Blue smoke on Decel, Think I understand now Geoff Options

[DNHunt]

Got the bad news yesterday. Geogg Bleyseng followed me to lunch from the AX and said "Blue smoke when you slow down, bad rings or valve guides".

I calmly say "Thanks I was wondered where all the oil was going". Meanwhile I'm thinkin "Aw $hit, more $$$".

He says "Do a compression check then do another one after you squirt some oil in the cylinder. If it improves its bad rings if it doesn't it valve guides".

I proceed to ask several questions that show how little I really know but, I got to thinkin about it last night at a wedding reception (damn this 914 thing is an obsession) and I think I understand it now.

2 ways for oil to get into the cylinder, past the rings from the crankcase and past the valve guides from the valve covers (from crankcase via pushrod tubes). On decel there is a high vacuum in the cylinder (and intake) therefore oil is sucked into the cylinder from one or both worn parts and burned leaving blue smoke from the exhaust and extra oil usage.

Compression should be lower than desired because of leakage past the worm parts. Squirting oil in the cylinders will help seal the worn rings & cylinders and result in improved compression. But, if the valve guides are worn it will not help compression.

Low oil pressure at idle results from more oil escaping at the bearings and therefor less oil reaching the sending unit at the oil cooler.

Guess I'll do the compression checks Wednesday. More to follow.

And I repeat "Ah $hit more $$$".

Dave

[DNHunt]

Geoff,

By the way, I know you would kick my butt, for now.

Takes grease to make a good burger. Shakes are the best, hand dipped hard ice cream. Great place even a picture of a big old 59 Caddy.

As far as my engine goes it was rebuit in 93. It's got less than 20K miles on it so it is relatively recent. It's coming out this winter anyway. If its the valve guides I'll probably get the heads done then. I really would like to do another engine in 2004 if this one will last me until then. I had hoped to build something like a 2270 with a more aggressive cam, freer flowing heads, lightened flywheel yadda, yadda, yadda. Gonna have to treat the wife real good. I'll run some test and hope for the best.

Kevin,

I'm gonna start testin this out Wednesday afternoon. Compression, then again with some oil, and vacuum. Hope to have some figures Thursday morning.

Dave