My somewhat damaged cylinder head

[HenryG40]

Well I was on the M25 last night, doing a steady 80mph for 10 miles or so, come off at the next junction and the car is really not happy. It's idle at around 1000rpm, can feel the car joggin at idle, tried to pull away off the lights (calmly) and it's not wanting to rev.

So I pulled over and did a little bit of investigating, this is what I found:





Needless to say, I had to ring the RAC

[baltiboyS2]

Thats bad luck need to get your hands on another head by the looks

cheers Raj

[s2_bo]

lets hope you can get away with replacing the plugs, leads and cam cover seals.

Hopefully there is no real damage to the head.

Looks pretty scary though.

[baltiboyS2]

Look at the pic again bo i think the plug is sitting at a angle and thats bits of the head beside the plug

cheers Raj

[pastures16]

looks like your plug has come loose destroyed the coilpack you might get away with a helicoil if the treads are fubar

[s2_bo]

Look at the pic again bo i think the plug is sitting at a angle and thats bits of the head beside the plug

cheers Raj

Yeah i think your right.. Its not looking good then..

[s2driveruk]

ouch! Hope you can get it sorted out soon

[Bowlerwell]

I had a plug come loose and destroy a coil pack.
Fortunately my head was just fine.

[UrS4boy]

Well I was on the M25 last night, doing a steady 80mph for 10 miles or so, come off at the next junction and the car is really not happy. It's idle at around 1000rpm, can feel the car joggin at idle, tried to pull away off the lights (calmly) and it's not wanting to rev.Needless to say, I had to ring the RAC

I am hoping that its only plug related but there is a lot more oil than I would have guessed from a plug issue. The coil-plug connector for No. 1 is completely soaked in oil (more than the others). The connector for No.3 has been stripped of its rubber jacket (very strange). I think that is what the bits laying around are (I think). Seems to me that the cam cover gasket set, particularly the "O" rings around the spark plug wells have been leaking for a long time, indicating that you haven't checked your plugs for proper torque for some time.

There is a well known issue of the plugs in the AAN heads working their way out of the head if they aren't torqued properly. I always advocate checking the plugs at least every oil change (tighten only 30 Nm or 22 lb-ft).

Everyone reading this thread might want to check these posts in the AudiWorld UrS FAQ:

http://forums.audiworld.com/s4s6/msgs/197836.phtml

Testimonials from those who have had plugs loosen:

http://forums.audiworld.com/s4s6/msgs/197842.phtml

Reasons why the plugs can work their way out of the head:

http://forums.audiworld.com/s4s6/msgs/197841.phtml

The problem is real, the results are costly.

Dave F.

[pastures16]

i had this oil problem before mine used to fill up to the plugs just turned out to be the rocker gasket

[UrS4boy]

i had this oil problem before mine used to fill up to the plugs just turned out to be the rocker gasket

The gasket set in question is No. 17 in the image below. PN 034 198 025 F (AFAIK)



HTH

[pastures16]

yep thats the one

[HenryG40]

Yeah, there were bits of No.3's lead all over the place, and the spring and tip have fallen down in with No.3's plug, so I need to get those out before I can remove the plug (for fear of dropping these into the cylinder!) No.3's coil looks to be intact but they've all had a fair coating of oil so will be interesting to see how well they still work.

Once I've got the plug out, I'll be able to see just how bad the damage is. To be fair the timing belt is due soon so I may just use this as an excuse to do it all at once. Just hoping that I can get away with using this head with some repair work.

Cheers for the kind words and useful links, hoping I can get this well on the way to being sorted by this week, Can't afford to not have it on the road as all the other cars are off the road too!

[Jas11n]

I always advocate checking the plugs at least every oil change (tighten only 30 Nm or 22 lb-ft).

Good advice. Mine get checked every 3000 miles, same time as the oil gets changed.
It takes 5 minutes tops. In fact, they'll be getting checked this coming Tuesday.

We've a sticky thread on audifans in the S2/RS2 forum warning of this problem.
Maybe one of the admins/moderators should do something similar here??

Someone mention a helicoil?? T-sert only in my opinion for a job like this. If needed that is.

Jas..

[Fat Audi 80]

Here is the Sparkplug tightening advice. Personally would agree with it. Unless you go mad with 3ft breaker bar, you should not be able to over tighten the spark plugs, although obviously care is required as it is a steel plug into an aluminium head.

When I last checked mine, one was loose!

This post was made by Jeff Gerner on Audifans in response to my AAN sparkplug ejection thread:

"Hello guys - this is my first EVER post on this site so I am "breaking my cherry" in order to shed some light on this sparkplug debate. I am a lifelong auto tech and engine builder as well as the owner of a very fast 94 S4 that I have "done all the work on" etc. I am no kid either at 54 years.

Anyway, on to the subject; Rule # 1. Properly tightened - notice I did not say torqued - spark plugs, just like properly tightened wheel lug nuts / studs, don't come out. Period!

The spark plug loosening problem happens for two reasons; First is the highly dissimilar "growth rate" of aluminum vs. steel / iron as in the cylinder head spark plug interface - the aluminum cyl head grows or swells more in dimension (under extreme heat) than does the spark plug shell. This
causes "cyclic working" of this joint between plug and head as the engine cycles repeatedly from cold to very hot. This problem is exacerbated by the rather extreme cylinder pressures and temperatures associated with high
boost engines.

The second and most causation related factor is that the factory listed torque value for the spark plugs is insufficient. The reason it is
insufficient is the relative disparity in the "crush load" requirement of the spark plug sealing rings. In other words the factory specified spark plug torque rating is insufficient to uniformly and consistently crush the little soft metal rings that seal the spark plug. (Remember the cyclic
working of this joint)

Here is what happens; Stock torque spec fails to sufficiently compress the seal ring leaving more room for further compression of the seal ring during heat cycling of the joint between head and plug which ends up leaving the
plug loose when it is cold! This will eventually let the plug loosen enough
to work its self completely out over time.

The fix; When installing new plugs VERY lightly oil the top half of the threads and the seal ring to aid the seal in crushing and then tighten the plug until you feel the seal compress and the plug become fully tightened.
You will feel the initial resistance of the seal meeting the head surface and you will feel the crushing of the seal ring as you slowly increase the torque. You will know when the plug is "properly tight" when the resistance
to tightening suddenly increases. If you have any "feel" for these type of things you will not have any trouble doing this. If you don't trust yourself just have someone who is a full time wrench do the job.

Note; some people will screen "blasphemy - must use torque wrench when installing plugs" The truth is that only 1 in 50 experienced techs use a torque wrench to install spark plugs - they don't need it because they can feel when the plug is tight enough to stay in while still not being over tight.

Hope this helps. "
Dave F. aka the Librarian