valve cover torque setting please. w126 300sd - Page 2 - PeachParts Mercedes-Benz Forum

nhdoc · #16 05-09-2007, 10:04 AM

Quote:

Originally Posted by Brian Carlton

LOL.......are you serious? You've got four screws trying to provide even force to a relatively flimsy cover and gasket.........and you want to "guess" the torque on those screws?

I'll make a wager that your nuts are nowhere near the specified torque and you run the risk of leaks below the gasket or twisting of the cover itself.

That torque on that valve cover is critical due to the design.

It's a classic case of a mechanic who thinks he's got more knowledge than the engineer who designed the fastener. All too common, unfortunately.

I totally agree with Brian, it's kind of important when it comes to gaskets that torque be not only even but to spec. I used to think less of this until I bought set of torque wrenches and went back to work I had done and then seen how poorly I had been estimating it.

This past weekend I went to put a new VC gasket on a 617 I recenlty bought and the nuts were so tight I almost had to use a breaker bar on them to free them. The bolts that held the linkage down needed a breaker to get them free - I was afraid the VC itself would break before they loosened. Whoever had previsously done work on that car surely didn't use a torqure wrench which is probably why it needed a new VC gasket anyway.

I had heard the spec was 10NM not higher than that though, so someone ought to double check. It sounds like they are using 10ft-lbs which would be around 13NM, probably wouldn't make that big a difference but I think the spec is only 10NM.

vstech · #17 05-09-2007, 11:03 AM

true brian, but, I am WAY more forgiving of the valve cover guess, than the HEAD BOLT!!!!! there is NO WAY anybody can FEEL those torque values!! I mean there is a procedure! and the bolts are torqued to yield! I feel sorry for anybody who gets engine work done by that guy!
John

Brian Carlton · #18 05-09-2007, 11:12 AM

Quote:

Originally Posted by vstech

true brian, but, I am WAY more forgiving of the valve cover guess, than the HEAD BOLT!!!!! there is NO WAY anybody can FEEL those torque values!! I mean there is a procedure! and the bolts are torqued to yield! I feel sorry for anybody who gets engine work done by that guy!
John

Definitely. The wrong torque on a valve cover nut yields a leak.............the wrong torque on a few head bolts..............

FWIW, I tried to tighten the nuts without the wrench. Then, I used the wrench to see how I did. The nuts turned another 1/2 turn or so.........I was much too low on torque.