off. Intakes
stick for one reason, lack of lubrication space between the guide and the
stem. Modern valve stem seals do an almost too good job of controlling oil.
Also, another thing to consider, is "has the engine been sitting a long
time without running or being turned over?" If the intake in question was
open exposing the valve stem to atmospheric air and humidity, they can and
do rust in place, and the pushrod will bend in that scenario as well. Worst
case, if there has been contact between the piston and the valve. Never a
good thing. Like Jim Bounds says, look carefully at the rocker arm
mechanism too.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Tue, Jul 3, 2012 at 6:48 AM, Matt Colie <matt7323tze@gmail.com> wrote:
>
>
> midlf wrote on Mon, 02 July 2012 21:20
> > started to open up the 455. Turkey tray and lifter valley were not very
> coked up but the intake manifold had been removed sometime earlier and
> cleaned up. The turkey tray had been cleaned up (wire brush marks) and
> reinstalled.
> >
> > However this was a "bit" of a surprise:
> >
> >
> http://www.gmcmhphotos.com/photos/engine-455/p44611-engine-disassembly-008.html
> >
> > Bent pushrod on the #1 cylinder. This is the cylinder that only has 25#
> of compression and the one that leaks air into the crankcase when air
> tested. No leaks noticed on the intake or exhaust.
> >
> > Any ideas what I'm gonna find when I pull the head tomorrow?
>
> Steve,
>
> This is most curious...
> - Most often exhaust valve gear is damaged by hydraulic lock - never the
> intake. This can crack pistons.
> - Intake valves are often damaged by "valve toss" during over speed
> operation. That damage is usually limited to the valve and the piston.
>
> I did see a warranty claim like this once and only once.
> The only scenario that made any sense was that the intake valve stuck in
> the guide at least one cycle (in this case, there was visible scuff on the
> valve stem - very rare on intakes). This allowed the lash adjuster
> (lifter) to expand to its full travel. On the next cycle, the expanded
> lash adjuster rammed the valve into the piston. This resulted in damage to
> the piston causing the ring land area to be crushed and so trap the
> compression rings. It also caused damage to the valve gear directly
> related to overload. As in this case, the rocker arm was distorted, the
> pushrod was bent (not this badly), and there was damage to the roller
> follower and and the cam surface.
>
> So, I bet you find a valve print on the piston crown. At least.
> But, do let us know so that we can expand the knowledge base.
>
> Matt (too long an engine lab rat)
>
> --
> Matt & Mary Colie
> '73 Glacier 23 Chaumière (say show-me-air) Just about as stock as you will
> find
> SE Michigan - Twixt A2 and Detroit
> _______________________________________________
> 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
|
|
|
|
|
|
| Re: [GMCnet] Engine - found this [message #175418 is a reply to message #175417] |
Tue, 03 July 2012 10:59 |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
|
Senior Member |
|
|
Air chuck the cylinder, both valves closed, use an external valve spring
compressor, remove the keepers, upper retainer washer and spring(s) as well
as OEM seals. Then, wd-40 and scotchbrite or a small wire brush. If you are
talking about the combustion chamber side, you are on your own.
Jim Hupy
Salem, OR
78 GMC Royale 403
On Tue, Jul 3, 2012 at 8:53 AM, A. <markbb1@netzero.com> wrote:
>
>
> winter wrote on Mon, 02 July 2012 22:04
> > usually the back cylinders are the hot ones which will build up deposits
> to stick valves, right?
> >
> > I hope its only a tight guide and the rest of the short block is still
> good.
> >
> > Good Luck!!
> What's a fairly reliable way to clean the deposits from around the valves
> without pulling the head?
> --
> '73 23' CanyonLands
> _______________________________________________
> 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
|
|
|
|
| Re: Engine - found this [message #175420 is a reply to message #175360] |
Tue, 03 July 2012 11:16 |
PettyVTX
Messages: 363
Registered: April 2011
Location: Winder Ga.
Karma: 1
|
Senior Member |
|
|
Steve
what are you going to do about blocking off the intake? I ordered the blockoff gasket for mine i hope that is enough to seal the crossover. I was lucky everything in my engine went back stock. Im getting the frame painted and cleaning up parts now.
Ex Avion now looking for a 23'
Jeep Wrangler Towd
|
|
|
|
| Re: [GMCnet] Engine - found this [message #175422 is a reply to message #175375] |
Tue, 03 July 2012 11:35 |
C Boyd
Messages: 2629
Registered: April 2006
Karma: 18
|
Senior Member |
|
|
Sir: usually if compresson comes back by adding oil it is the rings so this may not help you. I have had success by removing the valve cover and rocker and pushrod and soaking valve stem with wd-40 while smacking the valve with a brass or alum hammer to clean and free the valve stem as most of the time it is carbon that gaulds the valve and bends the push rod. If you do get it freed up and the dry compresson comes back after installing a straight pushrod and rocker you can use "top engine cleaner". Start the engine at fast idle and pour it slowly in the carb, it will smoke like crazy and will probably destroy a set of plugs. Automatic transmission fluid will work also.
http://www.ebay.com/itm/NOS-GM-Never-Opened-Top-Engine-Cleaner-67-69-Chevy-Camaro-68-74-Nova-Corvette-/230819043610?pt=Vintage_Car_Truck_Parts_Accesso ries&hash=item35bde3191a&vxp=mtr
| midlf wrote on Mon, 02 July 2012 22:54 |
| Ken Henderson wrote on Mon, 02 July 2012 21:41 |
Steve,
Sorry to say, the air leaking into the crankcase makes me fear you'll find
that valve, or part of it, went through the piston head. Just hope it
didn't score the cylinder wall before leaving the top side.
