barryvon

My 2000 A8, (4.2) auxilary fanis making a screaching sound and my coolent temperature rises almost to the hot zone. Beyond the fan noise, it is still spinning at seemingly normal RPM's.

I an not sure that this is the solo problem. Looking for anyone with similar engine cooling problems.

PaulW

If it's only at stop and go, around town, then it's probably the viscous coupler on the mechanical fan that is belt driven or the belt is slipping.

The electric fan provides additional cooling and for A/C.

barryvon

The aux. fan noise is somewhat constant. You can hear another fan running at high speed all the time once it is warm. Sounds like a loud refrigerator motor. So I have two different sounds happening, 1)screaching of the smaller, aux fan, and 2)once warm/hot, the main fan running overtime to try and bring down the temp. I purchased the aux rad. fan and will install, but I am not convinced that is the core problem, due to the fan still appears to be running, just noisy.?

PaulW

If you go out to your car when it is cold, turn the A/C head unit to "ECON" so the A/C will be turned off, the electric fan should not run.

Then you can see if you still have the scretching. If you do and the electric fan is off, you know it's either the serpentine belt or the viscous coupler on the mechanical fan.

The electric fan then runs in three seperate speeds (I believe) based on the temperature of the engine and A/C cooling loads. That's the one that sounds like the refridge motor.

I would look at it again when cold before replacing the electric fan motor. If the electric fan motor was making noise, that could be bearings, but most likely it was still spinning as fast as it should be, providing adequate cooling.

But your problem is INADEQUATE COOLING, so I would be looking at the mechanically driven fan, the viscous couplers have had a history of going bad (all types of cars including the older V8's) or the serpentine belt is slipping.

If you do replace the electric fan, there is a real trick to getting it off. That was probably the hardest thing to do when we did Skiracer's timing belt, it wasn't hard once we figured it out. I can post a few a pictures and the procedure if you'd like.

pw

barryvon

In Michigan, my A/C has not been used for many months, but I will make sure the 'e' selection is picked first. I did buy a Bentley manual and they dont even show the elec. fan. I do see there is a screw or rivet holding the fan at the bottem/side, and I can see how the fan must rotate to disconnect. That screw does not accept a screw driver that I own, and I can not see what type of head is there, as you are working in a limited space. The serp. belt seems fine. This coupler could be culprit in addition to the bearings being worn on the elec. fan.

Pics are great, so if you have any info. this keeps me from dealing with my Dirtbag Dearlership.

Thanks Paul, Barry

ryoung

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Unless in ECON mode, I believe the A/C continues to run, along with the electric fan, until ambient temp is below 40 oF. The A/C stays on even at these low temps to assist with windshield defogging.

I agree with Paul's noise analysis. The main fan is the one that's belt driven. I've never heard a failed viscous coupling make any noise, but the belt can certainly squeak/squeel if it slips. A problem with either the viscous coupling or a slipping belt could result in overheating.

The auxillary electric fan could also squeal if it has a bad bearing. But even with a bad bearing, it would provide "normal" cooling air flow. If the bearing got bad enough to slow the fan down, you'd probably blow the fan motor's fuse, and it wouldn't work at all.

PaulW

I posted the procedure to remove and install the fan.

I cannot take credit for this, Doug Banning (Skiracer) gets the credit. This is part of his write up for the timing belt replacement procedure.

You will need to replace the pin, the part number is on the page below.<ul><li><a href="http://www.audipages.com/Tech_Articles/A8_electric_fan_removal.html">Electric fan removal procedure</a></li></ul>

SWiseman

I believe we share the same problems. I agree w/ Paul's diagnosis, My car's temp would climb this last summer in hot stop and go driving. Before summer temps come again I am going to replace the belt driven fan's viscous coupler. I also posted a short time ago about my electric aux radiator fan motor starting to make a noise like the bearings going out. At this point it only lasts a few minutes and I have not replaced it yet. If it doesn't get any worse I'll probably wait and replace both at the same time.

barryvon

Please share with me the correct position of the needle on the water gage in the cockpit. I thought that the first hash mark on the left was where it is to remain. I find that once my engine is warm that the temp. remains at the highest hash mark before hot, regardless of being stopped or rolling; there is only a small varience in temp change. The weather has been around 40F. consistent. Thank you, Barry von

PaulW

Shouldn't move off the left (first) hash mark unless you are ryoung! Go S8!!!