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Discussion Starter #1
Morning, changing drivers side valve cover gasket and wish to disconnect fuel line (never done before) to allow clearance so I can be assured new gasket positions and seats correctly. It's a pressurized system; I see the Schrader valve cap towards front passenger. Uncapping and releasing through the valve; how much pressure
is there, do I expect a strong spray? Also, how much fuel will be expelled, couple hand towels enough to catch. When complete, there will be no more fuel coming
out of the valve? Seems I then crack the 17mm nut/connector at the end of the braided fuel line; guessing a little will trickle from here also? I found a few references
but not a complete simply explained step by step. I'm uncomfortable with pressurized fuel not knowing what to expect.
 

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Discussion Starter #2
so I braved the bleed myself from a pelican parts diy. disconnected the battery, pushed in the pressure release Schrader valve and a tiny tiny hiss and 1 drop of fuel...??
car has been sitting since past wed afternoon, so 4 days. Could I have lost pressure so fast and completely?
 

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Yes ,,I too have found only a small amount comes out the schrader valve,,
You will get a lot more come out the supply line ,,maybe 250ml ,,.

Mark the nut with a marker or scratch to show how much to tighten it back up when you are done.
 

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Discussion Starter #4
Thanks for everything, especially the diy links. I'm getting an education and gaining confidence with my tools (what normal person has a set of e-torx tools anyways...lol).
I did discover disconnecting the line at the rail yielded a fair amount of gas, had a trash bag and old towels at the ready. I've unfortunately discovered the reason for my leak.
I have an imperfection right above the half moon (cam) on the side. It is a slight dent with a slight depression that starts at the outer edge and will affect approximately half
of the gasket width where it will sit. That must explain why the previous service applied sealant. The sealant appeared to be mostly a clear product and was applied to the entire
gasket though in a very very thin film. I'm certain I will need a sealant also; but wondering if it should just be applied mostly to the area of the imperfection or maybe the entire
length of just that side. I'm thinking that should "even" the entire side between the metal to metal stops on the corners? I'm a little discouraged as I have only had the car
2 1/2 weeks. I work the next couple days so the clk will be infirmed until wed-thurs when I can try to sort this out. I have some Permatex ultra black sealant that I am considering
though many seem to prefer Loctite products.
 

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So , the dent /depression is in the head ?
I would say only put sealant over the dent and maybe just a smear 1 inch either way..
Cleanliness is critical ,,make sure you clean all traces of oil off the area with brake cleaner or non residue mineral turps.
Clear sealant is not usually used for engines,,,that could be a big part of the problem.
Use a quality gasket maker like I said in the other thread.

You can get tools like e torx etc on ebay ,cheap and quick.

Doing the breathers and vc gaskets is really a maintenance item on these M112 and M113 engines ,,,almost every one needs it done after about 10 or 12 years,,depending on mileage.
 

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Morning, changing drivers side valve cover gasket ....
Hi - just to correct your terminology here, you have a CLK 550 that will have engine type 273. This engine does not have the crankcase ventilation covers, often referred to as valve covers in the M112/M113 engines. Those covers have no gasket and rely on Loctite sealant, plus screws.

You will have removed a cylinder head cover from your M273 engine.. This also does not need a gasket, just Loctite sealant, applied as detailed in the WIS document below.
 

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Hi Keyhole ,,
Why do you think he has a CLK550 ?
Isn't 2004 too early for that car ? I thought they started in 2006 ....
 

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Discussion Starter #8
That sounds quite reasonable. I just ordered the original MBZ "black " sealant that people rave about, Loctite 5970? Without over thinking this; any harm in a light quick wipe on the gasket a cleaner (brake cleaner too harsh?) in the area whre I will apply the sealant? Just making certain the gasket is extremely clean in the area I apply the sealant over the
imperfection. Any suggestions would also be appreciated. I understand both surfaces have to be absolutely well prepped and spotless.
 

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Sounds ok to me ,,,
If you can please post a photo so we can see what you are talking about ,,,and confirm what type of engine you have..
 

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Discussion Starter #11 (Edited)
I'm having difficulties attaching an image from my phone. Can I forward a picture of the engine block divet to someones email account?
Please disregard and see follow-up post. Icloud problem resolved.
 

