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1983 300D Turbo
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377 Posts
Discussion Starter #1
Anyone know how much torque you need to put on the valve cover screws?

Thanks,

Austin
 

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2013 MINI Copper S Clubman, '84 300CD-weekend car
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10,152 Posts
No value listed, tighten a bit, see if it leaks, if so, tighten a bit more.

Using a new gasket will help.
 

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1979 240D, 1988 560SL
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394 Posts
I don't tighten them much because it doesn't do much once they've bottomed out. If you still get leaks, sand the posts/bosses down a little bit. If all 4 bosses don't have about the same clearance you can get leakage. It took me 15 minutes and made a huge difference in valvecover leakage.
 

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1981 W123 300D non turbo, 1992 190E 1.8 <=> 2.0
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6,561 Posts
Difficult to find but in chapter 5-210 for measuring valve clearances the M8 nuts for the cylinder head COVER (!) are specified as 15Nm
 

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2013 MINI Copper S Clubman, '84 300CD-weekend car
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10,152 Posts
Stretch is correct, the FSM says 15 Nm, but my Technical Data book has no value, I penciled in 15, as you can see.
 

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1983 300D Turbo
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Discussion Starter #6
so thats 15 pounds of pressure on my torque wrench?

sorry.. just dont know what a 15nm is.

(yea.. im a noob)
 

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1981 W123 300D non turbo, 1992 190E 1.8 <=> 2.0
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1979 240D, 1988 560SL
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Most torque wrenches have Nm and Ft-lb but to get as close as you need just multiply Nm x 3/4. So, 15 x 3/4 = 11.25 Ft-lb

Honestly though, it doesn't matter how much you torque or don't torque it if the bosses are proud of the sealing edge. Your goal is to compress the gasket between the valve cover and the cylinder head. Once you bottom out the valve cover boss against the cylinder head boss you could tighten it until the bolts are twisting apart and still not have a seal. The two valve covers I have seen both had poor surface finish (presumably from being removed/installed over the years) on the bolt boss that created a high spot and did not allow the valve cover to compress the gasket adequately.

However, do not sand the bosses down too much or you can cut the gasket in two!
 

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2001 ML320 2004 ML500 2011 E350 2015 ML350 2002 CL55 AMG
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Holy sheet - NO!...........Funny, what was going through my head when I read pounds....

The valve covers on the M119 (2004 V8) is only 8Nm.....which is close to inch pounds when thinking of what type of wrench to use. I had to buy a smaller torque wrench to cover this light of a setting....seems the Magnesium and Aluminum has some low torque values, not a big surprise.

My gaskets no longer leak so "higher torque" is not necessary.
 

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I know this is an
Most torque wrenches have Nm and Ft-lb but to get as close as you need just multiply Nm x 3/4. So, 15 x 3/4 = 11.25 Ft-lb

Honestly though, it doesn't matter how much you torque or don't torque it if the bosses are proud of the sealing edge. Your goal is to compress the gasket between the valve cover and the cylinder head. Once you bottom out the valve cover boss against the cylinder head boss you could tighten it until the bolts are twisting apart and still not have a seal. The two valve covers I have seen both had poor surface finish (presumably from being removed/installed over the years) on the bolt boss that created a high spot and did not allow the valve cover to compress the gasket adequately.

However, do not sand the bosses down too much or you can cut the gasket in two!

I know this is an old tread... but just in case anyone googles it; correct torque does matter ! do not over tighten..

over tightening the valve cover might make the seal change shape and it wont seal properly .. on all seals that have a rectangularish shape correct torque is very important.. the round ones too, but less so...

(I seen this numerous times on marine engines.. I used to work as a watchkeeping engineer at sea for several years )
 

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Run it down with an electric 1/4 bit impact. Never leaks. Good seal and clean surfaces are most important. NO SILICONE OR SEALANT!
 

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1989 W124 260E
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Original Mercedes gasket or problems will return i use 10 nm on my rocker box but its the 6 pot . At the moment its set down to 9 nm so i can remove it at a later date to fit new hydraulic tappets .
 

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1982 300D Turbodiesel (US Spec)
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153 Posts
It doesn’t take much torque. The thing is, you have to re-torque the nuts with engine warm after using the car 2 or 3 times.
 
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