Thermostat Replacement = FAIL

[Mr OCD]

Wasnt expecting this to be an easy job due to access but talk about a performance...

First mistake...

Stripping the airbox / MAF / etc off the side of the engine and removing the CTS housing to realise the thermostat is in fact on the front of the engine... I should have checked the manual before starting the job instead of making assumptions

Second mistake...

Putting it all back together after replacing the thermostat from CORRECT location... pouring in neat G12 and wondering why I had a big puddle on my garage floor...

Turns out when I put the CTS housing back in due to it being difficult to see I had mounted the CTS to the bracket under the housing instead of the housing to the block and the bracket mounted to the housing

So what should have been a 45min job took me three hours...

It was one of those days

 

[rydoo]

nice job lol least you got there in the end buddy

 

[JamJay]

sounds like good fun to me. I hate when it's a part that your car can't run without, you can't do the job right for some reason and you're running out of daylight.

 

[Mr OCD]

sounds like good fun to me. I hate when it's a part that your car can't run without, you can't do the job right for some reason and you're running out of daylight.

I wouldnt mind but I've been working on cars for over 20yrs!!!

I was doing the job in my garage but due to the location of the parts even a flood lit garage failed to light up the areas I needed to see properly...

In the end the Stat change was pretty straight forward in itself and although access was tricky it wasnt that hard.

 

[leon cupra r]

sounds like good fun to me. I hate when it's a part that your car can't run without, you can't do the job right for some reason and you're running out of daylight.

Know that feeling! - worst case I've had of this was my Rover 25, went to do a simple 20 min job changing oil + filter, went to take the filter off and the crappy tool I'd bought from halfords wouldnt get a grip on it! Ended up ramming a screwdriver straight through it to try and twist it off with that, obviously pissing oil everywhere from what was in the filter in the first place, but this just ended up with the screwdriver ripping round the filter - the garage I'd bought the car from had blatently not bothered to oil the filter housing before attaching it to the car, so the thing had pretty much welded itself on! Car with no oil in, and a filter with two whacking great holes in, running out of daylight and I was supposed to be at work at 6pm! Definitely bad times!

 

[LEE69]

I bet you won't make the same mistake twice Scott

The rubber o ring got me the fist time, as geneally, they go by the thermostat and not just on the housing.

 

[Lodgey180]

we get this all the time at work. People ask for thermostat housing then when they get it they wanted the cts housing on the head.

 

[slee86]

So do you get the o ring when buying the thermostat? Do I need to replace any other gaskets whilst fitting the thermo stat

cheers si

 

[LEE69]

I have both times lol

 

[cupragirl]

Just how do you get at the bolts on the stat housing?
I've spent about four hours with variouse extension bars and knuclke joints and I can't even get the socket onto the top bolt for sake .
Even thought about taking the alternator off, but couldn't figure out how to release the tensioner pully . All in all not a happy bunny.
Oh its a 1.8 Cupra BTW
P.S. I have seen Rafatt's guide on audiworld. But I must be a muppet.......

 

[LEE69]

You remove the bracket that is attached to the inlet manifold to give better access have a search on my phone so can't help sorry.

 

[Mr OCD]

You remove the bracket that is attached to the inlet manifold to give better access have a search on my phone so can't help sorry.

Yep thats how I did it as well...

 

[DJ-LIAMC]

How did you know your thermostat was gone? My cooling fans arent kicking in but i tested them and they work (by shorting out) so ive ordered a thermostat (or fan switch), is this what your problem was?

 

[adam cupra 20vt]

How did you know your thermostat was gone? My cooling fans arent kicking in but i tested them and they work (by shorting out) so ive ordered a thermostat (or fan switch), is this what your problem was?

The gauge drops from 90-60 when you go up and down hills or brake-accelerate hard.

Thats what mine did anyway.

 

[Muttley]

DJ-LIAMC wrote

How did you know your thermostat was gone? My cooling fans arent kicking in but i tested them and they work (by shorting out) so ive ordered a thermostat (or fan switch), is this what your problem was?

Thermostat or thermoswitch?

The thermostat is a purely mechanical device in the cooling system that stops water going to the radiator until the engine has warmed up. If it fails in the open position, the car takes ages to warm up, especially in weather like we've had recently, and will give poor mpg. If it fails shut the engine overheats - much more dangerous.

If your fans aren't coming on then the thermoswitch is a more likely candidate. This is set into the radiator itself and turns the fans on according to the radiator temperature. In a car with airconditioning there is also a fan control module which turns on the radiator fans at the same time as the coolant compressor, but at a low speed.

To test the thermoswitch it's easiest to take the plug off and bridge the contacts, then turn the ignition on to see if the fans start. Bridge red to red/white for low speed and red to red/black for high speed. If the fans work when you bridge those contacts then the thermoswitch is at fault.

 

[DJ-LIAMC]

Yes thermoswitch! thats what ive ordered, yea i did that bridged the connections there is three wires attached to plug Yea? when i bridged them, both fans came on full speed.

 

[Muttley]

Pretty conclusive then, the thermoswitch has failed. The three wires are power, low-speed fans and high-speed fans: the thermoswitch contains two separate devices, one switches on at about 90°C and off at 85°, the other goes on at about 100°C and off at 95° or so. Bridging power to just one of the two should get the fans on at low speed. Worth a check, to make sure your low speed fans are working.

 

[DJ-LIAMC]

ok will try the low speed thanks, but whats the problem if the low speed dont work?

 

[LEE69]

ok will try the low speed thanks, but whats the problem if the low speed dont work?

Under where the battery sits is a control module for the fans, these can fail and do.

 

[Muttley]

Fan control module can fail, but the one that get's mentioned in the forums most often is a failure of the fans themselves.

The resistor that is needed for the low speed setting is part of the fan motor assembly, and it burns out, rendering the fans only capable of full speed. This leads to the coolant getting much hotter before the fans cut in, and when they do its full speed, so the cooling is faster - the fans cycle on and off frequently, causing the fan motors to burn out eventually.