AAZ overheating

[jebiga41]

Hi installed an AAZ in the syncro runs fine but is overheating at 100 km and over, around 60mph. got a lower temp thermostat, flushed out the rad, bled the system which made a slight difference but still overheats can control the temp with the heater but a bit hot at the moment, one thing is that the rad fan doesn't come on have to change the temp sender and may even put in a manual overide switch. Am kinda thinking its the rad but when i had a 1Y in it before didn't seem to have any problems any ideas guys?

[Fully Loaded Cali']

I run an AAZ, they do run hot due to the turbo. My temp sender sits bang in the middle of the gauge until i go over 70mph or drive up any hill., then it starts to get hot, but not to the point of boiling over. At 60mph the wind blast should keep it cool. If i leave the van ticking over, after approx 20 mins the needle will steadily climb until the fan cuts in, then drops back. I am sure if the fan did not cut in the engine would overheat. Fan operation is a must - is your water pump / thermostat (new ones can be faulty)ok? If the heated water is not getting to the rad, then your fan will not cut in. Daft question, but are your main pipes to and from the rad the correct way around?

[dazzerT251900td]

a up mate,i do i know if my pipes on the front radiator are the right way round,cause its hard to tell when looking at the bottom of the radiator.I dont know if my fans working to be honest.cheers dude.daz

[smokeyjon]

No help for you jebiga.... just sympathy. Mine's doing exactly the same and I know it's something odd as I've also done a lot of miles already with the same setup at much lower temps.

I've done the same as you: rad flush, new VW thermostat (GSF etc ones are renowned for being rubbish). I'm going to follow up the following bits of advice next before buying a new rad:
1/ look for a leak in the system (I have very slight coolant loss) - maybe even a pressure test
2/replace the coolant cap, as coolant hasn't been flowing into/out of my expansion tank for some reason

the dreaded head gasket has been suggested to me, but I'd be surprised as I had it done 25K miles ago and haven't since had overheating problems

I'll keep an eye on your thread and let you know of any breakthroughs. Good luck!
ps - you can test the rad van by unwiring and shorting out the switch on the rad itself using a loop of wire. I've done that too!

[syncropaddy]

I once put a 1.6TD out of an Audi 80 into a T3 and it soon had the same symptoms as described in this post. There were two things I did which solved the problem ....

1. Sorted the operation of the auxiliary water pump by changing the sensor that switches it on / off
2. Replaced the cylinder head gasket

[smokeyjon]

Not the dreaded head gasket!!!! Aaagh! Thanks for the reminder tho - I'll check my aux pump too. I must admit that I haven't heard it for some time!

[billy739]

all things point to the fact that vw never fitted anything bigger than a 1.6td / 1.7 na in a t25 because of cooling issuse!

[smokeyjon]

jebiga - I have been advised that the impeller of the water pump wears out, and so pumps water around less as it gets older. I'm going to change water pump (under £40), and possible change the rad as well. For £40 it might also be worth you trying.... or if you can be bothered maybe you can get it out and check it?

[jebiga41]

Hi a quick update as i and others suspected it was the rad replaced it with a new one and engine temp dropped dramatically also found that the rad fan had a bad earth and connected another independent one temp guage sits around the quarter mark now and has only risen to just under the diode on a run left her idle for half an hour and the same would advise anyone doing the AAZ conversion to bite the bullet and install a new rad whilst doing the conversion thanks for all the replies guys appreciate it

[Fully Loaded Cali']

Where did you purchase the new rad from? Did it fit the cowling ok or did you have to modify the mountings?

[jebiga41]

gsf had to elongate the holes slightly in the cowling but if was going to get one again would probably get baxters if its oem for the extra few quid