Got a leaky gasket on the Cylinder head cover - not the actual cover gasket but the 2nd parts of the cover that sits on top of the main cover - not exactly technical but best i can think to describe it

Question is - Is this a proper gasket or a sealant one? i looked on the parts listing but it isnt shown. From looking at it, it looks like a sealant one but not sure.

 

Sealant - RTV.

 

Cheers, got some this afternoon just in case.

 

Hi, just a word of warning, when you take of the evaporation chamber to replace the black sealant the small torx bolts are made of soft aluminium and WILL snap if you get even remotely close to tightening them. Throw the away and replace with stainless steel allen bolts, they're a couple of quid on ebay. Still only finger tight though as they serve no real purpose other than to hold the chamber cover in place when the whole camcover is taken off.

The rest is a piece of cake.

 

There may be a good reason why they are aluminum screws, one might be that stainless steel and aluminum can set up galvanic corrosion under the right circumstances and eat the threads away.

They have to be replaced after a one time use as they have been stressed and will then easily break. I would sooner have them break than strip or ruin the thread in the covers.

Finger tight means something different to each person so what is OK with one may be too tight or too loose with another. The specified torque is good, but what that is remains a mystery to me.

 

Agreed, but the likelihood of damaging the thread removing a snapped bolt far outweighs that of damage caused by a galvanic reaction as this depends other factors such as the ratio of the surfaces; you should try to have a large anodic area (aluminum) and a small cathodic area (stainless steel). Furthermore it would also require the presence of an electrolyte such as salt water.....not impossible on our winter roads. However you have me doubting myself now so I will now have to do some more research and check my wisdom on this !!!

Replacement alloy bolts were a mystery to my local Chrysler dealer and Mercedes can't work out anything without a Reg number and the shutters came down at the mention of Chrysler!

Finger tightness in this case for me would be nipping the bolt up using the short angle on the allen key

The specified torque settings in the official Chrysler workshop manuals appears to be a misprint and massively wrong.

 

The galvanic action is only a slight possibility, but stainless steel and aluminum are farther apart on the galvanic scale than carbon steel and aluminum.
Mercedes must have had a reason to use more expensive screws than they could have, I'm sure the money men trim all unnecessary cost where they can.

 

Probably had storage bins full of left over W140 fender liner bolts left over...

And someone somewhere laughing about the perplexing question of "why"...