QT

My 2005 1.8 T A4 was cruising right along when the coolant light went on...checked the levels and nothing was wrong, so I let the engine cool off, but once on the road again the light came back on and the temperature went through the roof. Called my mechanic who claims it has to be the water pump and gives me an estimate of $700 with parts and labour.
Does this sound diagnostic sound correct, as well as the estimate?
Thank you,
Ryan

skr777

If your coolant level is OK and you don't have a faulty temperature gage, then the only other thing it could be is the water pump. $700 sounds pretty reasonable. It's probably 4-6 hrs. labour, and about $150-ish for parts. The timing belt needs to be taken off to do the job, so you might want to have that replaced at the same time, especially if you're over 100,000 kms on the engine. It's probably only another $50 or so to do it now, instead of $700 again to have it done later.

Edit: They recommend changing the timing belt on most cars at 125,000 kms or so, but I think Audi uses longer-lasting belts, so it may be good for much longer. I guess just have it inspected.

QT

thanks for the input...the car has 170.000km, but I was told it was changed....guess i was lied to by the seller, those are the chances we take i guess when dealing with used vehicles! I will do the timing belt as well, good suggestion, don't want to risk blowing the engine by cheaping out for an extra $100!
Thanks again,
Ryan

QT

so it's not the water pump....once the car cooled off over night it was checked the following day and diagnosed with nothing wrong...i am driving it now with no problems, but about when the temperature is 30 degrees like it was last time this happened....can temperature be causing this to happen, if so, what about the heat is making my car malfunction?
Any ideas?

skr777

Now that I think of it, there are a couple of other things it could be:

1. The rad needs to be flushed -- deposits can restrict flow, and therefore the ability to cool.
2. The fan is not working properly -- It could be just the controller not telling the fan motor to switch on, or the motor itself could be burnt out. This seems more likely to me.

Or, you know, if you were just driving the **** out of it all day, especially in the city, that will eventually get things pretty hot too, even if everything is in perfect order. :P

K04-S4

Suspect failing Thermostat could cause your issue.

Is your coolant discolored?

If replacing any of water pump, thermostat, t-belt, etc then strongly recommend installing a complete Timing Belt Kit with new rollers, tensioner, acc belt(s) and new coolant.

Electric cooling fan(s) operate in warm weather when stuck in traffic and typically do not operate while cruising. A VAG Scan should report an electric fan controller failure.

QT

I have been driving my car now for 3 days without any problems where the outside temperature has been constant at around 15 degrees. So, I am sure now that the problem is only apparent when the outside temperature is above 25 degrees celcius. Have I narrowed down the list of potential causes to the car thermostat to spike to 130 with no overflow or loss of coolant?

rusty_67

iTrader: (1)

I have a 2002 A4, and I know there is a recall on the coolant temp sensor. Mine never threw on the coolant light, but it did throw some intermittent codes and the temp gauge would bounce around a bit. Had it replaced at no charge and haven't had a problem since.

K04-S4

Has your Audi been VAG scanned yet? A failing CTS *usually* shows a DTC. At 170K KMs I would consider replacing CTS as Rusty_67 suggests because it is a common failure at higher mileage and it's inexpensive. A failing CTS could cause eroneous dash temp reading.

If your coolant is high mileage and discolored, it is contaminated / loses some of it's cooling properties and should be replaced. If your considering a TB Kit install, then that is a perfect time to replace coolant.

BTW overflow hose points underneath engine bay typically directly below coolant reservoir so you may not know it actually overflowed while on the road.

QT

So I called the dealership who has informed me that there are two different coolant temperature sensors for this year. The first is a green sensor that is a dual temp sensor and the other is just a waterpump sensor. Any ideas of which sensor is needed for this particular situation?
Thank you kindly!