Unusual automated oil filling

[Damian]

Hi, long time reader first time poster.

The problem i am having is with my engine oil. It seems to be automatically topping up.
I will tell my story from the start to give the best understanding.
I bought my Navara D40, 2008, 4X4 second hand around the end of May. First thing i noticed was the engine oil was drastically overfull. I dropped 5 litres of oil to bring it back to the correct height. Very surprising no damage was done. Back then i just thought the guy i bought it from was an idiot, but i see now there might be more to it.
About a month later i dropped the oil and replaced. i didn't notice at the time but i suspect it would have been overfull.
Another month and this was when i first noticed something was odd. The oil level was showing high on the dipstick and i had to drop approx. a litre out of the engine.
Another month on which brings us to today. You can probably guess what i was doing just before i wrote this post. Lying under the Navara dropping approx. a litre of oil out of the engine.
It appears that i am gaining a litre of oil every month.
My best guess on what is filling up my oil is diesel, but i dont know how or why.
If anyone has any experience of this please let me know. Your help is much appreciated.

Thank you

 

[Rumpig]

I think there's a fuel line thats inside the rocker cover that is known to leak. Having diluted engine oil isn't good and will cause engine destruction. More common on the patrols i think.

http://www.patrol4x4.com/forum/nissan-patrol-gu-gr-10/ip-problems-return-fuel-line-mod-50959/

Could be something else.

 

[Old.Tony]

Welcome to the forum.

That's the first time I've heard of this problem, but fuel in the oil would be my first guess because you would have noticed water in it - diesel is oily and would mix in the crankcase oil almost imperceptibly.

I imagine though that there's a test that can be done to determine if there's diesel fuel in the sump oil. I'd grab some of that oil fresh from your crank and have it examined, then go looking for the source. I think there's a fuel cooler embedded in the side of the engine block - that's one possible source.

 

[RustyNav09]

I'm interested to hear thew cause. My guess would be if you let the oil sit the diesel may settle to the top. Also have it tested aswell.

 

[nathand22]

Does it smell like diesel at all??

 

[tweak'e]

the fuel return mod was only for the ZD30 non crd engine as spill line goes back to inlet which becomes pressurized when adding a lift pump.

looks like crd has the spill line going direct back to injection pump, so that should not be an issue.

if it was a litre of diesel a month i would have expected it to smell of diesel and also your turbo would have blown by now.
are you sure its not the difference between hot and cold?
or that someone else is topping up the engine at the garage when they refuel?

 

[qqc d22]

blow by. will have low compression(stuffed rings) or valve seal gone probably. not the answer you won't but more than likely what it is. does it smoke really bad on start up could have a leaking injector and its filling a cylinder and slowly dribbling past the rings while its cool.

 

[Damian]

Thanks for the replies.

To answer some of your questions.
I've tried smelling the oil, but diesel engine oil has a strong smell to it and it would be very diluted so i cant be sure if i can smell diesel or not. In saying that, i am almost certain that it is diesel. All other oil levels have maintained the same and as Tony said water in the oil is quite obvious to pick. So what else could it be?
I am also trying RustyNav's thought on leaving some oil to sit and see if any diesel separates. I will check in the morning.

Question for Old Tony. I haven't seen any mention of a fuel cooler in the engine block in the workshop manual. Do you know where it is located?

Tweak'e i am positive its not the difference between hot and cold. This is the second consecutive time i have dropped a litre of oil and it is reading full on the dipstick. I usually check the oil after driving home from work when the engine is hot. Giving 10-15mins for the oil to settle.
There's no chance someone is filling up my oil for me. Nobody loves me that much.

Haven't checked compression due to not having a gauge for a diesel motor. But there is no loss in power and no smoke to speak of.

