Oil in Air Intake - Please Help

[n3833v]

Search rope & trick. One link is this;

http://cessna170.org/forums/viewtopic.p ... ick#p32664

John

[jrenwick]

Sorry, the "rope trick" has been discussed a few times in this forum, and I assumed it was part of the vocabulary. It's all about working on valves without having to remove the cylinder from the engine.

The trick is simply to push a length of rope (cotton clothesline is good) into a spark plug hole and fill the cylinder with it, at the beginning of the compression stroke. Then you can turn the prop forward until the rope is compacted and applying pressure to the valve faces. Holding that pressure, you can now compress a valve spring and remove the retainers so that you have access to the valve for what ever you need to do. In my case, I only wanted to be able to wiggle it and check for slop or a loose valve guide.

You could also remove the rope at that point and push the valve into the empty cylinder so you could ream or otherwise work on the valve guide. (Getting the valve back into the guide is another trick that can be done with a lot of fiddling and cursing.) When the work is done, you can push the rope back in, apply pressure to the valve face again, and reinstall the spring.

[GAHorn]

The reason oil ends up in the intakes is due to excessive valve-gude clearances. This can be due to either wear or improper reaming during rebuild.

Here's the scenario: The engine is run and oil is pumped by the oil pump to the rocker box cover. The engine is shut down and interior cylinder pressures cease. Oil now runs past the valve guide (no longer having to fight cylinder pressures and/or get sucked into the cylinder due to intake manifold vacuum) and runs down the cylinder intakes to the manifold (down at the carb) and into the airbox.

Similar leakage of oil can occur in the exhaust system, but goes largely unnoticed because hot exhaust gases burn off the oil in the next engine-run. The interior of the mufflers will exhibit carbon from this experience.)

My diagnosis: You have excessive valve guide clearances. (If you also have a cracked sump, that is a different problem.)

Sorry it took me a while to close this thread.
gahorn turned out to be correct in his post.
The oil sump came back from Canada with a bill for $80 for taking the digital pictures of the dye treatment. Called them and complained since there was no charge unless repaired promise. They agreed.
Send the sump to Drake which did a beautiful job of welding on a piece of metal on the outside of the pan. Problem fixed.
I wish I could post a picture - thats how nice the repair came out. Paid $550.00
All cylinders were re- reamed and problem is fixed. With the replacement of of one cylinder the whole thing came out to about $2500 in parts and the same in labour. Now running fine.
Thanks again for all the advice. GMAN

How about posting the most recent contact info on Drake? Thanks.

[Gman]

Drake Air, Inc
4085 Southwest Boulevard
Tulsa, Oklahoma 74107
(918) 445-3545
(800) 542-6899
Fax: (918) 445-5106
Email: ContactUs@DrakeAir.com