Has anyone ever used Lucas Oil Stop Leak and does it work for a Diesel engine? I have a small oil leak that appears to be coming from the head gasket. Was hoping that this might be a solution rather than tearing the engine down.

Fred & Cindy Cook
1990 32' Regency, Cummins

quote:

Originally posted by Jax:
Has anyone ever used Lucas Oil Stop Leak and does it work for a Diesel engine? I have a small oil leak that appears to be coming from the head gasket. Was hoping that this might be a solution rather than tearing the engine down.

Fred & Cindy Cook
1990 32' Regency, Cummins

Mechanic a can, I get this question every day in my shop. The answer is yes if the leak is coming from a worn out rubber seal. The only problem is the chemicals they use to "swell the seals" also weakens the seals only to have them fail completely a short time later. Also, every seal in the engine will now need to be replaced when before you may have only needed one. In your case I don't know if the head gasket is rubber so I cant be sure if would even be a temporary repair.

Where on the head does the leak show? There are many places where oil will leak, drip, spray out on the Cummins.

I had a head gasket go bad but it was a water leak, I had no choice but replace the head gasket.

I also would NOT recommend any type of additive to stop leaks either water or oil.

When I was in the Oil Bidness, these "fix-its" were called "mouse milk". None worked, and has been pointed out, many are harmful in the long run.

And an oil leak from a head gasket would be rare, but from a valve cover gasket, fairly common.

Thanks guys... I will not use the stop leak. It is leaking on the passenger side but it is also wet around the valve cover. The wetness around the valve cover does not seem to be enough to produce the volume dripping on the side of the block. It looks very deceptive as clean looking oil appears to be leaking out of the head gasket. I have already cleaned it up, so a photo now would not show much. I tightened the valve cover and will keep an eye on it and take photos after our next run to Branson next week.

Fred & Cindy Cook
1990 32' Regency, Cummins

On the passenger's side there is an oil pan breather hose. It is below the injection pump but still it get oil up a bit higher. I have replaced that hose and put a longer on it. If that hose is defective or not there, it will wt the entire side of the engine. Your being an 8.3L may be slightly different than mine.

Tightening the valve cover bolts usually doesn't help. Once the valve cover gasket is compromised, it need to be replaced. I do agree with Rusty that most of the top end oil leaking is from valve cover gaskets(s).

Pan bolts are another thing that should be checked.

If you have oil coming out of the bell housing, then you might have a rear main leaking. This is a problem with 5.9L engine for sure. That will wet the entire bottom end of the engine and leave a real mess each time you stop as it gets worse.

HTH