Cooling issues

Seatboy

Active Member
Oct 7, 2017
69
0
So I've had this issue a while
Started by doing the fan resistor mod
Changed green sensor
Changed rad sensor
Now changed thermostat but old one worked but waiting on flange to test but like I said old one opened

Other day plastic flange broke coming from rad blew broke spewing hot coolant everywhere
Drained coolant and coolant from rad at start was cold I'm at a loss to what it could be
Fans won't work on there own but 100% work tested them and they come on when tested and a.c. is turned on
I don't no if this plastic flange braking id's related or is just a one off
 
Last edited:

BadBoy03

A Mk1 Is For Life, Not Just For Fun
Sep 6, 2016
583
290
Somerset
Any chance you can get the car scanned? Would clarify the actual temp and probably alert you to any specific fault. I would have thought your thermostat was sticking, but you've replaced it so can't be that. A water pump failing would cause a rise in temp. My temp guage has given up & yet when scanned all working fine so points to the cluster itself. Sorry I can't offer any technical help, I know it's a pain in the arse & a worry. Good luck. :confused:
 

Jonnyaye

Active Member
Nov 14, 2017
27
0
Belfast
The flange which houses the thermostat going to the block? Did you try a genuine thermostat to see if that helped? Also, is there heat going into the cabin when the car has got to operating temperature? Its strange how its stuck around 100c!
Mine would have jumped to 110-120 and sometimes moved down to 60c and stayed there but after i had changed the thermostat and completely flushed the coolant system it helped enormously!

compression test looks ok also? Theres not much difference across all the cylinders.
 

Seatboy

Active Member
Oct 7, 2017
69
0
Right new thermostat in no difference
Got upto 100 c no fans comming on no heat from heaters just cold
 

Gaz20VT

Active Member
Aug 5, 2011
122
15
With the old thermostat out, have you tried flushing the system through with a hose? Sounds like you either have no water circulation, due to a water pump issue or a blockage somewhere in the system. Could a piece of your plastic flange have gotten into the cooling system, or did you manage to get all of the pieces together like a jigsaw to check?

You haven't said what engine you have, but I'm not aware of any particular bleed procedure on the petrols. I'm sure someone much more knowledgeable about the TDIs could chime in if there's something to do on the Diesels.

Do you get coolant circulating through the small diameter vent hose that goes back to the top of the header tank with the engine running? (you can tell with the header tank cap off - just be careful if the car is overheating and it boils up!)
 
Last edited:

Seatboy

Active Member
Oct 7, 2017
69
0
No haven't flushed do you do that via thermostat hose?
Yes coolant dose come from the little hose but on idle only every now and the should it be a constant flow
It's amk 210 and no flange broke clean and stayed in the hose
 
Last edited:

Seatboy

Active Member
Oct 7, 2017
69
0
Right flushed bleed squeezing hoses and it's better temp wise not going much over 93
But even when I had cap off still no fans and it went to 99 d
Fans work when tested and come on with a.c.
This is a head scratcher I've done the resistor mod
 

Jonnyaye

Active Member
Nov 14, 2017
27
0
Belfast
They self bleed so as said above it would’ve been more likely to be a waterpump failure or blockage. When you flushed the system it would have cleared out any old gunk that was lingering around! With reference to the fans, they shouldn’t need to come on unless the engine is overheating? I’m not familiar with the resistor mod you are talking about mate.
 

Seatboy

Active Member
Oct 7, 2017
69
0
Can resistor mod you out separate ones in to replace the fans ones I thought the low speed fan comes on at 95 and high speed at 100 what I'm saying is I was over heating and they never came on
 

Gaz20VT

Active Member
Aug 5, 2011
122
15
The resistor mod is to fix the low speed fan issue. The internal resistors in the motors become disconnected from the wiring, making the slow speeds of both fans inoperative.

So Seatboy when you say "they work when tested" - how have you tested them? If you put the air conditioning onto "Lo" with the engine running, do both fans come on to slow speed and run CONSTANTLY?

If you've tested the fans by bridging the switch on the bottom of the radiator you've only tested the high speed side of the fans.
 

Seatboy

Active Member
Oct 7, 2017
69
0
Low speed come on with a.c. constant high speed and low speed come on by bridging the thermo plug
 

Gaz20VT

Active Member
Aug 5, 2011
122
15
OK, so it's narrowing down to a couple of things then.

Either, the water temperature is not hot enough to warrant fans coming on. OR the radiator temperature sensor is not getting hot enough to turn the fans on - this could be caused by the previously mentioned water pump issue.

I have just checked my car for flow of the water returning to the header tank - this is with the car started from cold - well, cold since I got to work at 8:00 this morning after a few miles' drive. There's a constant flow of coolant into the little tray inside the header tank.

The other option is if your radiator fan control module is playing up, but seeing as you can get the fans to come on by bridging connections at the rad switch I'd say it's unlikely.
Does your auxilliary water pump work, and stay on when the engine is switched off?
 
Last edited:

Seatboy

Active Member
Oct 7, 2017
69
0
Seconary water pump is new and working well
Water pump flow to header tank is good
 
Progressive Parts, performance parts and tuning specialists