871 gear fuel pump
01-08-2026, (Subject: 871 gear fuel pump ) 
Post: #1
871 gear fuel pump
So a couple year or so ago I replaced my geared fuel pump and gasket(this is on an cm871)and it always seeped a little bit of fuel. I torqued bolts to spec even double checked after a while and still seeping. So about a month ago i installed new gasket thinking the old one was bad. Triple checked torque made sure everything was clean as well at install and lo and behold it still leaks. The ifsm was replaced at the same time as gear pump so I can’t see it being a bad mating surface.
I’m paranoid about stripping the aluminum bolt holes so is there some sealer I can use to help it?
The only other thing I can think of is my torque wrench may be to old and not working properly anymore. Thanks


User's Signature: 2010 kenworth t800 isx500hp cm871 13spd 3.55ratio
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01-08-2026, (Subject: 871 gear fuel pump ) 
Post: #2
RE: 871 gear fuel pump
maybe make sure the mounting surfaces are really flat?

As far as I know, I have never seen one leak like that, so something is likely wrong there in your situation.


User's Signature: ->: What I post is just my own thoughts and Opinions! --- I AM Full Of S__T!.
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01-08-2026, (Subject: 871 gear fuel pump ) 
Post: #3
RE: 871 gear fuel pump
O-ring look ok?


User's Signature: It's hard to win an argument with a smart person, but it's damn near impossible to win an argument with a stupid person
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Yesterday, (Subject: 871 gear fuel pump ) 
Post: #4
RE: 871 gear fuel pump
I will have to checkout everything when I get it pulled back in shop to fix some other things and run the overhead. Both the pump and ifsm are cummins. Honestly I do not remember what oring looked like the old gasket looked fine from what I could tell


User's Signature: 2010 kenworth t800 isx500hp cm871 13spd 3.55ratio
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