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  #1  
Old 10-02-2008, 11:17 PM
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External oil leak from head gasket?

Hey guys, what do you think about the attached pic?

This is an '82 240D 616 with 249,600 miles. You're seeing the front driver's side of the block from the top down, looking down on a huge bolt head whose recess is constantly filled with oil.
I have had a pretty considerable oil leak coming from high up on that side of the block but it only leaks under higher loads, like 65mph highway driving. I cannot see any leak if just at idle, but if I park after cruising the highway I always drip 4-6 drops onto wherever I park.
This is NOT the valve cover gasket. I replace that after every valve adjustment without question. All clean on the side of the head. Difficult to diagnose any other potential gasket leak since I'm unable to watch it happen. I can sop up the oil from the bolt recess and it'll be full after the next time I pull in from such a drive.

So it occurs to me that the next seal above this bolt recess that might blow oil under load is the head gasket. I have no other signs of an internal head gasket leak, so my question is: Has anyone ever seen one of these cast-iron heads leak oil outwardly from behind the timing chain area?
I hate to do a head gasket just to get in and find out it was not torn at all, and I'm kinda hesitant to think a cast-iron head on a cast-iron block would tend to rip one. Still, it's 26 years and 250k... And then again I've never heard of a head gasket leaking "out" rather than "in" - to the cylinders.

Please let me know if any of you have any thoughts on likelihood of the head gasket, paired with seeing oil pool up around that bolt recess being caused by any other gasket.

Thanks so much!
Garrison

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External oil leak from head gasket?-dscf0179.jpg  
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  #2  
Old 10-02-2008, 11:31 PM
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Im not sure if theres oil "channels" throughout the block like their are coolant passageways, but im pretty sure that on the front of the head the only oil your dealing with is just oil splashing off the timing chain and or draining from the valvetrain, which would make a leak unlikely since its not pressurized. What about fuel? Are you sure its not fuel leaking from the filter and appearing black as it lifts old grease off parts it flows on?


Can you hold the engine at 2500-3000 rpm in nuetral for a few minutes after you clean the oil off, and watch where its comming from? Ive diagnosed a under-load leak that way.


What about the little oil line that supplies the ip with motor oil? I think it connects somewhere in that area
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  #3  
Old 10-03-2008, 12:07 AM
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Not gonna be fuel leaking, since I definitely have to add oil to the engine regularly (too regularly!)

I might be able to rev it under no driving load but again, this doesn't start spewing until like 55 or 65mph with tranny load. (This is a stick shift BTW but that shouldn't matter.)

Oil line supplying the IP - haven't seen this so I'm gonna look for it and assess. Thanks! Would it shoot oil up onto the side of the block like that?
Other thing I have considered was the oil cooler lines leaking but they are not wet.

Worst part of this would be that if some other component is spraying oil up into that area, it seems highly unlikely that oil wouldn't also be all over the side of the head. but it's not; what you see in the pic is the highest point of visible oil - then the block gets covered from there down. But we can pretty safely attribute the "covering" to the wind & motion of the car that is in play at highway speeds. It starts at the front of the block, and then heads down & back from there. I note that this bolt is directly behind the little "L" portion of the head that accounts for the timing chain housing.

Thanks for the ideas - please keep 'em coming if you all don't mind!
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  #4  
Old 10-03-2008, 02:46 AM
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Check your valve cover seal, and yes there are oil channels that go into the head that lubricate the camshaft (also one oil duct, that transfers oil back to the pan at the rear of the head that usually leaks).
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  #5  
Old 10-03-2008, 03:01 AM
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Bet you ten bucks its coming from that recessed bolt. I believe there is some sort of rubber seal on that bolt. I am not to sure of its purpose tho. I had a friend with a 240 that had the same problem. I will see if i can track him down to chime in.
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  #6  
Old 10-03-2008, 12:10 PM
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Spamman450 is right

Hey Rory is right. in fact he helped me raplace it. On my 81 240D manual for the longest time she was consuming oil at a high rate. I assumed that since she had alot of blow bye that was the case. However we found out that that bolt pictured above is not all that it may seem. The bolt in question is not infact bolted at all and it sits inside of a chamber. It moves up and down with the pulse of the engine or the oil pump and oil is pumped through the bolt to engine components. I had a thread up here years ago and it seemed that no one knew what was the problem.
The cause is two rubber o-rings that have dried out and lost their seal. As that bolt moves up and down in the chamber it needs the o rings to seal the oil from getting out of the engine. when they fail it actually pumps out oil on every pulse. I ordered two o-rings from Inter auto parts in san diego...now known as north coast auto...it cost me a couple bucks and a half hour job...no more oil leak. It has been a couple years since I did this so I cant remember exactly how to do it and I cant remember the name of the bolt. However I do remember to acces the bolt you have to have an allen wrench for a bolt near the vacumme pump. search online for detailed engine pictures and you might be able to find out what the name of that thing is.....good luck one you know what you are doing it was a piece of cake
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  #7  
Old 10-03-2008, 12:41 PM
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Rory and Stephen, I should give you more than just 10 bucks for that help!!! For the 10 hours you saved me this weekend and the peace of mind that I know I'll be fixing the right thing - if either of you are ever in upstate NY please ping me cause I owe you dinner or something.
I'll post again here to the rest of you to confirm that this was indeed the issue after I do the work and test her out.
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Old 10-03-2008, 12:55 PM
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Wow, I have no Idea what you guys are talking about. Is this 240 specific?
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  #9  
Old 10-03-2008, 01:19 PM
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trust me...

