heater blows cold - 97 chim
Discussion
You need to check the supply and return hoses are both getting hot under the bonnet and also in the cabin inc post heater valve this will at least confirm you have purged the air , may be a failed heater valve or linkage issue if not furred/slugged up heater matrix is also a possibility Ole 
Try loosening one of the heater hoses at the back of the engine bay next to the rear of the plenum chamber. Do it with the heater valve open and engine running but before the coolant is so hot it might burn you!
Another useful bleed point is the blanked of hose near the oil filler cap.
Another useful bleed point is the blanked of hose near the oil filler cap.
OleVix said:
After changing coolant it wont blow hot anymore!
If the heater was fine before changing the coolant it's highly likely it's nothing more complicated than air in the system, this is extremely common.On my LPG Chimaera the vaporiser is plumbed into the heater circuit so the removal of all air becomes essential, if I have air in my heater circuit not only will the heater become ineffective but the vaporiser will also freeze up causing severe running issues.
I solved the challenge by fitting strategically placed bleed valves that TVR deemed unnecessary but all other car makers have fitted for years, these ones on eBay work perfectly and are easy to fit in the heater hoses in & out of the low mounted heater matrix.
https://www.ebay.co.uk/itm/New-in-stock-Caterham-W...
Cheaper options may be available but the above type worked perfectly for me with no leaks.
Also consider adding a further bleed point in the hose that goes to the swirl pot at it's highest point like this.
This is actually the highest point in the entire coolant system so a pocket of air will tend to sit here.
https://www.pistonheads.com/gassing/topic.asp?h=0&...
A large funnel fitted into the swirl pot during bleeding also helps a lot as it creates a big high mounted header of coolant, used with the hose squeeze and burp method plus a few strategically placed bleed valves and all air pockets are quickly and easily purged from the system.
ChimpOnGas said:
OleVix said:
After changing coolant it wont blow hot anymore!
If the heater was fine before changing the coolant it's highly likely it's nothing more complicated than air in the system, this is extremely common.On my LPG Chimaera the vaporiser is plumbed into the heater circuit so the removal of all air becomes essential, if I have air in my heater circuit not only will the heater become ineffective but the vaporiser will also freeze up causing severe running issues.
I solved the challenge by fitting strategically placed bleed valves that TVR deemed unnecessary but all other car makers have fitted for years, these ones on eBay work perfectly and are easy to fit in the heater hoses in & out of the low mounted heater matrix.
https://www.ebay.co.uk/itm/New-in-stock-Caterham-W...
Cheaper options may be available but the above type worked perfectly for me with no leaks.
Also consider adding a further bleed point in the hose that goes to the swirl pot at it's highest point like this.
This is actually the highest point in the entire coolant system so a pocket of air will tend to sit here.
https://www.pistonheads.com/gassing/topic.asp?h=0&...
A large funnel fitted into the swirl pot during bleeding also helps a lot as it creates a big high mounted header of coolant, used with the hose squeeze and burp method plus a few strategically placed bleed valves and all air pockets are quickly and easily purged from the system.
they are an air pocket hiding place due to the height 
My matrix was utterly shat up.....but I had never had any useful heat from the heater in 7 years of ownership.
Mat the Smith took the matrix out when he was changing my heater fan, took some photos, and we all had a lightbulb moment.
Before de-s
tting:
After de-stting:
Now I had never had any useful heat, so this is most likely not your problem at all - the airlock answer looks likely.
I now have a lovely toasty car, just like any normal car, warm from mile 2 of any journey.
But if some lurker is reading this and has had cold legs all winter, it just might help them.
Mat the Smith took the matrix out when he was changing my heater fan, took some photos, and we all had a lightbulb moment.
Before de-s
tting:After de-s
tting:Now I had never had any useful heat, so this is most likely not your problem at all - the airlock answer looks likely.
I now have a lovely toasty car, just like any normal car, warm from mile 2 of any journey.
But if some lurker is reading this and has had cold legs all winter, it just might help them.
QBee said:
My matrix was utterly shat up.....but I had never had any useful heat from the heater in 7 years of ownership.
Mat the Smith took the matrix out when he was changing my heater fan, took some photos, and we all had a lightbulb moment.
Before de-stting:
After de-stting:
Now I had never had any useful heat, so this is most likely not your problem at all - the airlock answer looks likely.
I now have a lovely toasty car, just like any normal car, warm from mile 2 of any journey.
But if some lurker is reading this and has had cold legs all winter, it just might help them.
fook me thats buggered up good! Thanks quietly bonkersMat the Smith took the matrix out when he was changing my heater fan, took some photos, and we all had a lightbulb moment.
Before de-s
tting:After de-s
tting:Now I had never had any useful heat, so this is most likely not your problem at all - the airlock answer looks likely.
I now have a lovely toasty car, just like any normal car, warm from mile 2 of any journey.
But if some lurker is reading this and has had cold legs all winter, it just might help them.
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