Loose spark plugs

[S-Express]

I'm new to S2 ownership and have only had my 94 Avant for a couple of weeks.
Its got FASH upto 145k, its now done 154k so I thought I'd give it its 40k service + cambelt. I've heard these stories about loose plugs, much to my utter amazement, 4 out of the 5 were loose (so loose in fact that I didn't need the ratchet to undo them - just turned them by hand!!)
So, what's the recommended mileage frequency for checking these things?
And anyone know why they come loose (1-4 were loose, 5 was tight as a ducks proverbial).
Thanks
Alex

[S2central.net]

Theory is that when they are overtightened (by a mechanic too lazy to use a correctly set torque wrench) that it causes the threads in the head to stretch and so leads to the plug working loose after a number of heat cycles.

Its wise to check this on every oil change - just don't overtighten them.

Manual says 25Nm, but 30Nm is a common view of some more safety margin. I dunno how much beyond that starts to create potential damage, but I wouldn't go more than 30Nm.


Paul

[S-Express]

Ah yes, the downside to an aluminium alloy head - the threads are soft!!!
Thanks for the advise.
Alex

[pastures16]

Theory is that when they are overtightened (by a mechanic too lazy to use a correctly set torque wrench) that it causes the threads in the head to stretch and so leads to the plug working loose after a number of heat cycles.

Its wise to check this on every oil change - just don't overtighten them.

Manual says 25Nm, but 30Nm is a common view of some more safety margin. I dunno how much beyond that starts to create potential damage, but I wouldn't go more than 30Nm.


Paul

i thought it was the fact of the plug washer getting over torqued not the threads getting stretched so change the plugs every time you have them out

[iain1067]

And if you don't check them then a big bill will usually happen, as a loose plug will **** the head quite nicely, as others will confirm, now where is my torque wrench....


Iain

[S2central.net]

i thought it was the fact of the plug washer getting over torqued not the threads getting stretched so change the plugs every time you have them out

Actually that is an equally good explanation... Suspect its the combination of both that causes the phenomenon.

[Greg_S]

I have just had this issue myself. Was due for service, (to be done last week) drove home from work. Misfire, sparkplug shot out, coil and lead destroyed = repair head.

all 5 were loose! Been sorted now though

[pastures16]

cheers paul im slowly learning the curve about these engines
guess what everybodys doing this w/end

[Bowlerwell]

My N0.3 shot out the top too, and destroyed a coil pack etc.
All 5 were loose.

£X,000 later, and it was fixed, but alas, too expensive to keep.

JB

[Fat Audi 80]

I will just add a little to this.

My no 3 Spark plug was loose too. I only found this out due to a misfire and the car running on 4 cylinders. Cam cover off revealed a loose plug and a lot of very fine metallic (aluminium) dust above the plug recess and on the back of coilpack.

I think I had a lucky escape there

I did NOT check my plugs when others suggested it may be prudent, and have been lucky.

It takes 10 minutes with the right tools, so get your plugs checked!

Cheers,

Steve.

[als2avant]

Sounds like I've been Fcking lucky on that as well, checked mine recently whilst replacing the cam cover gasket, 3 out of 5 were loose. Once I'd got the cam cover back on and torqued the plugs to 25Nm, the car suddenly started running better...

[UrS4boy]

If you need DIY help with the spark plugs, you can follow the procedure I wrote for my S4 FAQ thread on AudiWorld:

http://forums.audiworld.com/s4s6/msgs/149775.phtml

Dave F.

[Greg_S]

