Thermostat??? Heater bypass??? Matrix???

[weazgti]

check rj s guide in mk2 maitenance.

[HuwMk2]

First part successfully done. I've replaced the expansion tank cap with the new blue version from VW.

The car is still extremely slow getting up to temp, so guaranteed thermostat issue. However, its a little warmer than its been!

Hopefully have my new thermostat and housing fitted on Saturday morning.

[Dolly]

stick a hose pipe down the pipes going in and out the matrix, will clear some crap out. probably a tempory fix though, will eventually need a new matrix i reckon.

[gavL]

This is random but my heaters where suffering from very similar, bled the system out as you should (as said in the guide) ran through it all with no hope.

So thought maybe I had a small blockage in the matrix, waited for the car to reach tempature and then gave it a few blasts up to around 6k and somehow the heaters now work fine. Don't take that as advice.

[rubjonny]

yeah if you bleed the system you do need to give it some revs now & again to get the air out, sometimes it takes a proper blast on t motorway to get heaters fully going

[gavL]

It has jonnys stamp do take it as some advice

[muttley]

I had exactly the same problem as described on my '91 8v, finally spent some time on it last week.

I'd replaced the bypass valves last year, just put a new expansion tank cap on from VW. New water pump and thermostat in September '09

Tried bleeding the system and no difference.

Then connected the matrix inlet pipe up to the outlet side to back flush it and ran the car while lots of very dirty water came out the open inlet side, when it ran clean coolant I connected it back up again, topped up the expansion tank and started to bleed it. Still no hot air.

Then I ran the engine up to 3500 rpm for about 5 mins, quick bleed and now it's spot on, it really needs to be under some pressure to push it all round. Having to run it with the slider more on the cold side otherwise it's too hot. Keep persevering, it's worth it. I know I may need a new matrix in time if the sludge has damaged it but for now it's water tight.

Good luck.

[HuwMk2]

An update:

As mentioned in a previous post, new blue genuine VW expansion cap fitted.

New thermostat and housing fitted and blasted a pressure washer through the heater matrix. Car is so much hotter!!! Success!!! However, I'm sure over the next few days it will get even hotter when some of the air is released. Roll on!