300sd oil leak that wont go away - PeachParts Mercedes-Benz Forum

Biotour · #1 07-09-2010, 07:00 AM

first a little background: i first noticed i was leaking oil when driving back to ca from denver. i was broken down in denver for about a month trying to get it started, after having driven straight from tx. turns out the fuel injectors had a ton of carbon buildup on the tips... so much that i couldnt see the tips and it was just a mound of carbon. i dont know how that thing was even running. i now believe that i had picked up a bad batch of veg oil, which it was running on the whole time out to denver. i didnt notice any oil leaking during that time, but it may have been. anyways, once i wiped the carbon off the tips and reinstalled the injectors with new heat shields, it fired right up. the only thing i recall doing in denver besides pulling injectors was removing the manifolds and checked the valves. i reused the valve cover gasket and figured i must just need a new gasket, because from what ive read its supposed to be replaced each time the valve cover comes off.

so driving back from denver i added about a quart every 100 - 200 miles. the oil seemed to be leaking from the back passenger corner of the valve cover, and the whole underside of the car all the way to the tip of the exhaust pipe was just coated with a film of oil. i'd pull into a gas station for a couple minutes and a rather large (8" dia) puddle of oil would accumulate under the cross member by where the engine meets the trans. also there would be a trail of oil drips behind the car. i drove it back the whole way like this as i couldnt find anywhere that had the gasket in stock.

so i finally make it to ca and put in a new gasket. i didnt bother with a torque wrench as ive never used one for the valve cover before and ive never had any problems. i figure all is well, drove it around town a bit and no leaks. then i attempted to drive a couple hundred miles and the same leak came back.

I bought another new gasket, and this time used a torque wrench to 11 ft. lbs and made sure everything was clean and installed correctly. i also pressure washed the engine and bottom of the car so it would be easier to spot any leaks and id be able to isolate them. i drove from san francisco down to los angeles for the 4th of july weekend and hoped that i had fixed the leaking oil problem.. which of course i didnt.

side note: about 100 miles from la, i pulled off the freeway and shut off the engine to check the oil level, as i'd been having to check the oil level a lot and add oil frequently. i waited a couple minutes, checked the level, added about a quart to put the oil level between the two marks on the dipstick. then tried starting and it would just crank but not start. the exact same symptom i had in denver, except the engine was hot. so i pulled the injectors and wiped the tips, they weren't nearly as bad as what i saw in denver but put them back without new heat shields and it fired right up. strange.

so once in los angeles i thoroughly inspected the engine for leaks and determined that the leak was mainly coming from the oil filter housing to block gasket as there was a ton of oil underneath it, but i couldnt really see much leakage above it. there was also oil underneath the air filter housing and under the turbo wastegate actuator but i figure its just from excessive blowby.

i replaced the oil filter housing gasket, probably the hardest job ive done on this car yet. scraping off the old gasket took several hours and wasn't how i wanted to spend the holiday weekend! i was glad to have the updated gasket though and not have to worry about ever doing that job again.

needless to say i didnt end up driving the car again until the trip home, which of course didnt go as smooth as i had hoped. it was still leaving big puddles every time i stopped and the oil was still underneath the oil filter housing, as well as coated all over the passenger side of the engine, the dipstick housing, under the ac compressor, and i even noticed some oil film behind the passenger side headlight on the flat (level) part of the inner fender. not sure how that got there.

today i pulled the ip and oil filter housing because ive been meaning to fix the leaking freeze plugs. i am pretty stumped on this oil leak disaster though and not sure really where to start.

within the past few months i have sealed up the air oil separator inside the air filter housing so that my air filter doesnt get soaked with oil anymore, and have replaced the o-rings and gaskets for the turbo and all associated oil feed & drain lines. also replaced the o-ring under the air oil separator.

the breather hose from the valve cover is the updated flat hose. it is tightened onto the valve cover about as tight as i could get it but it is still leaking, and i bought a new oil fill cap from the dealer but that one leaks as well.

