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1997 S600 Coupe
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Discussion Starter · #1 ·
I'm putting a new water pump on while I'm doing other work. I don't know how old the one I had is, though it appears to have been replaced at least once (103K miles). The question I have, that I didn't find on other write-ups, is which way does the gasket face? Does the blue side go against the block, or the water pump?
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'99 S420 122K
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1,606 Posts
If you look closely at the water pump you will probably see slots in the pump housing for the BLUE material to "fit into". All I've ever experienced was smooth gasket to the block.
Someone please correct me if I am wrong.
 

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'99 S420 122K
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Be certain to apply the proper torque, and maybe someone can say if there is a sequence/pattern for torqueing the bolts.
 

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1997 S600 Coupe
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Discussion Starter · #4 ·
From what I've read, there's no specific sequence of tightening, but I do know the torque specs. I was assuming the flat side to the block, but there's no indentations on the block or water pump, nor instructions with the gasket or water pump (which also came with a gasket that looks similar to this one, but isn't from MB). It may not matter, but I just wanted to be sure.
 

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600 coupe, one of the very first built
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Going from memory, which isn't very good anymore....the gasket fits only one way :))

Just googled a pump for the M120 and I think I am right:

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I think MB also used some goo. When you remove the old pump, residue will be there.
I used gasket dressing too. The job is somewhat involved and I did not want to have a leak afterwards.
 

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'99 S420 122K
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I used Permatex "blue" gasket silicone as I recall(old school). I now suspect that blue on the gasket is the gasket sealer. You may not need sealer on the block side, what say you, Time Capsule?
You MUST have clean surfaces.
You don't want to have to do water pumps twice.
 

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99' E320, 00' E320, 03' E320T, 05' C230K
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Going from memory, which isn't very good anymore....the gasket fits only one way :))
I never seen a symmetrical water pump gasket for a car before. So............yeah, it only fits one way.
 
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1997 S600 Coupe
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Discussion Starter · #8 ·
You're right now that I think about. It is only able to be put putting in one direction. There didn't really appear to be any sealant on the pump or block (is cleaned the block thoroughly), and the main write-up I read was from another member here. It's on a site called V12 uberalles. He didn't mention any sealant except just a couple dabs on the "ears" to hold the gasket in place during assembly.
 

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1997 S600 Coupe
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Discussion Starter · #9 · (Edited)
One other quick question, just to make sure. Based on the write-up I mentioned above: do any of the bolts need thread sealant due to being in a water jacket (it doesn't mention any)? I ask because I know some vehicles require that, including my '95 Jeep Grand Cherokee with the 5.2.
 

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There didn't really appear to be any sealant on the pump or block (is cleaned the block thoroughly),
MB must have changed the assembly process. Below is a picture from my car. The pump separated easily from the front cover, leaving the entire gasket affixed to the block. Hard to tell after almost 30 years...

No evidence for thread seal on the bolts, but, since this is a repair job, and since you will be putting an aftermarket pump, if I were you, I'd use dressing on the gasket and sealant for the bolts.

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1997 S600 Coupe
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Discussion Starter · #11 ·
Thank you all! Looking forward to buttoning this back up and getting it back on the road. (Doing other things while I'm in here, including TT coolant hose, radiator, thermostat and crank pulley)
 

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Sounds like you're having fun.

Don't forget the two o-rings that seal the coolant tubes coming out of the front cover.
Even if you did not remove the whole thing, if they were disturbed, they will need to be changed (shown in red below)
Mine were hard as a rock,

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Discussion Starter · #13 ·
Yep, I got all 4 for that pipe and the one that goes between it and the pump. I'll also update my other thread about the TT coolant junction to show what was in there. And as for the crank pulley, the old one is rough shape and probably would have separated before too long. The price hurt though, $700, and that was the cheapest I found.😭
 

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And as for the crank pulley, the old one is rough shape and probably would have separated before too long. The price hurt though, $700, and that was the cheapest I found.😭
The damper is ridiculously expensive. I am surprised you found one that "cheap"
Usually, the best route would be to have your original one rebuild, but that is a subject for another topic (some info in the archives)
 

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Discussion Starter · #15 ·
Yes, I looked high and low. Found this deal online from Mercedes of Covington, LA. After shipping it was around $732 or so. Most places were closer to $1,000. I also looked into the rebuild route, but didn't want to be without for too long. I had looked at the archives and saww where there is a guy in CA that has rebuilt them for members on here in the past.
 
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