FBIII

Bought Kevin Michael's 89GT and want to start putting the engine back together.
Engine has 53K but likely hasn't been used since 1995. I plan on checking the rod bearings and if they are fine don't plan on splitting the crankcase. My conundrum: Would you pop the pistons and re-ring or would you leave them untouched? Is there a possibility of the rings becoming stuck in the ring lands from having been unused for so long?

docmirror

Wow, there's a lot of 'it depends' involved. Things to consider: Are the heads already off? Has it been stored in a fairly dry place continuously? Was it pickled on storage?

The 928 engine is less prone to ring sticking because it has Al cylinders and pistons. That doesn't mean it's not immune but if the engine were outside in an uncontrolled enviro, and the heads are off, I would sure knock the pistons out, and at least clean the lands. At that point I guess putting in new rings would also make sense. Gently scuff the bores with a green scrubber and some soap and then reassemble with plenty of oil.

namasgt

you dont need to scuff the bores. Just clean the bores with a soft tooth brush and some carb cleaner and your done.

docmirror

It's been sitting for 15 years. I don't think a toothbrush and carb cleaner will get the oxide glaze off. Like I said, a lot depends on how it was put up.

BC

From my (limited) experience of disassembling 6 928 motors and reassembling 4 of them, I feel as though you should remove the pistons, decarbonize them in berrymans (if that is acceptable to others) and re-ring. EVERY SINGLE one of the engine I have taken apart, (also true if I include BMW motors) have had impacted rings. Meaning rings which NO LONGER ROTATE and have no actual spring affect in the bore. Some more than others.

So while I would also separate the halves of the block as well, if you choose not to, at least remove the pistons - keep them labeled, and get them spot-free, rering, and install again.

To re-instill - if recently run motors all have impacted rings, then what would happen if the motor has not run since possibly when Clinton was in office?

FBIII

The rings loosing tension was another concern. All I would need is one marginal ringset causing lower compression or an oily plug in one cylinder and I would be regretting not having gone deeper. It does make a lot of sense to remove them and rering. Thanks all.

namasgt

people have been rebuilding their 928 and 944 engines without honing or scuffing, If you go pull up some threads you will find that touching the cylinder walls with anything that will scratch them should be avoided. Do search on "new piston rings" and "cylinder walls" in the 944 and 928 forum, there are people who have been doing this for a while and say no scuffing is needed, it will ruin the cylinder walls if you do so.
maybe some use scotch pad to scuff their steel sleeved Chevy or ford engines in their back yard but that's just redneck and probably better if they just have it honed to do it properly. Doing something like this on an Alusil block like the 928 or 944 is more harm than good. Alusil cylinder wall, and still sleeves are worlds apart on how they work and each need to be threaten differently.

Mrmerlin

I would suggest that you use simple green to soak the pistons, then a good tooth brush on the lands, this will clean the surface without damaging the chromium plating, the Berrymans might damage it.
( the surface will look dull green with some wear on the skirts)
Dont try to clean the skirts with anything other than the tooth brush

IcemanG17

if you decide to re-ring the engine (it looks like you will) then consider "total seal" rings...around $240 per engine and many racers use these with great success......

If you are taking the motor all the way down (might as well after pulling it)...do it right and do it once..ask me how I know

docmirror

Well, I don't know where you got equating using a scotchbrite pad with honing. BTW the correct final procedure is to use the felt pad with compound to complete the process once a bore has been reconditioned. Since the felt pads are no longer avail, the closest approximation is a fine scotchbrite pad with some Varsol and GENTLY stroke the bores. Washing it with a toothbrush won't do any harm, but it won't do any good either. Aluminum oxide and Silicone oxide is pretty hard stuff.

Now, if you take a brown or coarse scotchbrite and really dig in hard with the pad, yep, it's gonna destroy the bore. It's all in the hand.....