Oil Leak help, anyone seen this before?

[oldtymer]

First post here from a brand new T owner - just purchased in July. Has anyone ever seen an oil leak coming from the exhaust manifold? Its a 1921 Roadster Pickup conversion with 1924 engine that was supposed to be redone. Noticed an oil leak on the engine right side, thought it was coming from the breather, but after I cleaned it up, the oil is actually coming from the exhaust manifold at the #1 cylinder! I expected the old girl to smoke some but it seems to be more than I expected, especially after it is warmed up. I pulled the plug and sure enough it was wet with oil. Am I facing a cracked block as my first project?

Thanks for any help,

Doug Adams
817-350-3766

[GrandpaFord]

Hi Doug,

Welcome to the affliction. There are actually two problems, the manifold gasket is not sealing and you are getting oil in the cylinder. There are two kinds of gaskets for the exhaust manifold, a flat one which is an after market product, and copper rings that are used in conjunction with steel rings that locate the manifold. If the manifold is warped the flat gasket is the only one that will work. The surfaces of the block and the manifold have to be flat and the manifold surfaces should be in the same plane. The exhaust manifold can be dressed with a large file.

The oil can be coming from two sources: blow by from the rings and valve stems that are loose in their guides. If the engine has been worked on recently then it is possible that the piston rings have not seated yet. You can learn a lot by doing a compression check but will need to buy or borrow a gauge. You can do a simple compression check by cranking the engine over by hand and noting how much force it takes. If you can hear air leaking at the oil filler tube while you hand crank the engine over the rings are leaking. You should be able to develop 45 to 55 psi using a gauge. To check the valves you will need to take the head off and see how much sideways movement you get when the valves are up. You should not have more than about 0.003 inch movement. You can buy valves with larger stems and then ream the guides. If the rings are old and worn out you can buy new piston rings, assuming the bores are not worn too much.

Try to locate the person who last worked on the engine and ask them about the oil issue.

It is unlikely that an oil leak is coming from a crack in the block.

[Jem]

I have had oil sucked up into the cylinder by a poor fit of the spark plug, the thread in the head was worn. Not sure of the physics of why it did that but I fixed it by wrapping some aluminium foil round the thread.

Warped manifolds are common, you can heat it up to cherry red and clamp to the block till it cools (best done on a junk block) or just buy a new one. I'm running a repro, it is fine.

[oldtymer]

Thanks for the replies. So I contacted the previous owner and verified the engine was completely rebuilt with new babbitt, pistons, rings and oversize (.015) valves, .280 lift cam, Z Head. It also has the high volume external oil line kit installed. Previous owner stated the oil line could be why the #1 cylinder is the only one showing a leak. I plan to test the compression and if its OK, change the manifold gasket and call it good, expecting to clean the #1 plug more often.

Anyone else heard of issues with "too much" oil flowing to the #1 cylinder using the high volume external line?

Thanks!

[Norman Kling]

when the connecting rod goes into the pan, it throws oil up in the cylinder. The faster you go, the more oil is thrown up. If the rings are good, you shouldn't have oil going all the way up into the top of the cylinder. If the rings are new, there is a possibility, all the ends of the rings line up with each other and that would cause it to get oil into the cylinder. The rings should be installed with the ends of the rings in different places so the blowby doesn't go right through into the combustion chamber.
The other possible cause would be very loose valve guides which would cause oil to be drawn into the cylinder on the intake stroke. Oil should be forced back into the valve chamber by the exhaust if the leak were in the exhaust valve guide. So I think your problem is either ring problem or valve guide problem. Normally you would not have this much oil going into a cylinder if the engine were rebuilt. Possibly might have more oil until the engine breaks in. This would explain how the oil gets into the cylinder, but the leak out the exhaust gasket, would be a poor seal between the manifold and block. The above posts indicate how to fix the exhaust leak.
Norm