Oil leak search, questions
 

All right, though it sucks to say, the 300D I bought barely a week ago has started hemorrhaging oil. I have it in the driveway searching, but it's hard to see (and I thought it might be under the air cleaner; that's where the stream drips onto the pavement) so I disconnected the turbo air intake pipe and removed the whole air cleaner assembly.

There's oil all over, and the way the leak was coming out makes it seem like a leak when under pressure. If you fill the crankcase with oil, it'll literally puke a quart and a half out in a matter of an hour or two when being driven. Then, when the level gets down to a half-quart low, the leak slows to a tiny drip.

I cleaned the engine off yesterday but couldn't see well enough to find the leak, hence my removal of the air cleaner. ... Can I hurt the car by starting it with the air cleaner off? Considering there are oil hoses and some sort of oil separator in the air cleaner housing? (And what does that thing do, anyway?)

Any and all help appreciated.

On the 617 engine there are several areas notorious for leaks on that side of the engine.

The "thing" in the air cleaner assembly is an cyclonic oil separator. (Think PCV valve). On the bottom of the separator, there should be two o-rings that usually need replacing. This fits into a hard line which drains into the pan. What also happens is dirt gets into this line and causes the check valve at the bottom to malfunction and oil can literally come up the drain. Next oil change, run some motor flush through this line after you pull the drain plug. (Make sure the air cleaner mounts and bracket are in good shape as this is what causes all of this in the first place.)

Another area is the turbo oil drain. There is a gasket up top, near the turbo, two o-rings in the middle joint and rubber grommet at the pan. Any one, or all, of these may be sources of leaks. Do a search for "Whunter" and "turbo oil drain" and there should be an nice DIY write-up with pics. ;)

The more blowby an engine has, the more likely it is to leak in all the usual places. Spray/brush the areas with kerosene and degunk it. It will be so much easier to find the leak(s)

There actually is practically zero blow-by with this engine. So at least that's a good thing.

Still, can I start it with the air cleaner assembly off? Will I be blasting oil out of the cyclonic oil separator?

no, you shouldn't blast any oil out of there. If you have very little blowby, then your chances of reducing oil leakage are excellent. It's hard to find leaks while it's idling, and leaked oil blows around and moves while driving, so cleaning the area really helps. Good luck!

Answers
 

This contains oil leak information also.

Diesel Oil Thread!!!
http://www.peachparts.com/shopforum/diesel-discussion/110168-oil-related-topics-%3D-oil-thread-post997109.html#post997109

Note:
Your thread has been added.

Thanks, I'll keep looking.

From underneath (and gunky though it is) the biggest mess seems to be low on the engine. I know that sounds like "duh" because gravity of course will carry the oil down there even if it leaks up high, but the top of the turbo oil pipe is dry, there's light oil residue in other "upper" locations but not signs of heavy leakage, etc. ... Yet the underside on both sides is very oily, with a fresh coat on top of the old gunk. It's all over the A/C compressor, etc.

It looks like there's a slow leak all around the valve cover gasket, but not nearly enough to create the puddle I'm getting. When full, there's a steady drip at the front-center (to maybe even front-left) and at the passenger rear of the engine an outright uninterrupted stream. ... Then, when it gets about a half-quart or a quart low, it all reduces to very slow drips.

But I don't want to be driving the car around a quart low, y'know?! :o

Replacing Seals on Turbo Oil Drain Pipes
 

Caution!
 

When you said front left, I suspected the possibility of oil cooler lines. If these are leaking, you will want to change them out ASAP. If one of these lines blow, you have the possibility of ruining your engine in a matter of seconds.

Your steady stream almost sounds like an oil pan gasket. A torque wrench solved several leaks on mine. Do you have a Haynes manual?

Advice
 

You can not isolate the leak with the mass of oil and sludge covering the entire engine and bay area you describe.
Clean it off then begin diagnosis..

check these
 

My 300sd (same engine as yours) was leaking oil everywhere a few months ago and after several weeks of oil top offs and diagnosing the leaks I isolated them to:
1. Shutdown lever- located on backside of injection pump, small and cylindrical in shape. Mine had a blown gasket. Locate the component and wipe you finger under it. If there is oil there clean it off and check again after engine has ran. It is an easy fix. 3 bolts, gently pull and twist, should come right out. R&R gasket install lever assy. Make sure it is in right or your car won't turn off! put bolts back in.

2.Turbo oil return line o-rings, grommet and gasket. Kinda pia. I had to do it twice because gasket suface was not clean enough. Much easier to do 2nd time.

