ZBLKHELLRZR

Got a friend w/ a 355ci LT1 GM 847 cam and all bolt-ons etc. Currently rebuilt his engine just to refreshing the bottom since it had 120K on block. New rings and bearings is all he did. Stk oil pump normal psi before the rebuild nothing out the ordinary.

After the rebuild he put a canton pan 7qt and that's it. No oil leaks from the intake, or the oil pan. However he's got a slight leak from somewhere and it appears on the bottom of the tranny, starter, and the left side of the tranny where the that piece attaches to the tranny for the clutch (forgot the name).

Anyways after 500 miles he went from 7qts to 2 1/2qts! His psi would drop in turns and that was the only indicator but it would shoot back up to 45 psi and bounce on a occassion. So where is all the oil going? Can't be all from blowby and when he goes WOT no oil is shooting out the exhaust either. No blue smoke or black smoke. Blue on startup for 10 secs and that's it.

Any ideas? We are going to cut his oil filter and see if there are metal shavings in it. His drain plug had one sliver of metal and the normal build up you'd see but nothing out the ordinary. We are really scratching our heads here.

Thanks!

JPSartre12

Does he still have a cat on the exhaust? I've seen catalytic converters eat many quarts of oil and the engine never show a sign of leaking. I had a 4.3l motor in an 89 GMC Safari replaced because of a "scorched cylinder" that lost 2 quarts of oil a week and left no spots on the driveway or blue smoke out of the exhaust. We couldn't figure out where it was all going until we brought the van to the dealer and they checked everything, including the loaded cat. It was truly amazing.

ZBLKHELLRZR

Scorched cylinder? Well as far as the cats he ran no cats. Plugs looked fine too w/ no oil on the pucks or threads. That would suck if that's the case but I've never seen or heard anything like this before.

Gripenfelter

Rear main seal.

ZBLKHELLRZR

Grip? I was thinking the same thing but I just can't imagine a rear main leaking like that. For it to do what it does I'd think there would be no rear main back there at all! LOL! Guess we'll be tearing down the tranny in the next wk.

JPSartre12

Yep, scorched cylinder. Mr Goodwrench was kind enough to give me a whole new engine after that diagnosis. Good thing I had the extended warranty or I'd have paid $3600 for the new motor.

SSTAT

I put my money on the rear of the intake manifold, seems obvious to me...??

JPSartre12

No puddles in the driveway? No oil mist over the firewall? If it's at the rear of the Intake manifold, it should be all over the firewall and possibly, the ground.

ZBLKHELLRZR

No it's not on the back of the intake. Dry as ever as well as the VC's. Some people say their VC leaks because of the gaskets. Not on the firewall. We searched all that that's why I asked where did all his oil go. Only other place is the rear main seal. No puddles and only on the underside of the tranny, bellhousing and starter.

Looked at his oil filter and he's got nice particles in the filter. Look to be around 20 pieces or so the size of rice. Looks like bearing material and the 1st layer of the tri-metal fed mogul bearings he's running. Hopefully a thicker weight oil will cure that problem temporarily.