socalclimber

Background
2002 A6 4.2 AWN, 75,000 miles: stuck thermostat, leaking VC gaskets & cam adj seals, leaking coolant pipe, time for TB/WP since I'm doing thermostat.

I'm doing a full service timing belt/seals/VC gaskets/cam adjuster seals/WP/coolant pipe job on my 4.2 once all my parts/tools arrive from Blau. Got sweet coolant pipe from Jim Bufkin. Figured I would do crank seal while I'm in there whether or not leaking.

Question
Bentley CD says to "always replace center bolt" and torque to 200Nm plus 180 deg (2x 90 deg is also permissible).

Do you recommend replacing the center crank bolt (as it appears to be a stretch bolt)?

If not replacing bolt, do you follow same torque specs as new bolt? Thanks.

P.S. My dealer charges $18 for bolt and it's not in stock.

A6Gary

Absolutely yes, you ALWAYS replace that bolt because the bolt is tensioned beyond its yield strength, and hence has experienced some plastic deformation. I verified that that bolt yields and stretches when I was replacing it several times in the process of resolving an oil leak. If you re–use the bolt and re–tighten it per spec, you could cause the bolt to fail completely, i.e., snap off.

Redneck Truck

Don't remove that bolt. Unless you are sure your front main seal is leaking, just don't mess with it. With 130k miles and TONS of oil leaks I didn't touch the front or main seals, because they don't leak and I don't expect them to.

socalclimber

A6Gary and RedneckTruck,

Thanks for the advice! I bought the dealer crank bolt at $19, but don't know if I will replace crank seal or not.

Crank seal is dry for sure, and I'm only getting slight seepage at cam tensioner gaskets/half moon plugs, and I'm thinking of doing all the cam seals, tensioner gaskets, and plug on both sides, and VC gasket, but it's a daunting task if I have to remove both cams on each side to replace all the seals.

Redneck Truck

I replaced all the seals and gaskets you're talking about, and I didn't have to remove my cams. You remove one cam cap to get the seals out is all. One seal, one cam cap, and one valve cover gasket on mine leaked much worse than they did before the job, so if you've got slight seepage, you might just want to button it back up and address it when it becomes a problem.

socalclimber

Redneck Truck,

Thanks for the info on what you did. How about the cam chain tensioner seal and half moon? Did you just lift up the tensioner enough to replace the gasket and half moon?

I'm going for another round on the 4.2 after work tonight. We'll see.

My original problem was ONLY the coolant pipe leaking, then a stuck thermostat took me out for the count! The parts are piling up on my garage floor faster than I can put them back together!

Redneck Truck

Yes, I'm pretty sure it was just a matter of lifting it up high enough to get the new gasket in there. I'm still astonished that those didn't leak after I was done.

As for the constant battle, I know how you feel.

Airbag

Just did all this too and i agree with redneck completely. DO NOT touch that bolt. in fact even your Blau instructions will say don't mess with it if it is dry. you risk damaging the crank and the pulley it is holding in place ... this is one area that if is aint broke don't fix it.

I also did what what edneck did for my half moon and tensioner gasket. Although it would be nice to take everything apart I did mine fine with just lifting the tensioner. You have to be patient and meticulous with the cleaning but it can be done. I did both sides and actually found it easier to do the passenger side. But that is becsue I am a complete moron and didn't do it while I had the rear timing belt cover off while doing the TB. I buttoned up the TB job then started the tensioner job. What a mistake .. do the tensioner while you are doing your front cam shaft seal.

BTW i also replaced the two cam end caps. pretty cheap and effective fix. I still have a small leak as I can smell it around the engine .. but so small I can't even tell where it is coming fromm .. not like before when it looked like a native American sending signals that his blanket was on fire ..

socalclimber

Airbag, Redneck Truck,

Did the passenger side tonight (2 seals, end cap and tensioner gasket + valley plug) as you describe w/o removing the cams and took my time, feels solid, not going to touch the front crank seal. It was easier that TB and TB covers were all off.

On to rest of TB/WP/coolant pipe job now with added confidence! Thanks again!

Airbag

all it takes to work on these cars is a bit of confidence and a bit more patience .. great job.