Fuel in oil

[LB7_01DURAMAX]

Truck was making oil so I pulled injectors and had them tested. They came back ok. So put those back in and bought new return lines. Started it up and it’s still making oil. So I took oil fill tube off to look to see if the seal was leaking. Didn’t see anything. Had a bore scope to look as well. I also put fuel in a funnel and hooked it right to the return fitting on injection pump and no fuel leaked down. Pump was replaced in 2015 by previous owner at a Chevrolet dealer. I’m at a loss and very frustrated with this thing. Time for a pump or what?

 

[DAVe3283]

When you put the injectors back in did you pressure/vacuum test the return line before closing up the heads?

How the the high pressure fuel lines look, any corrosion or putting on the ends?

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[LB7_01DURAMAX]

When you put the injectors back in did you pressure/vacuum test the return line before closing up the heads?

How the the high pressure fuel lines look, any corrosion or putting on the ends?

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I did not pressure test them. I replaced injectors in 2016 and bought new high pressure lines then so they are good as well.

 

[DAVe3283]

High pressure lines can go bad in months if they get water on them, but so long as you carefully inspected them, they can be fine.

I would recommend doing a pressure test of the return lines, since it doesn't require removing the valve covers. Then you can at least rule them out at the cost of a couple banjo washers. Or maybe you find your problem.

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[2004LB7]

LB7: - Injector Return Line Leak Test

Hey all. I have a Mity Vac ready to go for tonight. I am aware of the 15 in-Hg vacuum test...and the 15 psi pressure test to find a leak if the vacuum test fails. However, could someone please point out all potential places to attach the Mity Vac? Valve covers are off, supply and return lines...

www.duramaxdiesels.com

 

[PureHybrid]

We tried to pressure test the OEM return lines at work, couldn't get them to seal up very well at the bolts we used to block them off. So he bought new return lines.

Also had the engine running with the valve covers off and didn't see anything... Told me it's putting half gallon of fuel in the oil just idling for a few minutes, probably wouldn't get that much even if the return lines were unhooked completely lol

 

[DAVe3283]

Yeah, if it is getting that much it has to be a CP3 front seal or a high pressure feed line.

 

[LB7_01DURAMAX]

Would you think

Yeah, if it is getting that much it has to be a CP3 front seal or a high pressure feed line.

If it was high pressure line wouldn’t you think it would seep up between line and nut

 

[DAVe3283]

Would you think

If it was high pressure line wouldn’t you think it would seep up between line and nut

At least some (probably most?) of it, yeah. I know when I tried to reuse questionable lines on my Suburban, a lot of the fuel was leaking out the top between the line and the nut. But I believe some of it was also going into the oil.

 

[LB7_01DURAMAX]

At least some (probably most?) of it, yeah. I know when I tried to reuse questionable lines on my Suburban, a lot of the fuel was leaking out the top between the line and the nut. But I believe some of it was also going into the oil.

So I decided to pull the drivers side valve cover off and hook it back up and start it up. It was leaking down into valve train between injector and high pressure line at a fast rate. So hopefully that’s the only issue. Gonna get new lines and do one side at a time with valve covers off to make sure they are good.

 

[LB7_01DURAMAX]

Next question. What high pressure lines are the best. Stick with GM from Lincoln diesel or is there something comparable that is the same quality

 

[2004LB7]

Lincoln diesel doesn't support this site anymore. Plus they've been slipping on quality and customers service. I'd suggest contacting Brad or one of the supporting vendors here. They can hook you up with the right parts that will be appropriate for your vehicle

 

[DAVe3283]

Don't get reman lines, especially from Lincoln Diesel. I bought a set that were worse than my factory lines when they arrived, and getting them to stand behind them was like pulling teeth.

The new aftermarket options are intriguing, but I don't have any experience with them.

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[Bdsankey]

Personally I'd recommend GM, Fleece, or DHD. GM are my first choice as they're extremely proven and very good quality but they come at a cost.

Fleece have been great for me and I've used a ton of them.

DHD have been good as well, had one line that needed to be replaced due to a manufacturing issue which they sorted out ASAP but I have far less usage of them than Fleece or GM. So far so good.

 

[LB7_01DURAMAX]

Ok awesome. I ordered fleece lines. Thanks for all the input. Hopefully have the problem fixed before the weekend so I can drive my truck again lol

 

[LB7_01DURAMAX]

Well got my new high pressure lines on and started it and drove it down the road. Truck doesn’t have any power has p0089 and p0090 codes but there is a positive…..There is no more fuel in the oil!!!

 

[2004LB7]

Did you forget to plug the regulator connector back in?

 

[LB7_01DURAMAX]

Did you forget to plug the regulator connector back in?

I don’t believe so. but I didn’t really check things over 100%, had to get other things done other then the truck lol

 

[2004LB7]

I don’t believe so. but I didn’t really check things over 100%, had to get other things done other then the truck lol

I thought I remember something about.the possibility of accidentally being able to swap the ECT sensor connector with the regulator. Just check that they are in the right one

 

[LB7_01DURAMAX]

I thought I remember something about.the possibility of accidentally being able to swap the ECT sensor connector with the regulator. Just check that they are in the right one

Just checked them out. From what I see the ECT come out of main harness right behind sensor. I also pulled the top off of the main harness and looks like the FPR wires go over to the main connectors off the drivers side valve cover. I don’t think they can be flip flopped. I didn’t find the other end of FPR wires. That’s a jumper harness isn’t it?