engine and drivetrain Eating oil....

[leonine99]

Ok gang, I need the collective intelligence here (since mine is severely limited). Got my '75 from Jack F for a short drive period of several tankfuls before I take it back to him to dial it in further, and one TROUBLING discovery is that the engine is consuming a LOT of oil - about a quart of oil for each 200 miles or so. The valve cover breather is not hooked up to the 38/38 (that carb is another story, for another thread), there is a film of oil on the inside of the hood, not a lot though. There are no obvious wet spots on the lower half of the engine, and no leak drips where it's parked. There does seem to be the smell of oil burning briefly when I come off of highway speed of 5000 RPMs or so, but not positive on this. The engine runs strongly, a bit of blow by when the oil cap is off, but no change in idle, it just doesn't seem like a tired engine, and it jumps off the line. I don't know the history on what the PO did engine-wise (althought the suspension mods he did are fab-you-luss). Anyway, I've heard something about forged pistons helping to consume oil....just want to get a general take on this - Higher viscosity oil, etc?.....an engine rebuild would change my plans on this car DRAMATICALLY. Or is it '75's are just oil eaters? Thanks for the help - I'm tired of scratching my head....

Jeff

[esty]

you sure it isn't coming out the tail pipe...being burned....

[leonine99]

I just let it warm up and gave the throttle a good push, and lo and behold, and significant cloud of white smoke out the back that I've not seen in the past.....worn rings? Engine rebuild? Oh dear.....

Jeff

[gwb72tii]

hold up a piece of white paper in front of the exhaust and have someone repeat what you do to get that puff of smoke. if the oil is being burned, you should see a residue on the paper.

there's only so many places it can go, right?

[Arshloch]

The cloud is supposed to be blue and it will smoke more where its warm. In such cases the the tail pipe will likely have oil residue. It will use oil for awhile untill you will see clouds of that stuff coiming out.

Try switching to heavier oil. Also your valve guides might be severly worn.

Take out the plugs and see if ithere is oil on them or just one of the plugs ( You might have broken a ring or some debry destroyed led to damage). Besides this, your oil rings might be sticky and with the worn out bore they seat improperly.

[Chris_B]

That is a helluva lot of oil to use. As has been suggested, looking at the plugs may be informative. Presuming you are seeing oil smoke (it is hard to tell oil smoke from steam if you haven't seen both- put your hand in front of the exhaust... if you are seeing coolant, it will feel damp), conventional wisdom says that smoke on acceleration means oil is coming up past the rings, whereas smoke on deceleration is oil being sucked past the valve seals. Having someone drive behind you to observe is helpful- particularly at night when smoke is more readily visible in the headlights.

When I bought my 02, it had the original motor with unrebuilt bottom end @ 200K miles, and a recent head rebuild (per receipts). It used a fair amount of oil (1 qt/500 miles). The number one cyl had an oily plug. I figured that I had a broken oil control ring on that cylinder. Much to my surprise when I pulled the motor, the intake valve on that cyl. was scrubbed completely clean by oil coming past the valve seal. I have since concluded that oily plugs mean oil is coming from the seals and not completing burning on decel. Plugs may still have a black, hard residue from oil coming past the rings.

I believe (and someone correct me if I am wrong) that forged pistons tend to expand and contract quite a bit more than cast pistons, so builders tend to leave them a bit looser in the cylinders. Therefore, more oil may be used when the motor is cold, but when it warms up the pistons expand and rings work as normal.

If you have not already, try some 20W50 oil.

[eastsidebimmer]

I have 2 engine leaks, and smoke on excel and deceleration. When I drive for long periods, I usually go thru most of a quart of 20W-50 between fill-ups which would be about 250 miles. I know how to fix these items, but I'm saving up to do it right for my car's 40th birthday present next year. Original Engine looks to never have been apart.

Ben

[RandyMolson]

I have 2 engine leaks, and smoke on excel and deceleration. When I drive for long periods, I usually go thru most of a quart of 20W-50 between fill-ups which would be about 250 miles.

Ditto with my 2.0L-equipped 1600. That motor is strong as hell but it sure goes through oil. I have at least one healthy motor to swap in, when I get around to it.

[leonine99]

Thanks, all very helpful, I suspect the valve guides have a role in all this, but time will tell. For now I'm going to head over to the local Kragen and pick up my weekly quart of 20w-50....

[leonine99]

So with a quart down I throw in some 20w-50.....still a little white smoke after pushing the throttle down hard......HOWEVER with the car warmed up, I felt the exhaust coming out......bone dry, no water, no residue.....so......after this clue, what do you guys think?

Jeff

[Chris_B]

Oil smoke is sort of grayish in color, but certainly more towards the white end of the spectrum than the black smoke caused by unburned fuel. Does the smoke come out while you are accelerating, at steady throttle or after (after you have let off the throttle)?

[leonine99]

There's only a little bit of white smoke when I push down hard on the throttle, but dissapates quickly and it's clean after that...no smoke on warm idle....I did notice on a freeway run today after coming off higher rpms (5000 @ 75mph or so) there was the smell of burning oil for a few moments, so I wonder if some is coming out the front top exhaust stud onto the manifold.....still, it would have to be a pretty serious leak from there......ah, well, Jack F will solve this soon enough.....

Jeff