Oil burning: Valve Seals or Rings?

[Bob B.]

Hi all,

Although I didn't figure out all this till after the fact, I had a piece of crud stick in the needle seat in my carburetor. This caused the carburetor to flood my engine and I had to keep the RPM at about 1,800 minimum to keep the car from dying. I was out of town and drove the car 75 miles to get it home. Now my newly rebuilt engine is smoking. Worst fouling of plugs is on cylinder 4. Some tell me that the extra gas washed the cylinder of oil and ruined the rings.

It seems to smoke the most when it has been sitting at idle and sometimes after going down a grade with the clutch in low gear. So, others tell me that it is the valve seals.

Is there a good way to really tell which is the problem? Is there a way to replace valve seals without pulling the heads? I'd like to try the valve seal approach first, but I don't want to do that and then repeat a lot of work all over again when I find it is the rings and I have to do that.

Thanks,

Bob

[Duke W.]

Re: Oil burning: Valve Seals or Rings?

I think you will get better analyses if you provide more information.

Year and engine option? OE or modified?
How many miles on the rebuilt engine?
Did you rebuilt the engine or was it done by a commercial service?
Did you notice any oil consumption prior to this incident?
Is the smoke biased toward one side or equal on both sides?
What kind of rings and valve seals were used?
Does the engine seem down on power?
Have you run compression and/or leak down tests? Results?

Duke

[Bob B.]

Re: Oil burning: Valve Seals or Rings?

Duke, Responses below. Thanks, Bob

Year and engine option? OE or modified?

1960 283/230. Stock.

How many miles on the rebuilt engine?

About 200 before the carb problem. 2K+ on Boston Road Tour and more at other events since. A can of Restore seemed to help. The engine is not burning a lot of oil, but it is burning some. Also, I changed the oil following discovery of the flooding problem prior to driving more than the 75 miles just in case there was some contamination of the oil by the gas.

Did you rebuilt the engine or was it done by a commercial service?

Local machine shop. Bored 30 over.

Did you notice any oil consumption prior to this incident?

No.

Is the smoke biased toward one side or equal on both sides?

More on the right. Second cylinder from the front right shows the most fouling of the plug.

What kind of rings and valve seals were used?

Rebuild kit from Auto Zone. This was in 2003, so not sure what brand. Car not driven till fall of 06.

Does the engine seem down on power?

No.

Have you run compression and/or leak down tests? Results?

Not yet.

[Duke W.]

Re: Oil burning: Valve Seals or Rings?

Isolating oil consumption to rings or valves can be a tricky diagnosis.

You should run a compression check - wet and dry paying particular attention to #4. A healthy engine should show consistent numbers across all cylinders.

Look at your rebuild documenatation and talk to the machine shop about the problem. Were the valve guides rebuilt? How? And what kind of sealing system was used?

Since you only had 200 miles before the stuck needle valve and noticed the oil consumption afterward, I wonder if the problem could have been there from the start. Understanding exactly what was done to the guides and what parts were used can be useful in making a diagnosis.

It's possible for fuel washdown to damage rings or walls, but this usually happens over a longer period of time/mileage, so I would not buy that diagnosis without further testing and analysis.

I think the first step is to do the dry/wet compression test and understand the nitty gritty details of the rebuild.

Duke