Overheating Alhambra

[concretebudgie]

I have a 2001 1.9tdi which has a tendency to overheat. My immediate thoughts are that it could be a faulty thermostat or water pump, but the symptoms are a bit odd (to me anyway).
The warning light and alarm came on whilst I was running the car at about 80mph, having driven approx 15 miles / 25 minutes.
The RAC attended, and found the system, though it had stood for about 45 minutes was pressurised when he loosened off the cap to the expansion vessel. The engine was run on tick over and then revved up, but the temperature remained normal (90 degrees according to the dial). I took a chance and drove it 20 miles home keeping revs and speed down (max 60mph). Occaisionally the temp needle strayed up a bit, but then dropped down.
The rad and some of the hoses remained cool, indicating a lack of water circulating around the system, but the pressure in the system / expansion vessel is puzzling me. Also, the heater / blower remains cool
From asking around and from experience , I feel it could be the Thermostat or water pump.

Anyone any ideas or anything similar?
Thanks

[kenney]

Hi Sounds like you have a head gasket problem.Overheating,when driven hard,no circulation,high pressure in the system and both radiator hoses cold

[concretebudgie]

Thanks for the reply. I presume you mean a blown head gasket. I did think of a head gasket problem, but discounted it as 1) a test was done to see if the coolant had been contaminated by combustion / exhaust gases, and it proved negative (or not positive) and secondly, there was no 'pull' noted on the coolant in the expansion vessel when the engine was revved up. Also, no loss of coolant or steam was noted. Having read this, do you still feel this is so?

[kenney]

Hi What do you mean by pull,as regards gas in the expansion, tank from a TDI it is very seldom you will see that.I think the gasket is in the first stage of blowing .But of course you must try changing the thermostat first that is the usual rutine.

[smokey0123]

If there no circulation I would change the waterpump, if it was the thermostat the heating would still work ok.

[freers]

Hi

New here, just having the same problem as ConcreteBudgie (same car), so wondering how you got on. Problems as follows:

1. Temp gauge goes up after a run 60-70mph for 45 mins, sometimes to warning level
2. Apparent loss of water after most trips (e.g. 2.5 pints after 50 miles@60mph in two trips or half a pint after a local trip)
3. No significant smoke/steam from exhaust
4. No mayo on oil filler cap.
5. No apparent leaks in radiator or hoses
6. System appears to relieve lots of pressure (sound of water draining to bottom of system) when header tank cap is released.
7. Fan seems to kick in as it should.
8. Heater works, but have a feeling it may only work when turned to max

I'm inclined to think it's a head gasket problem but nothing seems to stack up and don't want to take it to a garage and get roped into replacing radiator, water pump, thermostat and hoses before realising what the real problem is. In addition, have just realised the head gasket was replaced in April last year - could this have failed already?

If anyone can shed some light on this (along with some potential costs) it would be much appreciated.

Thanks in advance
Neil

[Marmalizer]

VAG for some reason or another decided to stop using Brass Impellers on the water pumps in their cars and moved to cheap plastic ones.

Now if your car overheats whilst the engine is at 2k+ revs but then soon settles when at tick over it is 90% of the time your water pump.

The plastic impeller becomes brittle and cracks on the spindle, and only shifts water at around idle.

The price for a brass impeller is not too bad only £24 it the 1hour and a half labour thats a stinger.

If you are losing water then you must have a leak somewhere. If you have no mayo and no white smoke then I would suggest that you park it somewhere dry and run the engine at 2.5k revs for about 10 mins and if after all that the floor is dry.
Then i would guess that you might have a leak in your heater matrix and check your carpets for damp, try turning your heater up to full and see if the windows steam up.

[freers]

Thanks very much Marmalizer, I have also asked around several local 'experts' who all seem to agree that the water pump is the problem, so have it booked in tomorrow for replacement water pump and cambelt.

I think the water is coming out of the overflow of the header tank - it sounds like one of the catch 22 situations, the car overheats due to the water pump failure, the water boils and forces it's way out of the overflow and makes the problem worse due to lack of coolant!

[Angarak]

Hello all,

I also have a 2001 tdi that has developed this of late.

Originally it overheated when on motorway journeys (usually when I was going uphill), however of late it can overheat on short urban runs.

When the car initially overheated, I put the heating on HIGH with the fans at MAX and this did help to lower the oil/water temps. However lately the heater system blows cold regardless of heat setting. I had to drive to Leeds a couple weeks back and I noticed that when going uphill on the M62 (towards pennine way) the oil/water temps would rise and the heater would go cold (when set to high temp), but when going downhill or on a flat section the oil/water temp would lower and the heater would start producing heat again!?!

I've noticed the car is losing coolant through the overflow on the header tank.

To date I have:

1> Replaced Thermostat (and tested new thermostat in boiling water to ensure it opened at temp)
2> Replaced the OEM water pump (with plastic impeller), the new pump has the brass impeller (and I've just taken it out to ensure its fine).
3> Checked all hoses for splits - none found
4> Checked radiator for leaks - none found
5> Checked oil for signs of water contamination (ie: headgasket failure) - none found
6> Taken it to SEAT and had it diagnosed - no faults logged, and more annoyingly they couldnt get it to overheat on their rolling road. They also believe the head gasket to be 'bullet proof' on these engines and the garage I took it to (Warrington) has never known one to fail.
7> Checked carpets for dampness to indicate heater matrix leak - carpets where bone dry.


I've heard that it could be a failed header tank cap. If its not sealing then it will boil the coolant at a lower temperature than it should, and it would also 'gas out' into the header tank. I've ordered one from SEAT but wont get it for a couple days.

I have also noticed something behind the header tank that is attached to the top heater hose (the one that runs over the top of the engine behind the oil filler neck). If I waggle the wire to this 'device' once I've just turned the engine off, it makes a whinning noise (as if an electrical fan/pump is working) and it releases pressure out of the coolant system (you can hear gurgling)....any ideas what this 'device' is?

Mystery Device:
:: http://mooch.pwp.blueyonder.co.uk/al...y_device_1.jpg
:: http://mooch.pwp.blueyonder.co.uk/al...y_device_2.jpg

One other thing regarding the head gasket, if it does fail wouldnt you notice a reduction in power? (something I have not noticed).

Any other possible ideas on the overheating that hasnt yet been covered in this thread?

Cheers
Simon

[freers]

Hi Angarak

Not sure I can help too much as i'm not a mechanic, but I assume you have checked top and bottom hoses are both getting hot, if not this could mean a problem with circulation, blockage in radiator perhaps?

otherwise I would suggest a pressure test and/or emissions test to check for cracks in cylinder/head gasket.

What about fans - are they both kicking in as they should as this could be a reason for the overheating around town?

Any white smoke from exhaust or mayo in oil filler cap?

Otherwise I have since replaced my Alhambra with a newer galaxy - and will keep all fingers and toes crossed for as long as I own it!!!

Freers