Smurf's cooling system....

Mnbrennan

Mnbrennan

Zorg Guru (IV)
British Zeds
M Power
#ZedShed
Joined
Jul 25, 2015
Points
153
Location
Aylesbury
Model of Z
BMW M Coupe / 2.8 roadster
So I'm stuck.

When I bought the car it was running a bit cool (just over the blue bit on the gauge), the heat in the cabin was continuous just not burning hot, as the car wasn't getting up to temp. so thought I'd replace the thermostat.

I'm struggling with getting the coolant circulating properly. When idling there is no warm air through the vents. When out on a run the temp climbs to around three quarters, then heat comes through the vents. The gauge drops to the middle, the vents go cool. The temp rises on the gauge to three quarters, I get hot air through the vents, the gauge drops to the middle and the vents go cold. So the cycle repeats.

I've tried filling through the expansion cap, tried filling through the top hose (with the heat turned and fan on one) . Massaged the hoses for ages, ran the car with the bleed screw open, the expansion bottle and both together.

I'm at the end of my tether!
 
Any water pump history Martin. We have had cars in at work where the impeller has split and spins on the shaft when under pressure to pump quick but does enough to circulate coolant.

Tony.
 
t-tony said:
Any water pump history Martin. We have had cars in at work where the impeller has split and spins on the shaft when under pressure to pump quick but does enough to circulate coolant.

Tony.
Click to expand...
It was checked under 15k miles ago and was as new apparently so wasn't replaced. I have taken the Viscous clutch off a number of times over the last couple of weeks, could it have been damaged?
 
I should also mention that the hose into the heater control valve is hot, and the hose coming out of the bulkhead into the block isn't. I can hear slushing when squeezing the heater hoses
 
Mnbrennan said:
It was checked under 15k miles ago and was as new apparently so wasn't replaced. I have taken the Viscous clutch off a number of times over the last couple of weeks, could it have been damaged?
Click to expand...

I wouldn't trust that, I've had a new metal impeller pump fail in around 20k miles quite suddenly...(the impeller was just spinning on the shaft - temp would drop if the engine was at high revs and overheat at low, lucky I was on a motorway so could keep revs up).

The viscous can have weakened in its operation- it has to be stored the right way up or something happens with the oil.
Do you have an aircon?
If you do and the aircon fan is working you can run without the viscous and rule that out completely.
 
Dino D said:
I wouldn't trust that, I've had a new metal impeller pump fail in around 20k miles quite suddenly...(the impeller was just spinning on the shaft - temp would drop if the engine was at high revs and overheat at low, lucky I was on a motorway so could keep revs up).

The viscous can have weakened in its operation- it has to be stored the right way up or something happens with the oil.
Do you have an aircon?
If you do and the aircon fan is working you can run without the viscous and rule that out completely.
Click to expand...

Thanks Dino I might just change to be safe. I don't have aircon so that's not an option for me without reengineering.

5harp3y said:
If both heater pipes aren't hot... Blocked heater?
Click to expand...

Could be, I was always thinking it could be the heater control valve?
 
Dino D said:
I wouldn't trust that, I've had a new metal impeller pump fail in around 20k miles quite suddenly...(the impeller was just spinning on the shaft - temp would drop if the engine was at high revs and overheat at low, lucky I was on a motorway so could keep revs up).

The viscous can have weakened in its operation- it has to be stored the right way up or something happens with the oil.
Do you have an aircon?
If you do and the aircon fan is working you can run without the viscous and rule that out completely.
Click to expand...
I also replaced the Viscous clutch as it sounded like a hoover before!
 
It's strange that I has constant heat before changing the t stay too. That would put me off thinking the heater control valve, but I could understand if the water pump was damaged during (multiple) removal
 
This morning I again tried filling through the top rad hose while squeezing pipes to try and release air.

I took it for a run, and the air started to heat up as the car warmed! And it continued to rise!

The good news is that it remained hot and the gauge stayed in the centre. The vents cool down a little when slowing down, but the gauge remains rock solid.

Must have been an airlock I suppose. So if your struggling with the cooling system try and fill through the top hose and squeeze the pipes

So happy!
 
That's more or less what I did except I didn't refill through the top hose. I just persevered with massaging the top hose. It took ages to sort but it's been good for the last couple of years.
I'm due to change the cooling fluid for next winter so I'm going to be prepared this time.

Glad you're sorted :thumbsup:
 
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