Has anyone used AT 205 stop leak in their engine? I have a small leak at the front crankshaft seal.

 

Stop leak products work by softening and swelling the seals (all of them). It will temporarily stop or slow a leak, until the softer seal material wears out. Great for a car you're about to sell, not so much for one you care about.

 

There is no reason to ask the same question in multiple forums. I doubt that will be effective for a crankshaft seal.

 

I'm no fan of stop-leak products, but they can be worth a try. In my 100k-mile 1990 GMC pickup, a pint of Lucas Oil oil-stop-leak, 5 years ago, stopped a drip for good. Lucas is a (synthetic?) petroleum, versus the seal-swelling solvents of yore. Lucas is mum about how it works.

And, I kid you not, the service manual for my 170k-mile 1995 DD actually says to try a radiator stop-leak before yanking the whole front end to replace the radiator. That fix also worked, for 40k miles; its new radiator arrived today.

Both cases were worth their respective $9 investments and 3-minute service times.

 

Permatex 82099 Leak Sealer Spray.

I have used it on oil pan end gasket to timing cover leak and it worked but a crank seal? No way I can think of to band aid that.

 

Best way to put an end to that type leak is to replace the seal and repair the worn area on the damper by either: 1. chuck the damper in a lathe and turn and polish if not too badly worn or, 2. install a repair sleeve on the damper.