Engine/Transmission (1994 - 1998) Vacuum pump leak

[JRS]

Looks like my gasket between my vacuum pump and the case is leaking again. (every 100,000 miles, like clockwork) Does the gasket also serve as some kind of shim? Meaning, if I don't use it, will I still have proper gear mesh? FYI- I've been racing sports cars for 10 years now. You always want to used the grey silicone for oil service parts and pieces. The orange silicone will work for a while, but then start to leak oil. The best stuff is available at the Honda dealer and it's called Hondabond. It's a grey silicone intended for oil pans, etc. There are two kinds, a squeeze tube (for applying over paper/cork gaskets) and a pressurized can for making your own gaskets. You have to follow the directions exactly. I've used it on my racing transmission (metal to metal flanges, no gaskets) and it's the only thing that worked for a whole season. It worked great on my Dana 80 cover. no leaks. A close second is the grey silicone from Loctite, but it's not as good as the Honda product. The orange silicone is best for high heat, like header gaskets.

 

[JKure]

Im having the same problem with my 98 leaking in the same spot and i can also here a slight air leak there to. Is it a large job to change that seal? Would i need to drain engine oil also. One more question what are dodge and cummins part number for that seal? Thanks

 

[CumminsPower98]

I have had trouble with this gasket on a couple trucks including mine. I started using black RTV on both sides of the gasket even when new but I think it was having a hard time sticking as the gaskets are slick. I have since gone to a no gasket program on mine using RTV only and it's working fine. There is no need for the spacing the gasket provides as there is nothing critical with the gear mesh. Just make sure you adjust the power steering pump to block bracket for the slight move.



JKure, There is no need to drain the oil. You don't even have to remove the pumps or unhook the power steering hoses to fix this leak. You can simply unbolt the vacuum pump/PS pump assembly, unhook the engine oil pressure line on the bottom of the vacuum pump, remove the brace and slide the whole thing back. Sorry, I don't have the part number for this gasket in front of me. I probably have it at the shop...

 

[Shadrach]

The Cummins seal and gasket kit for the vacuum pump is p/n 4089742. It's not expensive. It fits 1992-2002 trucks. Shadrach