oil level increasing? is diesel leaking into the oil?

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Mar 3, 2009
hi diesel experts,

i'm fairly new to diesels. i'm looking at a bj60 with 3b engine and the seller mentions the engine oil level is noticeably increasing...

what would be the most common reason for this? and is this something easy to fix?

if this has been going on for sometime, is it possibly causing major engine damage?

EDIT: IP = Injector Pump

I am not familiar with the drive on the inline IP for the 3B. I have never heard of diesel leaking into the oil from the IP (on a 3B but yes on a Nissan TD4.2). Some IPs on some diesels are gear driven off off the crankcase - like mine. It has one seal which keeps the diesel from the lift pump out of the crankcase. I have been told that it is very easy to spot when this seal goes - if you check your engine oil regularly. Your crank case oil thins and smells like diesel. Another possibility is that you have a head leaking coolant into the oil. It tends to froth up the oil.

The best way to figure out what is going on is to send a sample of oil in for analysis.

Bottom line - if engine oil level is increasing then you can expect a major repair bill.
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Maybe it's a Saudi version :)

Really, I'm with John. The 3B is a gear driven injection pump lubed by engine oil. I could imagine a bad seal though the injection pumps are pretty bulletproof.
Another possible cause is a defective injector, if the injector is leaking the fuel will not burn properly and it washes down the cylinder getting into the oil. Have the injectors tested.

If there's that much diesel leaking into the oil...don't you think you would be able to easily smell it in the oil?

my quick check indeed hinted some smell of diesel in the engine oil. did not have much time to investigate further though. i will probably take a mechanic with me next time i go check the bj60.

its a jdm 3b diesel, i don't know if its the same as us version...

thanks for the inputs so far.
its a jdm 3b diesel, i don't know if its the same as us version...

thanks for the inputs so far.

Depending on the date of manufacture it might be a rotary injection pump like the one on the 3B I put in my FJ45LV. I'm not sure how those are lubricated.
If it is a rotary IP, then the only lube it gets is from the diesel. It use to be the sulfur in the LSD which provided the higher lubrication needed. Now lubricant - such as biodiesel - is added to increase the lube quality of ULSD. The old rubber seals also relyon the aromatics in LSD to keep the seals from shrinking and cracking. ULSD is usually refined using a process which removes these aromatics. IP which use a viton type seal do not have these issues. If it is gear driven (not belt driven) off the crank case, then a diesesl leak trhough the drive shaft into the crank case is possible. At a minimum, it requires removing the IP and installing a new seal. Usually, people have all the seals done at that time and a possibly have it rebuilt. My preference would be for switiching to a rebuilt inline IP if this would be in the same ball park cost wise.
Or Next time use a decent fuel conditioner IMOP Bio has to much water in it scoring moving parts and veggie oils go bad or rancid if they sit in the tank ( sorry veggie) hippies I have done my homework. Yup thats right Chevron adds Bio to their ULSD for more Lubricity , John.

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