Fuel in oil

Craig_C

Craig_C

Resident Smartass
Joined
Apr 7, 2010
Messages
1,714
Getting fuel in the oil at a pretty fast pace, no white smoke, no hard start, runs good and smooth. Most likely CP3? And any way to diag for sure without removing pump and taking to injection shop?
 
I have been able to take off the cover and use a mirror and see them leak when started. Also have seen them run fine and it be leaking out of an injector as well.
 
I have got a jug of fuel and put dye in it and use and electric lift pump to pressurize system. Take the access cover off for cp3 gear and see if you get luck that you can see through there with a scope, but most likely will have to take front cover off to see it because the hub of the gear is almost as big as the access cover. But is worth a try before going through the work of removing front cover in my opinion
 
I have done nothing but change the oil to verify something weird was going on. Figured the easy route would be to pull the cp3 and have it checked. It's putting fuel in the oil at a pretty quick rate, and with no white smoke, no hard starts, no rough idle/running I kinda thought cp3.....though I do have this annoying clatter I can't get rid of with SSR, even after taking rail pressure below the factory settings
 
I always pulled the valve cover fired it up and then brought up to 1500 or so then shut it off. Rail pressure will speak and most times show the fuel leak.
 
X2 on dye in the fuel, u can get some from cummins. Dye and a black light works well.
 
Tried dye last night, at idle, no signs of the dye. No visual leaks with the valve cover off.
 
Ive got one doing the same thing, are yall finding it leak at the CP3 very often. I work for CAT and am very used to injectors leaking.
 
DRT086.7 said:
Ive got one doing the same thing, are yall finding it leak at the CP3 very often. I work for CAT and am very used to injectors leaking.
Click to expand...

On Acert engines? Where the fuel goes into the head and then to the injectors, and injector have 2 orings them I believe. Been a while since I worked on one. The cummins is a little different in design as it has a tube in the head that goes to the injector that in my experience can leak but seal in cp3 has seemed to be more common. Usually the cause if the tube leaking is them not being torqued to right spec whether its not tight enough or over tight. The correct torque spec is critical with the tubes.
 
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I was talking about the CP3 leaking. And I work on alot of CAT and Cummins I just rarely every get fuel in the oil on Cummins. Every time Ive seen a Cummins fuel issue its had to do with the quill tubes.
 
Ok revisit this.....had the cp3 and injectors tested. Neither are under warranty, and everything came back good. Being that they are not under warranty, I have to assume they truely are ok.

They are telling me that the issue is likely the connector tubes. I am having a hard time wrapping my head around how a leaking fuel tube could get fuel into the oil. The truck starts right up, no rough idle.

I don't want to keep running the engine looking for the issue and end up killing the bearings. Any ideas???
 
I assume all your o-rings on the injectors were good... return line pluged? What caused you to notice the fuel in oil, regular maintenance or recent upgrade??
 
I just spent ALOT of money overhauling the engine....so I check oil pretty regularly.

I did not notice any obvious cuts or nicks in the o-rings. The return is -6an out of the back of the head, into a manifold block, then to the stock return line. I would seriously doubt it's plugged though I'm going to check it.
 
Have you messed with the return system at all from the cp3(s) ?
 
Single cp3, it too has -6an into a manifold block.

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remove valve cover and unplug fca if you have a leaking injector it should show up there.

who tested your injectors?

Also If your connector tubes were leaking the fuel would just get returned the tank.
 
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