Volvo MD 11 C Water Pump Leak

[fresh water]

my fresh water pump housing leaks at engine interface. I sanded both faces with 800 grit. When I ordered gasket supplier sent an O ring which I installed still leaks.

[model 10]

If the mating surfaces need work, don't mess with 800 grit. That is way to fine. Start out with 120. Everybody hates it but silicone works great. Get the gray stuff, it's the hardest.

[fresh water]

thanks but I am worried about material coming loose and getting into engine. I have heard that a larger O ring might work

[barnakiel]

I use ferrari sealant (liquid gasket - red) seems to work fine.

b.

[MarkSF]

You use an O ring, or sealant, but never both together. You should find out why the O ring is leaking. Damaged surfaces, distorted ones, O ring under insufficient compression?

Are you sure it's from the joint? Could be from somewhere else, and running down to there. The water pump shaft seal springs to mind.....

Hang on, does it require a gasket or an O ring? An O ring has a groove. If you don't have a groove, an O ring is not appropriate.

Sealant CAN work together with a gasket. Don't use silicone though, as bits can block passageways. The best is a non-setting gasket helper like Permatex 2 :

http://www.westmarine.com/buy/permat...DQJxoCQrTw_wcB

[jimbunyard]

An oring with a thicker cross section might do the trick.

In an ideal world you shouldn't need or use sealant with orings. Problem is I've never been to this ideal world. A little judicious use of silicone won't hurt anything, and might solve the problem.

Volvo is notorious (in my experience) for using orings of insufficiently thick cross sections. When I rebuilt my TAMD41, I used OEM Volvo seals and my tappet covers, torqued to Volvo spec, leaked badly. Copper siliconed them and tightened to my intuitioned torque (tight enough) and they didn't leak anymore. The w/pump oring leaked too, I added a homemade gasket (and left the oring in place as well) and no sealer and stopped that too.

I assume that it is oil that is leaking?

You might check the crankcase pressure also. If it's too high it can cause oil leaks.