Do you need a torque wrench for valve cover gaskets?
 

So I did the valve cover gaskets and PCV hoses and gasket on my 2000 E320 Wagon M112 V6(only took me 7 1/2 hours because I'm the world's fastest). I was short on cash, and even if I had money my brother was in the 300SDL, so I tightened it without a torque wrench.

I didn't go crazy, I used a 1/4 ratchet and applied torque near the head of the ratchet.
Has anyone gotten away without using one?

No idea what the torque value is on the M112, but on the diesels it's only 10nm, which is just past "snug". You can kind of guess and get away with it, but if you want the gasket to last, it's a good idea to use a torque wrench to prolong its life.

Oh, I didn't know a torque wrench would increase the life of the gasket. I'll buy the 1/4 Tekton and re torque them. It's 8nm

Overtorquing flattens the gasket and distributes the clamping force unevenly. Depending on the valve cover design, it can also distort it to where it doesn't seal properly. Definitely worth doing right the first time and it won't leak until it gets old and hardens.

If it's like a 61x valve gasket, it'll be insensitive to the torque beyond a certain point because you're just bottoming the studs of the valve cover out on the head.

Welp it leaked, off to Harbour Freight I go! And possibly another gasket too

Valve cover gasket
 

WILL leak if overtorqued plus you run the danger of distorting the cast
aluminum cover.

The leak you experienced is probably from displacement of the gasket while installing. Some use a thin wash of gasket glue of some sort. I don't like to use that stuff. I think it makes the next gasket installation painful since it must all be carefully scraped off. I use a coating of assembly grease to hold it in place.

If you distort the cover it's wise to have it machined. If one doesn't know how to properly install a valve cover on an MB he probably won't be able to help straighten the bearing edge of the cover.

I didn't know how to do it but I could see from the design that it wasn't something that require a big man to do. A small child could over torque this.

The design of the cover is such that destroying it is easy... and overtightening will not accomplish anything...

Clean, high quality gasket, and minor torque is important.

This sounds pretty horrendous

Quality of wrench will be important at this low level, also range too - don't buy a 0 - 200nm thinking it will cover all aspects, it won't get something 0-30nm for low torque ranges certified.

Personally, at 10nm I would nip it up by hand - bolts are accessible, if it leaks just a tad more.


..just my approach not for everyone

Worst comes to worst, I'll acquire junkyard valve covers.

Welp I dun goofed

Problem with that idea is that you have no idea of the condition of the junk yard covers, and if they too are bent out of shape, each time you do the job, means more money spent for gaskets.