I have an 89 Firebird with the TBI 305. After an oil change I can go to about 1000 miles then I have to add a quart. No big deal really...but, after I add the first quart of oil I have to add a quart every 400-500 miles until the next oil change. Anyone else have this problem? Anyone know what might be the cause? I have already tried PCV valve and crankcase breather. Please help, I'm baffled.

 

well, if you are low on oil, its gotta be goin somewhere. Check radiator, check the ground under the car, and look at the undercarraige. If you cant find any oil there, that only leaves one other leaky spot. You are leaking it out your exhuast pipes. That sucks

 

Yeah, that is something I failed to post. I haven't found any sign of leakage on top or bottom of the motor. There is a slightly damp spot on the front seal of the intake, but I think that is from a bad thermostat housing gasket (need to replace). I'm not getting anything out of the exhaust either, no visable smoke and no liquid.

 

Are you running the smog pump? It could also be leaking in the rear somewhere. Like the oil pan gasket on the back side. Jack up the car and crawl under there.

 

I'll give that a look when I get the chance. Forgive my dumbness here...but, what exactly is a smog pump? What does it do, and why would oil leak from it?

 

Often times, if people pull the smog pump, they forget to plug the top hole.

When you pull the smog pump, there are 2 bolts that go into the engine block. the bottom one is ok. However, the top one is what looks directly at the fuel pump pushrod, if so equipped. However, by looking in to the fuel pump pushrod, you are also looking in directly into the crank case.

That is the front of your engine (well, so to speak). The bolt hole i circled is one of the smog pump mounting holes. It is also the hole that you have to plug if the pump is pulled.

 

Of course I haven't had the time to check this out yet...but, wouldn't a hole like the one for the smog pump make one heck of a mess rather than be a mystery leak? I don't know, I have a 1-hour 1-way trip to and from work every day...could be burning off.

 

Well, first things first. On your engine, is that hole bare or is it plugged? If its plugged, make sure its sealed good (no oily residue around the plug) and if it is sealed good, we're looking in the wrong area.

 

Will check this evening when I get home. I'll let you know then.

 

Do you puff smoke on a cold startup? Does your rear bumper get a coating of black soot on it? Lacking obvious oily spots on the undercarriage, the only other places the oil could go is the coolant or engine. Coolant would be obvious since the oil cannot go anywhere, it will accumulate, making the coolant look like a mess. A puff at cold startup is valve seals. Slight smoke during regular driving means rings. Have someone follow you while you tromp on the gas. Does grey smoke come out? A quick spark plug check can tell if you have oil problems and a compression check would confirm it.

 

Stekman, I checked for the smog pump and I believe it is still intact and not leaky.

I have had the valve guides replaced within the last few months to cure the cold start puff. That is no more. As for romping on it and seeing smoke I can't recall seeing any while driving since I had the guides replaced. Before you would see a little puff on deceleration...but, as far as I know that is gone. And the plugs look good too. I'm starting to suspect the intake gasket more since the front is a bit wet...it's just hard to tell because the thermostat housing has been leaking on and off. How long does a factory intake gasket usually last?

 

do you have the flywheel inspection cover on still ??? ive seen cars leak from the rear seal of the engine and almost fill the cover up with oil ...but usually you would notice some kind of oil spot on the ground under your car ........also have some one get in your car and gas it pretty good and you stand behind it and watch the pipes and make sure your not haveing blow by from the rings at higher rpms...if your drivin an hour to and from worK you wouldnt notice it smokin out the rear as much if your on the high way ...

 

When you say your front of the engine is damp, where do you mean exactly? Where the thermostat housing is mounted and the front china wall gasket is is a big gap. If the moisture is present mainly below the front china wall gasket, i would suspect that as a possibilty. But if its damp above the china wall gasket then yes, it probably could be blamed on the thermostat housing.

Have you done any disassembly/reassembly of your engine?

 

well, I know the thermostat housing leaks occasionally but it really doesn't go down the front of the intake so much as the side of the front. The gasket on the fron of the intake (kinda has that sealant that kinda hangs out) looks to be wet from the sealant down. But, it doesn't look like it is gushing or anything. But, it definately looks and feels wet...I don't think it is coolant either.

 

ttt

 

Are you sure it doesnt leave a puddle or anything on the ground?

 

I do park on gravel primarily. But, eventually it's bound to show up even then. I wish there was a puddle...it would make this much easier to figure out.

 

Take a paper towl, kleenex, anything white, and wipe along the front intake gasket. See if you cant pick up some of the residual leakage.

 

if you park on gravel just take a piece of cardboard and put it underneath your engine, any oil spots should show up if you have a leak.