2001 A4 1.8T Overheating

[gmack1129]

I just recently purchased a 2001 A4 with the intent of rebuilding the car from scratch. Long story short, I got the car in working order but am having a persistent overheating problem.

I recently changed quite a few parts including the faulty coolant flange and temp sensor, but that had no effect. I did notice smoke coming from the turbo side of the engine and figured it may be a clogged cat converter. I ended up removing the entire exhaust (it was easier at the time) and noticed that the car ran significantly better but the car still overheated on a test drive.

I am hoping that someone may have an idea of what I may need to check next.

[RagtagXMASTER]

any leaks from the water lines on the turbo i had a similar issue i had a torn o-rinbg on the cts sensor huge headache there. and i had a pinhole in my lower coolant line on the turbo, fun time replacing that.

[gmack1129]

The sensor is in good condition so I know that's not the issue. As far the the coolant line, I assume you're referring to the feed line which I did not check. I recently replaced the return line because it broke on the first test drive I did.

I was able to diagnose the smoking from the turbo side, cat was clogged and valve cover gasket needs to be replaced, but still no solution for the overheating.

Thank you for the tip. I will be checking on this tomorrow and will update you.

[xdewaynex]

Possible air bubble in the cooling system, or thermostat is stuck.

[gmack1129]

The thermostat may be a possibility as I have yet to tackle the whole timing belt assembly so I am unsure of its condition.

I will dedicate a day over the weekend to just troubleshooting the issue using both yours and the previous suggestion to see if either solves my problem.

Thank you for the input.

[SN95Audi87]

I just recently a few days ago got my Timing belt kit service done. My symptoms were that it was partially overheating while driving and in idle traffic. The Tech who did the service found my water-pump impeller broken in 3 pieces.

Check if the cooling system is holding pressure cap seal, themostat seal, and behind the head seal. Next check all your hoses for clogs/cracks. Then start going down the line to physical hardware such has thermostat and water pump. If your radiator is old it could be clogged as well. I would make sure that none of the passages in the block has clogs either, maybe an aggressive cleaning agent to flush out all coolant.

[pbcrazy]

Replace the thermostat, it's the easiest/cheapest starting point. When you are changing it, reach a finger up into the water pump and try to turn the impeller with your finger, if it moves your water pump is done

[Chrisw023]

I would first check to see if your coolant is circulating by bleeding it on the heater core hose, if not then you can pretty much narrow it down to the thermostat/water pump.

[gmack1129]

First off thank you guys for the replies. Unfortunately I have not been receiving any notifications and was not aware of any of your replies until now.

I did a full coolant system flush on Wednesday including the heater core, as well as replaced the thermostat. As expected, the residue was orange instead of pink. After installing the new thermostat, I turned the car on and let it warm up to operating temp and burped the system about 4 times altogether. The temp gauge went up 3/4, which was significant improvement than before, then made its way back to the mid-way line.

Just as I thought I made a break-through, I took the car on a test drive and less than 1/2 mile later the gauge shot all to way over.

I'm starting to lean toward the water pump even though it is in good condition, but would like to explore other possibilities before I go pull the front off the car.

[RagtagXMASTER]

Do you know if the water pump is the metal or plastic impeller. I had a plastic one and it shattered in the block ino 4 peices due to the temp cycling. Broke on the highway overheated and ran very hot if on boost. If you let the car run under 2k rpms it would cool via the radiator and fan but otherwise always overheat fast. Thats how i blew my first head gasket actually. So be careful


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