smoking flathead

[Phil Martin]

I know I'll hear criticizem for a dumb question but I'm a tough old man, I can handle it. When running for a while at 55 mph or so I let up and coast down to say 20 mph. I lay out a fair cloud of blue smoke. Does this indicate bad rings or valve guides letting oil by?

[greg g]

could be either, although worn valve guides will usually smoke pulling away from a stop light when the high vacuum at idle can pull oil up and into the combustion chamber. How is your compression??? But you can also be pulling oil past the rings under the highvacuum coasting withthe throttle closed.

[Phil Martin]

Doesn' smoke pulling away from stop, just when I step down on it after coasting down under compression. Last time I checked compression all were a little over 100. That has been a while and it seems to be getting worse after driving for a while.

[greg g]

good compression points to worn valve guides, or perhaps the valve galley area is not draining oil like it should.

[1941Rick]

Usually when decelerating and smoking indicates worn valve guides...wore rings will smoke under power.....as a rule...but then what are rules for....

[Rusty O'Toole]

Valve guides.

[Jim Saraceno]

I noticed my car will do that while engine braking going down hill. Probably similar conditions.

I know it's not the valve guides as they were replaced along with the valves (and just about everything else) when I rebuild the engine.

[Dodgeb4ya]

How many miles on your engine?

[Phil Martin]

Shows 57,000 don't know if thats right or 157,000 runs great but smokes

[B1B Keven]

Phil, my 218 did the same thing. Smoked so bad comin' up to a stop that the cars behind me would slow waaaaay down.

I added a can of Restore and it quit.

[Phil Martin]

I put a bottle of lucas oil in it last year and it helped. Went on a cruise last sat and it really got bad. Maybe time for a tear down this winter.

[Dodgeb4ya]

Sounds like a rebuild is necessary to do it right.

[Dan Hiebert]

Sage advice from the forum - valve guides. My car is just over 157,000, and you can always tell where I've been by the blue cloud I leave behind. (Comes in handy with these New York tailgaters ) Acceleration, deceleration, doesn't matter. It only doesn't smoke when I'm at a constant speed. I have no clue what the PO did with the engine, but I've done the bearings, rings, and cylinders. The smoking increased with the new rings and cylinder hone - meaning the compression improved in the cylinders so they are more efficient at sucking oil up past the worn valve guides on the intake downstroke. I'm pretty sure the valves and guides are original. I can only guess at what the acceleration vs. deceleration smoking difference is, perhaps a matter of just HOW worn the valve guides are. And yes, I am fixing that, it's my winter project this year.

[greg g]

Many shops used to knurl the interior of the valve guides. This is a rpocess where a tool raises some of the metal in the guide so that it seals better against the valve stem.

It is by its nature a temporary fix, that was done to used cars to prevent excessive smoking (at least for a while) or old beaters that didn't get much use. I wonder if there are any places that still perform the process. It was one of those thinks that could be done withthe engine still in the car.

[Young Ed]

I wonder if there are any places that still perform the process. It was one of those thinks that could be done withthe engine still in the car.

I'd bet our engine guy would do it.

[dezeldoc]

New guides are cheap, it would cost more to knurl them. 1941Rick is right on the money with this statement.

[Phil Martin]

Planning on tearing down this winter. The repair manual makes it sound easy to replace guides. I'll find out. Also new rings and rod and main bearings. hope its not too hard to pull an engine with fluid drive.

Edited November 18, 2011 by Phil Martin
added more

[Dodgeb4ya]

You will probably find damaged piston ring lands too.