Engine runs with no air !!

[Jerome74911S]

OK, it's getting air from somewhere, but this is a puzzle to me.

First start after a winter slumber, and I let it idle at about 2200 rpm to get the oil up to operating temperature, but there was a small burble in that high-speed idle every now and then. So, after checking the oil level at 900 rpm I shut it off to have a look.

I could not see anything that looked 'off'. I checked the tightness of wires, looked for any evident air leak sources, etc.

I started it back up and once again set the idle at 2200 rpm.

When I firmly placed my palm over the air intake snorkel, the idle only dropped to about 2000 rpm !

This would suggest a colossal air leak, wouldn't it? but when I returned the idle speed to 900 rpm the engine idled fairly well. True, it wasn't silky smooth at idle, but it wasn't rough or popping, as a serious air leak would suggest.

Thoughts ?

[timmy2]

Vent line from oil tank will supply lots of air to the popes hat. The air filter box cover isn't sealed well and the vent tube on the bottom is an air leak before the metering plate.

[blucille]

I'd look at how your air filter and air box meet the cover

[john walker's workshop]

The brake booster hose can rot and split down by the trans, where it loops over the torsion tube and attaches to the tube through the tunnel. A mysterious high idle you can't turn down. Clamp the hose in the engine area where it comes out between 2 and 3 intake runners and see if the idle drops.

[Jerome74911S]

Well, duh. I plead insanity.

The oil tank cap was still off, and also the snorkel/air cleaner cover was ajar. That must be it.

I'll verify this analysis by running the engine again, but it will have to wait for a couple of hours.