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jayd_2 10-18-2012 10:14 AM

1989 SBC Using Oil
 
I've got a 1989 SBC that was a rebuild that had about 5000 miles on it when I got it. It runs great but uses oil and fouls the number 8 plug but does not smoke. The plug fouls after several hundred miles, all the other plugs are good. I just replaced the valve stem seals on number 8 but I doubt that was the problem. It uses half a quart in about 300 miles. The oil pressure is 30 lbs at idle and 60 lbs at rpm.

It doesn't smoke when cold or when under a load or when you let off at high rpm. How it could use so much oil without smoking? There are no oil leaks and the crank case pressure is good, pcv valve is dry.

Is it possible that the intake is leaking on one cylinder, it's got an aluminum intake and I've heard some gaskets are too hard and don't seal well on aluminum.

oldbogie 10-18-2012 01:07 PM

Quote:

Originally Posted by jayd_2 (Post 1600442)
I've got a 1989 SBC that was a rebuild that had about 5000 miles on it when I got it. It runs great but uses oil and fouls the number 8 plug but does not smoke. The plug fouls after several hundred miles, all the other plugs are good. I just replaced the valve stem seals on number 8 but I doubt that was the problem. It uses half a quart in about 300 miles. The oil pressure is 30 lbs at idle and 60 lbs at rpm.

It doesn't smoke when cold or when under a load or when you let off at high rpm. How it could use so much oil without smoking? There are no oil leaks and the crank case pressure is good, pcv valve is dry.

Is it possible that the intake is leaking on one cylinder, it's got an aluminum intake and I've heard some gaskets are too hard and don't seal well on aluminum.

It could be a leak from the intake into number 8 but before pulling the intake off remove the rocker cover on number eight's side roll the engine over and observe the rocker movement to see if a cam lobe is wiped out.

Also, a vacuum check before diving in, a leak into the manifold should show a low but steady needle on idle that corrects as the RPMs come up. A wiped lobe will show a normal needle that dips everytime that cylinder comes around and stays that way as the RPMs are moderately raised.

Bogie

hcompton 10-18-2012 02:47 PM

I use print-O-seal gaskets for alum intakes. seem to work fine.

first thing in the morning with the engine cold. get someone to hold a white sheet of paper behind the exhuast and start the car and rev it up a few times.

Let it dry there should be water. then look to see if there is any oil on the paper. If so its burning oil for sure. Also check for black dust on the back of the car and bumper around the exhuast. check both pipe if you have dauls so you can compare.

A good running engine will burn a lot of oil without showing many signs. Its usally the old engine that shows the oil burning with thick white smoke.

I would do a leak down and compression test before taking anything apart. no reason to pull the intake and replace the gasket if you have a broken ring land. A broken oil ring land will still run ok in a v8 but will burn oil like mad.

Hope this helps

jayd_2 10-18-2012 06:32 PM

The 2 center intake bolts are at a different angle than the outside bolts, what type heads are these?

Plaintoast 10-18-2012 06:40 PM

normally those are referred to as throttle body heads.
good chance they are either 191 or 193 castings, assuming 350 and not 305.

jayd_2 10-18-2012 08:08 PM

Quote:

Originally Posted by hcompton (Post 1600543)
I use print-O-seal gaskets for alum intakes. seem to work fine.

first thing in the morning with the engine cold. get someone to hold a white sheet of paper behind the exhuast and start the car and rev it up a few times.

Let it dry there should be water. then look to see if there is any oil on the paper. If so its burning oil for sure. Also check for black dust on the back of the car and bumper around the exhuast. check both pipe if you have dauls so you can compare.

A good running engine will burn a lot of oil without showing many signs. Its usally the old engine that shows the oil burning with thick white smoke.

I would do a leak down and compression test before taking anything apart. no reason to pull the intake and replace the gasket if you have a broken ring land. A broken oil ring land will still run ok in a v8 but will burn oil like mad.


Hope this helps

What will cause a good running engine to burn lots of oil?

hcompton 10-18-2012 08:28 PM

Quote:

Originally Posted by jayd_2 (Post 1600648)
What will cause a good running engine to burn lots of oil?

Borken ring land, rings upside down, valve seals, some strange restriction in the oil system causing oil not to leave the head fast enough and flooding the heads, scratched or out of round bores, missing rings and so on...

Gaskets are always the first suspect.

Pretty much as long as its fresh and has good strong compression it will burn up a ton of oil. Wouldnt be suprised if its still strong on 7.

they make oil fouler devices its like a tube that moves the spark plug back. It can stop it from craping out the plug every few hundred miles. But not a fix for sure. even if its just a gasket you dont want the carbon build up.

A leak down and compression test will shed some light on the problem.

jayd_2 10-18-2012 09:07 PM

Quote:

Originally Posted by Plaintoast (Post 1600616)
normally those are referred to as throttle body heads.
good chance they are either 191 or 193 castings, assuming 350 and not 305.

Do these heads require different gaskets than previous sbc heads

Plaintoast 10-18-2012 11:30 PM

the head gaskets are standard, the intake gaskets from fel pro will had just a small bleed hole in the rear water jacket crossover, but a standard one will work. the valve covers are different and not interchangeable

jayd_2 10-26-2012 01:39 AM

The intake gaskets were leaking oil on all cylinders, replaced the Felpro with some soft gaskets. Oil consumption problem solved and it runs much better.


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