Pulled Pan - Spun Bearing! - 3000GT/Stealth International Message Center

stephenson · 02-23-2008, 12:59 PM

Rod closest to the transmission - about half thickness!

Assuming everything else is OK (appears to have the indicated 135K) - and, given what appears to be a tendency on these engines to spin bearings, what's best course of action? JDM engine or rebuild this one?

I would do the rebuild, minus machine shop work - so, time isn't the issue - just hate idea of a replacement engine that does the same thing after a few thousand miles ...

Thoughts from those that have been there?

Thanks!

jbavousett · 02-23-2008, 01:10 PM

If you rebuild it you know what you have, if you replace it with used, you never know.

stephenson · 02-23-2008, 01:18 PM

That's kinda what I was thinkin, too ...

What if I just replaced all the rod bearings? If the one rod bearing is the only one that was affected - and, assuming I can get close to an in spec measurement on the remainder - is there a chance I could get a few thousand miles out of the engine?

Not main car, just a project ... :-)

HugeJay · 02-24-2008, 06:01 AM

When I spun mine in my one stealth, I pulled the engine, took the block and heads into the machine shoppe, had them rebuilt, and the crank re surfaced, I supplied the some parts, costed me about a grand to the machine shoppe.

phantomrt · 02-24-2008, 08:03 AM

Quote:

Originally Posted by stephenson

That's kinda what I was thinkin, too ...

What if I just replaced all the rod bearings? If the one rod bearing is the only one that was affected - and, assuming I can get close to an in spec measurement on the remainder - is there a chance I could get a few thousand miles out of the engine?

Not main car, just a project ... :-)

Nope. That will not work. At a very minimum, the one connecting rod needs to be replaced and the crankshaft replaced or rebuilt. Ideally the entire engine should be torn down and thoroughly cleaned of the metal debris. At least one cylinder head will have to come off to replace the connecting rod. So, may as well do the whole thing.

HugeJay · 02-24-2008, 09:16 AM

oh btw, dont think changing the rod bearing after its been spun will work right, chances are like the other poster stad the connecting rod needs to be replaced, I tried just to change the bearings it worked, but I still had a slight knock, to do it right you have to get it rebuilt. take our advice once you spin a bearing, its time to rebuild.

phantomrt · 02-24-2008, 01:25 PM

Sometimes the old bearing is welded to the connecting rod or crankshaft, and can't even be removed per say. The welding came from heat buildup. Here's an example of a spun bearing connecting rod:

Your rod probably looks similar.

stephenson · 02-24-2008, 06:04 PM

Yikes - mine doesn't look that bad, but likely does need replacement ... will get more pro opinion when I deliver it all to the machine shop. The bearings themselves were very evenly worn, with only the very ends being a bit thinner than the middles - looks to be about half the normal thickness.

I did measure the journal - old micrometer, but looked to be about 30 thou over already - again, will get expert opinion from machine shop I use.

Oh, yeah - forgot to ask - should I pull trans with the engine? Manual trans felt OK - will still be able to examine the clutch - looks easier to leave trans in ... recommendation?

Thanks - am lookin forward to the rebuild!

Ondontii · 02-24-2008, 08:41 PM

If the engine is always properly oiled...it should be fine. Make sure your pan, pump, oil feed + screen etc etc are all in proper function and clean.

phantomrt · 02-25-2008, 07:23 PM

That picture was of a pretty beat up rod. Often they're not that bad, but often they are. Either way, at a minimum, it needs reconditioning, if it can be done.

If your connecting rod cannot be reconditioned, a good source for them is from the Chrysler 12 valve 6G72 engines found in the minivans and other front-drive Chrysler products. There are literally millions of them litering the local Pick 'N Pulls and can be had for dirt cheap. I found the numbers on them to be different, but are otherwise identical. In fact, I am running a 12 valve rod in my TT Stealth right now. In 1991 and 1992 the crankshafts are the same as the ones in the Chryslers as well. And again, are very readily available.

I'd very much like to see pictures of the the main bearings in your engine to satisfy my curiosity. I'm predicting that they're going to all be worn equally, whereas the twin turbo cars like to wear out the two center main bearings.

I'd pull the engine/transmission as an assembly out the top. I don't think it is even possible to leave the transmission in place because of clearance issues when seperating the engine from the transmission. The service manuals state to remove the transmission first (out the bottom), and then the engine. To poo with that. Leave them together, and with some mildly aggressive tilting of the engine/transmission assembly, it'll come out the top very nicely.

02-23-2008, 12:59 PM	#1 (permalink)
stephenson New User - Please be kind Join Date: Feb 2008 Trader Rating: (0)	Pulled Pan - Spun Bearing! Rod closest to the transmission - about half thickness! Assuming everything else is OK (appears to have the indicated 135K) - and, given what appears to be a tendency on these engines to spin bearings, what's best course of action? JDM engine or rebuild this one? I would do the rebuild, minus machine shop work - so, time isn't the issue - just hate idea of a replacement engine that does the same thing after a few thousand miles ... Thoughts from those that have been there? Thanks!

