Gurgling in the cooling system.

[SteveOS3]

I came back from a short run last night to test the new fan and noticed that when I turned the engine off there was a lot of gurgling coming from the cooling system. It wasn't overheating, the fan cut in at 90c and was spinning away merrily until the engine was turned off. The heater was working fine and there wa no sign of steam anywhere, the expansion chamber was about half full, as was the swirl pot.

I would have expected the swirl pot to be full to the brim, could it be a faulty seal on the swirl pot cap sucking in air? Does anyone have the part number for a non-pressurised cap?

I have a new pressure cap on the expansion chamber and a fixed cap on the swirl pot.

Steve

[Barkychoc]

Might be a bit of air in there - have you tried bleeding the rad with the bleed valve on the top?

[SteveOS3]

Thanks Barky,

I'll give it a go tonight - that may explain the fluctuation in the quality of the heating sometimes.

Steve

[ChrisGadd]

Interesting ... I've had exactly the same issue for some time and I too have put it down to a poor seal on the blanking cap on the swirl pot allowing the system to not presurise properly and then boil. Steve when you remove the cap from the swirl pot can you hear if it is pressurised ?

[SteveOS3]

Chris, there's no real sign that it is pressurised. I have a new set of silicone hoses and can't see any evidence of leaks on them. I'm going to replace the swirl pot cap, try bleeding the radiator and see if that makes any difference.

I'll keep you posted via this thread.

Steve

[Gerald-TVR]

Not wishing to start yet another discussion (but I will) on whether the pressure cap should go on the swirl pot or expansion tank mine is on the swirl pot and a non pressurised cap on the expansion tank and it works just fine with no gurgling, why not try swapping caps to see.

However the gurgling (irrespective of where the caps are) would indicate that there is air in the system. Firstly I would suggest using the bleed valve on the radiator, run it up to temperature allow to cool and top up system, dont forget to leave the heater set on hot. If that dosent do it then remove both caps run the engine up to temperature topping up the swirl pot as needed. let the fan cut in and out. Allow to cool, top up swirl pot and replace caps. I would suggest pressure cap on swirl poy and non pressurised cap on expansion tank. Run it and see waht happens, you a always swap caps if you feel the need later.

Let us know how you get on.

Norman

[tozerman]

Gerald-TVR said:

Not wishing to start yet another discussion (but I will) on whether the pressure cap should go on the swirl pot or expansion tank mine is on the swirl pot and a non pressurised cap on the expansion tank and it works just fine with no gurgling, why not try swapping caps to see.
Norman

Oh no you've done it now !!

[SteveOS3]

Thanks Norman, the seal on the blank cap looks a bit old and flat. Is it a standard Ford part or do I have to look around?

Steve

[mep12345]

SteveOS3 said:

Thanks Norman, the seal on the blank cap looks a bit old and flat. Is it a standard Ford part or do I have to look around?

Steve

I won't rise to the bait, but refer to my previous description of how the system should work either way around with advantages and disadvantages of both - just search on "stirring a hornets nest" (my work won't allow the system to do the search - don't know why but always return "no results" from work machine but works ok at home). I would suggest that you change the seal on the blanking cap first (make one from some old bicycle tube or other rubber and see how that goes (also clean up the top of the swirl pot) and check the hose to the expansion tank is properly fitted, not perrished, not collapsing as the water cools and "sucks back" and not allowing air in.

It is possible in these cases that the water will expand up to the expansion tank and then on the cooling cycle suck in some air as the seal (or collapsed/persished hose or bad seal on hose) is "pulled" in the opposite direction and leaks. This results in no noticable fluid leak but a slow build up of air in the system and a gradual increase in your coolant level at the highpoint. Once enough air gets in then the expansion may not be enough to move the water up to the expansion tank any more and just air flows back and forth hence the gurgling in one (or both) of the swirl pot and expansion tank

If the above is the case the expansion tank will have roughly the same level of water in it when hot or cold and the swirl pot level will rise and fall dependant upon temperature

This is a very rough and ready discription but I hope it helps

Mark

[Jed-S]

That gurgling noise - are you sure it wasn't just oil draining back into the sump? Just a thought....

[Barkychoc]

If your radiator has any greeny blue deposits on it (anti freeze coloured) your rad could have a slight leak / be letting air in as it cools down. Look particularly in the bottom corners from underneath (ie from the front of the car).

[SteveOS3]

Didn't get any time for a full inspection last night but noticed that the gurgling was noticeable from the heater matrix when I was sat in the car.

It's probably going to the weekend before I can do any more as I have another 20m of trench to dig for armoured cable to the new garage.

[Barkychoc]

It might be worth flushing out the heater matrix - I did this on an old V6 granada once - trust me don't do it on your drive you would not believe the muck that comes out.
I connected a garden hose to the output and disconnected the inlet hose (you could put a hose on this I guess to channel it somewhere). I did swap it around once or twice (inlet/outlet) till it ran clear - the thick brown rust and muck that came out was like treacle.

If you can clamp the inlet / outlet hoses so you're not losing antifreeze (mole grips will do but not too tight).

Chris

[jimed]

Not wanting to get into the usual debate here but I suspect the header tank is not designed for the 15psi pressure the system works at; failure of it could be quite messy and I for one don't want that all over the engine bay so - I have the pressure cap on the swirl pot and the blank cap on the header tank which I believe is the correct way (OK don't say no - you can have it the other way if you want but note what follows!). The system blows water into the header tank when it heats up and sucks it back via the pressure cap as it cools. That means the swirl pot is always full - why would we want to run with it not full - that surely means water isn't everywhere it should/needs to be? Anyway it has been that way on my car for 11 years now with no problems.
Jim

[Roy C]

jimed said:

Not wanting to get into the usual debate here...

TVR Factory Bulletin - S series Radiator Caps

My cooling system has always gently gurgled when cooling down.

[Gerald-TVR]

I think that TVR's bulletin should end the matter, they designed the system and applied to how many cars?

I'll go with the factory.

[mep12345]

Gerald-TVR said:

I think that TVR's bulletin should end the matter, they designed the system and applied to how many cars?

I'll go with the factory.

Yes, I'd agree normally but the first line of the bulletin note says they got it wrong and changed their mind!!! - who says they didn't change their mind again.

My previous response to a thread (stirring a hornets nest) attempts to explain the system from a theoretical perspective, the outcome of which is it will work both ways and there are advantages (and disadvantages) to each. It is therefore up to you (just don't fit two pressure caps as someone suggested doing). JIMEDs runs ok with the caps the opposite way round to my preferred way and mine runs ok too - so pays your money and takes your choice.

Mark

[Roy C]

mep12345 said:

the first line of the bulletin note says they got it wrong and changed their mind!!! - who says they didn't change their mind again.

I don't think they changed their mind. They just cocked-up the original note. They also wanted to point out that the expansion bottle (Ford) level indicator was above where the level should be on an S.

AFAIK all the S series left the factory with the caps as per the bulletin.
However, both ways will work.

[page3]

Mine gurgles and makes the occasional 'plink plink' noise. Assumed that was normal

Edited by page3 on Thursday 13th November 09:35

[Roy C]

page3 said:

Mine gurgles and makes the occasional 'plink plink' noise. Assumed that was normal

Edited by page3 on Thursday 13th November 09:35

Are you talking about your car or your son?