105 Heater Problem

Hi All
Just been surfing the net to try and get some technical info, and came across this forum. Signed up immediately

I have a 1968 spider veloce 1750. The heater has ceased to work since the system was bled to fit new carb mounts (inlet manifold off).
Both the inlet and outlet pipes to/from heater remain cold. engine cooling is fine and normal. I wonder whether this is an air lock, or should I start looking at the heater valve? If it is an air lock in the matrix, how would I solve?

Any help gratefully received

Hi and welcome to AO.

My Bertie is in bits and I'm not th eexpert you need, unfortunately.

However, in my Imp back when I had a thin waist and knees that didn't crack...


You'd set the heater to full hot, take off the rad cap, run the engine and watch for the the bubbles and keep topping up....at least I think that's what fixed it!

I'm sure someone with better knowledge will be along shortly! Good luck with it!

It does sound a bit like an airlock, did you leave the heater valve open when you emptied and refilled it?.

As Mitch says you need to make sure the heater is set to hot when you refill. There are two points you can vent air from - there is a bolt on the top of the water pump and also a big bronzey coloured nut near the thermostat housing which is reverse threaded. If you run the engine so it's hot (thermostat open) crack these joints and bleed until water comes out and then nip back up. Then re-check your level.

Thanks guys. I did have the heater valve open, and have bled the system as suggested, to no avail. Hence my thoughts on checking the function of the heater valve. I shall go and have another poke around!

Strange one!! I wouldn't have thought there's much to fail in the heater valve. They are available as replacements if required so have a big swing at it with your hammer!!

http://www.classicalfa.com/shop/category6_1.htm

Just a thought. The thermostat is still in there isn't it?

....also make sure that the thermostat is in fact opening. Had a problem like this once on a Scimitar. I would drain down the system and part refill then continue slowly filling with the engine running and the heater valve open. This solved the poblem of airlocks.

Jesus..... is that Brass nut reverse threaded, no damn wonder i could never shift it, I've been trying off and on for four bloody years now!!!!

Alfa's dont you just love em

Originally Posted by VeloceMitch

Jesus..... is that Brass nut reverse threaded, no damn wonder i could never shift it, I've been trying off and on for four bloody years now!!!!

You said that last time I told someone it was reverse threaded!!!

I think you've been opposite locking through too much cow dung.

My "Brass Nut" is normal anti-clockwise to undo!!!

How does the operation of the thermostat affect flow into the heater matrix?

Be aware that the plastic heater valves have a bleed screw on them (not sure about the metal valves). If no bleed screw on the valve, try bleeding the cooling system in the regular manner (with heater valve open and fan off) but with the engine at a very fast idle (like 2k rpm).

If your intake manifold bleed screw loosens anti-clockwise, my bet is that it's from a 2l car (or a later 1.3/1.6/1.8).

Originally Posted by MrCuttlefish

How does the operation of the thermostat affect flow into the heater matrix?

Isn't it something to do with back pressure?
i.e. if the thermostat has been removed it adversely affects the flow of water. I was just checking that it hadn't been left out in the rebuild - you know, like those nuts and bolts you always get left over!


On these engines if the thermostat doesn't open, can water get into the heater??? Not sure....

If it is a metal valve then it could be like mine which was clogged with a jelly/crystal crud. Opening or closing the valve mechanism itself would have no effect on the flow.

Originally Posted by RicksAlfas

You said that last time I told someone it was reverse threaded!!!

I think you've been opposite locking through too much cow dung.

Did I
I'm loosing it......

Originally Posted by RicksAlfas

On these engines if the thermostat doesn't open, can water get into the heater??? Not sure....

Yes. The coolant in the intake manifold, which is always flowing when the engine is running, supplies the heater from a fitting on the rear of the manifold. The heater return hose then connects to the waterpump input.

If it doesn't help venting the cooling system, try forsing some water the reverse way thru the heater with the heater valve open-
Fit a garden hose to the outlet hose and disconnect inlet hose and point out of harms way. Bend the garden hose so water flow is block and get someone to open the water valve all up and open the bend suddenly.
If the heater unit is full of grud and debits, you will have blown them out. Connect heater hoses and bled the system.
Erik

Thanks for the suggestion, I was wondering whether I could backflush the heater as you say. I suppose if I cant get any water through it, it is probabaly the heater valve at fault.