Airlock?

[Guest The Modfather]

Guys, just fitted a 32/36 DGAV carb with auto choke and manifold, started it up, but no water circulation. I had to change water hoses as the old ones suited the old carb (28/32 Weber 1.6) but now the water doesn't appear to be circulating, and the heater blows cold.

I've undone the various joints but still no circulation. When I switched the engine off, the rad spewed water out ( I had cap off).

 

Why is it doing this, and how do I sort it?

 

I had a look at the bleed valve thingy on the thermostat but this is solid with crap once I took the rubber stopper off. I take it this should be clear?

 

Thanks

 

Darren

[Andi]

Fill her up with water and run to temp with the cap off, and continue for another 5 mins. You`ll get the odd splurge of water come out the cap (give it a few revs at this point and it should be ok.

Works for me, I would still open the cap slow after a short drive though.

Ive heard of all sorts of remedies though including hoisting the font end right up in the air. eek!

[Guest The Modfather]

Thanks Andi.

I actually ran it for about 10 mins and it did spew a bit out, but I didn't want to run for too long in case I boiled it. My heater inlet and outlet is higher than my rad top, is this an issue?

 

Darren

[speedtripledan]

when i had a v6 coupe pug the header tank was lower than the highest point on the water circuit trick i used was to cut the bottom off a 2.0L coke bottleand insert it into the header which then raised it above the height of the water circuit.

 

worked for me everytime.

Dan

[Guest Noddy006]

Hi Daz

I have just fitted a heater in mine and I filled the system then with the cap off ran it for about 10 mins. As I don't have a header tank and whilst still running I undid the pipe to the choke and let it flow for a few seconds. Kept topping up rad. Heater runs nice and hot. Unless you have a block in the heater matrix it should!!!!! work.

Best of luck

Ian H.

[Guest The Modfather]

when i had a v6 coupe pug the header tank was lower than the highest point on the water circuit trick i used was to cut the bottom off a 2.0L coke bottleand insert it into the header which then raised it above the height of the water circuit.

 

worked for me everytime.

Dan

 

I like that idea Dan, thanks mate, I'll give it go tomorrow. I take it that you filled via this bottle until all pipes were warm, and then removed and allowed the overspill in order to get the right level?

 

My heater always worked before, blew lovely and hot, so the matrix works fine.

 

Darren

[johnlrichardson]

The rad cap or header tank should be the highest point

 

someone will tell me if im wrong

 

HTH jon

[Guest The Modfather]

The rad cap or header tank should be the highest point

 

someone will tell me if im wrong

 

HTH jon

 

 

This is definately not the case in my situation. I'm sure that this is the same for most people, that the heater inlets and outlets are indeed above the filler cap.

I'll give the bottle trick by Dan (above) a go and see what happens. I will post my progress or sadness

[chris n]

Hi Darren,

Silly question is there anything obstructing the coolant flow in the manifold or the water jacket in the head?

[Guest The Modfather]

I blew the manifold out with compressed air, and the engine appeared clear. Even blew out the choke. I can only assume that because the heater is higher than the rad cap that it is that that is causing the airlock.....

 

I'll give it another go in the morning.

 

Darren

[Longboarder]

It's always a good plan to design the cooling system with the high points being able to self bleed. It's then fit and forget. Any system will produce air over a period of time and this will collect at the highest points. If it's the top of the rad it blows out first into the expansion bottle and sucks back water as i cools. If it's somewhere else like a heater hose then tee off a bleed to a pressurised expansion bottle. Both give automatic air removal.

Failing that fit a bleed valve of some sort at the high points and manualy bleed at intervals. You can make an effective bleed with a 16mm copper plumbing T, bits of pipe and olives and a bleed valve as below. Or find one in the scrapyard.

But it's always best if you can get the system to self bleed.

 

Nigel

[speedtripledan]

The rad cap or header tank should be the highest point

 

someone will tell me if im wrong

 

HTH jon

Not on most a lot of modern cars they have bleed nipples at various points in the water circuit.

 

Dan

[Guest The Modfather]

The airlock is now sorted thanks to to Alan popping over and lending his pair of hands. I will fit a bleed device in the top heater hose in the near future just to make it a one man operation

 

Thanks to everyone for helping and giving advice.

 

Darren

[thespannerman]

When bleeding with the rad cap off make sure the end off the expansion overflow pipe is in a big bottle of coolant. So when the rad cap is back on and the engine is cooling down, coolant is drawn back into the radiator not air. Can suck back a good litre.