Leaking Past Valve Cover Bolts

mca · 06-13-2006, 04:59 PM

I have oil leaking past the bolts on my lower valve covers and it is dripping on my exhaust.

My shop replaced the gaskets and bolts 8 months ago but I was still leaking oil - so they did them again under warranty.

Just got it back tonight and noticed that oil is STILL leaking at the bolts (just 2 of them though).

If anyone can help I would greatly appreciate it - thanks!

walt · walt's Garage

First I would make sure they are not warped with a straight edge or laying them on a flat surface. If they are straight you can try some upgraded gaskets that have a silicone bead or for a few more bucks go all silicone. Its also important to tighten these bolts to the correct torque.

mca · 06-13-2006, 05:22 PM

Supposedly they are perfectly flat and the gaskets have the silicon bead.

The gaskets themselves are dry - oil is just coming through the last two bottom bolts closest to the rear.

Are there other possibilities besides a warped cover and insufficient torque?

walt · walt's Garage

Are you sure the leak is coming from the cover. Sometimes oil can leak from above and find its way down to the valve cover. I spent weeks thinking I had a valve cover leak until I found the real problems.

Halm · 06-13-2006, 06:03 PM

Cracked rocker shafts will cause leaks as you describe.

Dan in Pasadena · Dan in Pasadena's Garage

Have you already upgraded to Turbo valve covers? I assume you know about this upgrade - most do - but if you don't, the earlier covers can warp at temperature. Its probably NOT your problem but has to be eliminated before searching for the next possible source. Good luck.

mca · 06-14-2006, 03:54 AM

I do have the turbo covers and I am sure that the leak is coming through the bolt - I do, however, have other very minor leaks but this is the one that drips onto the exhaust creates smoke.

The entire engine has been cleaned up on 3 separate occasions in order to determine the source of the leaks. When I inspected the underside last night, everything was PERFECTLY clean except for the drops of oil forming around the valve cover bolts.

Also, is it bad if the valve cover gasket extends beyond the cover? I can actually touch the gasket with my finger.

thanks

mca · 06-14-2006, 04:23 AM

Clarification ......... the 'touchable' gasket is not on the same side where oil leaks through the cover bolts.

pookie · 06-14-2006, 04:39 AM

Mine leak too, everytime I do a valve adjustment I always replace with new nuts. I put a small dap of silicone on each nut. It seems to take care of the problem.

Wil Ferch · 06-14-2006, 04:44 AM

I'm hoping someone like John Walker or Grady Clay enters this discussion.....My personal feeling is that we need special washers for the valve cover bolts...those that have a "built-in" elastic/rubberized washer on their ID..and the rest is metal. I have a number of these parts on my Toyota valve cover through-bolts as Toyota OEM...and they work.

- Wil

klaucke · 06-14-2006, 04:55 AM

Wil, while those type of washer, or a dab of silicon may help from oil leaking from the bolts, these should not be required, because the valve cover gasket surrounds the studs and should isolate them from any oil. So if you studs are dripping, the valve cover gaskets are still leaking, albeit inside the valve cover and possibly only surrounding the stud.

New nyloc nuts (which are required as per spec) may also help in this regard.

RoninLB · 06-14-2006, 05:07 AM

Quote:

Originally posted by pookie
Mine leak too, everytime I do a valve adjustment I always replace with new nuts. I put a small dap of silicone on each nut. It seems to take care of the problem.

ditto

mca · 06-14-2006, 06:32 AM

so ... any thoughts on the gasket being 'touchable'?

RichMink76 · 06-14-2006, 06:34 AM

Just throwing this out there, did they replace the aluminum washers along with the nuts?

Rot 911 · 06-14-2006, 06:38 AM

As many valve adjustments as I have done on 911 engines I have never had leaks from the valve cover studs. Like klaucke pointed out, if you have a good gasket and a flat valve cover there is no way for oil to reach the valve cover studs.

WERK I · WERK I's Garage

I had one leaking on the top stud around #5 exhaust ever so slightly. Tried new nylocks and washer to no avail. Took Curil T and applied it to both sides of the aluminum washer and a tiny bit to the stud threads. No leaks for over two months.

sand_man · 06-14-2006, 07:14 AM

I have a new engine and as part of the routine am running with new nylocs, washers, and silicone valve cover gaskets. Only slight torque has been applied and I've got what looks to be some leaks around a few of the nylocs. I've added a little more torque to the nuts, but have a couple that are still weeping. At first I was thinking that my rocker shafts (with RSR seals) might need another turn, but it really does look like the oil is weeping from the nuts! Maybe I'll try to add something to seal the nuts. I like Wil's idea about special washers.

Cordts · Cordts's Garage

So what happened here??

fred cook · fred cook's Garage

Go get new washers (flat, aluminum) and self locking nuts. The shop may have reused the old ones which can contribute to leaks like you are describing. If you can't find the washers and nuts locally, let me know and I will send you a couple.

Good luck!

David E. Clark · 01-25-2007, 12:00 PM

Quote:

Originally posted by walt
First I would make sure they are not warped with a straight edge or laying them on a flat surface. If they are straight you can try some upgraded gaskets that have a silicone bead or for a few more bucks go all silicone. Its also important to tighten these bolts to the correct torque.

Very good advice. If the nuts are either too lose or too tight they will leak. New "crush" washers are imperative. The "crush" is part of the sealing process. Finally, the silicone gaskets, while a bit more expensive, do a much better job of correcting for minor imperfections in the valve cover and around the bolt that might cause a leak. Pelican sells all the appropriate parts here.