Puma trying to overheat - dodgy hcv?

[DanS]

Currently got a 51 plate thunder, was enjoying my so far brief ownership til the other night! Fuelled it up and noticed a lot of coolant on the floor, topped up with water til I could get it home and have a proper look at it.
Coolant gauge never moved from midway previously.

Anywho, found the leak was from a knackered thermostat housing. Changed that and the stat and all seals, ran up and no leaks, happy days.
However, it's been trying to overheat ever since. I've given it two good bleeding sessions this weekend getting loads of air out both times, but it still tried to overheat this morning on the way into work.

Some other symptoms, if I move the heater dial off fully hot even a touch it'll try overheating even at idle and heater goes freezing just one click off fully hot. If driving on motorway I have to stick to under 3000rpm with heater and blower on fully hot to keep gauge in the middle.
When the heater dial is moved slightly and cold air comes streaming in moving it the one tweak to fully hot it takes an age to get hot again (goes from freezing cold to scalding hot)

When I was replacing the thermostat and housing I had a feel of the water pump and when spinning the pulley I could feel the blades moving. Does it sound like the hcv has failed or I've still somehow got a massive airlock in the system?

 

[CherryVimto]

As an idea, remove the two pipes that go to the HCV from the engine and join the two ends together with a small length of copper pipe.
That will take the HCV out of the system totally. OK, you'll have no heating in the car, but it might prove whether the HCV is faulty or not.

 

[DanS]

I shall see if I've got anything suitable kicking about.

As a side note, my missus has just informed me when she was holding revs at 2500rpm on Saturday night as I was trying to "burp" the system when the heater dial was on cold, hot air was coming out of the vents?

 

[3dcandy]

Sounds like a dodgy HCV to me
Could also be the dash panel though

 

[Wild E. Coyote]

I just fail to see how could dodgy HCV lead to overheating? It either opens, or closes the circuit to the cabin heater. Of course, the heater (if circuit is open) takes away some of the coolant heat, but the system has to withstand that being closed as well; during summertime none of us will turn on the heating, won't he?
My prime suspect would be the thermostat; this would not be the first case of brand new thermostat not functioning properly

 

[DanS]

I thought it would be a bit odd. But according to this poster here: http://www.projectpuma.com/viewtopic.php?f=19&t=25449&p=318748&hilit=over+heating#p318748" onclick="window.open(this.href);return false; it wouldn't be unheard of for a hcv to cause issues like I'm having. Regardless, I'll pull it all apart this weekend and dunk the stat in boiling water to see if the new one is doing what it's supposed to

 

[DanS]

Pulled the new thermostat out today. When plonked in some water fresh out the kettle it works and opens and it should so in theory it's doing its job. Ran the hose through the rad while it was in pieces just to make sure that's clear. Double checked water pump, no play and spins as it should so going to throw a new hcv on it and if that doesn't work a gallon of petrol and a few matches!

 

[CherryVimto]

Remember the stat is supposed to open at around 83 degrees (but I could be wrong) so dumping it in freshly boiled water at around 90-100 degrees will probably make it open anyway.

The only true test would be to put the stat in a saucepan with a thermometer and boil the water up to see if it opens at the correct temperature.

 

[Wild E. Coyote]

The thermostat starts opening at 82 degrees and should by 88 be fully opened. So boiling water is way to much