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Using silicone sealer from outside ?

2K views 10 replies 6 participants last post by  Joe-V12 
#1 ·
I have to seal area on the engine where timing chain cover meets engine housing/upper oil pan. Some of you know that in my case that's actually a source of leaking the oil which then drips on the lower oil pan and makes impression that oil pan gasket is not right.

I wonder if using silicone gasket maker will do the job. So i intend to put a couple of millimeters thick layer around the problematical area. Even in my dream i do not want to seal the thing as it should be sealed because i do not want to take the front of the engine appart. BTW, sealing of the problematical area from outside demands a lot of work (harmonic balancer etc. must be removed).

the problem started when one of the most careless and stupid mechanic in the world replaced all chain guides several years ago. I was actually forced into replacement because that idiot turned crankshaft in anticlockwise direction and timing chain jammed ...
 
#2 ·
Just a suggestion. On my previous CL500 an idiot mechanic replaced the valve cover gaskets and sealed them up with silicone. Six months after I bought the car, I bought a new MAF because silicone attacked the sensor in the MAF. (So they tell me.) I don't allow silicone anywhere in the engine compartment. You might want to look into this first.
Anziani
 
#3 · (Edited)
i know what you mean to say. my leak is a small leak but it bothers me. I do not think that silicone in this case will contaminate oil at all ... it is just my impression.

P.S.: it is amazing how many idiots is among mechanics. The guy which i mentioned was specialized in KIA cars (ok, so maybe I am an idiot too because I allowed him to touch and look at my car) and he commented as: "oh, how badly this mercedes is designed" and "what an idiots engineered this car".
 
#4 ·
I would say that it would work to help seal the area; But, only if you prep it properly. You will have to get the area super clean, and make sure that none of the oil residue is left in the area prior to application. ANY residue will effect the silicone sealing to the metal surfaces; making your effort to seal the leak a waste of time.
 
#9 ·
Loctite 5900 is recommended to be used as a sealant on the M120 for the timing chain cover, it's black. Clean off all the areas with liberal use of brake cleaner or metho or something that dries 100%. With the area cleaned of all dirt and oil residue apply sealant to the outside of the leak and an extra half an inch around it for it all the stick to, even scuff the area with some scotchbrite. It won't be pretty but it should hold up fine.

If you were close I'd give you the rest of mine, I have heaps left over as we can only buy it here in the big tubes and it has a used by date.
 
#11 ·
You can probably find a better sealant more suited to surface leak sealing than 5900, there are some pretty aggressive sealants available if you really start looking around.

eg. I have used Devcon HP250 to glue aluminium together, after proper surface prep and set time in testing it needed a chisel and hammer to get it off.
 
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