currently i am thinking that i have quite excessive blowby, causing a brand new oil fill cap to leak, the breather hose to leak, and pressure to force oil out from under the new valve cover gasket by the rear passenger corner. also this pressure is causing oil to leak out from around the top of the dipstick tube, and since the inside of the u tube is soaked in oil, my air oil separator is obviously not doing its job. possibly the check valve for the air oil separator drain is clogged? or the oil passages from under the valve cover down to the sump are clogged?

i'm not sure how to proceed at this point.

layback40 · #2 07-09-2010, 09:15 AM

Excessive blow by is probably cause by stuck rings from the WVO use. The carbon build up is probably the result of the WVO not being hot enough at the injector tips.
Did you clean out the oil separator in the valve cover?
I think the best way for you to proceed would be a ring clean & run on diesel for a year & see if that saves the motor.

Another case of "Death in a Jug!"

I wish you good luck solving your problem!! I'm glad its not me with it !!

cirrusman · #3 07-09-2010, 07:40 PM

Obviously the problem wasn't the oil filter housing gasket if after replacing it the problem persisted (unless you made a mistake in the installation, which could be possible). You mention that you thought that the leak was there because you saw a lot of oil in that area; but, did you pinpoint the point of exit? After pressure washing the motor did you see where the oil was coming out from exactly? Oil can go from its point of exit and just accumulate downstream which is what I'm thinking hapened here since the leak wasn't fixed. I'd clean the engine once more, start it and try to locate exactly where the oil is coming from first.

79Mercy · #4 07-09-2010, 08:15 PM

If you stop running that poor old 617 on crap it will start up anytime you need it do.

Pull the valve cover off and pull the seal off and lay the cover back down in place and make sure it sits level. If not you have have worn out shims.

Yak · #5 07-09-2010, 09:21 PM

Oil line from filter housing to turbo?

I'd inspect the turbo itself. Are you sure you got the gaskets right when working on that?

dsmess · #6 07-10-2010, 06:54 PM

If the valve cover gasket is leaking (presumably in the rear where you cannot see it), you should be able to feel the wetness with your hand, feeling around from the top of the engine. I recently had a crack in the turbo oil line...if you have this problem you will see oil dripping from the banjo where it enters the oil filter housing. Other possibilities are front and rear engine seals.

Scott

Diesel911 · #7 07-10-2010, 09:48 PM

Quote:

Originally Posted by Yak

Oil line from filter housing to turbo?

I'd inspect the turbo itself. Are you sure you got the gaskets right when working on that?

I agree with the above; the Steel Oil Supply Tube to the Turbocharger.

Take a good look at the Clamp that holds it to the Cylinder Head. With vibration the Clamp could have eaten a hole in the Tubing.

If you are running the Stock Bosch Injector Nozzles and tips of the Injector were covered with Carbon; surely the holes in the Spray Nozzle Pintel (#14 and #15 in the second pic) are completely plugged with Carbon.

Biotour · #8 07-14-2010, 07:41 PM

Turbo feed hard line was replaced as well, forgot to mention that. The only place I noticed oil on drivers side is leaking out of small hole near top of dipstick tube. And on pass. side I see it dripping down from the u-tube. I pulled the oil pan to clean out the air oil separator drain valve but noticed the oil pump strainer housing was broken. The bottom of it was sitting in 2 parts loose in the oil pan. I sprayed brake cleaner through the air oil separator drain valve, and it seemed to wash through just fine so im assuming that valve is good. Where can I order a replacement oil pump strainer housing? Didn't see one on fastlane.

I picked up a 240d external air oil separator so i will be plumbing that in with wider dia. hose to see if that will help stop the oil blowing out of the dipstick hole. I'm thinking I'll run the drain via steel line back to oil pan, and output from that into the stock air oil separator in the air filter housing. So it will effectively be two air oil separators run in series. The drain from the stock separator will go into a bottle to see what accumulates. Any thoughts or better ways of setting this up? I'd like to keep the stock air filter but am open to other ideas. I know it'd be simpler to just get a k&n style cone filter, but i'm worried about dirt and water getting sucked into the turbo. not to mention the hot air intake effect.

