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Be advised that 'stop leak' products soften and swell rubber, sort of like oil does to untreated rubber. This will make it seal again, but also compromises/weakens every rubber seal/gasket in the engine.
Be advised that 'stop leak' products soften and swell rubber, sort of like oil does to untreated rubber. This will make it seal again, but also compromises/weakens every rubber seal/gasket in the engine.
That is true, but, like my case, it may get you down the road for a good while until some bigger issue causes you to replace seals/gaskets as part of the work...
Use Blue Devil - it often stops the leak:
It stopped my rear main seal leak on the 63 until I replaced it during a bearing replacement...it takes a couple hundred miles of driving to work...
I tried Blue Devil 'power steering stop leak' on my '67 PS valve, it was leaking like a faucet. It actually worked to my own disbelief. Still OK after one year and 1500 miles.
So I tried an experiment, I took 4 O-rings of 2 different sizes, and boiled 2 in BD Stop Leak. The second picture shows the 2 O-rings on the left are bigger after boiling them; they were the same size as the rings on the right, before boiling them. They didn't shrink back either.
I tried Blue Devil 'power steering stop leak' on my '67 PS valve, it was leaking like a faucet. It actually worked to my own disbelief. Still OK after one year and 1500 miles.
So I tried an experiment, I took 4 O-rings of 2 different sizes, and boiled 2 in BD Stop Leak. The second picture shows the 2 O-rings on the left are bigger after boiling them; they were the same size as the rings on the right, before boiling them. They didn't shrink back either.
Always good to see actual data. Thanks for doing the experiment.
I just added some to my 02 S10 with 270k miles on it. Seems better but I didn't clean the pan I have under it yet. It leaked a qt in 1000 miles so I will gauge it that way.
The newer "stop leak" products are plasticisers that mix well with automobile fluids, not like the old "ground pepper" or thick goo that used to clog leaky areas as a solution (and engine passages in some cases)....
There isn't much downside to trying the BD product other than your leak might not clear up. It can't fixed pinched or munged gaskets or seals - it doesn't fill holes... Nor fix the problems MikeM mentions above... Its not a panacea for poor repairs or owner screw-ups...
Last edited by Frankie the Fink; 03-28-2020 at 08:10 AM.
Well, this thread is timely! I just popped on to post something very similar about my '66! I have an oil pressure leak that I've been having trouble finding and results in a few drips after driving. After cleaning up the bottom of the engine and letting the car sit on ramps for a few days, there was nothing. Took the car out for a ride yesterday and when I got back, some small drips were there on the bottom of the engine.
This is a nice laundry list of things for me to check!
Originally Posted by MikeM
It might stop a rear main seal leak but it won't stop a leak....................
A loose oil line on your oil pressure plumbing to the distributor and gauge at the top rear of the engine.
A dislodged rubber seal under the end of the intake manifold gasket.
A valve cover leak
An oil pan gasket leak
Or most any leak on the front of the engine.
If you haven't already, check all these places first and confirm they aren't the source of the oil wetting.
Ten years ago I had a persistent leak that I swore was coming from the rear seal. Replaced the rear seal, which looked perfectly normal. Still had the leak Found out that the cam plug on the rear of the block was the source of the leak. Two teardowns to figure that out. Careful inspection is really what is needed like described above or it can cost a lot of wasted time and money.
03-27-2020, 09:05 AM
Lucas Stopleak
