Why is my car STILL boiling over ? (update - it did it again at Stoneleigh)

[Nick Woods]

To cut a long story short (ish), my K-series keeps overpressuring the cooling system. Its been tested for exhaust gases in the coolant (none found), drained, refilled and bled. I fitted a tee piece to the heater top hose to help drain and refill

 

I took it for about 50 miles a couple of weeks ago and after it had cooled I started to undo the pressure cap (also new) and it began to force coolant up inside the expansion tank, so I did the cap up and undid the radiator bleed screw. A lot of air came out and the expansion tank level went back to normal, and I then put 1/2 a litre of coolant in (Comma Coldstream)

 

I've been out on a blat with some Carrotlanders today, about 180 miles in all and kept a close eye on the temp gauge but it didnt overheat. After it had cooled down this evening (for about three hours) I checked it and it has obviously boiled over at sometime during today - I suspect when I got home as there was still liquid coolant on the back of the rad fan.

 

I undid the rad bleed screw and got a lot more air out, then put in 3/4 of a litre of coolant, although some or this must be to replace the coolant I lost.

 

Any ideas ? - could this still be air in the system ? Could it be drawing air in somehow ? Could I have a head gasket problem despite the negative test ?

 

This has been going on since Christmas so I'm starting to get a bit fed up with it now ☹️

 

Nick

Red and Black 1.6K supersport

visit Carrotland.co.uk

 

 

Edited by - Nick Woods on 18 Apr 2004 23:01:35

 

Edited by - Nick Woods on 2 May 2004 21:59:52

[Peter Carmichael]

Dear Confused of Carrotland,

 

You are at least thinking about this in the right way. Where does all this air come from? Why is liquid coolant showing on the outside of the system?

 

You have a leak. Could be a leaking radiator. Could be a leaky joint. Could be a cracked expansion tank. Do you ever see white "smoke" from the exhaust? You have described adding 1 1/4 litres of coolant to the system which is a non-trivial amount. With all this topping up you are doing you better be damn good at bleeding the system or you may introduce problems. Sounds like you know not to release pressure from the system

 

Another good test for head gasket integrity is to run the car up to temp and then with the bonnet off switch the engine off while watching the coolant level in the expansion tank.... If it rises, then the head gasket is not in too good a state or the head of the engine is not properly bled. Why? Because the heat soak is able to heat a volume of gas in the engine and displace fluid into the expansion tank - this indicates whether or not there is any gas volume in the head of the engine, however it may have arrived there.

[Nick Woods]

Thanks for replying Peter. I see white 'smoke' for a short while when i first start it up but I've been assuming that is just because its cold. I've never noticed any smoke once its warm.

 

Thanks also for the tip about the 'engine off' test - i'll try it this evening and see what happens.

 

Up to now i've been thinking about head gasket problems and havent thought much about leaks because I've not noticed anything. I'll have a much closer look this evening, and will also give the water pump a closer look as its a bit whiney sometimes.

 

Is it possible for a leak to suck air in which then expands and blows off coolant later on ?

 

I'll also get a compression test done to see if that shows anything.

 

 

Nick

Red and Black 1.6K supersport

visit Carrotland.co.uk

 

[thinfourth]

Have you had your cooling system pressure tested?

 

Also dodgey radiator cap (i know its not fitted to the radiator but it does the same thing venting above a certain pressure hell i don't even know if these ones do vent but if they do then it might be the suspect)

 

Blatting round aberdeen wondering wether to buy a jumper or heater

[Tight fart]

The early top water rail is know to crack, you can only see a weep if you know were to look.

But once it's gone it will suck air in on cooling and hence over heat.

 

T.F@O.F.

A7 RDP

Pics here

[Nick Woods]

I've not had the system pressure tested because it hadn't occurred to me 😳. The cap was new in January after the first boil-over.

 

I'll check the water rail for leaks - where does it crack ?

 

Nick

Red and Black 1.6K supersport

visit Carrotland.co.uk

 

 

Edited by - Nick Woods on 19 Apr 2004 15:20:23

[Nick Woods]

I've been to see Mark Hicks at Anglia Sevens. He did a compression test and it was all ok, the biggest differnce was 15psi (190-180-190-195) so its not the head gasket (I had the cooland anaylsed a couple of weeks ago and it was fine)

 

We then spent a lot of time looking for leaks and found one from the thermostat housing, which I have to own up as being my fault as I checked the thermostat a few weeks ago and I must have overtightened it when it put it back together.

 

My only thought now is that it was ejecting coolant well before I made it worse, so once the housing has been replaced Mark's going to do a pressure test on it to see if that shows up anything

 

 

 

Nick

Red and Black 1.6K supersport

visit Carrotland.co.uk

 

[Peter Carmichael]

A compression test won't show up imminent head gasket failure.

 

Sounds like you are on the right track now.

[CHRIS CLARK]

My first thought was non-opening/sticky thermostat. What happens if you run it without one (apart from the fact that the engine temp won't appear to get warm in these conditions!!)?

Test stat itself by placing it in a suitable vessel (Pyrex measuring jug) that has had its water boiled in the microwave. Should see it 'open' fairly fast. If it doesn't it, err fu, had it

[Nick Woods]

Peter - can you elaborate a bit ? Are you saying that it could still be the gasket on its way out despite the compression and coolant tests all being ok (or am I misunderstanding what you mean ?)

