The V8 Owners Forum -

ok,here is my problem,my water isnt pumping round the whole of my system it flows around the heater matrix and back but when it gets hot it doesnt flow through the radiators,at first i thought it was the thermostate but i changed it for a brand new one and it still doesnt pump around the radiators,im confused
its A HOTWIRE SYSTEM

Cooling system hasn't an airlock ]

Is it piped up correctly , whats it in

Is it a new setup, or anything changed recently?
Airlock; run car from cold, with cap off till top hose nice & hot. Sometimes helps to jack the car up at the front, depends on setup.

its in a kit car,it always worked before but now if i fitted this new hotwire system i cant seem to get the water to flow past the thermostat,iv done everything i can to get air locks out,im miffed,im going to take the thermostat off tommorrow and test it but its brand new so it should be working

Alley Kat wrote:Is it a new setup, or anything changed recently?
Airlock; run car from cold, with cap off till top hose nice & hot. Sometimes helps to jack the car up at the front, depends on setup.

i have changed engines and from flapper to hotwire,i have tried running it from cold to get any air out of the system i also bleed everwhere i can bleed, and still wont work,the thermostat is opening but the water isnt going through there,i cant figure out y not,it seems to be pumping round the by pass through the heater matrix and back but won pump past the open thermostat,
anyone got any ideas,

Is the thermostat the right way round? does it have a bleed hole in it? this will help to purge air

Very odd, how about running without a stat briefly just to 'eliminate it from enquiries', then if that gets the rad heated try another stat in its place.

How do you know the stat is opening?

GreenV8S wrote:How do you know the stat is opening?

boil it in a pan of water. and watch for the valve to lift,

its definatly opening,iv tested it and i tested the one i took out of it and they both worked,last time i had the water system running ok was when the flapper system was on it so i think il just put the hotwire system on the flapper inlet manifold,hopefully that will fix it,

there is no reason why the manifold would make a difference unless you have plumbed it in wrong or the manifold is blocked in some way.

yeah i scrapped that idea now,im going to carry on with this and try and fix it,
the water is definatly pumping around the themostat bypass through the heater matrix and when i rev the car the level in the water bottle goes down quite a bit then when i let the revs off it goes back up,

im going to take the thermostat out and see what happens from there i think,

ian.stewart wrote:

GreenV8S wrote:How do you know the stat is opening?

boil it in a pan of water. and watch for the valve to lift,

You can confirm from the top hose temperature whether there is any water flow down the top hose. If you have water flow but a cold rad, this implies an air lock in the rad. If you have no water flow you have either a blocked rad, or the stat isn't allowing water through. Testing the stat in a pan of water is all very well, but doesn't prove that it is actually opening in the engine. If the stat is physically prevented from opening, or surrounded by air instead of water, it won't allow water past. You can even get an effect where the pressure difference across the stat is so great when the engine is revving that the stat can't overcome the pressure (and then comes open with a bang when the revs drop).

I cut a small section from the flange of the thermostat. About 5mm square. I fit the stat with the cutout at the top of the housing. That ended all my RV8 air locking probs.