Chasing oil leaks.. - PeachParts Mercedes-Benz Forum

fezcabdriver · #1 10-23-2016, 03:57 AM

So I posted on the other forum for the passenger side leaks on the engine. I didn't get any responses so I'll post my driver's side leak questions here.

I think my lift pump is leaking. There is a bunch of caked on black oil looking stuff beneath it, above the engine arm mounts, and along the bottom of the injector timing pin area??

If my lift pump is leaking, is it possible that motor oil would be leaking out of this location or just fuel? I think I read something about a seal inside mixing fuel and motor oil. If I have to fix this, is there some sort of kit that you all can point me to? If I pull it out, will a lot of fuel and motor oil come out?

Related question to this, does my injector pump require me to drain and place oil in it or does it use the engine oil to lubricate everything. I have an 1985 300D Turbo (federal if that matters).
Additionally, can the injector timing pin leak as well? With both fuel and motor oil?
And finally, can a leaky valve gasket result in oil at the backside of the injector pump facing the firewall/oil filter housing?

Thanks!

Diseasel300 · #2 10-23-2016, 10:14 AM

The lift pump has a gasket where it attaches to the IP housing. If the gasket is hardened or cracked, it can weep oil out there.

Every diesel engine I've ever seen has a nasty injection pump. There's always gonna be a weep or leak or something at some point in its life that leaves an oily residue behind and it eventually collects dirt and debris and looks nasty. You can clean it off with some degreaser, see how quickly it comes back. If it comes back fast, you could have an oil leak somewhere, or even a fuel leak. There is a cover on the back with a gasket, and the gasket could be leaking/weeping, same goes for any other access plates on the pump. Cleaning it and watching it will help you tell if it's worth worrying about. If it's just a "sweat" I wouldn't lose any sleep over it.

Your injection pump uses engine oil for lubrication. I don't know the date when they switched the design over, but it was before 1985.

fezcabdriver · #3 10-23-2016, 12:47 PM

THanks Diseasel300! It looks pretty nasty all along the bottom and motor mount arms. I'm going to do a wipe down as you mentioned and keep an eye on it.

Is the mixing of the motor oil and fuel due to the failure inside the lift pump's o-ring a cause for concern? I have to take care of my p/s tubes and figure while those are off, it will be easier to access the lift pump.

SD Blue · #4 10-23-2016, 04:15 PM

When I had oil appearing in that area, it was due to leaking oil cooler lines. Ensure they aren't leaking and secure, because if one breaks free, it could cause a disaster.

Charlie Foxtrot · #5 10-24-2016, 06:27 AM

The primer pump on the IP could be the source. The white handle pump is infamous for leaks. It's a simple, easy fix.

fezcabdriver · #6 10-24-2016, 10:15 AM

Quote:

Originally Posted by Charlie Foxtrot

The primer pump on the IP could be the source. The white handle pump is infamous for leaks. It's a simple, easy fix.

Yeah, I replaced that awhile ago with the newer style pump.

Quote:

Originally Posted by SD Blue

When I had oil appearing in that area, it was due to leaking oil cooler lines. Ensure they aren't leaking and secure, because if one breaks free, it could cause a disaster.

Good point. My lower line at the oil cooler looks a bit wet. Towards the other end, it looks good. I'll probably be doing this job in the near future.