Heater not working

[jpsmit]

The temperature gauge was normal so it didn't seem to be overheating, any thoughts?????

When the water level drops below the level of the sender - it can't register. Took me a very long time to realize this. (like 600 miles )

[vauxhallbitz]

An air lock in the heater circuit. The air expands a lot and forces out the water. When filling the radiator make sure the controls are set to hot and slip off the hose to the heater valve. Pour water in the hose end until water comes out of the valve......no more air locks.

Thanks for the advice I presume that the hose you take off is the one which comes off the bottom radiator hose and you fill from there?

[lord13]

no, the top heater hose that fixes to the valve, it's the top most point of the system. Pour water down the hose, it will fill the system forcing any air bubble through the system and out the heater matrix, when water comes freely out of the heater valve itself you know the system is clear of any air, re attach the hose and all should be well

[vauxhallbitz]

OK I think I fixed the airlock however once the engine is running for about five minutes it starts to lose water through the radiator overflow.

This is before the thermostat opens up, the temperature gauge stays in the middle and there is no overheating.

I have just noticed the bottom radiator hose is cracking at the jubilee clip as I saw it bubbling and a trickle of water coming out of it.

Could this be the cause of the loss of water or am I barking up the wrong tree??

[1972nail]

If the hose is cracked it will probably leak some water. Possibly only a drop or two, but they would evaporate off and therefor not be noticeable. Your radiator overflow will loose some water as the water heats up and expands until the correct water level is reached i.e. equilibrium between hot and cold.

Your cap could also be at fault it should be a 13lbs 'long' cap. There is only a few millimeters of difference between long and short caps and you could have a short cap which will never achieve the correct pressure.

[vauxhallbitz]

Checked the cap it is 15lb and measures barely 20mm, this is the cap that has always been on the car but the problem has only shown up since putting anti freeze in???

Just tried a longer reach cap from my CA Bedford however it will not fit, the neck of my Viva radiator is shorter than the one on the Bedford so should mine be a short reach????

[1972nail]

It may be, if the rad has been rebuilt in the past it may have been changed. Barely 20mm is still shorter than a short reach cap so maybe the spring has lost it's tension.

[vauxhallbitz]

Yes the radiator was a rebuilt one from Fred, I am going to try another cap is 13lb correct for the 1256 engine?

[vauxhallbitz]

Tried another long reach cap but it will not close so mine must be short reach, the saga goes on.

This time filling slowly into the highest point heater hose the water comes out the top of the radiator instead of through the heater valve, does that mean the thermostat is stuck closed?????

Don't want to become a pest on here but this is driving me mad!!!

[lord13]

Tried another long reach cap but it will not close so mine must be short reach, the saga goes on.

This time filling slowly into the highest point heater hose the water comes out the top of the radiator instead of through the heater valve, does that mean the thermostat is stuck closed?????

Don't want to become a pest on here but this is driving me mad!!!

filling the system from the heater hose will force the water all the way around the system and out of the first open point, that point being the heater valve, if any part of the system is open, water will come out of the first 'hole' it finds.

so coming out of the top of the rad? you mean the overflow right? Because the rad cap must be on the rad when you refill from the heater hose or the water will come out of the radiator top, it being the lowest open point.

If water is coming out of the overflow then the rad cap is not correct because when closed and cold it shuts off the overflow exit.

Another thing occurred to me, is the ignition timing correct? As my OHV kept boiling up when i put it back together. It hadn't run for a while and during my initial 'messing about' to get it to start, I moved the dizzy about whilst cranking to get it to catch, it worked and fired up nicely, but ran on a fast tickover and after a while boiled up. after much messing about with the carb, my simple brain decided to remind me about the dizzy, so a bit of static timing with a bulb and a socket on the crank got me to a basic timing setting that didn't boil over after half hour of tick over

of course if you've not messed with the dizzy then it shouldn't be that.

Another thing, take out the thermostat, run it without. It's summer, the engine will warm up quickly, of course it won't regulate itself, but if you up the antifreeze content then it should be just fine I used to run mine in the summer with no stat and a 50/50 mix in the rad.