ltooz_a6_a8_q7

I'm helping my brother in-law to fix his overheating problem. 1st the cooler pipe is leaking. 2nd we think the thermostat stuck closed.
There are instances that people replaced the thermostat without removing the timing belt. We opened it up and it's totally different from my 98 A8.

-How do we loosen the timing belt, I removed the roller that has T40 torx. I can't seem to find any place to release the tension of the 2 center rollers.



I see the pipe on the side behind of the passenger pulley where the thermostat would be (I assumed), how many bolts/screws needed to remove this whole aluminum plate to get to the thermostat? Some pointers would be greatly appreciated.



While were there, something was broken, a link between 2 vacuum diaphrams, what does this do?



Please help ASAP...

By the way, the oil cooler is also different from the 98 A8, please give some tips also if you did it before.


Thanks,

Louis

silverd2

First, the broken link is for part of the manifold changeover...3 stage intake to spread out torque evenly over rpm range...3 lengths of internal intake pipes. With one link disabled, you won't get all 3 stages. Both vacuum pods are closed(pulled back) at idle and open one at a time at higher rpms to change lengths of internal tubes to increase torque.

I've done the belt and thermostat jobs recently on my 40V, but it was time to change the belt anyway. I did NOT pull my front end to do this, nor did I remove either cam gear. Once fans were out of the way, I had plenty of room. I don't know if it's possible to get thermo housing out with belt in place. The 2 tensioners are different. One on right(driver side) is simple old fashioned eccentric...Loosen bolt and tension falls off. One on left is controlled by hydraulic-spring damper below it , BEHIND the torque support plate on engine. It has to let off slowly with great effort on an 8mm allen slot on the roller lever...THEN a 2mm drill bit has to be inserted into hole in top of damper (BEHIND torque support plate on engine).

Belt job is easier than earlier models in general, but I used Bentley as a guide and some helpful links.
3 bolts hold the thermo housing...One right below that broken link (that's just above the actual thermostat) one a few inches below that and another over to the left behind the viscous fan pulley. Again, I can't imagine getting the housing out with everything inplace(?)

I've also done my oil cooler recently, which was a BEAR, I went by a link shown below...gotta be REAL careful...easy to round out inside of upper left allen head...this job was as tough as all the timing belt stuff put together.

I know this is a VW toureg, but very similar...But I highly recommend the Bentley manual for a lot of the steps and final adjustments.

http://www.clubtouareg.com/forums/f7...-v8-36595.html

http://tech.bentleypublishers.com/th...=3787&tstart=0 ...."Titanium" ,at bottom of thread, is me.

For the oil cooler, Bentley doesn't tell how toget it off, just how to rebuild it. I used this link:

http://www.audipages.com/Tech_Articl...reinstall.html ....bottom of page has additional 40V info.

I didn't cover it step by step...I'd have to copy a lot of Bentley stuff...the CD won't let me do a complete copy and paste for some reason.... But I'll be happy to answer anything else I can.

silverd2

P.S. The thermostat housing can come off with the engine torque support plate still on engine, BUT the tensioner damper can't be accessed with that plate in place.
Crank vibration damper pulley and accessory belt tensioner need to come off before removing torque support plate from motor...also the torque support rubber 'biscuit' has to come off...I left the body mount portion in place, without a problem.

This isn't everything, but hope it helps.
Give me a shout here for any other details...happy to help.

silverd2

P.S.S. If the photo of the broken vucuum link was shot with the engine off, then both are stuck in the idle/low rpm position anyway (Idle thru 3360rpm). Both levers that are operated by the 2 vacuum pods should close under spring tension when motor shuts off or higher rpms are hit(and vacuum pods should "inflate") . Stage 2 = 3360-5200 rpm and Stage 3 = 5200-redline.

These are prone to seizing in the position shown in photo and motor will run fine like that. When operating correctly, you'd notice a wider torque band at the upper rpms, though.

Audi says NEVER disassemble the manifold, but I've had a little luck freeing up the levers with spray silicone lubricant in the front pivots , behind the spring levers. I carefully removed each lever end, one at a time, detensioned spring and pulled "tube" out of manifold just a few milimeters to get as much lubricant to the pivot as I could (on outside,too..a little seaps in). BE CAREFUL, though...don't pull out any furthur or turn much...you could destroy inner "flaps" on tube. PLUS the tube fits into an invisible pivot on the far back end of the manifold internally...I had to "feel" mine back into place.

**CAUTION !!!!** Doing the lubricating job I did is very delicate and chancey AND NOT recommended by Audi. It did free up the pivots on my manifold changeover some, but had to do it a couple of times to get enough lubricant into such a tight spot. As I said, motor will run fine with them stuck in place (just high end torque drop off).

The 3 stage manifold is a GREAT idea, when it's working...BUT yet another Audi screw-up in longevity design...they all seem to lose lubrication and start sticking eventually.

ltooz_a6_a8_q7

Hello Silverd2,
Thanks for the info... I got it done today... both thermostat & coolant pipe... what a PITA... but it's done... I'll have tons of pictures... My brother in-law's been driving with the broken link, he didn't even notice anything with the performance... may be the V8 is tooooooo powerful...

Thanks again,

Louis

ltooz_a6_a8_q7

MarkA8L gave me some tips on this job...

this made it very easy to get at everything.

I did not release belt tension or remove anything other then the one small idler on the passenger side of the engine by the cam gear.

I used a lot of plastic wire ties to hold the belt in place on both cam gears and anywhere else I could tie the belt to something.

I also used a permanent marker to mark the belt and to make reference points on everything.

This way I was hoping that nothing would move on me - which it did not.

I then used a torx to remove the screws on the thermostat housing.

