No hot air

[Ziggy]

Just rebuilt my engine and have all new coolant pipes/rad, the whole coolant system has been stripped and cleaned, but after refilling the temp is perfect but when the fan is on I get no hot air at all, is this an air lock? if so, how do I get rid of it? 1973 mk4 Spit 1300.

[dougbgt6]

Sounds like it! Could be blockage in the heater, but did it work before? Disconnect heater hoses from block and fill heater externally, reconnect, try again. By trying to fill you will learn if more water was needed, or not. If not then thermostat or worse ☹️. Tell us what happens.

Doug

[Pete Lewis]

release the top heater hose jubilee clip and partly pull the hose off the heater spout do this with engine running and up to temperature ,any air will escape but watch out for hot water 

did the  the  thermsat have a jiggle pin in its outer disk to bleed air when filling , if not drill a 3mm hole in the rim /disc 

Pete

[NonMember]

19 minutes ago, Pete Lewis said:

release the top heater hose jubilee clip

I think the MKIV Spitfire heater is the same as the Mk3, or similar, anyway, and doesn't actually have a "top" hose. The matrix goes up one side, there's a pipe across the top, then down the other side, so both hoses are at the bottom. Makes bleeding a pain.

[Pete Lewis]

in that case   ,  well have you tried collapse the rad hose when the stats open forcing flow round the heater 

or put car up on ramps so front is much higher than the back  or any other wierd ideas  you can try 

Pete

[Ziggy]

6 hours ago, dougbgt6 said:

Sounds like it! Could be blockage in the heater, but did it work before? Disconnect heater hoses from block and fill heater externally, reconnect, try again. By trying to fill you will learn if more water was needed, or not. If not then thermostat or worse ☹️. Tell us what happens.

Doug

I will try that. I will remove the heater out pipe as that is cold when engine running, but the inlet is hot, so must be an air lock. No idea if it worked before, but I have had it all out and flushed it so I know its not blocked, I have restored the car bottom up, so most stuff is all new. 

[Pete Lewis]

with the bleeding problems I would now drain as much as you can then   fill the system with heater  valve fully  open and engine at a fast idle ???   so air is bled out as you fill  ??? 

Pete

 

[Colin]

Have just developed the same prob with a couple of first tentative runs after much get-back-on-the-road runs:- have recently had heat from the vents whikst working on her and checking but on last test run I had no warmth from the vents (to remove the steaming up of window my body geat was causing). This won't risk the enginr seizing will it? But what's causing it? I have ordered a new 'stat and will replace unless I can find summat to test old one in :- but if it's an air block, what's causing it - and how to rid . . . ?🤔🤔

 

[Pete Lewis]

we have one in dunstable being a pig to clear any air lock the guy is pulling teeth and  nothing seems to solve it 

what happens if you charge fill  with a  garden hose on the heater hose   

after that its change heater, change valve ,change pump, change stat  , change bypass ,   .............change  Car 

has the stat got the jiggle pin or a bleed hole in the rim ??   sorry    must have asked that before  

its a virus thing  , 

[Colin]

Have just developed the same prob with a couple of first tentative runs after much get-back-on-the-road runs:- have recently had heat from the vents whikst working on her and checking but on last test run I had no warmth from the vents (to remove the steaming up of window my body geat was causing). This won't risk the enginr seizing will it? But what's causing it? I have ordered a new 'stat and will replace unless I can find summat to test old one in :- but if it's an air block, what's causing it - and how to rid . . . ?🤔🤔

 

[Colin]

Hi Pete. I'm amazed you followed my post. Just re-read it. What do you/does anyone think about running her up to temp with the rad cap of - just to the point where the stat opens (if it will) and begin to see the water circulating? Surely at that point it'll be clear that the stat os - or isn't opening. This thing about taking heater box pipes off anx trying to ram water in seems wierd to me and a goid way of introducing even more air into the system . . . 🤔😊

[DanMi]

it could also be a blockage in the heater valve or in the pipe that runs under the manifolds, my mk2 has always filled without issue and the only time the heater failed it was a build up of gunge sorted by flushing with a garden hose. No problem running it with the radiator cap off to see if the thermostat works

[poppyman]

Hi Colin, are the pipes to the heater hot? Also if not run with rad cap off, any air will still be in the system.

Tony.

[Pete Lewis]

well the smiths heater valve is prone to be clogged 

the stat must have a bleed hole or jiggle pin in the rim 

the by pass needs to be clear , often clogged up especially the adaptor union  into the pump

running with the cap off is fine , you should see the ebb and flow  across the top tank   as the stat opens and closes , 

should be able to drive for miles with the cap off ,  ( not when the header /filler is below engine heights  like eg  GT6 )

Pete

[Colin]

Hi Pete. I'm amazed you followed my post. Just re-read it. What do you/does anyone think about running her up to temp with the rad cap of - just to the point where the stat opens (if it will) and begin to see the water circulating? Surely at that point it'll be clear that the stat os - or isn't opening. This thing about taking heater box pipes off anx trying to ram water in seems wierd to me and a goid way of introducing even more air into the system . . . 🤔😊

[Colin]

Hi chaps. I ran my Herald, rad cap off. All heater pipes came up hot before the rad water started to boil ! Just shut her down before everything got covered in boiling anti freeze! I guess, if the rad water boils visibly like that, that the stat is working (or hot water could not make its way to the rad, right?).

So I'm guessing I'm safe from seizing the engine if rad cooling is available to me.

Leaves me this conundrum:- windscreen vents put out virtually no warm air when the cabin vent is shut.

Later, after a short run, I checked driver's side of the cabin vent and was horrified the air was not warm. Tried the passenger side which proved to be warm!! 

So how come that disparity for starters and, the fact that either way round,  othing warm is coming through the window vents!!??!! 

 

[NonMember]

1 hour ago, Colin said:

So how come that disparity for starters and, the fact that either way round,  othing warm is coming through the window vents!!??!! 

It's worth checking the air plumbing! It may be the heater itself is working fine but the hot air can't get to the screen vent because the hose has fallen off.

[Pete Lewis]

I doubt it was actually boiling   

if you got a volcano of hot water out the filler there is an air lock , the air expands and pushes  your coolant out 

then localised boiling occurs ,  a bit chicken then egg   

your herald  should run quite happily with the cap off

assuming the cable is operating the heater distribution ?? flap  the flap is very crude and has wonders of nasty rubber and foam to make it effective deflecting to toes or screen 

Pete

 

[Iain T]

On 09/06/2020 at 10:23, Pete Lewis said:

or put car up on ramps so front is much higher than the back

I did this on my Vitesse and it worked! Not sure if it was by luck or design?!? 

Iain 

[Pete Lewis]

errr      yes  

ha !

ive always done refills with the engine on a light rev ,  

problems seem  always start if the thing is half full /not fully drained out 

 

Pete