02-23-2008, 01:10 PM	#2 (permalink)
jbavousett 1992 Stealth R/T Join Date: Oct 2007 Location: Lubbock TX Drives: N/A Beauty Queen Trader Rating: (1)	Re: Pulled Pan - Spun Bearing! If you rebuild it you know what you have, if you replace it with used, you never know. __________________

02-23-2008, 01:18 PM	#3 (permalink)
stephenson New User - Please be kind Join Date: Feb 2008 Trader Rating: (0)	Re: Pulled Pan - Spun Bearing! That's kinda what I was thinkin, too ... What if I just replaced all the rod bearings? If the one rod bearing is the only one that was affected - and, assuming I can get close to an in spec measurement on the remainder - is there a chance I could get a few thousand miles out of the engine? Not main car, just a project ... :-)

02-24-2008, 06:01 AM	#4 (permalink)
HugeJay Forum Member Join Date: Nov 2000 Location: Niagara Falls, ON Drives: 92 R/T Trader Rating: (2)	Re: Pulled Pan - Spun Bearing! When I spun mine in my one stealth, I pulled the engine, took the block and heads into the machine shoppe, had them rebuilt, and the crank re surfaced, I supplied the some parts, costed me about a grand to the machine shoppe.

02-24-2008, 09:16 AM	#6 (permalink)
HugeJay Forum Member Join Date: Nov 2000 Location: Niagara Falls, ON Drives: 92 R/T Trader Rating: (2)	Re: Pulled Pan - Spun Bearing! oh btw, dont think changing the rod bearing after its been spun will work right, chances are like the other poster stad the connecting rod needs to be replaced, I tried just to change the bearings it worked, but I still had a slight knock, to do it right you have to get it rebuilt. take our advice once you spin a bearing, its time to rebuild. Last edited by HugeJay : 02-24-2008 at 09:52 AM.

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02-24-2008, 01:25 PM	#7 (permalink)
phantomrt Forum Member Join Date: Mar 2007 Location: Minnesota Drives: fast Trader Rating: (0)	Re: Pulled Pan - Spun Bearing! Sometimes the old bearing is welded to the connecting rod or crankshaft, and can't even be removed per say. The welding came from heat buildup. Here's an example of a spun bearing connecting rod: Your rod probably looks similar.

02-24-2008, 06:04 PM	#8 (permalink)
stephenson New User - Please be kind Join Date: Feb 2008 Trader Rating: (0)	Re: Pulled Pan - Spun Bearing! Yikes - mine doesn't look that bad, but likely does need replacement ... will get more pro opinion when I deliver it all to the machine shop. The bearings themselves were very evenly worn, with only the very ends being a bit thinner than the middles - looks to be about half the normal thickness. I did measure the journal - old micrometer, but looked to be about 30 thou over already - again, will get expert opinion from machine shop I use. Oh, yeah - forgot to ask - should I pull trans with the engine? Manual trans felt OK - will still be able to examine the clutch - looks easier to leave trans in ... recommendation? Thanks - am lookin forward to the rebuild!

02-24-2008, 08:41 PM	#9 (permalink)
Ondontii SOHC you in the FACE Join Date: Feb 2005 Location: Seattle and SaltLake Trader Rating: (0)	Re: Pulled Pan - Spun Bearing! If the engine is always properly oiled...it should be fine. Make sure your pan, pump, oil feed + screen etc etc are all in proper function and clean. __________________ Brent 1992 Duster -13.0@104 - 8psi boost and slipping clutch -13.9@107.4 - 5psi - 6g72 3.13L "built" SOHC, Precision T67 P-trim, Tial 38mm open dump, 3" downpipe, 20x12x3" evo style intercooler, 7:1 compression, balanced, shot peened rods, heavily ported heads (+40% on flowbench), Ferrea Competition Plus +2 +1 stainless valves, Nielson Vintage 278 duration custom turbo cams, RPW Cam gears, Custom Ram Style short runner intake manifold, Walbro 255hp, 6*47# injectors, +0.096" Forged Venolias, Total Seal chrome gapless top rings, Fidandza Flywheel, Clutchnet 3 puck solid hub, OBX Helical LSD, Zeitronix wideband/EGT/Boost sensors, 100watt DevilsOwn Meth Kit. 1994 Spirit - 13.987@101.89 - 5psi- 6g72 SOHC, K27 Turbo

02-25-2008, 07:23 PM	#10 (permalink)
phantomrt Forum Member Join Date: Mar 2007 Location: Minnesota Drives: fast Trader Rating: (0)	Re: Pulled Pan - Spun Bearing! That picture was of a pretty beat up rod. Often they're not that bad, but often they are. Either way, at a minimum, it needs reconditioning, if it can be done. If your connecting rod cannot be reconditioned, a good source for them is from the Chrysler 12 valve 6G72 engines found in the minivans and other front-drive Chrysler products. There are literally millions of them litering the local Pick 'N Pulls and can be had for dirt cheap. I found the numbers on them to be different, but are otherwise identical. In fact, I am running a 12 valve rod in my TT Stealth right now. In 1991 and 1992 the crankshafts are the same as the ones in the Chryslers as well. And again, are very readily available. I'd very much like to see pictures of the the main bearings in your engine to satisfy my curiosity. I'm predicting that they're going to all be worn equally, whereas the twin turbo cars like to wear out the two center main bearings. I'd pull the engine/transmission as an assembly out the top. I don't think it is even possible to leave the transmission in place because of clearance issues when seperating the engine from the transmission. The service manuals state to remove the transmission first (out the bottom), and then the engine. To poo with that. Leave them together, and with some mildly aggressive tilting of the engine/transmission assembly, it'll come out the top very nicely.