O ring lube

37chief

Well-known Member
Location
California
My dodge water pump has a large O ring instead of a gasket to seal the water pump to the block. I thought about just some grease on the O ring to help it to seal. What do you think?The person before me used a sealer of some kind. The block surface had to be scrapped off, of what ever the sealer was. Any thoughts? Stan
 
37 chief,

On my Dodge Cummins, I lubed the square-cross section rubber ring with antifreeze, just got it wet enough to ensure it didn't bind, twist, cut. Figure the original manufacturer did the same, if not less.

D.
 
I would be hesitant to put any kind of sealer on it. The seal is made by compressing the O-ring into the groove when you tighten it down. Sealers could interfere with the sealing ability of the O-ring. I would suggest some non-hardening grease to keep it in place during installation.
 
I used to just rub on Vaseline until I discovered Plumber's Lube in a tube. It's a fairly light grease that works well.
 
I am cautious about using any petroleum products on orings. If they are pure rubber the petroleum can damage the oring. Grease and Vaseline are both petroleum products. If the oring has a lip to hold it in then I would use soap to lubricate it when installing it. If you need some thing to hold it while you install the water pump Then get a silicone paste lube made for orings. It is thick and will hold the oring while you install it.
 
I have used white lube on these type of rings many,many times,and never had a leak.If I have any doubt about an o-ring,or it's mating surface,then I use silicone sealant,usually red or grey.Mark
 
O-rings seal on their own. The only reason for lube is for installation to it doesn't roll or pinch. I took the thermostat out of my '99 5.4 Ford and put it back with the old one about eight years ago. Never leaked. As far as petroleum? Common O-rings are either nitrile or Buna N. Both are OK with oil, antifreeze and hydraulic fluid.
 
Those orings are not rubber ones. They are Neoprene or Nitrile they will not be hurt by petroleum products.

Think about the orings used in cylinder blocks around the cylinder liners. They can easily be damaged by petroleum products. I have seem an injector pump seal fill the crank case with diesel fuel. shortly after that the liner orings can fail leaking water/antifreeze into the oil. This is why most liner kits tell you to use soap to lube the liners during installation not any petroleum products.

So when I do not know the composition of the orings I steer away from using petroleum products as lube.
 
(quoted from post at 20:04:51 02/07/16) My dodge water pump has a large O ring instead of a gasket to seal the water pump to the block. I thought about just some grease on the O ring to help it to seal. What do you think?The person before me used a sealer of some kind. The block surface had to be scrapped off, of what ever the sealer was. Any thoughts? Stan

Number 2 Permatex. 8)
 
I have used Only Vaseline to lube sleeve O-rings for over 40 years not one has ever failed to my knowledge, I started using it at CASE recommends it,,, just the way I do it,,,, but I NEVER install it on the orings before they are installed on sleeve or in block as this can and will cause them to roll and fail,,,, I cannot count how many I have done over the years
cnt
 
You worry about oil and o rings????? What do you use to seal hydraulic orb and ors fittings then? Or cat flange? Most o rings are made to take oil just fine except for a few exotic ones
 

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