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Engine Rebuild Saga - 993 Turbo

 
Old 05-16-2019, 12:35 PM
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JEllis
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Default Engine Rebuild Saga - 993 Turbo

Backstory,

I bought a 96 993 Turbo back in December. The car had been driven 11K miles over the past 13 years (ish). It had a 25K mile old top end rebuild and was mechanically in great shape. I picked the car up in New Hampshire and drove it back to Fort Worth, TX.

For months the car ran great, although I was basically just enjoying it on the weekends. About a month ago it developed what sounded like a lifter tick or exhaust leak. I decided it was time to change the oil as I investigated the noise. After removal, on the end of the crank case drain plug, was a garter spring from an engine seal. Which seal is still TBD (too small for RMS). Pic below.



Obviously this was concerning, as was the metal flakes in the oil. I sent the oil out to Blackstone and received this back.



Nothing too crazy, and I expected to see increased metal/copper in the oil. I spoke to a few different engine builders that thought it was unlikely, or rare, if the spring, or pieces of the spring went through the bearings etc. The overall recommendation, at the time, was to monitor the oil at shorter intervals and do analysis. But, I wanted to get the possible bad lifter fixed so I took the car to Chris at Mayo Performance in Bedford TX.

Upon opening the drivers side valve cover, Chris found these pieces in the oil.



The initial thought is that this is valve guide material. Unusual to see a broken valve guide like this. The engine tear down is still in process. The hope is that none of the "hard" metal in the engine is damaged. I am hoping to have the motor cleaned out of all valve guide debris, replace the broken parts, replace the bearings and then re-seal. I will let you know how this goes.

My initial thought is that this could have been caused by an over-rev. But, I have no recollection of a money shift. I do remember hitting the rev limiter a time or two as I was getting to know the car but the ticking started months later.

More to follow.
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Old 05-16-2019, 12:48 PM
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Those bits and the spring,, kinda look like parts from a valve guide seal.. Good Luck !! Dont let them dive too deep too fast..

Worst possible way to start working with a shop is: "I think my engine needs rebuilt" <-Cash Cow on the hook..
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Old 05-16-2019, 01:12 PM
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Could also be the oil ring from the piston (top right on picture:

https://www.google.com/search?q=993+...CbIq5lTKhGGzM:
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Old 05-16-2019, 02:08 PM
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Hi JEllis,
The spring could have been from a seal previously replaced that fell in during the removal and possibly of little consequence where it sat at the bottom of the engine.
The bronze parts could be just local to the valve train and also not an indication of a wider systemic issue.
Good luck with this. I hope your results prove that minimal damage was done if any.
Seems to me that if big chunks of the bronze or the spring got chewed up against some parts you would see other stuff at the drain plug. Hoping the best for you.
Andy
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Old 05-16-2019, 05:19 PM
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That's wild. Never seen a valve guide disintegrate like that (assuming it's the guide -- but if those chunks were sitting inside the valve cover I can't imagine how it could be anything else). Yikes.
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Old 05-16-2019, 07:07 PM
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Any chance the chunks are rocker bushing bits?
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Old 05-16-2019, 11:00 PM
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Damn!!!
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Old 05-16-2019, 11:07 PM
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Ugh.... this hurts. Keep us posted and we'll hope for the best.
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Old 05-16-2019, 11:09 PM
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Originally Posted by ed devinney View Post
Any chance the chunks are rocker bushing bits?
That actually makes a lot more sense than a valve guide, given what the chunks look like. The garter spring looks like it's from a valve stem seal. Something went badly wrong, curious to hear what happened.
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Old 05-17-2019, 03:34 AM
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Originally Posted by ed devinney View Post
Any chance the chunks are rocker bushing bits?
+1
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Old 05-17-2019, 11:16 AM
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Thanks for the comments guys. The motor is out of the car and I should know today what the extent of the damage is.
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Old 05-17-2019, 11:19 AM
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Originally Posted by pp000830 View Post
Hi JEllis,
The spring could have been from a seal previously replaced that fell in during the removal and possibly of little consequence where it sat at the bottom of the engine.
The bronze parts could be just local to the valve train and also not an indication of a wider systemic issue.
Good luck with this. I hope your results prove that minimal damage was done if any.
Seems to me that if big chunks of the bronze or the spring got chewed up against some parts you would see other stuff at the drain plug. Hoping the best for you.
Andy
The oil is glittery. The Blackstone report was not as bad as I was expecting but there was definitely glitter throughout the oil tank filter and in the oil.
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Old 05-17-2019, 12:06 PM
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This sort of failure is the reason why I invented my rebuildable piston squirters. Besides finding the cause of this problem, your other biggest challenge will be completely cleaning out the oil galleries and removing the squirters to make sure no trapped metal lives inside them.

The motor needs to be "metal free" before a rebuild, and if you have glittery oil, you basically already bought yourself a full rebuild.
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Old 05-17-2019, 06:55 PM
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That does not look like valve guide to me. I think intermediate shaft bushing. Whatever it maybe I am not surprised it traveled to the valve cover. Those oil return tubes are HUGE so with some G's anything in the engine case will find it's way into the valve cover.

Whatever the case I doubt it was operator error. Hitting rev limiter on upshifts is no big deal. Grabbing the wrong gear and forcing a mechanical over rev is where the problems lie.
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Old 05-18-2019, 10:48 AM
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Here is the latest. Looks like the exhaust valve failed.









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