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Hi everyone, I have finally bit the bullet and pulled the engine on my 87 951 because of substantial leaks. A little background first, for what it's worth. I've had the car for about five years now and have done quite a bit of work to it, including suspension and brake upgrades, rebuilt ECUs, rebuilt K26-6 turbo, Tial wastegate, Lindsey chips, gutted cat (that sounds gross). A lot of this was done with an eye toward having a fun street car that I could also use for track days and autocrosses. But, the leaks that were there when I bought the car were just getting to be too much. After researching the best the way to fix them, I felt like an engine-out approach would be best. I'll try to document the work here, and would welcome any commentary and suggestions as I go along.
The car:
Engine on it's way out from the bottom. The cat in this photo is not gutted:
Removing clutch and flywheel in preparation to bolt to the engine stand. I know for sure I'll be replacing the pressure plate and clutch, but does this flywheel look like it can be resurfaced?:
Good idea.
So much nicer to work on an engine while sitting on a chair rather than on the floor with grease falling in your eyes.
Check the workshop manual or search for flywheel thickness spec, but I'd bet yours could be resurfaced OK.
Machine shop might be able to just check it for flatness (warpage), if it's OK they can just clean it up rather than cutting any meat off.
Good idea.
So much nicer to work on an engine while sitting on a chair rather than on the floor with grease falling in your eyes.
Check the workshop manual or search for flywheel thickness spec, but I'd bet yours could be resurfaced OK.
Machine shop might be able to just check it for flatness (warpage), if it's OK they can just clean it up rather than cutting any meat off.
Thanks. I love working on engines on a stand. Hopefully the flywheel can be cleaned up. This is going to add up fast!
Next question: can I just remove the timing and balance belts and reset later to the timing marks on the crank, cam, and balance shafts? Obviously the flywheel is off now so I don’t have that reference point.
Next question: can I just remove the timing and balance belts and reset later to the timing marks on the crank, cam, and balance shafts? Obviously the flywheel is off now so I don’t have that reference point.
as long as the crank doesn't move.
can be verified with a wood dowel in a spark plug hole, or if the engine is at TDC now without the flywheel just make a sharpie line from crank flange-> block.
Yeah this is probably my first mistake, because I removed the flywheel for access to the rear main seal, but I didn’t set TDC first. I think I’ll just use the dowel trick on the number one piston to get TDC, confirmed by the cam mark, then remove the belt. The cam tower is coming off anyway, so I’m going to have set all this correctly when it goes back together. Probably rod bearings too, and I don’t know if the crank has to rotate to do that (probably).
I think that's pretty clean compared to the many I've seen. How many miles? Original head gasket? You know where i'm going with this line of questioning right?
I think that's pretty clean compared to the many I've seen. How many miles? Original head gasket? You know where i'm going with this line of questioning right?
Well, it is true that it could be worse. About 130k on the motor. Probably original head gasket, and this will be one of the big questions. Do I preemptively replace it? I don’t mind the labor, but at some point I’ll have to wave the white flag in terms of dollars.
...I don’t mind the labor, but at some point I’ll have to wave the white flag in terms of dollars.
Lol my last engine out “reseal” set me back over $4k, it’s easy to get carried away with wyit jobs. Clutch, plate, flywheel skim, head skim and refresh, rod bearings, rings, baffle plate, scraper, mounts, water pump, foes, belts, bearings, gaskets, seals and sealants.
A head is relatively easy to do with the engine back in, though if it’s the original gasket I’d be tempted to give the head a skim and fit a new gasket. Doing anything else would depend on what your compression and leak down numbers were like.
The head gasket is no longer a question for me. At 130k I go right down to the short block, remove one piston, inspect rod bearing and journal, measure rod bearing clearance, remove rings, inspect carbon build up in piston oil return passages, measure ring end gap with old ring and new ring, I try to leave the crank in, measure crank end play and compare measurements with the WSM specs. For the head, measure valve guide clearance, at least lap valves, new seals, surfacing is usually a good idea. Surfacing the flywheel is essential. I also try to not spend money on "performance enhancements". That's the slipperiest of all the slopes!
Last year, around 150k miles, I failed emissions. I replaced the CAT with a NOS one.. no change. Did all the regular tune-up things; no change. Opened up the engine and cleaned out all the carbon, obviously installing a new HG (though the old one didn't show any obvious problems).
Passed with numbers I have never seen so good in the ten years I've had this car. Anyway, I bet your pistons have this crap on them too!
BEFORE
AFTER
I would imagine this is a much nicer job--esp cleaning the mating surfaces of head + engine block--now that it's out
02-17-2019, 12:02 PM
Engine out reseal