Quote:
Originally Posted by yogarda View Post
Rory and Stephen, I should give you more than just 10 bucks for that help!!! For the 10 hours you saved me this weekend and the peace of mind that I know I'll be fixing the right thing - if either of you are ever in upstate NY please ping me cause I owe you dinner or something.
I'll post again here to the rest of you to confirm that this was indeed the issue after I do the work and test her out.
Trust me, i didnt think that it would work either after having to fill up on engine oil every week. but it was the best dollar i ever spent for sure. once you get that "bolt" out you will see that the old o ring is flush with bolt and can peel or break away like brittle plastic. make sure none of the old o-ring falls into to housing as it will probably clogged your oil ports. oh yeah and one more thing many parts people tried to sellme the entire bolt set up which would cost like 100 bucks. you dont need the bolt as it is not a wearing part only the o rings....unless you see otherwise I would suggest just the o rings for now.
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78 300d non turbo SOLD
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1981 300SD 360,000 miles I think she's doomed for a parts car but has a good engine SOLD the engine to spamman
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1978 240D Manual
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  #10  
Old 10-03-2008, 01:24 PM
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pretty sure...

Quote:
Originally Posted by Bajaman View Post
Wow, I have no Idea what you guys are talking about. Is this 240 specific?
I am pretty sure this is specific to the earlier mercedes engines because it is not on any of the 80's SDs that I have and I faguely remember it on my 78 300d non turbo. At the time I was the only person that had experienced this problem and of all the years i have been on the shop forum here, this is the only other time I have seen this that someone else has this problem. but the parts place had the o rings in stock. however i am sure those o rings can be used for other applications as well. its just an o ring and nothing special about them.
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68 250s SOLD
78 300d non turbo SOLD
1980 240d manual SOLD
1981 300SD 360,000 miles I think she's doomed for a parts car but has a good engine SOLD the engine to spamman
1977 300d non turbo SOLD
1985 300SD california car
1978 240D Manual
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  #11  
Old 10-03-2008, 02:44 PM
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Okay guys I have more info from Mercedes after looking at some of their parts group diagrams. This part is found in Group 01 Subgroup 015 in the Benz computer. Engine is 616.912 - not sure if it applies to the 5-cylinder.

It's called the "Plane bearing shaft to oil pump".
The official part number is 615 181 0026.

Like you said, the dealership won't sell just the o-rings and it's $85 for the whole shaft plus a 2-week wait cause it has to come from Germany. Tiny little thing according to the diagram. Looks like maybe a 21mm bolt head that is as wide as it is long.
I will pop it out tonight and see if I can find matching o-rings at the local parts store to replace the brittle ones with. Otherwise I guess I wait! I'll let you all know how it comes out.

You guys are all fantastic help.
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  #12  
Old 10-03-2008, 04:46 PM
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another idea

I would be almost positive that you can match those o rings at the parts store unles there is some weird metric o ring or something. Like i said if that doesnt work you can call Inter auto parts in san diego and have them ship it to you
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68 250s SOLD
78 300d non turbo SOLD
1980 240d manual SOLD
1981 300SD 360,000 miles I think she's doomed for a parts car but has a good engine SOLD the engine to spamman
1977 300d non turbo SOLD
1985 300SD california car
1978 240D Manual
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  #13  
Old 10-03-2008, 05:01 PM
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i remember now

So there is a bolt above the vacumme pump to the left that you have to loosen to get the assembly out of the housing the bolt on the side locks the "bolt" in place. Once you get the top off, there is a allen wrench at the bottom of the housing that eirther allows you to pull the assembly out or just lossens it. I cannot remember the specifics but research a little more. I dont recall the name that you gave to this part. I do belive that the entire assembly that goes from the top bolt all the way down to the oil pump in the sump is what you are found and refering the part to. The "bolt" is inside that assembly and has a different name. From what I can remember the bolt looks very similar to a glow plug and is about the same length but a little bit more fat and hollowed out inside. It is really hard to explain something in detail when it happend a couple years ago. and for my young age (23) I should be able to remember all of this, but it ascapes me at the moment. I hope this helps and I am not confusing you more!
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68 250s SOLD
78 300d non turbo SOLD
1980 240d manual SOLD
1981 300SD 360,000 miles I think she's doomed for a parts car but has a good engine SOLD the engine to spamman
1977 300d non turbo SOLD
1985 300SD california car
1978 240D Manual
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  #14  
Old 10-03-2008, 09:15 PM
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Just found the whole procedure in the FSM, 05-410 "Removal and installation of helical gear shaft". They make a point of saying in this procedure that the o-ring (there only appears to be one) should be checked and replaced if needed in step 8. Looking at the diagrams, I think you can probably get away with replacement of just the o-ring without having to get into steps 5 and 6.

For any following in these footsteps in the future, the retaining bolt you reference is torqued to 45 Nm and the cap bolt (the thing you see in the picture) is torqued to 50 Nm.

Will keep you posted...
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  #15  
Old 10-03-2008, 09:39 PM
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This same cavity and bolt head exists on a 220D/8, and I was told it gives access for mechanics to hook up a mechanical tach when doing engine service work. Don't know if it is true, but had to replace the O-ring on the 220D many years ago as well.

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