Hello,

Car: 1987 Mercedes 300SDL OM603
Part: Upper bolt for belt tensioner shock.
Problem: Trying to determine if bolt is broken off in block
Question: How long should that bolt be? I can only access 10mm in that hole in the engine block...

Details:

I can only get in the hole 10mm, which I think is too shallow. I was wanting to see how deep that hole should be.

First shows the hole I'm talking about, it is located, as you are facing, to the left of the shock spring lever.



Second picture is the shock itself.
Ignore the M8 x 1.25 x 40mm bolt on top, I was just testing the fit.
The bottom bolt is correct and is the one that came with the car.

Over 90% of the strength is achieved once you've gotten six full turns into the threads. I suspect that the threads are 2.5mm per turn, so you are maybe getting four turns? Sounds like too shallow to me.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

I just removed and measured the bolt on my '87 wagon (same basic engine) and the threaded portion of the bolt is about 28mm long. Thickness of the shock is about 8mm, so about 20mm (2cm) of the bolt goes into the hole in the block.

In other words, you've got a problem and something is stuck in that hole.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

Mr. Dillon,

Thank you sir. You are a gentleman and a scholar. I appreciate your effort!

That information will help me think of how to tackle the problem. I have a set of screw extractors, but a voice in the back of my head is saying that it's broken off real good in there.... If the screw extractor doesn't work, maybe drill/tap/ and put in a ez lok threaded insert

Oh I'm not enjoying this... lol

Thank you again sir.

Robert

Before you do anything drastic, maybe start a new thread about extracting whatever is in there. There are many clever people on this list who can probably guide you in the right direction. Getting good access is an issue, probably need to remove the radiator and the fan.

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC