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I'm having an issue with my front timing covers. I recently hit 100k in my 2014 GLK350 and did water pump, thermostat, plugs, timing cover re-seal (was seeping/had never been done).
I have the WS manual and followed all instructions, including torque and procedure for cleaning the previous gasket with MB chemical remover.
All went well, but the driver side cover started leaking again after only about 2 heat cycles...leaking from the right-bottom-most screw (when staring at engine bay from front of the car). Passenger cover is not leaking. I'm sure the leak is local to this bolt area and not running down from other parts as I clean/watch with each drive.
I assumed it was error in preparation, some contamination etc. So I again bought new bolts and sealant and did the driver side again. But it again started leaking after 1-2 heat cycles.
I read a bit about anti-corrosive grey coating and that causing issues with sealant. I also saw some recommendations to 'remove' the coating.
So - how are you guys handling this? I cant seem to find any online retailer who has the cover in stock, and I also have no idea how to remove the anti-corrosive coating.
Use a good metal straight edge to find what is bad. FCP euro might have it , eBay is a lot cheaper . Wherever you buy check it with a straight edge first . You never know , I bought a new water pump and the shipper dropped the box and bent the pump ! FCP sent out a replacement no problems at all . With carefull measuring you will find the cause
I'm having an issue with my front timing covers. I recently hit 100k in my 2014 GLK350 and did water pump, thermostat, plugs, timing cover re-seal (was seeping/had never been done).
I have the WS manual and followed all instructions, including torque and procedure for cleaning the previous gasket with MB chemical remover.
All went well, but the driver side cover started leaking again after only about 2 heat cycles...leaking from the right-bottom-most screw (when staring at engine bay from front of the car). Passenger cover is not leaking. I'm sure the leak is local to this bolt area and not running down from other parts as I clean/watch with each drive.
I assumed it was error in preparation, some contamination etc. So I again bought new bolts and sealant and did the driver side again. But it again started leaking after 1-2 heat cycles.
I read a bit about anti-corrosive grey coating and that causing issues with sealant. I also saw some recommendations to 'remove' the coating.
So - how are you guys handling this? I cant seem to find any online retailer who has the cover in stock, and I also have no idea how to remove the anti-corrosive coating.
Heeeeeelp!
I never had this issue on my ‘15 GLK350, but I’ll share experience from some of my other MB engines. Inspect the cover carefully. Some of them are made from magnesium and are prone to micro cracks. If yours are okay, then the solution may be to fabricate a gasket from 0.75mm compressible gasket material and use gasket sealer. A thicker gasket can’t be used because of the adjuster magnets.
I also used regular bolts, but I hesitate to recommend that because the tightening sequence of xx nm + yy degrees takes into account stretching of the one time bolts and a mistake here will could strip the bolt holes, which most DIYers can’t fix in their garage.
I was able to tighten up some notoriously leaky MB engines. Good luck with it.
Thanks, I also thought micro crack or warped issue, so I bought a used cover from wolf auto parts.
it arrived yesterday and I noticed it’s even ‘more grey’ than mine, and after even more digging, it seems like the revision number is stamped onto the cover itself. My car has 004 revision, and what I ordered was actually older at 001 revision.
some more digging and I found a nice (used) and shiny, not grey, 022 revision part and ordered that. Will install the newer revision cover which apparently doesn’t have the anti corrosive coating, new bolts etc etc. one last time and hope for the best.
attached is a photo of the lower right bolt in question, shown as ‘moist’ underneath. This is after I dabbed away the about-to-drip oil. It really must be: cracked, warped: anti corrosive issue. I really can’t imagine two brand new beads of MB sealant with uber attention to surface prep could leak so quickly.
Does that bolt hole go into a space where liquid is present? Alternatively, is the bottom of the hole compromised, by, for example, screwing the bolt in when there is something incompressible in the hole? Either way, liquid will migrate up the threads and out under the bolt head. The fix is thread sealer, but be aware that will affect your torque procedure.
The workshop manual doesn’t say to do anything special for this bolt, and the opposing side (passenger side cover) doesn’t have this issue with the bottommost left bolt. I do not believe this bolt should need thread sealant. I was considering adding it next time just in case the thread journal has a crack, but I don’t think this is the case.
