Oil Leakage Source. Stumped! - PeachParts Mercedes-Benz Forum

BrierS · #1 10-10-2003, 09:52 AM

My '87 300TD has oil leakage on the left upper side of the engine and I have not been able to figure out the source. The signs of it begin just behind and under the #1 injector. The immediate injector area is dry. It traces from the rear of thermostat housing, along the glowplug, accumulates in the lower row of torx type bolt heads 1-3 (moving front to rear) only. It is below the induction/intake runners yet traces are present at the lower most parts of those. Not that these are necessarily related but worth adding . . . this commenced (I noticed) awhile after I switched to syn oil and has been accompanied by what I believe is lifter noise. This is a daily driver for me so I haven't pulled the cam cover yet because I am hoping to get seals, gaskets needed for the entire operation. One other thing, the lifter noise is most likely coming from only 3rd or 4th cylinder and both of those have slight leaks in the fuel return lines.
Help . . . Please
Steve

#2 10-10-2003, 10:36 AM

Steve,

Check out the related active thread for om603 injector pump leakage. Your injector pump may be leaking.

What brand of synthetic are you using. Mobil is supposed to leak less than Rotella.

Clean the area and spray with foaming foot spray to help locate the leak. (never tried it but it sounds like a good idea)

Also, did you change out the o rings in the oil filter center post. That is related to start up valve clatter.

let us know

bob c

BrierS · #3 10-10-2003, 10:57 AM

Bob,
Thanks for the quick response. I did change to Mobil 1 and as far as the oil filter stem seals, no I did not have any when I did the one and only change. However, when I inspected during the change I noticed they need replacing so I now have them (Fastlane). The other related issue was that I could not get even air to move through the tube. I soaked, cleaned and blew it out to the point that I was getting some flow. My feeling when I put everything back together was that it may not be sufficient flow. Problem for me is I have nothing to benchmark my thought from. After reading your response, I believe I should change the filter and o-rings NOW even though it is not due for nearly 3,000 more miles. Your thoughts on that???

As to the injection pump possibly being the source of the leakage, I went out and attempted to see if that was something I missed. Though I can see some oil/fuel accumulations at the very bottom of the IP, it is minimal. The bulk of what is leaking is higher than the top of IP and appears to be migrating from the area just at the back of the thermostat housing. I'll try the cleaning and see if I can do a better job of isolating the flow.

I am still too new to the world of MB diesels yet love them. I have purchased the CD repair manual set, the Haynes manual, and the MB Electronics Parts Catalog (latter not yet installed) yet I still do better looking and keeping my hands working.

Thanks again and I'll post my progress (probably more questions also).
Steve

Ken300D · #4 10-10-2003, 07:39 PM

Possibly a leaking intake manifold gasket.

The intake manifold gets a lot of blowby oil in it and this can condense as the car cools down. Then it will flow downhill toward the intake ports on the head. If the gasket is leaking it will run down the outside of the head.

Probably not your problem, but a possibility. If you go as far as to take the intake manifold off to replace the gasket, this also clears access to the glow plugs. So, depending on mileage you might want to replace them too.

I have a thread somewhere with pictures of this operation.

Ken300D

psfred · #5 10-10-2003, 08:41 PM

Several possible sources. Most likely is the manifold gasket -- it someone took it off to change the glow plugs and used the old gasket, it will be more likely to leak.

Other possibilities are a slow leak in one of the overflow lines -- this leaves only the "heavy" end of the fuel, so it looks like oil.

Valve cover leaking (very possible, the gaskets get rock hard with age).

Oil spill from the filler cap -- will look like a valve cover gasket leak. Gasket here will die, too, and I beleive oil can track down the valve cover and the #1 injector, but I've not looked for a while and can't say for sure. It does on the M103!

Bad seal on the #1 injector, allowing "cracked" diesel to ooze out around the threads of the injector. Common problem on badly sealed DI engines, especially old Cummins with the two small bolts holding the injectors down, almost impossible to get the copper seal to work 4" away.

That's not thermostat housing by the way, it's just the upper hose connetion. Thermostat is in the bottom radiator hose on the other side of the engine. Took me a while to find it, and had to change it by "braille" as I coudn't get a good look at it!

