[nuron]

Hey all,

I'm having to replace my VC and gasket (URO warranty) again after doing it just a few months ago due to a leak, and I'm thinking it's because I either tightened the bolts too much or did them unevenly. I read a lot more forum threads on the procedure and wanted to confirm a couple of things:

1) the torque should be 8.6 nM plus an additional 90 degrees?
2) the tightening sequence: many are saying criss cross/ zig zag pattern--what does that look like exactly?

I've attached an image of a valvecover if anyone would be willing to draw what the tightening sequence should be, and also some online image editing links:

https://pixlr.com/x/
https://www.fotor.com/

Thank you in advance!

[ctuna]

[jwalker87]

Here is what the Bentley manual has to say about it. You didn't say what engine you have, so I have the turbo and non-turbo pages. Where did you get the +90* info from? It's just a straight torque number, no angles needed.

For the sequence, just start with the two in the middle, then cross back and forth from left-to-right and front-to-back as you get all of them. I usually torque something this big in two stages as well (one around half of the spec, then do the same sequence with the full spec).

[mainbearing]

I think the problem you had was the extra 90 degrees turn. That might have cracked the plastic valve cover. The angle-turn was meant for metal covers.

In my case, the bolts were tightened in stages with an inch-pound torque wrench, in a criss-cross pattern from the center out. Same for my transmission pan, not having used the OEM sequences but just eyeballed them for anything out of the ordinary common sense.

I also used a Uro valve cover and RTV'ed the new Mahle valvetronic motor gasket that came with it. Worked well, Uro!

[PhaseP]

Rule of thumb for any rectangular cover or plate, you start tightening from inside (the middle) fasteners with spiral pattern expanding outwards. This allows the plate to extend as it is being tightened from middle to outwards.

The untightening is the opposite:

http://www.boltscience.com/pages/tsequence.htm

That said as "mainbearing" wrote your problem seems to be the using the torque spec that is for magnamenesium cover on plasticomesium one.

[Denny347]

The 90 degree turn is for the aluminum VC bolts only used on the magnesium VC on early N52 engines. Plastic VC use steel bolts and are not torque to yield thus do not require the 90 degree turn.

[mweisdorfer]

Originally Posted by nuron

Hey all,

I'm having to replace my VC and gasket (URO warranty) again after doing it just a few months ago due to a leak, and I'm thinking it's because I either tightened the bolts too much or did them unevenly. I read a lot more forum threads on the procedure and wanted to confirm a couple of things:

1) the torque should be 8.6 nM plus an additional 90 degrees?
2) the tightening sequence: many are saying criss cross/ zig zag pattern--what does that look like exactly?

I've attached an image of a valvecover if anyone would be willing to draw what the tightening sequence should be, and also some online image editing links:

https://pixlr.com/x/
https://www.fotor.com/

Thank you in advance!

Which engine is this for?

[nuron]

Thanks to everyone for the replies so far. I have an '07 328i so it's the N52K engine.

I drew out one diagram of how I might want to do the tightening sequence. Start with the three middle bolts first (all labeled "1") and then start the spiral from there.

I also have another diagram of doing it in two-bolt sequences.

Additional thoughts?

[jwalker87]

Looks good to me. I'd still recommend torquing in 2 stages though.

[nuron]

Yeah, I always try to thread in finger tight first and then start the final process from there.

[nuron]

Just got time to finish it today. Torqued it to 40 in.-lb for first stage, then 80 in.-lb for final stage. Went around 3-4 times just to make sure as well. Fingers crossed!