I then used a pry bar to move the thermostat housing out of the way, while slightly twisting the timing belt to allow for more room.

Once the housing was out of the way I had someone else reach in and remove the thermostat while the pry bar was holding the thermostat housing to allow access.


Installed the new thermostat and put it back together.

Do not forget to remove the wire ties!!!!!!!





Can't be lazy... must remove the bumper and I had to do the oil cooler...

release the tensioner.

move the belt halfway out, tie down the sprocket, loosen the black metal backplate to clear the thermostat cover.
<img src="http://www.dognmonkey.com/media/2000a8/sprocket.jpg">
prybar to clear the thermostat removal/replacement
<img src="http://www.dognmonkey.com/media/2000a8/prybar.jpg">
verify the new/old thermostat, new opens, old doesn't
<img src="http://www.dognmonkey.com/media/2000a8/thermostats.jpg">

Oil cooler,

The new coolant pipe that caused more grief than the 32 valves.
<img src="http://www.dognmonkey.com/media/2000a8/oilcooler.jpg">
the new and improved oil cooler for 40V
<img src="http://www.dognmonkey.com/media/2000a8/oilcooler1.jpg">

I'll have tons of pictures and full write up on my website when I have time.

Cheers and thanks again MarkA8L,

Louis

PS: The Audi of Steven Creek in Santa Clara wouldn't sell the 8 shape alone, and forced my brother in-law to buy the whole set of rubber rings and the pipe for $85. Now we have the whole bags of rings that we don't use. This is why Audi dealers are stealers, Palo Alto Audi did sell me the 8 shape ring alone. I was glad that I didn't buy my Q7 from this stealer. The part salesperson doesn't have the knowledge to recommend a ring for the metal coolant pipe, we have to use the old one. Now we used 1 pipe, 2 rings, 1 8 shape ring for $85...

silverd2

Very cool! I love a shortcut, especially when I expect to change another thermostat well before another belt. The one I put in was the 3rd in under 100K miles...the stealership changed the one before, under warranty.

I got my oil cooler seals from these guys:

http://www.audiwholesaleparts.com/pa...?siteid=215295

They sell the "8" seal alone.
Their site is a little odd to navigate, but if you got the part #'s it's easy...you just type em in on their home page. They got every odd part you can imagine for Audis.

077 115 441 ..."8" oil seal
077-117-411-A ... Water pipe
077-121-437 ... O-ring for metal and plastic pipe (x3)

I got all of em for about $40, including shipping.

The extra seals in the kit 077 198 405 are for rebuilding the cooler while it's out, if you think you have coolant/oil mixing.

Yes, I believe BrianC72gt, from the Audipages link, said that if he had the cooler job to do again, he WOULD pull the front end. I did mine while I had everything out for the belt/thermostat change...I got it done, but it would have been a bit easier with that extra space.
The belt change, however, was no problem at all with the front end in place...I'd definately do that again the same way.

Last comment about the oil cooler and I've ask this before:
What the hell is up with that water pipe being made of PLASTIC!!?? WHAT were they thinking...when it's SO hard to get to?!!
Mine had crumbled into "brown sugar" on the motor end of the pipe and was leaking profusely. Thanks Audi!

ltooz_a6_a8_q7

Silverd2
I know, plastic pipe, someone on here sells aluminum pipe with heavy duty rubber rings for very good price, but it's just a hassle to order and wait to get it. I do recommend any A8 that has over 130k miles that oil cooler pipe has not been replaced should order these aluminum pipe in advance because the day it break or leaks is very near. This 2000 A8 has 133k miles on it. I'm sure this little pipe will last him until his next car... another 100k miles?
For those who has this leak, and try to bandage it by pouring radiator leaks sealer into the system, I think this caused the thermostat to seal itself up and the overheating began. This radiator sealer may also block the radiator's little pipes and would cost the whole new radiator. My brother in-law is lucky, just the thermostat sealed tight, not the radiator because last night on the way home, his temperature stayed normal the whole 31 miles trip. It was always the last bar to red as soon as he got on the freeway.

Cheers,

Louis

silverd2

Louis,

In retrospect, had I shopped a little more and known about an aluminum version, I'd have ordered one. I have a spare car to drive in the meantime ('90 Passat wagon w/200K miles). When my '01 A8 was overheating and leaking, I left it parked for a week while I ordered the parts. I came very close to taking the new plastic pipe to a local machine shop to have an aluminum one fabricated...but a combination of knowing the plastic pipe would probably last beyond my ownership of the car and wanting it back on the road quick (love drivin the car), I went with what I had.

I had already learned my lesson about stop leak and wouldn't consider using it on this car. Maybe on an old junkard you're just tryin to keep running, don't care if your heater works or just about to unload a car (kidding...not nice). In the distant past, I even had some luck using pepper for a small coolant leak in my first ($200) car. Otherwise I'll never use the stuff again...pure evil and not worth the potential complications.

My wife's 2000 Passat GLX 2.8 was in a minor frontend accident and repaired well (I thought). Months later, it developed a slow leak in the radiator, right near the collision site, in the seam between the plastic side cap and aluminum coils. I used stop leak, worked great and it bought me a couple of months, in hot weather, until the radiator split apart beyond repair. Cold weather was coming on and I soon discovered that the heater core was clogged. It took me forever to clear it, required multiple flushes and coolant changes to get all the crap out of the system.

Keep up the good work,

Sam

ltooz_a6_a8_q7

Sam,
Like you said, quick fix to drive home while you're hundreds/thousands of miles away, I think it's OK, but I rather not to use it at all. Any who, the full write up for the thermostat on the 2000+ 40V V8 4.2 is done.

http://www.dognmonkey.com/audi/2000-...ng-t-belt.html

Cheers,

Louis

If I missed anything, please let me know...