Water

[Gremlin]

can any one tell me that has a 1.9 Z3 after you have been for a run and car is up to normal working temperature dose the hose from bottom of radiator to thermostat still feel cold and the one from the engine back to top of radiator feel to hot to hold. My reason for asking is my hoses are like this I had to call RAC out yesterday as I had a water problem he felt theses pipes and said they should be same temperature and felt it was thermostat not opening causing a circulatory problem.
Ok I thought I know I replaced this along with water pump just over a year ago when I got the car but things can pack up so I drained the whole system down replaced with another new thermostat ( I did test the one that came out which worked ) I’ve flushed every pipe through blocking off various pipes to make sure all have water circulating I’ve taken out and checked pump that is ok looks as good as when I fitted it a year ago. I flushed the heater out and have checked that the heater valve operates properly while off that’s ok. I’ve flushed the radiator through and back flushed it.
I have now refilled with water and anti-freeze bleed the system while doing it left car running until up to temperature heater works great so I know there’s no air lock there but this bottom radiator hose is still cold. Problem I have is I don’t know if it’s always been like this as I’ve never really had cause until now to feel them as all has been ok.
So just nip out and have a feel please and let me know.

 

[Mnbrennan]

It could be that the radiator is blocked. When the car is up to temp and the thermostat opens that pipe should be hot

 

[Gremlin]

It could be that the radiator is blocked. When the car is up to temp and the thermostat opens that pipe should be hot

Not sure on that as I have had the radiator off as well and had hose pipe running through it on top to bottom and bottom to top and through the pipe to expansion bottle all seems to run ok. But I suppose the core could be blocked I’ve no way to tell that though. Thanks any way worth a look.

 

[t-tony]

Have you got a laser thermometer to actually measure the temp on both hoses? Also at various points round the system


Tony.

 

[Gremlin]

Have you got a laser thermometer to actually measure the temp on both hoses? Also at various points round the system


Tony.

No not got one of those, I’m almost certain that it is these after market thermostats I got from euro car parts I don’t think they are opening at correct temp it says on there it should open at 95 but the one I’ve got in now dose not open until it’s been in boiling water for 3 to 4 mins I’m sure that can’t be right. The one that came out is the same.

 

[g8jka]

The thermostat has just been changed on mine and everything seems to be working as normal but I also have the same situation with the bottom hose being cold and the top being hot. @gookah ran his round yesterday to find out if it was normal and his was the same, bottom cold and top hot and all is running as it should. Both of ours are 2.8's. Never noticed this before so don't know if its normal or not?!

 

[t-tony]

That's why I asked about checking the hose temps. the bottom hose should be cooler as the radiator does it's job. It won't be cold as such but cooler than the top hose which is feeding the coolant straight out of the engine.
Those laser thermometers are dirt cheap on eBay these days. Very useful for checking brake temps etching.

Tony.

 

[Gremlin]

That's why I asked about checking the hose temps. the bottom hose should be cooler as the radiator does it's job. It won't be cold as such but cooler than the top hose which is feeding the coolant straight out of the engine.
Those laser thermometers are dirt cheap on eBay these days. Very useful for checking brake temps etching.

Tony.

Thanks all I’d expect some difference especially at this time of year but it was the RAC guy that wrong footed me.I think the problem I had was an air lock after topping up anti-freeze and it blew the water out lucky I was watching temp gauge and pulled over. Boy was that cold yesterday at 5am in the morning waiting for him he was there with in an hour but I was nearly in hypothermia when he got there lol.

 

[Stevo7682]

Is the car actually getting up to temp properly.
If anything in the bottom hose / radiator was blocked the car would overheat .
I reckon that you take it out a 15 / 20 min run bring back then leave it stationary and run at fast idle .
One of 2 things will happen either the car will get up to proper temp ( remember winter cold outside) and the bottom hose and radiator will heat up then if continued to heat viscous fan will lock to cool engine
Or there is a problem and it will start overheating then turn off and look into it

 

[Gremlin]

Is the car actually getting up to temp properly.
If anything in the bottom hose / radiator was blocked the car would overheat .
I reckon that you take it out a 15 / 20 min run bring back then leave it stationary and run at fast idle .
One of 2 things will happen either the car will get up to proper temp ( remember winter cold outside) and the bottom hose and radiator will heat up then if continued to heat viscous fan will lock to cool engine
Or there is a problem and it will start overheating then turn off and look into it

I fitted last year new pump new thermostat new plastic fan and hub all new hoses put on a good second hand but I tested it heater control valve. It was completely flushed out engine heater matrix and radiator and fan belt and refilled with anti freeze coolant. It has been fine until yesterday when it chucked out all its water. Today as I said I’ve pulled every thing off and gone through it. The pump is good I changed thermostat just in case flushed whole system out and checked all hoses had water flushing out nice and clean. Sat it on idle until it got to normal working temp took it for a run around came back left it to idle while I put tools away. That bottom hose was all most cold not freezing but cold. I left it then to cool down went out and checked water it was where I’d put it on the level half way up expansion bottle.
Tomorrow I’m putting a new radiator in as it’s the original one at moment and could be bunged up in the core, which won’t be good when weather dose warm up. But as I say it’s that bottom hose being cold that’s bugging me. Ah just one more thing I’ve got a new pressure cap for it from BMW because the one on there looks suspiciously like it’s not venting.

 

[Gremlin]

At last have gotten to the bottom of a long standing problem changed the radiator today and boy what a difference it’s made top hose hot bottom hose just a little cooler not cold like before, got a great heater in the car and the car comes up to temperature as it should I can now watch the gauge and see when the thermostat opens. So thanks to every one for suggestions and advice.

 

[t-tony]

Great news mate.

Tony.

 

[petecossie]

You got there in the end, must have been very frustrating with changing the smaller items and then biting the bullet to install new radiator.
It seems that the unblocked cores on the old radiator allowed sufficient water through to give impression that it was OK.
Thinking about it I suppose one of those infra red thermometers would have perhaps pinpointed the blocked cores on the radiator when the engine was running.
Great result though, well done.