Full coolant change & stat

[00mike00]

Hi guys,
Thought I’d best do a flush of the coolant system and refill as and when I get the parts.
As the top rad hose has gone, as a precautionary I’m replacing the thermostat to. I’ve done coolant changes and stats before but not on the Rocco.

It looks like an easy job but is there some things I should keep in mind whilst doing the job? What Is the best way to avoid air locks once refilled?
I’m going to pick up the thermostat tonight and remove the pipe I need to, while I wait for the new one to arrive.

Car is a 1988, 1.8 injection GTX

Cheers

[mark1gls]

When filling up the coolant I unplug the top hose at the radiator end so you can pour coolant straight into the engine, hold up the hose and slowly fill till it's near the top then quickly pop it back on the radiator.
Make sure the heater is set to hot and slowly pour coolant into the expansion tank till it's up to the max, leave the cap off and start the car, squeeze the hoses to get the coolant moving around and top up if needed after a couple of minutes you should start to get a flow of water into the expansion tank from the thin hose (going to the the top of the radiator) if you rev the car the flow should increase. If this is happening refit the cap and let the car warm up, check the heater in the car is blowing hot air and check for any leak, wait for the fan to kick in then switch the engine off.
Leave for a few hours to cool then check the coolant level.
Job done.

[james butler]

be very careful of the 2 bolts holding the elbow onto the thermostat housing as these are quite often seized.
if you shear the bolt you will need to budget for a water pump with new housing too.
don't forget a new ring for thermostat housing as I've picked up genuine vw thermostats that didn't come with one.
when I've refilled mine back up I've just filled the expansion tank up and then turn the car on topping up as it warms up.
the system is supposed to be self bleeding but theres no harm in doing it mark1gls way.

[00mike00]

When filling up the coolant I unplug the top hose at the radiator end so you can pour coolant straight into the engine, hold up the hose and slowly fill till it's near the top then quickly pop it back on the radiator.
Make sure the heater is set to hot and slowly pour coolant into the expansion tank till it's up to the max, leave the cap off and start the car, squeeze the hoses to get the coolant moving around and top up if needed after a couple of minutes you should start to get a flow of water into the expansion tank from the thin hose (going to the the top of the radiator) if you rev the car the flow should increase. If this is happening refit the cap and let the car warm up, check the heater in the car is blowing hot air and check for any leak, wait for the fan to kick in then switch the engine off.
Leave for a few hours to cool then check the coolant level.
Job done.

Thanks Mark, this sounds pretty much as I had imagined it.
The last section I haven’t flushed is the heater matrix itself, I tried to remove the hose from the engine to stick the spray gun down but managed to break the centre HT lead in the process. It was very brittle so it seems!
Unless there is an easier way to do this, I think I’ll just finish the job as pre your post. m

[Jerry Atric]

Forgive me jumping in your post 00mike00 , but hoping that Mark may have some advice for me regarding re-filling a "system " .

I re-filled via the expansion tank and have found some problems with the cooling system, namely it gets too hot and the cooling fan is not cutting in. It would seem to be that water is not circulating through the thermostat. Thinking it was stuck closed, have replaced it with a second one ( but first checking the operation of both of them in hot/boiling water and they both opened ok )
However, the problem still seems to be the same with the second thermostat now fitted. The radiator is new and gets very hot,as does the top hose, but it takes forever for water to start passing through the bottom hose and because of this , hot water is NOT reaching the cooling fan sensor and so no electric fan kicking in.

I'm suspecting an air lock, has anyone else encountered the problem and if so is the best way to overcome the problem to use Marks way of replenishing the cooling system? I know on some of the old Audis I had, there was an air bleed screw on one of the top hoses, but the Scirocco has no such refinement.

Any advice gratefully received.

[scrappy1382]

turn your heater dial to hot inside the car, with expansion cap off, squeeze quite a few times the rad hoses untill they 'feel' like they are all full, then start the car and repeat the process, then after a few mins put bottle cap on and see what happens.

[Jerry Atric]

Thanks for all the ideas above, but yesterday whilst driving , was suddenly aware of water dripping around my feet, closely followed by the flashing red light on the water temp gauge signifying low water level. Luckily was only half a mile from home so limped the car back gently and found still about a third of the reservoir full of coolant. So obviously a problem with the heater matrix or its pipe connections. However, as the cars radiator was virtually crumbling to pieces, don't hold out too much hope for the heater matrix.
Now I need to get this damned car through an MOT soon so it needs to be running and useable; have looped the hose connection under the bonnet for the heater and also removed the thermostat. Now the hoses all heat up at the same rate, the fan cuts in as required and on cue, and this will have to do for the time being.


Later, I may investigate the heater matrix , but a quick glance at Haynes Manual seems to indicate its not the quickest of jobs for sure to replace the matrix, assuming they are still available.

The speedometer needle still flicks around and thats because someone in the past has bodged a bulkhead repair and covered over the hole that the speedo cable and rubber bung should fit in . This means with the flexing of the clutch cable, the speedo cable also moves causing the needle to flick. BU**ER ! Then there is all the water that has dribbled out over the past few weeks and saturated the carpets underneath, not to mention a recent discovery of a rear tyre which is starting to perish. Plenty more , but that s enough for one miserable post!

I just wonder what the car has in store for me next as its a never ending saga of things that are going wrong . REMEMBER! No more barn finds !!