Hope your luck is better.
Ken H.
|
Yeah - that is what I'm suspecting. Although, with oil, the compression is #150 for the first stroke. My engine builder is still rebuilding his shop from a fire so I am using this delay time to start pulling my engine apart to determine if my cores are good or if I should start making arrangements for a replacement core.
I sure don't have to roll that pushrod on glass to determine if it is straight.
|
C. Boyd
76 Crestmont
East Tennessee
|
|
|
|
| Re: [GMCnet] Engine - found this [message #175424 is a reply to message #175420] |
Tue, 03 July 2012 12:21 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
|
Senior Member |
|
|
Ted,
Don't depend on just a gasket to block the crossover -- it won't withstand
the heat. Either use SS plates, like Dick Paterson's, or mill the manifold
to accept thicker steel plates -- that's what I recently did on my latest
Cad500. It's easy to do freehand with a router & 1/4" carbide bit.
Ken H.
On Tue, Jul 3, 2012 at 12:16 PM, Ted Petty wrote:
>
>
> Steve
> what are you going to do about blocking off the intake? I ordered the
> blockoff gasket for mine i hope that is enough to seal the crossover. I
> was lucky everything in my engine went back stock. Im getting the frame
> painted and cleaning up parts now.
> --
>
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
|
|
|
|
| Re: [GMCnet] Engine - found this [message #175428 is a reply to message #175402] |
Tue, 03 July 2012 13:45 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
|
Senior Member |
|
|
Had that happen on an RB 383 once - slightly North of 7K and missed a shift. W/O a telltale, I've no idea what rpm it was making when it all touched and let go. 'Lunched the mill' - tore it to pieces. I suspect the exhaust valve hit, but the thing was so much junk. We didn't spend a lot of time worrying, since we knew what caused it. Powershifts, while sometimes necessary, are Not Your Friend.
--johnny
'76 23' transmode norris
'76 palm beach
From: Matt Colie <matt7323tze@gmail.com>
To: gmclist@temp.gmcnet.org
Sent: Tuesday, July 3, 2012 9:48 AM
Subject: Re: [GMCnet] Engine - found this
midlf wrote on Mon, 02 July 2012 21:20
> started to open up the 455. Turkey tray and lifter valley were not very coked up but the intake manifold had been removed sometime earlier and cleaned up. The turkey tray had been cleaned up (wire brush marks) and reinstalled.
>
> However this was a "bit" of a surprise:
>
> http://www.gmcmhphotos.com/photos/engine-455/p44611-engine-disassembly-008.html
>
> Bent pushrod on the #1 cylinder. This is the cylinder that only has 25# of compression and the one that leaks air into the crankcase when air tested. No leaks noticed on the intake or exhaust.
>
> Any ideas what I'm gonna find when I pull the head tomorrow?
Steve,
This is most curious...
- Most often exhaust valve gear is damaged by hydraulic lock - never the intake. This can crack pistons.
- Intake valves are often damaged by "valve toss" during over speed operation. That damage is usually limited to the valve and the piston.
I did see a warranty claim like this once and only once.
The only scenario that made any sense was that the intake valve stuck in the guide at least one cycle (in this case, there was visible scuff on the valve stem - very rare on intakes). This allowed the lash adjuster (lifter) to expand to its full travel. On the next cycle, the expanded lash adjuster rammed the valve into the piston. This resulted in damage to the piston causing the ring land area to be crushed and so trap the compression rings. It also caused damage to the valve gear directly related to overload. As in this case, the rocker arm was distorted, the pushrod was bent (not this badly), and there was damage to the roller follower and and the cam surface.
So, I bet you find a valve print on the piston crown. At least.
But, do let us know so that we can expand the knowledge base.
Matt (too long an engine lab rat)
--
Matt & Mary Colie
'73 Glacier 23 Chaumière (say show-me-air) Just about as stock as you will find
SE Michigan - Twixt A2 and Detroit
_______________________________________________
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
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
|
|
|
|
|
|
| Re: Engine - found this [message #175439 is a reply to message #175360] |
Tue, 03 July 2012 16:06 |
kingd
Messages: 592
Registered: June 2004
Karma: 2
|
Senior Member |
|
|
Re bent pushrod. I would wonder about the amount of "oil" in the combustion chamber, maybe from the crack in the intake manifold, if some how a lot of oil got into the #1 cylinder and the valve couldn't. open due to the oil. Yes I realize the cylinder would have to have been 100 % full and where is that oil now? The "normal" happening would be for the engine to lock up and maybe break the piston. I wonder what the rings and piston look like ?
DAVE KING
DAVE KING
lurker, wannabe
Toronto, Ontario, Canada
|
|
|
|
Goto Forum:
Current Time: Thu Oct 10 17:35:56 CDT 2024
Total time taken to generate the page: 0.02014 seconds
|
GMCforum
Search
Help
Register
Login
Home