Biotour · #9 07-14-2010, 09:39 PM

first picture is the pieces i found in the bottom of the oil pan. the screen itself was still attached to the oil pump but the two plastic pieces broke off, and then there was a mystery piece of silicone gasket maker from who-knows-where. any idea what this may have come from?? i do know the turbo drain gasket was replaced at some point.... this could have fallen into the pan when that was replaced. its about the right size..

pic 2 is the dipstick leak

pic 3 is the u-tube leaking onto turbo housing etc

pic 4 is the completely coated crossmember between engine and trans. this is where most of the oil ended up, and a large puddle forms under this after driving on the freeway.

pic 5 is one of the injectors i pulled, while stopped on the side of the highway after pulling off to check oil level and finding that i couldnt get the car to start back up. all this buildup occurred within 1500 miles of driving on wvo. other injectors had similar buildup. when previously pulled, tips weren't even visible at all.. the buildup had been about 4 times worse.

kerry · #10 07-14-2010, 10:30 PM

It sounds to me as if you are spewing oil from every possible place. I think you need to do a blowby test. You can get the official MB measuring tool, use the garbage bag method described here, or post a YouTube video. I think Layback40 had the right idea.

RML · #11 07-14-2010, 10:50 PM

I am certainly no expert with all of these symptoms, as I have not had to get that deep into the engine. Yet. But I do agree with Layback40's comment above. I would first change the diet for your engine. That is, go off of WVO and feed it diesel or biodiesel. Then do a compression test to see if you have a problem with a ring. Members on the forum have mentioned a leakdown test as well. Again, I am no expert here and have not done these procedures but I think this is the direction you need to go in to get at the root of the problem.

Regarding collecting oil in a bottle coming from the air cleaner housing, I think you are just treating the symptoms and wasting your time. What difference does it make how much you collect? You know it is way more than it should be. I assume you are referring to a quantity when you say you want to "see what acccumulates" and not "what" accumulates. I think we can all assume it will be oil.

Regarding the K&N filter, again, don't waste $$'s treating symptoms. Solve the root problem first.

Good luck.

Richard

Bob Albrecht · #12 07-16-2010, 12:26 AM

In my opinion, you have at least two problems.

1. WVO - it will foul your injectors after 12K miles. You can get an injector cleaning kit online. It is a pain, but "free" fuel will cost you. Homebrew biodiesel with residual glycerin will cause similar problems. Diesel mechanics see the results of WVO. Some on Shop Forum really don't like it.

2. I think Your turbocharger is leaking oil inside, and it gets out through the rubber air intake tube. I know this because I have very similar symptoms right now. Check the metal intake tube, it will be icky. Look inside the turbo at the compressor intake. You will probably see oil.

I need to rebuild my turbo. It is slowly getting worse. Rebuild kits and balancing services are available online (look for rons turbos). Oil from the turbo will worsen injector fouling.

By the way, I had a bad leak on the turbo oil line, it was twisted and broke. I replaced it. The return line had a small leak too, but is fixed.

Diesel911 · #13 07-16-2010, 01:07 AM

Since someone mentioned the Turbo Drain Line I replace the O-rings and Grommet on mine a few weeks ago as well as the O-ring at the bottom of the Blow-by Drain Tube.

I now have no Crankcase Oil leaks from that side of the Engine.

hey_allen · #14 07-16-2010, 01:17 PM

I had similar symptoms on my 300SD's engine, but it was a poorly maintained car that I picked up knowing that it had issues.

When I pulled the breather hose, or even the oil fill cap, it looked like a locomotive due to how much oily smoke was spewing upward from the valve cover.
The final blow for that engine was when the back pressure overcame the oring holding the dipstick in it's tube, and proceeded to spray over a gallon of oil all over the engine bay, from the tube.

Before that point, it had all the symptoms you describe. Oil seeping from every seal point, oil in the intake (from the oil air separator in the filter housing), drips and dribbles on the pavement just about everywhere...

iceman104 · #15 02-13-2014, 01:13 AM

Help. I have a 85 300sd. And when I bought it I didn't relise many oil leaks at all really. A few not a. Lot or large amounts because alot of gaske been replaced. But now the air filter breather box is leaking oil out of the bottom of it. Is this a blow by issue? Do I need new rings. Could a valve adjustment help? Its leaking a faily large amout. Thanks in advance to all who can help.