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Discussion Starter #13 (Edited)
so I'm waiting for my MB black sealant to arrive to address my block issue. I have decided to only apply the sealant to the affected area (or other suggestions?).
I have several options (and questions)
A) apply thin line to center of gasket where it will sit over damaged area (maybe also thinly "feathering" away from the area for an inch). I will need enough right over the damage
to assure it will fill the indent. place/set it carefully and lightly finger tight and wait to torque properly in 2 passes, gradually increasing torque. I don't have the sealant so I don't know
if I have to wait before setting the valve cover and or before torqueing.
I could also just try to apply closer to the outer edge of the gasket.
B) try to fill the damage channel directly on the block as even as possible (again following directions when I get the sealant) and then placing the valve cover with dry gasket.
I could also apply a thin layer to the gasket to "marry" to the sealant applied to the block.
Interestingly enough the damaged area was not the leak problem, the leak was on the top edge closet to the firewall.
This is all new to me and appreciate all the help. Without over thinking I really want to get this right.
I am also seeing strong opinions on the MB sealant not compatible with a rubber gasket and coming loose. An aviation blog suggests Loctite gasket sealnt 2 and the racing and biker blogs all suggest yamabond. Also I've seen MB sealants require a 7 day full cure?
 

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Hi dgdrx ,
I would go with option B. Apply the sealant directly to the dent using your finger ,,filling it up to about 2mm above level for an inch or more in each direction ,,but not very thick on the side close the inside of the engine..you don't want to apply so much sealant that it may be squeezed out inside the engine.
Also apply a thin smear to the gasket sealing face where it will meet the damaged area.

Have the gasket already seated in the vc and ready to go on ,,,after you apply the sealant you want to fit the cover asap ,,,and then torque it in stages up to 8 Nm ,,,,,also asap.
That way the sealant cures in it's final position.
I have never used genuine MB sealant or Loctite 5970 which is the same thing ,,,,so I can't say from experience ,,
I do know that Dow Corning Silastic Gasket sticks very well and basically permanently to everything ,,rubber gasket and metal surfaces,,,I would have thought that 5970 would be the same ,but the advantage is that it is neutral cure ie,does not emit any acetic acid when curing ,,,and takes 25 mins to skin ,,which gives you plenty of time to apply it and torque it down.
 

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Discussion Starter #15
Thanks, I agree with your plan. On another note does anyone know the marking on the baum engine oil dipstick for my 04 clk55 engine for full. I've seen a few
references that disagree. Is it the 160 mark?
Thanks again, wish me luck sealing this valve cover.
 

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This is the dipstick chart from the WIS for your engine 113.987

This shows the OK range is 163mm to 165mm.
Hi Keyhole ,,
Thanks for the chart ,,,my car is a W209 with engine 113.988,,,,does the chart still apply ?
Any idea what the difference is between 987 and 988 ?
 

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Discussion Starter #18
I haven't had chance to use the dip stick yet but I seem to recall it will not go all the way in; so you "bottom it out" as far as it will go? I've read a couple inches will
remain? How bizarre. I've also just noticed my driver side view mirror could use replacing. $250 on line for original heated auto dim. Also install looks fun trying to clip
in.
On another note my magic MBZ black sealant has been curing for 3 days; time to see if I successfully sealed the valve cover.
 

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The dipstick tools are used on different engines with different length tubes ,,so yes , you bottom it out,,,
It should be checked 5 minutes after stopping the engine ,, with hot oil ,,,
Be careful not to overfill,,,,I aim for about 200ml less than full. ie , 8.5l oil change ,,, I measure and add 8.3l and then see if the car is happy. It usually is.
 

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Discussion Starter #20
Just took a little ride and so far no leak, but we need to drive more. I did notice a slightly rougher "stumbling" idle, very subtle. I did disconnect the battery and
replaced a few breather hoses as well as clean the MAF sensor. I have read about a throttle "position/switch or the sort" reset sometimes required?
Any ideas/suggestions or do I just need to drive for a bit and let the "computers" reset/figure it out?
 
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