Thoughts on overheating car

[apexit1]

Going to go look at a car. Guy says it overheats and the fans aren't blowing. He claims to have change the water pump.

Car is an 04 A4 1.8T Quattro with 140k.

Aside from testing the fans and fan controller what else may cause this? I'm planning on checking for codes with my vagcom and checking to see that the fans are getting voltage. Not sure what else I should be looking for. Ideas or tips on what to look for in general?

[maurizio]

Would that explain the fans not working though? Or are you saying that the fans not working doesn't explain the overheating?

Probably a big air pocket?
Lift the reservoir until it comes out of the hard pipe / heater hose.

Go here to measure them

[apexit1]

Would that explain the fans not working though? Or are you saying that the fans not working doesn't explain the overheating?

[chad99]

These AMBs don't like overheating, I wouldn't be surprised if it also needs a headgasket.

[maurizio]

oops, read right past the fan part.

[Furly]

These AMBs don't like overheating, I wouldn't be surprised if it also needs a head.

Ftfy

[apexit1]

I did some reading. What I saw was that the heads/ gaskets dont usually go on these but you guys are saying they do. I didn't get into the different varients of the 1.8T motors, would that explain it? Either way I'll be checking the oil and seeing if theres any smoke on start up. Pretty sure I'm getting a decent deal on it and I'm OK with DIY stuff especially when given a guide that are everywhere on here.

[PreciseD]

Would that explain the fans not working though? Or are you saying that the fans not working doesn't explain the overheating?

If it's not a large air pocket or a stuck thermostat then the fan control module took a shit... They are like $300-400 or so and need to be wired into the old harness. Also Furly is right as if it has overheated enough the head will probably be toast...

[mjmatos]

I've had my AMB with overheating problems on two separate occasions both cause me to replace my head gasket, first time I cracked the head in 5 different places, so just be weary of that, itcost me 600 to DIY the head gasket/head replacement fwiw

[123lilc]

possibly the fan relay i believe if not the fan controller

[crazyquik22023]

I did some reading. What I saw was that the heads/ gaskets dont usually go on these but you guys are saying they do. I didn't get into the different varients of the 1.8T motors, would that explain it? Either way I'll be checking the oil and seeing if theres any smoke on start up. Pretty sure I'm getting a decent deal on it and I'm OK with DIY stuff especially when given a guide that are everywhere on here.

Essentially, AMB's have a 210 deg thermostat when other 1.8t's have a 192 deg. Many people have problems with heads warping and cracking on the AMB's because of this.

[Charles.waite]

The head gaskets don't usually go without some external factor like overheating. The main problem is warped/cracked heads from overheating. I would do a compression test and test the coolant for oil/combustion traces. And check for misfires on cylinders 2 or 3.

[RDA990]

Found a B7 with the same symptoms, car would overheat sitting in traffic but not with normal driving, neither fan would turn on. Checked everything from relays, fuses, Vag-Com, Fan Control Module, etc. Turned out to be that one of the fans had gone bad, and somehow kept the other one from turning on. If you decide to get it PM me & I can go into further detail on how I diagnosed it. I have a few Fan Control Modules laying around that I bought to test on the car too if you're going to be looking for one.

[1/4 scale]

test fans with a jumper wire. if they work then my bet is on the fan control module

[johnwiz]

test fans with a jumper wire. if they work then my bet is on the fan control module

This^

I went through this late last year, thought it was my FCM as neither fan would come on. Replaced the FCM, no change. So I tested the fans with a 12 volt jumper, turns out both were bad. Not sure if the main cooling fan went first and then the A/C one - but regardless wound up having to replace both.