Heater: 850: - Water problems

br850 · Sep 19th, 2009, 22:24

I have a very smart 850 20v 2.0 with 265000 miles on it.
Just recently it started getting very hot after only short journeys .
The radiator had been leaking some time ago and I put some sealer in to get me home but the rad was leaking again yesterday so I bit the bullet and replaced it. Prior to yesterday the temp gauge only climbed to half way up the scale even though the engine was very very hot. So... replaced the rad, very little water came out and took very little to fill it. Fired the car up and within 5 minutes the temp gauge went to the top of the scale. The hose from the thermostat was very hot but the bottom hose and nearside of the radiator were cold. Heater only blows lukewarm air even on hottest setting. Could it be the thermostat?

Chris_Rogers · Sep 20th, 2009, 09:58

Sound like you have a massive air lock in there, if the heater is not getting hot then it can't be the stat as the heater water bypasses the stat.

I'd suggest you try squeezing all the large hoses with the engine cold and the top up cap off to see if you can shift the air.

RSF · Sep 20th, 2009, 13:46

Quote:

Originally Posted by Chris_Rogers

Sound like you have a massive air lock in there, if the heater is not getting hot then it can't be the stat as the heater water bypasses the stat.

I'd suggest you try squeezing all the large hoses with the engine cold and the top up cap off to see if you can shift the air.

I would agree with that.
leave your water cap off,start engine and squeeze the water pipes.Mine still never went to the top of the heater guage so I'm guessing you have a faulty thermostat,probably locked open.

Is your fan kicking in?Ive had a switch to switch my fan on as the 850s relay is terrible.
Check if you fan comes on.

br850 · Sep 20th, 2009, 19:08

An airlock seems most probable cause. The fan is kicking in ok and stays on for a while like it should when I switch the engine off. I have been around all the hoses and tried squeezing them to move the air out of the system and overnight the level in the header tank dropped . The pipes in and out of the heater are getting warm now which they were not doing before.
Will persevere and will change the stat next weekend just to be sure.
What's this I have read about a green header tank cap being better?

Sep 19th, 2009, 22:24	#1
br850 Member Last Online: Yesterday 20:55 Join Date: Nov 2008 Location: Rotherham	Water problems I have a very smart 850 20v 2.0 with 265000 miles on it. Just recently it started getting very hot after only short journeys . The radiator had been leaking some time ago and I put some sealer in to get me home but the rad was leaking again yesterday so I bit the bullet and replaced it. Prior to yesterday the temp gauge only climbed to half way up the scale even though the engine was very very hot. So... replaced the rad, very little water came out and took very little to fill it. Fired the car up and within 5 minutes the temp gauge went to the top of the scale. The hose from the thermostat was very hot but the bottom hose and nearside of the radiator were cold. Heater only blows lukewarm air even on hottest setting. Could it be the thermostat?

Sep 20th, 2009, 19:08	#4
br850 Member Last Online: Yesterday 20:55 Join Date: Nov 2008 Location: Rotherham	useful info... thanks An airlock seems most probable cause. The fan is kicking in ok and stays on for a while like it should when I switch the engine off. I have been around all the hoses and tried squeezing them to move the air out of the system and overnight the level in the header tank dropped . The pipes in and out of the heater are getting warm now which they were not doing before. Will persevere and will change the stat next weekend just to be sure. What's this I have read about a green header tank cap being better?

Sep 20th, 2009, 09:58	#2
Chris_Rogers VOC Member Last Online: Apr 10th, 2017 16:55 Join Date: Jan 1970 Location: South Kent Coast	Sound like you have a massive air lock in there, if the heater is not getting hot then it can't be the stat as the heater water bypasses the stat. I'd suggest you try squeezing all the large hoses with the engine cold and the top up cap off to see if you can shift the air.

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