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1. muddodger - Member

   Afternoon all... hopefully someone can answer a couple of questions regarding issues with my wife's '98 VW golf GTI turbo.

   Had the thermostat changed about 2 months ago as the temp gauge never actually reached 90, once replace all seemed ok with gauge. Unfortunately in my rush to buy the part it was a cheap part not VW and what I've now noticed is that the hose from the thermostat housing or the radiator isn't getting hot, only warm, and the fans don't come on.

   So my questions are... does the water flow through the thermostat away from the engine toward the radiator .... or from the radiator to the thermostat....and could a faulty thermostat cause a cool water pipe?

   Would this in turn cause the fans not to come on? ... logic says this is the case.

   another small issue is that when driving, if you back of the accelerator pedal and then accelerate sometimes the car will 'jolt' slightly, (like a slight misfire) not a prolonged misfire, could this be down to the throttle body needs cleaning? it's a low mileage car for its age so I'm wondering if this has a effect on things clogging up.

   Sorry for lack of detail, unfortunately I'm no mechanic!

   Posted 10 months ago #
2. Junkyard - Member

   the thermostat traps the water in the engine so that t can heat up to warm the engine faster once a set temp is reached it opens to allwo water to flow.
   Warm water passes it then cool reaches it it closes and the cycle repeats till it stays open once up to temp it is open.
   It flows from the engine to the radiator from the highest tube out of your engine in to the top of your radiator. [ heat rises so it draws cooler water from the bottom.
   iirc they are designed to break open rather than be fixed close.
   What does the temp gauge say when operating?

   My first thought is to check the system is full of water. You may have a bleed port somewhere to do this if you have pipes above the header or engine.
   You will also have a thermostatic switch for the fan this may be broken or faulty. The tubes should get warm ish but they may be well insulated so that 70degrees does not feel all that warm. It will if you have been running the engine for a hour or so.
   HTH

   Posted 10 months ago #
3. beanieripper - Member

   water flows from the block/therm housing into the top of the rad when the therm opens... sounds like a poss water pump prob youve got...is your heater hot?

   Posted 10 months ago #
4. Junkyard - Member

   aye thats a good point but it will be overheating as well if this is the case- that is overheating in the engine not the radiator as the water supply will not be moving.

   Posted 10 months ago #
5. mc - Member

   Any cooling system issues on these is most likely down to the water pump. The impellers split and become slack on the shaft.

   Depending on the engine, sometimes you can take the thermostat out, stick your finger in the thermostat hole and see if you can move the impeller.

   However, they normally overheat if that is the problem.

   Posted 10 months ago #
6. muddodger - Member

   Gauge reads 90 when running, if engine is switched off and restarted reasonably soon, the needle can be 110ish...
   no other sign of overheating other than once in traffic temp got to 120, this dropped as soon as got moving though

   I'll look into getting water pump sorted, and new thermostat

   Posted 10 months ago #
7. beanieripper - Member

   sounds like wp...the impellors disintegrate gradually...

   Posted 10 months ago #
8. muddodger - Member

   Thanks for all your replies, I'll probably have to take it somewhere to check, but at least I'll sound as if I have some idea of what's wrong!

   Thanks again, Rob

   Posted 10 months ago #
9. BigJohn - Member

   A lot of old golfs have a problem with stuttery throttles (Mrs BJ's used to stutter when she was turning right across traffic into our drive). Cured by cleaning out the injectors.

   Thermostats can stick in the open position.

   Posted 10 months ago #

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