Block/cylinder head crack??
11-10-2011, 12:46 PM
#11
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The problem is often counter holding the water pump flange and getting enough clearance to remove the fan.
Depending øn how handy you are it might be easiest to just put the front end in service position; others might be able to do it by removing the electrical fan housing..I dunno if that can be done w/o going to service position.
I've never tested a viscous coupling by attempting to hold it while the engine is running and I'm not sure the way the mechanic did it is valid. The coupling has to be HOT for the valve in the coupling to operate and allow the internal fluid to couple the fan tø the shaft. Perhaps if the engine were operated to hot and shut off before you grab the fan and attempt to hold it while the engine is running?
Only test I've ever done on viscous fan couplings was auditory...the fan should roar upon initial startup and then stop roaring (indicating startup coupling/decoupling when cold) and when engine/radiator gets hot enough the fan should roar again, indicating coupling with the fan shaft and moving air through the radiator. If this doesn't happen, the fan coupling should be replaced.
One other note, at least one company, MB, has a speed–dependent viscous clutch..above 4100 rpm or so the clutch internals cover up a port (centrifugal force actuated valve) and disengage the clutch. Dunno if Audis do this but part of the MB diagnostic routine is to note loud roar of fan during good operation below 4100 rpm and run the engine up to 4500+ rpm and fan should decouple. Probably to avoid over revving the fan. I wouldn't be surprised if audi did this as well because these engines redline at 6K (S6 4.2 at 7K), etc.
Depending øn how handy you are it might be easiest to just put the front end in service position; others might be able to do it by removing the electrical fan housing..I dunno if that can be done w/o going to service position.
I've never tested a viscous coupling by attempting to hold it while the engine is running and I'm not sure the way the mechanic did it is valid. The coupling has to be HOT for the valve in the coupling to operate and allow the internal fluid to couple the fan tø the shaft. Perhaps if the engine were operated to hot and shut off before you grab the fan and attempt to hold it while the engine is running?
Only test I've ever done on viscous fan couplings was auditory...the fan should roar upon initial startup and then stop roaring (indicating startup coupling/decoupling when cold) and when engine/radiator gets hot enough the fan should roar again, indicating coupling with the fan shaft and moving air through the radiator. If this doesn't happen, the fan coupling should be replaced.
One other note, at least one company, MB, has a speed–dependent viscous clutch..above 4100 rpm or so the clutch internals cover up a port (centrifugal force actuated valve) and disengage the clutch. Dunno if Audis do this but part of the MB diagnostic routine is to note loud roar of fan during good operation below 4100 rpm and run the engine up to 4500+ rpm and fan should decouple. Probably to avoid over revving the fan. I wouldn't be surprised if audi did this as well because these engines redline at 6K (S6 4.2 at 7K), etc.
Well, the test was made this way: I arrived there with the engine very hot. About 110-120 Celsius.
I stopped the engine for a little moment just to talk with the man. Then he asked me to start the engine (it was still hot, very), he grabbed a standard oil filter paper box, folded, introduced in the fan course and it stopped easily. I didn't accelerate during the test, so the RPM was around 1200.
This same test was made by the second shop and concluded the same. But since Audis are complicated cars, do you think this test is valid?
Thanks a lot!
11-10-2011, 01:29 PM
#12
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Yes. I would replace the fan clutch.
11-10-2011, 03:31 PM
#14
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Thanks guys, you are great. I'll go ahead and replace the clutch than.
I'll post the results to help the ones with similar problem.
BTW, I bet you guys don't know but you helped me fixing my Audi many times, thanks to all of you for the invaluable help.
I'll post the results to help the ones with similar problem.
BTW, I bet you guys don't know but you helped me fixing my Audi many times, thanks to all of you for the invaluable help.
11-12-2011, 08:24 AM
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Thanks a lot!
11-13-2011, 08:40 AM
#17
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There are a couple of shortcuts to working that nut off the shaft.
1. Put a bunch øf rags between the engine and the radiator on the drivers side and put a long open end wrench on the viscous fan nut....whack the end of the wrench toward the rag pile...the impact will often loosen the nut; the rag pile will catch the wrench.
2. Use an air hammer with a pointy tip to do the same thing...the rapid impact of the air hammer will loosen the nut...make sure you hit the nut toward the right edge. I noticed my old clutch had these marks on it from the dealer's replacement øf my fan clutch under warranty.
1. Put a bunch øf rags between the engine and the radiator on the drivers side and put a long open end wrench on the viscous fan nut....whack the end of the wrench toward the rag pile...the impact will often loosen the nut; the rag pile will catch the wrench.
2. Use an air hammer with a pointy tip to do the same thing...the rapid impact of the air hammer will loosen the nut...make sure you hit the nut toward the right edge. I noticed my old clutch had these marks on it from the dealer's replacement øf my fan clutch under warranty.
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