Procedure from Audi world

1. Purchase five Bosch F5DPOR spark plugs
2. Use 5 mm allen hex socket to remove the four bolts holding the "20V Turbo" coil pack cover down. Note: there are springs underneath the coil cover that push the cover up as you loosen the bolts. I always loosen the hold down bolts evenly from rear to front rather than totally removing the rear one and then the next one, etc.
3. As you remove the bolts, place them somewhere, e.g. black plastic plenum tray where you won't lose one. (Don't ask).
4. When they bolts are all out. Grasp the coil pack cover by both ends and lift straight up until the spark plug connectors ("boots") clear the top of the cam cover.
5. Then lay the coil pack cover on its back,spark plug connectors up, on the black plastic injector cover.
6. Examine the connectors. If they ripped or discoloured, you should consider replacing them. They are made by Beru and typically can be purchased for about $5 from a non-dealer parts supplier. Audi park number is 034 905 447. (Beru 0 300 122 103)
7. Examine the OE coil wires. If they are showing signs of cracking, you will need to replace the wiring as soon as possible. This is a source of high boost missing.
8. Examine the spark plug wells. They should be clean. If they are rusty looking, the coil pack cover gasket (a big rectangular "O" ring) needs replacing. If the wells are oily, you need to replace the cam cover gasket (includes spark plug well gaskets).
9. Find (or purchase) the smaller size spark plug socket. Spray the inside, including the rubber grommet with WD40. This will help prevent the socket from sticking on the spark plug. (Don't ask).
10. With the small sized spark plug socket on a long (at least 6 inch) extension (locking IF possible), and a torque wrench, try tightening (clockwise) the plugs to 22 ft-lb. This is just a test to see IF any of your plugs have tried to come loose. (Lots of times they do). Don't try too hard because you are about to remove them. (NOTE: Sometimes,if you forgot the WD40 trick above, or you don't have a locking extension, the spark plug socket will get stuck on the plug. Don't panic. (Don't ask). All you need is a large pair of needle nose pliers to retrieve the socket. (NOW spray it with WD40!!)
11. Remove the spark plugs (counterclock-wise) one at a time. Lay the plugs somewhere, in order, so you can examine them when they are all out.
12. Examine the ends of the plugs. They should be a light beige (whitish brown). IF they are black, it may indicate a fuel issue. IF they are black and oily, you may have either a cam cover gasket problem OR a valve seal or ring problem.
13. Clean the bottom of the spark plug well. I like to use a vacuum to suck out any debris (shouldn't be any but...) and then use a cotton cloth wrapped around a 5/8" dowel to muck out any residuals. This will help to seat the new spark plug compression gasket/washers.
14. You may want to do a compression and leak down test at this point (Find instructions elsewhere). IF you do a compression test, remove Fuse No. 17 from the panel at the end of the dash (with the left hand front door open) to prevent the injectors from working during the compression test.
15. If you are skipping the leak down test, then start installing the new F5DPOR spark plugs, one at a time: spray the socket with WD40 if you hadn't already, insert the plug into the socket hand then with just the socket and plug on the end of the extension, start the plug by hand (clockwise). Continue until the plug bottoms on the gasket and then connect the torque wrench. Torque to 22 ft-lbs. Repeat four more times.
15. Add the new spark plug connectors to the coils if they need replacing.
16. Holding the coil pack by both ends, pick it up, turn it so the connectors are pointing down and lower the whole until down, making sure the connectors go down their respective spark plug holes.
17. When you reach the point where the springs contact the cam cover. Grab one of the coil pack cover bolts you stashed conveniently close by and push down on the coil pack cover while installing (by hand) the first coil pack cove bolt in one of the two holes closest to the middle of the coil pack.
18. Then grab another bolt, push down and install it in another hole. Continue this, by hand, until you have all four bolts in their holes and well started. (I do this by hand only until the cover is almost touching or is touching the cam cover.
19. With a 5 mm allen hex socket, tighten the cover bolts until they are snug. (I go middle, end, the other middle, the other end, etc. until they are all nice and snug.)
20. About a week of driving later. Remove the coil pack cover and retorque the plugs (ONLY turn clockwise - DON't back off and retorque - JUST TIGHTEN).
21. Check torque once or twice per year or more (e.g. at each oil change).

HTH

Dave F. aka the Librarian

[Jas11n]

Got a small thread running on fans with this problem. All apart from two of the people who have checked (myself included) have had at least one plug loose.
Scarey issue
Check mine every oil change now (5000 miles).

Jas..

[Fat Audi 80]

The only thing I would add to that guide, is for an ABY you will need to remove the throttle damper bracket to allow the coil pack cover to come off. This entails the use of a "star" type fastener bit (not torx) to undo them...

Cheers,

Steve