HELP WITH COOLING SYSTEM

[Dino D]

It seems I've now joined this illustrious gathering of Zeds that only throw out heat when being driven properly
I had the coolant changed over a year ago and don't think I had any issues with heating (didn't really need it) until this month. I also did the viscous fan delete around 9 months ago and never had any issues with overheating and still don't but can only get heat in when I raise the revs so it looks like I'll be trying the above solutions!
Where is the best place to flush the system from?
Cheers

You northerners are really tough: only needing the heater at the end of Jan when the snow comes!
I’ve had my heater in use since those chilly September evenings, gets cold in Kent I tell you!

Sorry to hear you got this weird issue, at least you not alone, hope you get it sorted soon!

 

[Stevo7682]

Take the pipes off at the back of the engine bay and flush through there. I haven't got round to doing it yet!

Martin if you are planning to flush the matrix here is my word of warning.
Take care wgen i did lynne's the 1st time when it was still pretty blocked water from the hose sprayed back out a bit water all over back engine bay and gearbox ( nothing wrong with that i here you say there waterproof ) And yes you'd be right that wasn't the problem.
At this point in proceedings i was still chasing roof repairs and leaks so the interior carpets etc out .
After my hose efforts hadn't really got anywhere i went in for a cuppa to muse over the problem came back out with the decision to attempt matrix removal.
I had opened tge passengers door and had a look a matrix decided wanted a look closer grabbed a torch knelt down stuck my head in under dash put my elbow down in the front floor straight into a large puddle of clear water took a few minutes to click what had happened. Turns out the seal at the bulkhead the matrix pipes go through aint particularly waterproof at close range glad the carpets weren't in at the time so be careful if you plan to do this .
Stephen.

 

[Mnbrennan]

Martin if you are planning to flush the matrix here is my word of warning.
Take care wgen i did lynne's the 1st time when it was still pretty blocked water from the hose sprayed back out a bit water all over back engine bay and gearbox ( nothing wrong with that i here you say there waterproof ) And yes you'd be right that wasn't the problem.
At this point in proceedings i was still chasing roof repairs and leaks so the interior carpets etc out .
After my hose efforts hadn't really got anywhere i went in for a cuppa to muse over the problem came back out with the decision to attempt matrix removal.
I had opened tge passengers door and had a look a matrix decided wanted a look closer grabbed a torch knelt down stuck my head in under dash put my elbow down in the front floor straight into a large puddle of clear water took a few minutes to click what had happened. Turns out the seal at the bulkhead the matrix pipes go through aint particularly waterproof at close range glad the carpets weren't in at the time so be careful if you plan to do this .
Stephen.

Thanks for the warning mate!

Does anyone know what these matrices are made of?

I'm quite tempted just to replace it when I get the dash out

 

[Stevo7682]

Aluminium same as radiator

 

[Mnbrennan]

At least it won't corrode then, so worth flushing and cleaning out

 

[Wilko58]

Just to summarise the above:

• Add Rad Flush (or similar) to cooling system first and allow time to work.
• Flush heater matrix out via the heater pipes being careful not to flood the interior!
• Refill entire cooling system with nose up, heater open, engine NOT running, radiator hoses (?) and put radiator cap back on.
• Run engine, massage radiator pipes, open bleed valve and close when no more escapes.
• Top up cooling system and check and repeat bleeding if necessary?

Please feel free to amend any of the above!

I was told to fill cold by a BMW specialist garage owner (motorsport & performance orientated).

 

[Wilko58]

So, I nipped into my local independent BMW garage and he took the coolant header tank cap off told me to run the engine with heater on and it turns out the coolant level was low and while the engine was running loads of air started bubbling into the header tank until it started filling up with water (at which point the cap was put back on!).
I've got to fill it with coolant and re-bleed as soon as it stops b****y raining!

 

[Wilko58]

It seems I might have had an air block for quite some time - the coolant was replaced at a service last year and I've not noticed any leak or overheating yet it needed 2 litres of antifreeze/water to top up the system! All seams fine now so no need to flush the heater matrix or indeed do anything else (I hope)!

 

[Mnbrennan]

How did you get the final bit out?

 

[Wilko58]

By accident I guess! I took it to the garage who changed the coolant and he took the reservoir cap off and said start it up (then he disappeared to his office) so I'm stood there and think to myself "I know, I'll turn the heater on full!"
Literally two minutes later there are loads of bubbles appearing in the reservoir tank and the float starts rising quickly so I put the capback on.
I drove home, parked it up (it's slightly nose up) and a few days (weather was c**p) later I top it up (heater dial on hot) and it takes 2 litres of fluid to get to max.
Seems to be running okay at the moment.

 

[topnotchrally]

After reading the horrors here I was freaking out about refilling my coolant after changing the water pump. However, I had no troubles, here's what I did...

1999 Z3 2.8l manual

I did not remove the block drain plug, so not a full drain, I guess. I drained the rad by the drain plug and removed/replaced the waterpump (much water came out).

I turned the heater on FULL.
I opened the bleed screw on the expansion tank and left the cap on loose.
I removed the top rad hose and filled the rad, then filled the engine through the hose until it started pouring out the rad. This took about 6 litres.
Reconnected the top rad hose.
I filled the expansion thank slowly until it was just over full according to the floaty stick thing. This took about 1/2 litre.
I put the cap on tight and started the engine.
Water immediately starting coming out of the bleed screw. I let it leak for about 30 seconds then tightened the screw.

I left it idling (outside temp 20degC). Within 5 minutes there was plenty of heat inside the car. I left it idling for another 10 minutes the thermstat didn't open (bottom rad hose still cold). I drove at 100km/hr for 5 minutes, heat on full. Bottom hose still cold.

I turned the head off (duh) and drove 5 minutes. Bottom hose warm, all is well!

When it had cooled down (4 hours later) I checked the level and it was perfect.

Yeah...lucky me?

I hope this helps someone.