where could be the leak?

[bcjm]

I have been trying to track down an oil leak for a while.  I think it is somewhere under the exhaust manifold behind the thermostat housing.  That looks like the wettest area. The oil stain is around the water pump in the front of the engine and all the way down to the oil pan.  

The alternator bracket block that area I can't really get a good look.  Is there anything there could be the cause of that before I tear everything apart?

[tuultyme]

I had a similar leak.  Per Joe A. suggestion I found the culprit.  Remove the valve cover.  Remove the oil in the little well near the chain tensioner; front right corner.  Will find a bolt down there; remove place sealant on the threads; reinstale.  Leak gone.  During casting the bolt hole came out behind the thermostat housing in the engine block.  Also place some sealant on the other bolts going into the front of the engine.

Bruce; 268Blaugrun(green) 1970 280SL; IL

[TheEngineer]

This is an Allen head bolt, takes a long 5 mm allen socket wrench. Be very careful not to drop the bolt into the engine. Hint: Stuff rags into all slots! Sealant is good: Use the stuff MB uses but put an aluminum sealing washer under the bolt head. It belongs there.
Edited on 8/28: The MB sealant is MB part number A002 989 47 20 10

'69 280SL,Signal Red,113044-12-007537,tired engineer, West-Seattle,WA

[bcjm]

What sealant does MB use?  Is there a name?  Any generic sealant be Ok?

[al_lieffring]

The chain tensioner has an O ring seal that will cause a leak in that area. It would require unbolting the compressor/alternator bracket to get to the chain tensioner and replace the seal. If you do have to dig in this deep change the thermostat bypass hose too. It is also inacessable with the a/c bracket in place.

113-042-10-014715
built 11 Jan 66
904/396 blue, Ivory Tex
condition- rust bucket

[bcjm]

By looking at the whole thing, I think one of the AC bracket bolt is blocked by the crankshaft pulley and crankshaft pulley is block by power steering pump bracket.  This could be a much bigger job than I anticipated.

[Vince Canepa]

The bolt mentioned by the engineer leaks exactly as you describe.  Airflow blows it back on the exhaust side of the engine.  It is easy to check and I would look there first.

Vince Canepa
1967 250SL
113.043-10-001543
568H Signal Red
116 Caviar MB-Tex

[bcjm]

How do you check if this bolt is leaking?  All views are blocked?

[Bob G ✝︎]

Since someoneelse brought it up I too have a leaky gasket.My poor 280SL has been sitting against a wall like I put it on detention for being bad!!! now  for the second time I have a transmission leak under the car. Last time this happened I refilled the transmission to were it should be and drove it. Its been fine but it back in venence again. Could the modulator be the cause of the leak??
What should I check ??

Thank You
frustrated car nut.
Bob Geco

[bcjm]

Took the valve cover off, found the allen bolt.  I am suprised to see how little space I have to work with.  The allen wrench has to tilt a little bit.  The bolt is very loose. I can turn it by hand with an 'L' allen wrench bar.  Now I have to find a long allen socket first.

The sealant mentioned previously cost $47 from local dealer.  Going to look for a generic one.

[George Davis]

Permatex No. 2 is a good sealant, available at any auto parts store.  Probably don't need to use much, just coat a few threads.

George Davis
'69 280 SL Euro manual

[Vince Canepa]

To gain access to the bolt there are two options:

1) Remove the cam sprocket and the chain tensioner arm
or
2) Find a long shank "ball end" allen socket

Vince Canepa
1967 250SL
113.043-10-001543
568H Signal Red
116 Caviar MB-Tex

[bcjm]

"To gain access to the bolt there are two options:
1) Remove the cam sprocket and the chain tensioner arm
or
2) Find a long shank "ball end" allen socket
"

Funny you said that since I was just in the garage trying to remove the bolt with the "L" allen bar since it is already loose.  I thought the metal piece (tensioner arm?) on top of the bolt prevents the bolt comes all the way up.  That is why I stopped.  I will try it again.

Went to few parts stores today can't find a long allen socket not to mention a "ball end" one.

[Vince Canepa]

I had to do this repair last year.  I removed the sprocket and chain (carefully), then the bolt covering the pivot pin for the tensioner arm, then drew out the pivot pin (it is drilled and tapped so you can insert a bolt to draw it out), then removed the tensioner arm.

I didn't have a long ball end driver in that size at the time.  You can find them on a Snap-On or Mac tool truck.  Industrial tool suppliers should carry them also.  I have also seen them a fastener suppliers.  Here are a couple possibilities on the web:

http://www.wihatools.com/369mmserie.htm
http://buy1.snapon.com/catalog/item.asp?P65=&tool=all&item_ID=2471&group_ID=11446&store=snapon-store&dir=catalog

I have since purchased several ball end hex wrenches and hex sockets.  Seems like I find more use for them every day.


Vince Canepa
1967 250SL
113.043-10-001543
568H Signal Red
116 Caviar MB-Tex

[bcjm]

Vince,

Can you confirm that the bolt does come out without removing the cam sprocket and the chain tensioner arm?

Thanks Bob

[Vince Canepa]

No - I cannot.  However, the bolt is relatively short.  Personally, I don't think you need to pull the bolt out.  I just tightened mine up and I don't have any leakage.  I pulled the arm because I couldn't get a straight shot at the hex with the tools I had and I didn't want to round it out.

Vince Canepa
1967 250SL
113.043-10-001543
568H Signal Red
116 Caviar MB-Tex

[Naj ✝︎]

Hi, Bob,

 

quote:Can you confirm that the bolt does come out without removing the cam sprocket and the chain tensioner arm?

After reading your post, I too decided to tackle the job this afternoon. The tensioner lever assembly is spring loaded so if you wedge a screwdriver between the head and lever, it will give you a bit of extra room to get the screw out. Mine was loose too and I used a magnet to take it out. Also used a syringe with a bit of pipe to suck the oil out of the well.
I suggest you use a non-ball end hex to tighten the bolt. I used a ball ended one with a rachet and it rounded the bolt head.

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Also checked valve clearances while the cover was off.  

Hope this helps...

naj

68 280SL

[tuultyme]

Look at the previous Thread:
"How many leaks? Let me count the ways" From back in 30 December 2004.  In my picture of the tensioner bolt the "leaky" bolt was different than Naj's; my car is a 70 280SL.  Mine was down under to the right of the tensioner arm; so once the oil was removed it was easiy to remove and reseal.  I found the correct sized T "ball end" allen socket at the local Ace Hardware.  I have also since bought a whole set of these T "ball end" allen sockets; at the local car show.

Bruce; 268Blaugrun(green) 1970 280SL; IL

[bcjm]

It worked!  I got the bolt out without removing the tensioner arm.  Once the tensioner arm is pushed using a screw driver, it provides enough space to remove the bolt.  I didn't need to use a ball end allen wrench.



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