VERY HOT! - HELP!

[MontanaGTD]

Right i've got a mk2 1.6 GTD (Sb engine code - intercooled)

After fitting a new water pump the thermostat was found to be a little sticky (tested) - so bought a new VAG thermostat and seal and thought I'd run it a while and get it changed before anything else went wrong. But the thermostatic switch on the radiator packed up - so as a temporary measure I fitted a switch to the dash to turn the fan on when the temp started to climb.

All things went fine until yesterday when the fan seized solid and the temp shot through the roof! (on the mk2 temp gauge it was on the last line from the top!) So stripped out the thermostat and drained the system - flushed it through with some water and then refitted the new thermostat with the new seal and refilled it again with anti-freeze and water.

The fan is still knackered, but surely driving at a steady 50-60 mph the temp should come down with the forward motion?

Nope the temp is still as high as it has ever been and i dont want to blow the head gasket!

Anypne got any ideas??

I have the new rad switch still to fit and i have a mate who has a spare rad fan. but he is almost 30 miles away! Should I creep through and stop when it gets hot for a while? or get him to come to me?

[Black Smokin' Diesel]

Temps should be normal even with no rad fan driving on the highway. If not, the thermostat is bad or you've got an air lock in the system.

And get your friend to drive to you, don't take any chance.

[MontanaGTD]

How can i sort an airlock?

Is it possible to fit the thermostat the wrong way round?? (Its spring-in towards the waterpump)

[bigblockchev]

I have found that if you bleed the air off at the different hose ends by loosening the clamps one at a time & letting the air escape it helps somewhat . There is also a radiator testing gizmo which puts the whole cooling system under vacuum to test for leaks, if the vacuum holds then there is a hose that you can place in a bucket of coolant and when you open a valve the coolant is drawn into the engine. It works because all the air is drawn out to begin with. Otherwise you can fill your coolant tank, warm up the engine a bit  shut it off and let it cool down to cold then do the same again and a third time. Three times usually works for me. Cheers Dan

[Black Smokin' Diesel]

How can i sort an airlock?

Is it possible to fit the thermostat the wrong way round?? (Its spring-in towards the waterpump)

I don't think you can install the thermostat the wrong way. You may be loosing pressure through the coolant tank cap. If the system can't keep it's pressure, it won't cool properly.

[MontanaGTD]

I'll check the cap tomorrow!

I fitted the thermostat exactly the same as the one which came out! Just 2 of my mates mentioned it!

Where does everyone elses temp gauges sit - mines sitting about 2/3, but the light on the dash hasnt shown up at all!

My mate with the spare fan recons its just down to the thermostat actually working correctly now as the old one may have been sticking open and flowing water around the rad all the time which is why the temp gauage sat so low for so long and the heater in the car was crap until you had done 20-30 miles!

[bigblockchev]

Both of my  temp guages sit at either dead center or no more that 5% to the right of that.

[Black Smokin' Diesel]

Both of my  temp guages sit at either dead center or no more that 5% to the right of that.

Ditto. Varies a bit but not much.

[MontanaGTD]

Watch this video on youtube - http://www.youtube.com/watch?v=zZYQlCTC0Z4

Thats what it always use to sit at - now it sits just a bit higher than half way.

[jtanguay]

i bought a faulty t-stat from the DEALER.  i thought i had huge problems!!!  go on the highway, faster i drove, the hotter it got. 3/4 of the gauge at times and it was pretty spooky... i've heard of people overheating and blowing heads so i got a bit scared.  never took the car on really long trips.  in the dead of winter it was fine though... more heat than i knew what to do with even with -20c air blowing into the front of the car.

changed the t-stat, and voila.  no more overheating problems!

[MontanaGTD]

really? maybe I could check another one and see what happens!

[jtanguay]

really? maybe I could check another one and see what happens!

test it in water with a thermometer on the stove.  if it doesn't open FULLY then its faulty... mine was opening slightly at around 90-95C and never did quite open as much as the 160F one i bought.  good for the winter time, but bad for summer, or even spring!

when testing my coolant bottle temp it did drop when it reached around 86C... around 2 degree drop so i thought it was working okay... idling it would hold its temp no sweat, but throw large amounts of heat at it, and it couldn't cope.

hope this helps you out!  i will always be testing my thermostats before installation from now on... i've learnt my lesson!

[Eli]

Yeah, I bought a new faulty thermostat once as well. It took me awhile to figure out that was the problem. I'm testing from now on too.

Good luck man,

-E

[rubadubdub]

You can get thermometers from Wilkinsons brewing sections for about 2-3 quid which go up to 105 degrees C. More than enough to check opening temps of the thermostat as described.

Also, did you do any electrical work on the car at then same time? Any senders swopped places? My temp used to go up and down and worry me until i realised it was an electrical problem that was causing it. Obviously err on the side of caution when considering this option!

[MontanaGTD]

Spoke to my mate lastnight and he recons that my quick 2 mile drive wasnt enough to get the water hot enough to get the thermostat to open - So I took it out for a longer run this morning (15 miles) and the temp gauge went up quite quickly - in fact i'd probably say it was the quickest warm up ever. It got to just about 1/2 way and then sat there all the way round my run. When I got back to the house I checked the lower hose on the rad and it was still cool to the touch.

Looks like the thermostat is ok and everything (other than the fan) is as it should be. I'm going to swop the fan and see how things go. I can always wire up another switch on the dash too!