Overheating 4.2
10-12-2003, 05:52 PM
#1
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Overheating 4.2
Outside temp 78 F, normal around town driving, when all of a sudden the A/C starts blowing warm. I check gauges and H20 guage is 1 bar from "H", oil temp still around normal (200-250)so I pull into first service station and the Coolant warning comes on. I shut her down and check level in over flow. Its right where it should be (just a hair over Max), so coolant loss is out. Im running the proper coolant, no mixing with the green stuff. Vbelt was replaced 3000 miles ago and is intact. What gives? I'm assuming (more like praying) it is my thermostat stuck closed. The car has 60,000 miles so the water pump isnt out of the question. What is the life expectancey of the Thermostat and the Water Pump? And Is the thermostat an easy do DIY job?
10-12-2003, 06:03 PM
#2
Re: Overheating 4.2
the thermostat is not that easy because you need to remove the timing belt
just replace a thermostat and water pump on a A8 2001
same motor as yours
if you change the thermostat also change the pump not a lot more of work involved
if you in los angeles area e-mail me
just replace a thermostat and water pump on a A8 2001
same motor as yours
if you change the thermostat also change the pump not a lot more of work involved
if you in los angeles area e-mail me
10-12-2003, 06:06 PM
#3
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Very well could be thermostat
The A8 5 valve motor has had a lot of themostat failures, and the temp goes high. It could also be a bad electric or mechanical fan too, but not as probable.
The thermostat is not that hard to get to, but you will need to drain the coolant and pull the coolant hoses. I think that's it. Look at the timing belt procedure below for some pictures, and a few more <a href="http://www.audipages.com/Tech_Articles/Body/frontendremoval.html">here</a>. The thermostat is above the timing belt enclosure, a 4 valve motor is shown, but yours is not that much different.<ul><li><a href="http://www.audipages.com/Tech_Articles/enginemechanical/tbreplace0.html">http://www.audipages.com/Tech_Articles/enginemechanical/tbreplace0.html</a</li></ul>
The thermostat is not that hard to get to, but you will need to drain the coolant and pull the coolant hoses. I think that's it. Look at the timing belt procedure below for some pictures, and a few more <a href="http://www.audipages.com/Tech_Articles/Body/frontendremoval.html">here</a>. The thermostat is above the timing belt enclosure, a 4 valve motor is shown, but yours is not that much different.<ul><li><a href="http://www.audipages.com/Tech_Articles/enginemechanical/tbreplace0.html">http://www.audipages.com/Tech_Articles/enginemechanical/tbreplace0.html</a</li></ul>
10-12-2003, 06:35 PM
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I would say almost 100% not. I will bet 10:1 that one or more of the aux fans stopped working
the real clue there is that the ac blew warm, which would not be effected by a bad thermo, but would be effected by the aux fan not pushing air over the AC coils
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10-12-2003, 07:23 PM
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Re: it's not the thermostat anyway, I would guess aux fan relay
I just went out to the garage and fired her up. With the A/C off just the engine driven fan is spinning. When I turn on the A/C both electric fans engage. HOWEVER, the electric fans are only operating on low, they are not kicking into their "screaming loud turbine engine speed"(for lack of a better descriptor-but I'm sure you are all familiar with what I'm refering too). Any further thoughts? Isnt there some sort of electronic thermostat controlling the fans, and if this fails, resulting in the fan stuck on low, is that enonough to overheat the car (even at steady 50-60 mph speeds for 5-10 minutes)?