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Jerry
Jerry, Master Mechanic
Category: Audi
Satisfied Customers: 17218
Experience:  ASE Master, 30+ years exp. imports and domestic, former shop owner
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I have an Audi C5, A6 Quattro 4.2 Liter V8. The year is

Customer Question

I have an Audi C5, A6 Quattro 4.2 Liter V8. The year is 2000. I've been noticing lately that the engine has been overheating when in hot weather and in stop and go traffic. At first I thought it was the thermostat but nothing changed when I replaced it. But here's the odd part: The coolant temperature stays at the 12:00 mark until the oil temperature rises. Once it gets to 250 degrees, then everything overheats. Including my transmission oil (got up to 220 degrees during this, which I know isn't overheating, but more than I'm comfortable with). When I pull of the fuel regulator hose (tiny one that's a more translucent brown color) there's no compressed air or fuel expelling from it. I don't know if this is related. I have 2 error codes, a P1136 and a P0422. The O2 sensor (bank 2, sensor 2) is lazy and stays stuck at .4 volts. I'm convinced that this is the reason for those fault codes. But I wouldn't of mentioned that if on the off chance it were actually relevant. Other than that, car drives great. Though the timing advance seems a bit high (23 degrees BTDC @ 1500 RPM's) and I guess maybe that could be related? I've been using a 87 octane fuel because the 91 octane where I live is non oxygenated. And I know these engines were made to run with an ethanol level of 10%. I mention that because I thought the timing advance was maybe due to that. I'm sure this may be a information overload, so I'm interested to hear your thoughts.
Submitted: 1 year ago.
Category: Audi
Expert:  Jerry replied 1 year ago.

Hello and welcome. My name is ***** ***** I will be happy to assist you today.

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They are sometimes bad about the radiators clogging up and causing an overheating. You can have that tested at a radiator shop or feel around the core when the engine is hot to see if there are any cool spots that would indicate a clog.

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However, with any engine that runs hot, overheats or has been overheated it is best to check the integrity of the engine, (head gaskets and heads, etc.)

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The first thing that you want to do is check the cooling system for any exhaust gases. Make sure that it’s full first. There is a tester for that, that you can get from Autozone for about $20. They will normally lend you the tester and you just buy the fluid for about $8. It comes with instructions, but there is a blue fluid that is used in it, if the fluid turns yellow, that is exhaust gases.

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Block tester available is:

Napa BK.(###) ###-####/p>

OEM/Block Tester AUTOZONE

Part Number:
27145

http://www.autozone.com/autozone/accessories/Tools/Block-Tester/_/N-25dh?filterByKeyWord=block+tester&fromString=search

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*****You will want to check it at different RPM’s and at different temperatures***

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If there are any exhaust gases in the cooling system, that will cause more pressure than desired and will allow the engine to burn coolant and/or heat the coolant up too high. Most times not filling the crankcase with coolant either and not smoke out the exhaust.

If there are, then there would be an internal engine problem, like a head gasket or head.

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Please don’t forget to rate the answer, **** THAT IS THE ONLY WAY I GET PAID **** if you need any more on it, I will be here.

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Expert:  Jerry replied 1 year ago.

If for some reason you don’t wish to rate the answer please state in a post that you are happy with the answers and the service I have provided so that I can send it in as a no click rating and get paid for my time, thanks