Peter

BrierS · #6 10-10-2003, 08:49 PM

Nearly every time I looked for the source, I kept coming back to the intake manifold yet I couldn't see how that could be the culprit. The trails of leakage do seem to point to that. Let me throw this one out to you . . . if it is the intake manifold gasket, could that bear any relationship to the slight noise that is similar to lifters? They both started at about the same time.

I have pulled the oil filter tube to replace the o-rings (should have been replaced when I did the oil change but didn't have them). As the first time I inspected the tube, I am concerned with how little flow thru there seems to be. What is the recommended procedure to clear any accumulations from inside of the tube?
Thanks
Steve

BrierS · #7 10-10-2003, 09:09 PM

Quote:

Originally posted by psfred
Several possible sources. Most likely is the manifold gasket -- it someone took it off to change the glow plugs and used the old gasket, it will be more likely to leak.

Other possibilities are a slow leak in one of the overflow lines -- this leaves only the "heavy" end of the fuel, so it looks like oil.

Valve cover leaking (very possible, the gaskets get rock hard with age).
Peter

Peter
Thanks to you also (KenD mentioned this also). As your reply was coming in I was typing the one below yours.

Loved the correction on the "thermostat housing". That's one I wouldn't have missed when the time comes to change it. Guess you can tell my instincts run along the older gasoline engines.

As I wrote in my earlier reply, I do believe it is going to be the intake gasket. To me it didn't make sense (still don't understand diesels enough) even though the leakage patterns kept pointing to it.

I do know that it is not the #1 injector since there are absolutely no signs of leakage in that area. Same for the filler cap and cam cover gasket. Those areas are completely dry.

I know I have limited leakage from # 4 & 5 overflow/return hoses off the injectors yet they are not the source of this particular leak.

My intent (probably get shot to hell anyways) is to find the probable culprit and then order parts. I am hoping to not get caught without certain seals and gaskets. In fact, I would prefer to have more than I need. The cam cover will likely be coming off since my stethoscope seems to lead me to slight lifter noise around the area of the same cylinders that have the leaking return or overflow lines. As far as I can see that means the gaskets for the air flow tube (not going to pull the manual out to see what it actually is called right now), and as you suggested changing the glow plugs that should be added to my parts list. Adding CAREFUL R&R of the overflow/return lines (I try to read as many past posts as I can make time for) I'll have a fun next-weekend project. Actually, I'll need to build my parts list up since I like to take advantage of the free Fastland shipping. Glow plugs should help that cause.
Thanks again and I'm loving the 300TD more every day!
Steve

psfred · #8 10-10-2003, 09:40 PM

Steve:

Overflow lines are really very easy unless they are totally petrified. Use a pair of needle nosed plier with sharp jaws and just "nip" the sides of the hoses and tear them off sideways to remove the old ones. Don't bite into the nipple, but anything less than that works. They are surely soaked in fuel so you don't want to handle them anyway. Use the pliers to put the new ones one, too -- grasp the hose just above where the nipple will be when the hose is all the way on and push it down all the way.

If they ARE totally petrified -- the ones on my brother's SDL were so hard they had to be snapped off! -- you will need to get a small pick set and carefully fracture all the glassy stuff off the nipple or the new hose won't fit down and seal. Big PITA, but not hard.

For sure it's the manifold gasket. Get the gasket and o-ring for the crossover pipe, too. Oil seepage at the crossover and intake runners is NORMAL on a diesel, there is ALWAYS some oil from blowby in there, and it will eventually leak.

Plan on cleaning the crossover pipe and intake manifold, there will be considerable crap in there from the EGR, worse if the PO ran dino oil in it.

Tappet noise can be bad tappets, too, from synthetic oil removing the varnish that kept them working. Usually the opposite, all my valve noise went away when I changed to Mobil 1.

Change the oil filter when you put the o-rings on, it's probably full of crud from changing to Mobil 1 -- that stuff will clean up the innards of the engine wonderfully, but all the crud washed loose ends up in the filter...

I love my 300D ALMOST as much as I love my 280 SE! Win more drag races in the 280, though....

Peter