If you have an oil leak you should replace the head cover gasket. The gasket makes the seal not the bolts. The bolts are there to provide even pressure all around so the gasket can do its job.

Over tightening the bolts can cause leaks by deforming the cover and / or pinching the gasket. The bolts should be evenly tightened according to the attached drawing. Cranking down on a couple of loose bolts most likely will make the problem worse.

The tightening spec is only 10Nm (7.38 ft lbs) With that torque value you are going to want to use a torque wrench scaled in the 20 -200 inch lbs range (a wrench scaled for ft lbs would be too coarse at that low value).

FWIW, I'd recommend to anyone planning on DIY maintenance that they pick up a couple of torque wrenches to cover the various torque ranges found on your vehicle. Doing so will help prevent over-tightened / stripped hardware while ensuring clamping force(s) are adequate for safety.

If the head has been damaged by over-tightening I would suggest not drilling for bigger bolts. Best bet would be to remove the head and have it repaired by a machine shop that has the tools to properly do the job

 

Hi FNChaos,

Thanks a lot for the response on that, appreciate it. I should have known better that overtightening the cover bolts can lead to a leak but it did not cross my mind. Unfortunately, that was done by my car's previous owner, as the leak was already there when I bought it (found it a bit late), and me trying to correct the torque on the bolts most likely made it worse. On the positive side though, it's good news to know I won't need to deal with new bolts with an increased diameter.

I assume the best solution for me would be to replace the gasket and the cover (provided it's most likely bent), and even use a gasket sealant. The toque wrench is a must I agree, it's been noted down.

I will report back on whether this has solved the problem.

 

The valve cover is plastic so typically it's not going to "bend" from over tightening, it will crack instead. The cover also contains part of the oil separator, which can also crack creating issues with the PCV system. Replacement at this point is probably a good idea. Do not use sealant/silicone here, the purpose and beauty of the gasket is to avoid that very thing--using excessive sealant can end up in the oil which can either get into the valve trail or down into oil passages and block them.

 

That's exactly what worries me - that the cover might have cracked. I've bought a new gasket with the hopes that's all I need but since I will have to take off the rocker cover anyway, I will inspect that as well.

In terms of the PCV system, I have inspected it visually and have not seen any issues with it, or leaks at least, but that is only at a first glance - I understand there might be issues not so easy to spot.

"The cover also contains part of the oil separator, which can also crack creating issues with the PCV system. Replacement at this point is probably a good idea."
- With the above, I assume you are talking about replacing the rocker cover, not the PCV, yeah?

Thanks in advance.

 

That's exactly what worries me - that the cover might have cracked. I've bought a new gasket with the hopes that's all I need but since I will have to take off the rocker cover anyway, I will inspect that as well.

In terms of the PCV system, I have inspected it visually and have not seen any issues with it, or leaks at least, but that is only at a first glance - I understand there might be issues not so easy to spot.

"The cover also contains part of the oil separator, which can also crack creating issues with the PCV system. Replacement at this point is probably a good idea."
- With the above, I assume you are talking about replacing the rocker cover, not the PCV, yeah?

Thanks in advance.

Yes the cover contains part of the PCV system, that "raised square part" of the cover is that section. Take a look here for more complete info:

SHIRO - PCV system explained

Why another PCV thread? Because I see that even after the subject has been discussed a lot of times many people still don’t understand how the system works. There’s really good info out there, but too much misleading information too which confuses a lot of people. With this thread I’m hoping...

www.audizine.com

and

A look inside the Valve Cover (Pics + Video) - 2nd oil separator

First of all many thanks to Steve(Sweir1171) who sent me his bad valve cover at his own expense after I started this thread http://www.audizine.com/forum/showthread.php/563243-Who-has-a-BAD-Valve-Cover-for-research-purposes Here's a video I took while removing one plastic cover piece on the...

www.audizine.com

The cover shown in the first link is silver but it's the same (on the B7 A4s Audi often made them silver, for whatever reason).

In the second link our friend Shiro takes the bottom apart...the black flat part he pries off, that's the part that can crack leaking to issues.