16v Thermostat replacement tips

[mk3valver]

Hi people, I've been told by a mechanic friend that my thermostat needs replacing as the cars running a bit lumpy until its very hot and my temp gauge is staying in the white (under 70). I've also noticed now that my fans not kicking in like it used too (or at all). It used to come on whilst driving but also, it would sometimes come on after I'd turned the car off and stay on for 10-15 minutes. Now my engine code is ABF and Ive bought a thermostat,  now the guy in the parts place told me that there were 2 different types of thermostat on the 16v and mine is the more difficult of the 2 to replace (I've got to get under it apparently ?). What I was wondering was, has anyone done this before? And if so can you please give me any tips on how to do it myself as my mates in dubai for 3 weeks and I'm doing a few hundred miles this weekend so want to make sure the cooling systems working properly.

     Thank's in advance, Matt   

[Paul86S2]

Your thermostat should be in the base of the coolant pump.

Drain the coolant, you will then probably need to remove the power steering belt and undo the power steering pump and move it out of the way. No need to disconnect the power steering fluid lines. Remove the hose from the thermostat elbow / cover. Remove the elbow / cover (2 bolts) and then remove and replace the thermostat (should just pull out). Clean up and refit using a new seal and I personally would use new hose clips.

Refill the system using the recommended amount and type of anti freeze, run the engine with the coolant tank cap off until it starts to boil. Squeeze the pipes and keep it topped up as you do this. Then turn off check the level and replace the cap.

I would then run it up to temp again and make sure the fan cuts in at the right temp.

Job done.

Paul

[Len]

Crikey!

Hope I never have to change it on mine then! 

[Paul86S2]

Sounds worse than it is! Most frustrating bit is getting all the air out of the coolant system.

Paul

[Len]

Yea, that was always a pain on my Pug!

[mk3valver]

Cheer's paul! I have just been out and and ran the car til its hot and the water is near boiling, the pipes at the top of the rad are hot and the pipe at the bottom are stone cold, does that and the fact the fans not kicking in at all sound like the thermostat? Im sorry, just wanna be 100% sure it is before I get down to business!

[Len]

Sounds right to me!

Could be a relay for the fan.

[Paul86S2]

Yes if the bottom pipe is staying cold then it sounds like the thermostat isn't opening up. It should stay cold until the thermostat opens and then get very hot quickly.
The new thermostat should fix the problem.
You can test the old thermostat when its out by boiling it in some water, you should see it open when the water gets to the right temp.

The fans won't be kicking in because the fan sensor is in the rad and the hot water won't be circulating past it. Whilst the system is drained it may be worth fitting a new fan sensor to the rad (they're preety cheap) just to make sure. The top hose will be getting hot because it will draw heat out of the head flange but the heat won't go far enough back to activate the fans.

If it isn't the thermostat then it will be the water pump itself - but thats another scenario.

Change the thermostat.

Paul

[justalex81]

i found that disconnecting the pipe from the top of the bottle that connects to the top hose on the rad helps to vent any air locks when filling the system back up. disconnect it and keep it up high.

[mk3valver]

Thank's guy's! Has anyone done this on the floor (without jacks)? And can anyone tell me how to drain the system before I start?