bengxe

I have a 90 with almost 300k on the clock. It burned oil badly (thick smoke, oil fouled plugs), so Im in the middle of a rebuild. The compression numbers were (1-4) 188, 183, 188, and 192. The cylinder walls look fine. Do you think its worth doing rings and a re-hone? Normally I wouldnt, but Im having a hard time explaining where the oil burning is coming from.
I have the head off and in pieces already. The headgasket shows no evidence of ever leaking and according to my straightedge, the head isnt measurably warped. So my plan for that is new valve seals, thoroughly cleaned out the HLAs, stiffer springs, cleaned up intake valves, and new supertech exhaust valves. The carbon buildup on the original exhaust valves is alot thicker and more durable than on the intake valves, so I bought a set of the supertech exhaust valves cheap on ebay. The stiffer valve springs I ordered are the sealed power vs855, meant for a volvo b20 (mentioned here: Solomiata : Engine : Randy's engine ). Im kind of worried about using these with HLAs. Any opinions on that? i.e. will the HLAs support the extra spring force? Ive read about solid lifter conversions, but those seem like more money than I want to put into this car, especially since it looks like I would need cams with a solid lifter friendly profile. I did some really slight porting on the exhaust ports and polished them, mostly just to get rid of the carbon build up. On the intake side I just ground off the larger burs and casting seams.
I tore down the engine thinking I would find the source of the oil burning once i got into it, but I dont think I ever did. Im assuming the valve seals were leaking because the plugs were fouled, but that really doesnt explain the amount of smoke coming out the exhaust. I wish I had thought to unhook the pcv valve while it was running. Is there any reliable way of checking for leaks there, with it out of the car?
Any thoughts/ opinions would be greatly appreciated.

Gotpsi?

iTrader: (5)

If you where burning a lot of oil its probably your rings, and with that many miles you might need new valve guides to. If you are going for a cheap rebuild at least do the rings and hone you can DIY.

aphongt

iTrader: (1)

Oil control rings are a possibility. I guess it really depends on how much oil you were burning. The top two piston rings seal the piston to cylinder so you can have good compression but if the bottom ring cant control or scrape the oil out of the cylinder walls, then alot of oil would be getting into the combustion chamber.

Or there is extreme valve guide to stem clearance and its just letting large amounts of oil right into the chamber.

bengxe

Thanks for the replies. It looks like I need to do rings. Im thinking Ill do bearings while Im in there. Anyone know if theres an easy way to get the oil pan off without pulling the block out of the car? Im assuming Im going to be pulling the block.

aphongt

iTrader: (1)

I haven't done it myself but according to my Haynes manual it looks like a pita. The other guys should be able to chime in. When you do get the pistons out, I'd be sure to check the cylinder walls by measuring it with a bore guage to ATLEAST check it for taper and out-of-round and make sure its all in spec before you do anything.