I pulled the rocker cover off this afternoon and had a look at the fuel spill line. Its hard to say but there was no obvious leakage and as Tweak'e pointed out the line isn't pressurised, infact it has a vacuum so if there was any leakage it would be very minimal.
My guess is a leaky injector or two. After shut off there could still be some pressure in the lines resulting in the injector leaking onto the piston and then seeping past the rings into the sump. By the time i start up the car the diesel would have drained off the piston which is why i haven't noticed any smoke. A litre of fuel over a month isn't as much as it sounds. I think a leaky injector could achieve that especially if it is more than one.
That's my thoughts at the moment, but i could be wrong. Getting injectors checked and maybe replaced is not going to be cheap.
I should start saving.
If anyone has any other idea's i will gladly take them into consideration.

 

[Old.Tony]

My mistake, was thinking of another engine that has it in there. Ours is under the floor.

Your notion about the injectors is possible. Left alone, it would have to lose 30ml per day or just over 1ml per hour to add a litre in a month. That's a slow drip! Have you tried injector cleaner?

 

[JPMC]

The vacuum specs for the spill line are
Standard: – 53.3 to – 66.7 kPa (– 533 to – 667 mbar, – 400 to – 500 mmHg, – 15.75 to – 19.69 inHg) outside of this the gasket may need replacing.

If it's injectors I have a source for brand new Denso euro 4 injectors for cheap (around$300AUD each) or you maybe able to get yours reconditioned cheap locally.

 

[tweak'e]

injection pump could be leaking through the front seal into the crank case.
if it was injectors i would have thought it would be running poorly.

i would not drive it and take an oil sample to be tested. that will tell you if its fuel or not.

 

[qqc d22]

I don't know about crd diesel but both petrol and older diesels will run fine with a leaking injector you only usually notice it on start up. Oh and your oil level can grow sometimes

 

[qqc d22]

My 2.5 in my d22 actually looks to be Growing oil slightly to. I havent had a proper look yet but Im sure it was just under the full mark when I did a oil change now it is probly 7mm above the full mark. How much is yours moving on the dip stick mate just Curious

 

[Damian]

Yes 30-35ml per day. But 1ml per hour would mean the car is in operation 24hours a day. If i am right i am getting the fuel seeping into the oil after shut off when there is still some residule pressure in the lines causing the injector to leak.
I use the car approx. 1-1.5 hours a day, but more importantly in two trips. So it's approx. 15ml each time i shut the car off. Which could be spread along a couple of injectors.

 

[Dave]

How's it start in the mornings ?

 

[Damian]

Its starts fine in the mornings. Probably 2 cranks on average and no smoke to speak of.

 

[Damian]

Both times i dropped a litre of oil it was showing above the highest bump on the dipstick. Probably 10mm

 

[Damian]

How would i check if it's the fuel pump Tweak'e. Is there places i can look to check for signs of leakage or does it need to be removed to get in to it?

 

[tweak'e]

not to sure on the cover layouts but pull off the front cover .

 

[Damian]

I went with my gut and pulled the injectors out and took them in to be tested. Turns out the injectors are fine, working perfectly...unfortunately.
So now i have to put everything back together. Making sure everything is in shipshape. I will buy some new copper washers for the spill line and vacuum test it to make sure there are no leaks. There is still a chance that it had some leakage.

The mechanic mentioned the Diesel Particulate Filter might have something to do with it. I used to think it only worked when the indicator light came on, but after what the mechanic told me and researching it on the forum i realise that he may have a valid point. From what i understand the DPF is more like a system that runs all the time using information from the various sensors in it. It changes engine operation to better burn off the excess soot and particles in the exhaust. The indicator light only comes on when a certain amount of particles have filled the filter and it needs assistance to burn them off, eg. by increasing the rpm to create a hotter exhaust.

So this makes me think it could be something faulty in the DPF. I have heard one of the ways the DPF works is by increasing fuel delivery or double injecting in certain pots. Which would create an excess of fuel and if this is happening often it could be enough to seep down to the sump.
What are your thoughts?
I will have to have a better look at the fuel pump as well, next weekend.