Here is a 002 revision valve cover plate compared to a 022 revision plate. Notice the newer plate seems to not have any of the anti corrosive coating.
Also note that the 002 revision part has significant deformations in the coating on the mating surface (in the red circled areas I can feel a difference in the surface height, and it isn’t dissolvable with gasket remover, thinner etc). Neither of these are from my vehicle, I bought both as used. I will use the newer revision part to try and finally solve my repeated leak.
Well....on the first run with the 022 revision cover, all looked okay until turning off and letting it sit for 5 mins. Then, some oil appeared in the SAME SPOT.
I really am out of ideas, the camshaft solenoids are not leaking, and there is nothing else that looks like it could be oozing...the oil is just right on the sealant bead and just in the lower right corner....but I've done this 3x now, new sealant each time, properly dissolving and ensuring a flat and clean surface. I'm stumped!
2010 GLK350, 2021 Taco, 2019 Lexus GX460, 2009 BMW 335d, BMW 328xi
What a massive pain in the neck! Have you checked to make sure there isn’t an obstruction in the bolt hole in the block? Some oil or grunge in there can shorten the effective length, not allowing the bolt to torque properly. Another possibility is that the hole in the block is either not drilled deep enough or threaded deep enough. Could also be the bolt is too long, or the tip of the original bolt broke off inside. You can verify by threading the new bolt in while the cover is off. You should be able to turn it in by hand to past the depth where it would be stopped by the cover, by at least a couple mm’s. Wouldn’t hurt to turn in the correct metric tap to make sure the threads are clean and healthy.
I resealed 24h ago. Letting it cure until Sunday, and will report back.
one thing I noticed: I could use a plastic trim tool and the MB gasket dissolver to get the mating surface on the valve head ‘silvery’ with very little trace of black residue, apparently ready for new adhesive. Using microfiber and mb dissolver as well.
however, upon using mb gasket dissolver in combination with a paper towel to really ‘scrub’ the surface resulted in more grey black removal from the surface. This leads me to believe at lease the last time, and maybe more, leaks were result of seemingly visually perfect, but still incomplete surface prep. Let’s hope….
i am still using the 022 revision cover because why not
2014 GLK350 base model (active) ; 2001 E320 base (retired); 2001 Wrangler soft-top
Originally Posted by pappe
Note that I cleaned the threads each time with q-tip and degreaser. There’s no oil evidence in any screw holes.
if it still leaks this time, maybe this is to blame?
That tiny scratch? Can't imagine it would.
However, if I want to be sure, I'd use a straight-edge and flashlight (or similar) to verify.
And I would verify the complete mating surfaces, including the engine-side.
Doing so will verify required flatness.
2010 GLK350, 2021 Taco, 2019 Lexus GX460, 2009 BMW 335d, BMW 328xi
Originally Posted by pappe
Note that I cleaned the threads each time with q-tip and degreaser. There’s no oil evidence in any screw holes.
if it still leaks this time, maybe this is to blame?
Have you checked the depth of the threaded holes in the block compared to the bolts you are using? In my ling-winded comments and questions above, the main point was that if the bolt is bottoming out inside the block, it will not hold the cover tight. Check the bolt length and make sure it’s not too long.
the main point was that if the bolt is bottoming out inside the block, it will not hold the cover tight.
Or it will punch through the bottom of the hole into the interior, allowing oil to migrate up the threads and out.
The scratch in the photo doesn't extend from the interior to the exterior and so shouldn't be a problem.
The machining marks on the cover would be more of a problem, but the gasket and sealer should eliminate that.
If this attempt fails, you might try using a product called "The Right Stuff" and skip the gasket. I've used it on problematic valve covers with good results. Put it on and install the cover bolts finger tight. Let it set up overnight then torque the bolts.
Thanks all, I did check thread depth and ensured all holes can accommodate the length of the bolts, and also no oil in any of the thread holes or on the bolts when removed, so we can eliminate cracked threads as a suspect.
ill check out the right stuff, i also bought some 0.8mm gasket material. If this attempt fails, I’m going full sealer mode.
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