3. Valve cover gasket. kinda seepy but not leaky. Put new one on anyway.

hope this helps, zachariah

GlennCraven,
Looks like you have all the steps for finding your leaks and in answer to your questions. I know the "cleaning" should be a first step since you will need to locate the leak and then clean the area prior to doing any repairs/tightening. I believe that is why the "cleaning" has been mentioned more than once. On my two, the engines and bays are not spotless yet there is little if any excess. When anything starts seeping, I can ususally spot the source quickly and even estimate the rate of flow. I for one find this very helpful. So clean first and look as you go.
Steve

I'll try to get it REALLY clean Sunday afternoon. I sprayed it with degreaser and hosed it down at the car wash earlier this week and still got nowhere near all the gunk off.

Two things that I can say:

1. When I park it, there are two leaks, one in a half-moon shape (so to speak) right under the oil pan, in the very shape of the pan's rim. I'm hoping that's the oil pan gasket leaking and not some major leak above running down to that point and just dripping over the rim. (Although it's very dirty above the pan; blown up there during driving?)

2. The fastest leak when freshly full of oil and engine idling is a steady stream (not just a drip) seemingly running straight downward from the vicinity of the air cleaner, back nearer the firewall on the passenger side. But when I pull the air cleaner off I don't really see a potential source. ... There is light oil residue inside the air cleaner in the vicinity of the cyclonic separator, and some inside the turbo intake tube from the air cleaner. But not a lot. ... Unless I'm completely imagining things, this rearward leak becomes only a drip (but a fast one) as the oil level in the system steadily drops.

Thanks for the help. I think the turbo pipe isn't leaking and I think the valve cover gasket IS, but a seep and not this blowout level. Or maybe I'm wrong and the back passenger-side corner of that valve cover gasket is simply gone or something.

All right ... tell me how stupid I am. Or something.

Now I wonder whether I really have much of an oil leak at all! (OK, some, but not a lot.)

I sprayed the engine liberally with Gunk-brand degreaser. Hosed it off. Got it pretty clean for the most part; very few additional gunky spots.

With the engine cool (sat overnight in the driveway) and sitting about at the bottom of the "safe" zone on the dipstick, I added a quart of Rotella that brought it up to the top. Then I backed the car out into the only available sunny spot on our acre and let the engine run a bit.

I looked down from the top; no apparent major leaks.

I got underneath; no apparent major leaks.

One of the two big stain spots was right around the rim of the oil pan, dripping off pretty much the whole right side and front edge of the lower pan. That pan is now very clean (for a 216K-mile car) and there's not a drip. None. I put a clean rag underneath to catch any drips that came down, ran the engine about three minutes, cut if off and let it sit for 10 minutes, not a drop of oil.

Back near the passenger firewall, where there was such a flood, I can't see dripping at all. I didn't put anything under it to catch, so it's possible a drop or two went down, but nowhere near the constant stream I'd experienced before.

Here's what I think: At least in part overfilling.

When I test-drove the car, I took it about two miles down a service road and parked it in an empty business lot and did a walkaround. I looked under the hood while it was running, then shut off the engine and checked the oil. It was at the top notch on the dipstick.

When I paid for and returned the car to where I was to meet my wife, it was spewing oil. ... When I've filled it up to that point on the dipstick again after getting the car home, it spews.

I do realize that you should check oil while cool and on the flat. As the manual says, checking the oil right after the engine has run can give a faulty reading because some oil might remain in the upper portions of the engine. But I didn't think it would make potentially this much difference.

After filling to the top in the driveway today, running the car at most five minutes, then shutting it off, the dipstick showed a half-quart low. And when the car sat for five minutes, still a bit low. Sitting 20 minutes, it's now up to the midpoint on the stick. I'll bet when I get back outside after writing this, it'll be back to the top of the proper range on the dipstick.

I'm really wondering whether the car was overfilled with oil when I bought it, resulting in me freaking out at the purge of oil (from where all it came, I don't know) and thus I overfilled it to compensate for all that I seemed to be losing. Especially because it seems to take 20 or 30 minutes for the oil to work its way back into the lower pan from the upper parts of the engine after parking.

Now, I do know that there's a seepy-sort of leak at the valve cover. That's readily apparent. But I really wonder whether the oil-puking I've experienced was from overfilling.

What do y'all think?

It very well could have been an overfill situation. Which, on a diesel, can be a hazard. Since a diesel can literally run on oil, a combination of factors can come together and literally cause the engine to feed off its own oil resulting in a runaway situation. Most diesels have a warning label cautioning against over-filling.

A couple of things may have happened. If it was serviced by a quik-lube type of place, they may not realize that oil capacity includes the oil cooler which is almost never drained. Therefore resulting in overfilled. The other quirk is what you noticed. A diesel utilizes oil for many things including cooling the bottom of the pistons by small injectors. Therefore, it tends to take a long time for all of the oil to return to the pan.

Considering this, I rarely fill above the lower full mark with a cold engine. With a warm engine, and sitting for a moment such as when you are refueling, a quart low is not out of the ordinary. Remember, your oil capacity is nearly 8 qts. for a 3.0 liter engine where most gasoline engines barely use 4 qts, if that, for the same size engine. Hope that helps.;)