chagnobu

Need some advice. I have owned (3) Audi A6s. Did the timing belt change on the 2.8L last year, without a cam lock tool, just marked the cam gears with the engine at TDC on the crank. Everything worked great, car ran awesome before being totaled in an accident. Now I have a 4.2L with 107,000 and it needs a timing belt change.

Followed the same process as the 2.8L, with the covers off the cam and crank arrangement is similar. Marked the cam gears with the crank at TDC, removed the old timing belt. While taking the belt off, the right gear, drivers side, jumped clockwise about 20 degrees. I put it back in postition with a wrench, and realized that it was close to jumping either way. I had a second person hold the cam gear in place with a wrench while I installed the new belt and set the tensioner. Everything is lined up. I pulled the engine through two rotations and everything lines up again. It looks good.

Question, could any damage have occurred when the right cam jumped clockwide 20 degrees? Your opinions and advice would be appreciated.
Thanks

2.7Lturbo

it either did or it didnt, only way to know is to start it. if the timing marks are set, theres not much more you can do without tearing it apart

4Driver4

No damage. But get the tools and do the job right. You really should be resetting the cam timing when you install the new belt. There's no good reason not to.

2.7Lturbo

other then the fact that 90 percent of the people doing TB jobs themselves dont know how to manually reset cam timing, it is easier for them to just mark and reset.

chagnobu

I know that I did not perform the timing belt change as per the Audi book, but I did follow the procedure posted in the Audiworld tech articles for a 1999 2.8L. Not the isdentical engine, but the parts are similar, and the engine design is the same. I actually go a step further after throwing a straight edge across the cam gears, and mark two teeth on each cam to a respective mark on the cam cover. This at least restores the alignment to the timing that existed before replacing belt. There are probably a lot of out there following this procedure. Hopefully it's not bad advice.

4Driver4

Easier still to do nothing at all, but that doesn't make it a good idea.

Setting the timing is a critical part of the process. It is the cheapest horsepower you can buy. I find it hilarious that people who ask about ways to get two or three more horsepower out of their engines will not take a few minutes to set timing. Besides, how can you change the cam seals without the tools?

If you can read, you can figure out how to set the timing. It's not hard to do, and there are plenty of folks out there who are happy to lend the tools.

4Driver4

That's great assuming the timing was dead on before you started, and assuming the parts you bought are identical to the parts on the car, and assuming that you install the waterpump in the exact same spot that the old one was in.

Using the tools is the difference between doing the job so that the car runs Ok and doing the job right. I picked up noticable HP in my old avant by setting the timing correctly. If I cheated, I might not have noticed, but why leave the power on the table.

How did you service the cam seals?

audiworldzane

I am in the middle of a 4.2L change and faced a similar problem. I aligned the cams using the tool and have the crank at the right spot, but during the belt removal the right cam spun as you described. I don't understand how the recommended method of releasing the gear from the camshaft is safe. At that point, if the cam moves you are hosed unless you remove the covers and reset everything. Anyway, I was just curious. I am trying to fix a coolant leak on my oil cooler before I start it back up. And that has been a painful process at best.

NJA642

It is perfectly safe & the correct method of doing this job.

The 'winged' pieces that the cam lock tool attaches to are keyed to the cams, but will be free to move a bit when the cam bolt is loose. The cam gear itself is not keyed to the camshaft, hence the infinite adjustability and requirement for the tools to do this right. The winged piece will always be physically aligned to the cam/cam lobes when the cam bolt is in place & snug.

Cam Tool aligns the wings, wings are physically aligned with the cams, Belt & Cam sprockets align the cams to the crank when tension is set & the bolts are tightened.

When you are ready to set timing, Take the cam lock tool off if it is on, put the belt on, re-align the keyed 'wings' on the cam, tighten the bolts slightly, so the 'wings' set into the keyed protrusion on the cam (trapezoid), put the cam lock tool on the cam that is not in line & gently pull the bar down to line up with the opposite cam. Make sure your belt tension is good & tighten the two cam bolts.


As far as which method to use (by the book w/ the tools or by counting teeth), I'm of the opinion that every rotating part of the timing belt routing should be changed to do the job correctly & that includes the eccentric pulley. Changing that pulley means you are changing/setting the tension on the belt. If the eccentric pulley isn't replaced at precisely the same angle and/or the belt is not nearly identical in flex to the old belt on the car (when that belt was new), the right hand side tension & as a result, timing, will be different. ECU is doing its best to burn fuel as efficiently as possible by changing spark timing, so 'slight' variations might not be obvious.
hp is one argument for being exact, maximizing mpg is another.
If anyone is in north west NJ or would like to drive there I will happily loan out my tools (cam bar, crank lock plug, cam chain tensioner tool) to a fellow AWN 4.2 owner.

Good luck w/ the oil cooler & post a picture of the stupid broken plastic pipe.

Philhawtin

Can you set timing with vag com? is it that simple?