Coolant... rather too hot

[Beddo88]

I have just returned home and had to stop mid journey as my temperature gauge was WAY over warm... like coming pretty dam close to the white line on the right. Car made the 90 mile journey to uni without a single problem.

Have recently sorted a few issues i had with her, and have been driving ehr a bit mroe aggresively, would this send water round the head etc more pwoerfully than at low revs? The reason i ask is i had a very calm cruise back today (sitting between 50/60.. to save petrol) and this was when the problem occured. Speeding up to 70 reduced the temp gauge but it was still reading higher than it should.

Could it be possible that gunge etc in the coolant system has been 'free'd' from the radiator etc could have caused a small blockage? What would happen if the water pump had gone? I am gong to flush through the radiator tmoz, i know it was in an interesting state when i got it, flushed 40 odd litres through it before and it was still coming out orange :S

Basically... any advice?!?!

[RoccoGTII]

Had the same problem a month or two now. Resolved the problem after doing the following jobs one by one to resolve until finally I bought a new rad.....

1. Flush the whole system and clean the radiator through with a hose from the top. Then took off the water bottle and cleaned it to get rid of rubbish at the bottom.. Check no leaks or block and water flowed around the system
2. Changed the thermostat (wasn’t opening and closing)
3. Changed the water pump (looked rusty)
4. Changed the radiator and check the wiring to ensure the fan came on at the right time.

Now the temp dial sits where it should in the middle.

Worth doing the who lot if you have the cash – runs much better and can sit in traffic for longer without worrying.

Good luck!

[Beddo88]

Lovely. I suspect the fan isnt helping as it doesnt ever seem to turn on... how can i check it?

And it was overheating whilst moving at speed so im guessing its either a blockage somewhere or the water pump (although it looks reasonable from the outside, which i suppose is no use to anyone )

shall try flushing the system through anyway srarting, as you say, with the radiator and water reserve.

[ianaudia4]

Your fan should kick in at about 92-93 degrees, let the run run and see if it comes on, if not change the sensor, it is located on the side of the radiator.

[jbo]

Check out awesomegti.com! I bought a low temp thermostat and a low temp thermoswitch for the rad. Including the postage it was about £30ish quid. It brings your temp down and makes the fan kick in sooner but not to the point of the engine running too cool.

The guy i bought my car from took the thermosat out!!!!

[scirocogtx]

Sounds like a radiator leak to me.
It may not be too obvious but if you start the car and have a look inside the expansion tank the jet of water that comes from the top of the radiator should be strong and not just a dribble. As you up the throttle the jet should get stronger. If it is just a slow trickle at idle/low revs I would say that there is a pressure leak ie your radiator is leaking/weeping or possibly one of the radiator hoses.
Have a look down the sides and the bottom of the radiator for any crystalised coolant. There may not be a lot but a small weep affects the pressure.

I may be wrong but that's what I would look for first.

[Nate]

i suspect your problem is down to a blockage in the cooling system. this could either be a build up of sludge or a sticking thermostat. it could also be that the water pump has failed.

run the car with some cooling system cleaner in it for a few days - personally i use biological washing powder, works really well and leaves your engine bay smelling fresh like a summer hillside - then flush the system through with a hose until the water runs clean. refill with water only at this point to see how well the system is now working.

change the thermostat. personally i wouldn't recommend fitting a lower temperature thermostat unless you are using the car for heavy towing (unlikely with a rocco) or for serious racing (normal driving with a heavy right boot don't count) Get either a stock 'stat from your local VW dealer or one from the likes of GSF or eurocarprats. don't forget to replace the rubber seal at the same time.

i would expect the problem to now be much improved. do this and report back. total cost so far will be under a tenner.

[Beddo88]

Have flushed the whole system through and just driven back to uni after a shorter test drive yestterday. Worked fine both times. Put water through both the radiator (which originally came out slightly orange) and the expansion tank had 3-4mm of gunge in it so removed that and cleaned it. Also flushed through the head as best i could, which also, surprise surprise, came out orange.

So hopefully now there is a lot less crap floating around it! I shall run some proper stuff through it when i get a chance, (final month of uni) and change the stat. The fan i dont think comes on early enough, or not at all. Havent had the patience to find out yet!

I have read that there is a gromit on the back of the head by the manifold that often cuases low pressure issues. This apparently had a few other side affects which affect the fueling and running o the car which i also get. So... will do that as well when i get a chance, which should hopefully solve my jittery cruising at low revs. (apparently)

PS. forgot to say, seems to have solved the coolant issues, all for the price of a few litres of water and an hour of my time. :)

[Nate]

would be well worth chucking some washing stuff in it (daz etc) and running it for a few days. it will get rid of loads more of the orange slime. when you've done tinkering with the cooling system, don't forget to add the correct antifreeze - it stops corrosion, which is what causes the orange slime

[Beddo88]

Ahh cool, well i've just replaced the rad thermo switch thing, and finally the radiator fan works :D So.. hopefully my problems should be sorted. Its been re-filled with anti-freeze for the moment, so it should keep it in a semi decent state until i can spend more time on her over summer. (intending on doing a few track days :D )

Cheers for all the help guys, great as ever!

PS, just picked up a new stat and gasket for her, so that'll be going in soon :)

God bless the almighty student loan!!

[DRobbo]

Got a similar problem atm, car is overheating in ten min from cold... Very frustrating!

Trying to source a new fan for it, but GSF only do the dual speed fans with three pin plugs. Does anyone know where I could get the correct two pin setup for less than the £150 VW charge?

Thank you!

[jbo]

Got a similar problem atm, car is overheating in ten min from cold... Very frustrating!

Trying to source a new fan for it, but GSF only do the dual speed fans with three pin plugs. Does anyone know where I could get the correct two pin setup for less than the £150 VW charge?

Thank you!

Just use a three pin fan but only two of the pins. My mate did the same. He just chopped off the connector and crimped on a couple of crimps. Ive got a coupld of spare fans for sale. Check out my for sale thread.

JAson

[Nate]

Got a similar problem atm, car is overheating in ten min from cold... Very frustrating!
Trying to source a new fan for it

if it is overheating within 10 minutes of starting from cold, then i'll stick money on the fan not being the problem. either you have a failed water pump or thermostat, or something more sinister.

does the rad get warm? can you see any movement of coolant in the header tank? you're probably gonna be needing a new stat and a coolant flush and change.

[DRobbo]

Got a similar problem atm, car is overheating in ten min from cold... Very frustrating!
Trying to source a new fan for it

if it is overheating within 10 minutes of starting from cold, then i'll stick money on the fan not being the problem. either you have a failed water pump or thermostat, or something more sinister.

does the rad get warm? can you see any movement of coolant in the header tank? you're probably gonna be needing a new stat and a coolant flush and change.

Seems to have been a bit of a carb issue... Cleaned the jets out as it was very blocked up, and the car hasn't overheated since. Perhaps running very weak up to this point may have been an issue? Either way it's stopped overheating now

[Beddo88]

I realise im digging up an old topic, but the problems come back again :( The fan still works, but the temp gauge seems to falter between vertical and the point at which the fan kicks in. Which is annoying.

Gunna flush the whole system through, then going to run some radiator cleaner through it tmoz, and er.. hope for the best!