ok, so i've put the new radiator in thinking that would solve all problems and i'd be out finally having some fun.........NO.

i'm finally narrowed it down to a air lock in the heater bypass pipe......drained the system and refilled it tonight, for the reason of banging my head against a very hard wall i desided i have nothing to lose so took off the bypass pipe while i was filling it up.

put around a gallon of water in the system and water started pouring out of the outlet in the inlet manifold, blocked that up and took the theory that surely water would build it's way up through the pipe coming from the pipe........no! it's trickled out and thats it. blew into the header tank and water came shooting out of the bypass pipe so it's not blocked.

i've tried time after time to bleed the system but still there seems to be air in it somewhere.

fill the system, run the engine with the pressure cap off and the coolant starts rising within a few minutes then overflows, turn off and the coolant drops right down......just does this over and over again.

pitures off the bypass pipe are included just incase i've done something daft with it?





it's officially annoying now!!

My carb is different but the pipe from the inlet manifold on mine goes to the header tank and from the header tank it goes to the water pump,the bleed on my thermo house is not there but i did block my old bleed outlet off on the previos thermo house.

Bottom hose on rad to big water pump fitting and top hose on rad to the thermo house,mine gets hot but not over the top once the fan kicks in.

I'll try and sort some new pics as i have changed mine a bit since the photo archive pics but you should get the idea,the only other thing apart from the pipework is the rad looks a little low but i'm not sure if this has been compensated by the height of the header tank.
Normal procedure is to have your rad tank or header slightly higher than the cylinder head water level at thermo house,not sure if it makes that much difference if marginal.

Try re-routing the by pass pipe so that it is lower than the inlet manifold. I did this on mine to make sure that it filled up as the rest of the system filled, instead of it filling last. In the end I removed the pipe completely as I decided it weren't needed. On my engine the automatic choke housing is the highest point of the water system so I undone one of the pipes going to it a filled it up till water poured out to bleed it.

Can I ask how air escapes from the top of the rad? There appear to be two lines to the header. Are they both under the water level to avoid air being drawn back in on cooling?

the raditor is pretty much in the only posistion it can be put it, it's got about 1/4" clearence around each side of the nose cone so can't raise or lower it.

plumbing goes -

pipe from bottom of header tank goes to bottom of radiator

raditor top hose to thermostat housing

raditor bottom house to water pump

pipe from water pump to inlet manifold (heater bypass)

small pipe from thermostat housing back to headertank working as expansion/return pipe.

the raditor is getting hot in a even manor, no cold spots or hot spots so i'm taking that to mean it's not air in the rad causing the problem.

Suggestion, blank off thermostat small outlet,

Now use the pipe to the inlet manifold with a tee piece to go to the expansion tank.

Hi John,

So you have 2 pipes into your expansion/header tank. Yes?

Are they both into the bottom of the tank, i.e. below the water level ?


I have a pipe from the TOP of my rad, to remove the air lock,
(rad level is below that of the t/stat housing) that tees into the expansion
pipe that goes from the t/stat housing to the bottom of the expansion tank,
i.e. blows air & water into the tank, but can only suck water back when it cools.
Can post a pic if you don't get what I mean.

hth

Paul G

907, yep thats right i have 2 pipes into the header tank, only the bottom one which fills the raditor is below the water line though, here's a pic



the top one which comes from the thermostat housing constantly when the engine is running has water coming out of it. you've got me thinking now though about the whole thin of it sucking air in as the water cools, surely it being a sealed system though it shouldn't do that though?

of all the parts of this bloody car i never thought the cooling system would give me so many problems!!

[Edited on 17/9/05 by john_p_b]

[Edited on 17/9/05 by john_p_b]

For peace of mind I'd be inclined to take the head off and check for hairline cracks. I had exactly these symptons on both a Pinto and A series(many years ago) and it turned out to be a cracked head on the Pinto, and a warped head on the A series.

Sorry, don't mean to be pessimistic but you could spend weeks treating the symptons instead of the cause, and end up angry and frustrated. Like I did!!

Hi again John,

As an experiment:

disconect both pipes from the expansion tank.

Put the one that was on the top, from the t/stat housing, on the bottom.

Block off the other pipe from the bottom of the rad with a bolt & clip.

Block off the upper conection on the tank.


You will now have a sealed system with a tank that air & water can expand into
but no constant flow.
When the engine cools water will be sucked back.

My tank has a rad cap on it so that surplus air pressure is expelled without loss of water.
My rad is sealed with a flat cap, i.e. no spring.
I assume your rad has a normal cap and that it is lower than the engine.

hth

Paul G

I had the same and had to be recovered but it was only my stat gasket blowing water out. Out of curiosity try running it without a stat to see if it still gets hot. I only fitted a header to save trouble filling up as I previously had to remove the nosecone.I ran the small pipe from the stat housing to the Clio header neck and just teed into the pipe to the manifold for the other connection. I have a 2ltr Pinto with an Escort radiator and ran for 3 years without a header tank and had no problems. Check you get this view of your stat when you remove the housing or it's the wrong way round and will keep the hot water in the block. While you have the stat out drill a couple more 3mm holes in the flange to let air out easier as the rubber in there can block the one it has.
Rescued attachment stat.jpg

Have you tried a swirl pot to take out the airlocks?

The bottom hose is scarilly close to the exhaust headers.

I took mine right down from the expansion tank and along the lower chassis rail.

Pat...

Couple of suggestions, check your local scrappies for an in line bleed valve to fit into highest part of heater bipass hose, some french cars may have suitable parts . Is the header tank the highest point of the cooling system ? get it as high as you can. Also as already suggested headgasket?head cracked ? .It should be possible to get it tested without removing head using a test kit with a blue liquid placed on top of the header tank , if combustion gases are present liquid will change colour. Any decent garage should have this kit . Has water pump been checked? very rare but I have had problems with loose/worn impellers. Is cooling fan operating at a sensible temperature? Its possible to get switches that operate at lower temp. HTH

i think it's cured!!

i honestly have no idea how but just been running it up and got this great gurgling noise from the headertank, water level dropped, topped it up just took it for a 12 mile run and the temp held at a steady 75-80 degrees! started creeping up a little at trafic lights but as soon as got going again it dropped back to just above 70!

i'm not saying it's fixed as i've thought this before but its the coolest i've ever had this engine running at!

Sounded like a nice big airlock,hope thats sorted then.

I've bypassed my fan thermo switch so i can switch it from the dash as well,this seems to help when i get into traffic to keep the temp down as the ford thermo switch i use is not exactly exact when it kicks in.

Sounds very much like you had an air lock , possibly trapped behind thermostat? Would stiil suggest a bleed valve in heater bipass hose in case of future problems.

Is that a Renault header tank?

Cheers,

Pat...

deffinately think it was a air lock but it sure seems cured now! just done 38 miles in it and all i can say is wow!

pat, yes that is a renault header tank, from a kangoo to be exact. had it laying around at work after we wrote one off a few months ago and it seemed the best fit to get me by! it'll be replaced with a nice shiny one once funds have become a little more healthy!

well done ! its nice when things sort of fix themselves. a good result !