Oil Filler Cap

[joeinbcs]

Hi All,

Thanks for all the help on various issues.

I just had my carb rebuilt and the intake manifold plug replaced.

Now my car is forcing oil out of the breather-style filler cap.

My mechanic told me that the original cap should not have a breather.

Several of the pictures I've seen of cars like mine do have the breather cap, and I'm just looking for some guidance...I know, pretty elementary, but, can somebody tell me if I have the right cap?

If so, why is oil leaking out of it fouling my engine and causing it to smoke?

Thanks again for all the great support, Joe

[CTX-SLPR]

Is the PCV setup still functional? It screws into the back of the carb then has a hose running off of the metal line. It is originally a breather and it's the inlet for the PCV system.

[joeinbcs]

Yes, it is still functional and I replaced the PVC valve when the carb was rebuilt.

Its attached to the valve cover on the passenger side of the car.

[RivNut]

If there is oil being forced out of your breather that means that pressure is being built up in the crankcase and the pressure is forcing the oil through the breather instead of being sucked into the the carb through the pcv valve. The breather lets air in so the pcv doesn't create a vacuum in the engine.

If it didn't smoke before you had the carb rebuilt, I'd start with the carb to make sure that there's vacuum at that port on the base. Then check to make sure the hose isn't plugged and the pcv valve itself isn't clogged. Is the splash shield in place over the rockers where the pcv hole is in the valve cover? If not, oil can be splashed into the pcv valve and clog it very quickly.

If none of that works, then I'd surmise that you're getting a lot of blow by past your piston rings and that's putting more pressure in your crankcase than the pcv valve can handle. The only way of fixing that is to re-ring the engine. Hopefully you'll find something before it boils down to that.

Ed

[joeinbcs]

Hey Ed,

Thanks for the interest.

I checked the vacuum lines, and the one on the top rear of the carb was off.

After a little more investigation, I realized that the smoke was not caused by oil being forced out of the filler cap and dropping on the exhaust manifold. It seems that smoke is coming out of rocker covers, both at the oil filler cap and at the PVC valve if I remove it. Is this normal? Any idea what could be the cause?

Thanks, Joe

[RivNut]

Joe,

It sounds like an excessive amount of pressure in the crankcase. In the earlier years, before emission concerns, the valley cover had a draft tube running from it to the bottom of the engine. It allowed all of that pressure and resulting oil smoke to be routed to the road.

Was it like this before you had the carb rebuilt? If not, start there.

If it was smoking before, it might be time to run a compression check. If you don't have any compression to speak of, the pressure from the compression stroke is allowing air to enter the crankcase past the piston rings and it's pressurizing the crankcase. If that's the case, it's time to re-ring the pistons. Hopefully before you have to do this, something will turn up.

Ed

[joeinbcs]

Thanks, Ed.

No, it was not smoking before.

The guys who did the carb rebuild had the valley cover off to replace the gasket. I don't think there was anything wrong with it, but they recommended doing it as long as the intake manifold was off to replace the plug on the underside (which had deteriorated).

Where exactly would I look for the "draft Tube"?

Thanks, Joe

[RivNut]

Joe,

I emailed you directly.

I'd go back to the shop where the carb was rebuilt and tell them what's happeing. It almost sounds like there's no vacuum in that large port on the back of the carb base. That port has a T screwed into it and supplies vacuum to your brake booster and the PCV valve. Do you have vacuum in your booster?

If this is something that wasn't present before the carb was built, I'd be headed over there first thing in the morning and talk with them.

Ed

[joeinbcs]

For anyone who may be interested...

I took the car back to the guys who did the carb rebuild today.

Unfortunately, I was not there to see exactly what was on the intake manifold when the car was originally disassembled. But, the guy who did it claims that the stainless steel baffle was cut exactly like the gasket. Because he couldn't get the gasket off, he used the new stainless baffle that I provided from Old Buick parts, which I learned today was not the same as the old one. It did not have a cutout like a smile in the front, matching the gasket.

When we took the thing apart today it was quite apparent that the new baffle was missing the front cutout that seems to mirror the opposite (back side) of the carb. This was quite a puzzler, as it seemed that the carb or intake was on backwards. As there was simply no other way to put both pieces on, we drilled and cut the baffle to match the gasket and put it back together.

I don't know yet if it will solve the smoking problem.

I'd be interested if anybody else has had this issue come up.

But, I now have a new, slightly more urgent issue. While coming home from the shop, the accelerator stuck open and it was a wild ride until I realized I could reach down and pull it our. Not sure what's causing this either.

Any thoughts from you "been there, done that" fellas will be appreciated.

Thanks, Joe

[RivNut]

The stainless gasket does not have the 'smile' cut in to it. The fiber gasket's 'smile' allows hot air to reach the stainless gasket which in turn heats the base of the carb. If you let the gasses from the smile make contact with the aluminum base of the carb, those gasses will corrode the aluminum.

There's only one way to put the carb on, that's with the linkage on the driver's side. Chances are your return spring for the accelerator came loose.