coolant boiling up 1990golf 16v And Water pump replacement advice

[Garrydohc]

My Heating in my golf 16v blows hot for a few seconds and then goes cold almost immediatley.  I am loosing coolant from the expansion tank in the engine bay; the water seems to boil up in the expansion bottle and come out the overflow holes at the top of the bottle (you can hear it and see it do it.) after driving 3 miles or more  the expansion tank warning light comes on.  The oil temp is hotter than it used to be but the car dosent seem to be overheating. although I havent wanted to risk driving it more than 4 or 5 miles!  I have changed the thermostat and flushed the coolant sytem though.  The radiator is clear and water runs though it ok and water runs though the engine ok too.  I took off the heater matrix bypass things and cleaned them too and water  seems to be running though them ok too.  I have now purchsed a water pump and heater matrix but need some advice on how to replace the water pump.  Does the timing belt run off the pump or is it just driven by the power steering or alternator belts.  Has anyone else had the problems I have described above.  The car does seem to make a slight whining noise when accelarating now but otherwise runs great.  Any advice appreciated!!

[monzablue16v]

Have you changed the thermostat?

[Garrydohc]

Hello. I replaced the termostat with another one last week. And before that flushed water through the radiator and the engine and it went though ok.  I did think the headgasket first but there is no water in the oil, or oil in the expansion tank.  My local garage done a compression test on the engine and that came back with good results.  My heating does not work in my car though. Iam going to try and replace the water pump tommorow and after that ive ran out of ideas

[pegasus]

replace your expansion tank cap 1st with a new one from VW.. if its boiling over you might find that the seal in the cap has perished and wont allow the water system to pressurise.

If this fails, then try the W/Pump, its certainly alot easier to change than the matrix!!

[monzablue16v]

Hmm could be the expansion cap leaking it's pressure that stops the water from boiling so if the cap has gone then no pressure builds up and it boils, might be worth a new expansion cap from VW get a genuine one as I have seen a coupleof duff pattern part ones.

[DarnPB]

Silly suggestion, but you may have trapped air in the system. Try removing the temp sensor and bleeding the system first.

[gixerthrasher]

Heyy Garry, I've just replaced the complete cooling system on my '90 16v as it was doing the exact same thing.. so I left it & my heater matrix blew up, stuck in town traffic! There are some valuable tips for fitting a matrix on the Maintenance Info pages on this forum, but it sounds like your water pump's going mate, an easy job once you've moved your alternator away, Use decent long handled pliers to get the B'STD VW hose clips off leaving just 4 bolts holding it to the engine block & she's away. Also check the state of the metal coolant pipe that runs behind the oil cooler & around the right of your engine.. Mine had rotted with rust inside that restricted the flow..£30 from VW dealer..
I have removed the by pass valve on mine as it too was furry inside, many have suggested it's fine to do and will definitely help in pumping hot juice to your matrix.. And definitely a new expansion bottle cap to screw on once you've bled your system proper like..
Good luck Dude, you know it's worth it??

[grace_golf91]

We've spent the best part of a year battling with my mk 2's overheating problems. This weekend the thermostat was changed and it seems to be better, but still not right. Overheating when moving and fine when running stationery. We're going to try a new expansion cap, as suggested here but does anyone know the best way of bleeding the system as we are also convinced there is air trapped somewhere?

[monzablue16v]

Start the engine with the cap off and turn heaters onto full hot and number 3, run with cap off until radiator fan comes on topping up as needed then replace the cap and it will be bled.

[rubjonny]

dont need to set the heaters to hot in a MK2
Check the how2 section for my post on how to check & bleed the coolant system
Check that the small hose to the top of the header tank spits out water when you rev the engine, if this is blocked the system will never self-bleed!