 

Chris - I tested the thermostat when I replaced all the hoses a few weeks ago and it was ok. Having said that I'm going to fit a new one with the new housing, the current one is 76C and from browsing techtalk it seems that 82C may be a better one for me. The car runs quite sool and only gets up to 80-85ish on the guage when idling - the fan then cuts in and brings it down again

 

Once its all back together i'll get it pressure tested in case there is another leak I havent found yet - the problem predates me causing the thermostat housing to weaken

 

 

 

Nick

Red and Black 1.6K supersport

visit Carrotland.co.uk

 

 

Edited by - Nick Woods on 20 Apr 2004 09:27:32

[Mark Piper]

Was fine in my hands Nick - you been thrashing it or something

[Nick Woods]

Obviously harder than you did *tongue* *tongue* .

 

The oil pressure is still 4+ bar when cold and 3+ when hot and compression figures are good so its not coming to any harm

 

Nick

Red and Black 1.6K supersport

visit Carrotland.co.uk

 

[Mark Piper]

I look forward to seeing it on the Rumble if not before

[Smegnoguk]

I had a similar problem all last summer in my VX 1600 Classic. I posted numerous requests for help about overheating and loss of fluid. I eventually noticed steam coming from one of the top seams on the radiator and located a hair line fracture in the solder. I decided to buy a new radiator rather than get it repaired. To my surprise, the replacement was an aluminium racing type instead of the old steel/brass one. Not only does it look nice, it cured my water loss and overheating problems and I can now sit in traffic jams without fear of overheating.

 

Member No. 10421

[Peter Carmichael]

Nick, I meant exactly what I wrote with no hidden meaning. A compression test is so momentary that it won't show up a leaking fire ring. A compression test will show up valve sealing and piston ring problems only.

 

A leakdown test is more useful. In a leakdown test the cylinder is maintained at pressure by an air line and you get a chance to observe where the air goes.

 

The coolant anaylsis is probably the most definitive piece of info you have, however I connot emphasis enough how important it is to get this sorted before using the car again. You are talking about "lots of air" and "half a litre of coolant". The coolant was either never in there in the first place or is leaking. Both these situations will give rise to head gasket problems or worse (softened head, so scrap it and start again).

[Nick Woods]

Thanks for the updates

 

Peter, its going in to have the thermostat housing and water pump replaced tomorrow and then its having the cooling system pressure tested. I'll ask about doing a leakdown test at the same time

 

Unfortunately its already been driven a few times with me thinking it was all ok, so I'm just hoping that I've not done any lasting damage. The bulk of the air seems to come out from the radiator bleed screw although I obviously dont know how much is also in the head.

 

If the head is porous where would the coolant leak out ? Would it go into the cylinders or is there a route out which would allow the cylinder compression to stay up (assuming a leakdown test is ok) and also to not show anything in the coolant analysis ?

 

smegnoguk - we spent a lot of time looking at the rad last night but couldnt see anything. I hope that the pressure test will show up a problem if there is one. Thanks for the tip

 

Nick

Red and Black 1.6K supersport

visit Carrotland.co.uk

 

[Nick Woods]

ARRGGGHHHHH 🙆🏻 🙆🏻 🙆🏻 🙆🏻 🙆🏻 🙆🏻 🙆🏻 🙆🏻

 

ITS STILL BL *mad*DY DOING IT 🙆🏻

 

The water pump, thermostat and thermostat housing were replaced a few days ago, and the cooling system was pressure tested with no loss of pressure after 30 minutes. It was carefully bled and after two or three shortish runs of about 25 miles we spotted no leaks and it seemed ok.

 

I went to Stonleigh today and after leaving it for about 6 hours decided to check the coolant just to be sure it was ok. There was coolant, both dried and wet, all over the engine which appears to have come from the expansion tank and has been thrown everywhere. From the pattern of marks it must have happened while I was driving yet the temp gauge was fine all the time (75-80 all the way).

 

It took about half a litre to fill it up again although I suspect the vast majority of this is to replace what was thrown out when it boiled over

 

Bearing in mind its already had a coolant analysis (which was ok) and we cant see any obvious leaks, what could this be ? Is it the first sign of a head gasket failure or is there a leak somewhere that we just cant find ?

 

The only things I havent tried are a new expansion tank in case mine is weak (the cap is new) and bypassing the heater incase the valve is letting air in which is overpressuring the system

 

Nick

Red and Black 1.6K supersport

visit Carrotland.co.uk

 

 

Edited by - Nick Woods on 2 May 2004 21:57:52

 

Edited by - Nick Woods on 2 May 2004 21:58:26

 

Edited by - Nick Woods on 2 May 2004 22:02:49

[Nifty]

Nick,

 

Can't see that it would be a head gasket failure, otherwise the system would pressurise as soon as the vehicle was running. The tests you've done support this.

 

Did you inspect the car on arriving at Stoneleigh or just when you were leaving?

 

Give it a good long blat tomorrow before you turn up at the Cornwallis to try to replicate the problem then we can have a mass brain stormer with the evidence in front of us.

 

 

Keep off the straight and narrow 😬

[thinfourth]

Cap seal ? cap sealing face?

 

erm little people did it.

 

Blocked radiator fins coupled with dodgey temp gauge.

 

Blatting round aberdeen wondering wether to buy a jumper or heater

[Paul Ranson]

How full are you filling it?

 

Leave it idling and watch to see what happens?

 

Paul

 

Edited by - Paul Ranson on 2 May 2004 23:08:35

[stevefoster]

I can concur with Peter C about the compression test.

 

I helped Peter D on Saturday with his K. Similar problem. Pressurised system, expansion tank filling up and overflowing. He had lost coolant due to a heater hose problem before this started.

We tested the compresion no problems.

We bled the system with the nose very high running up to temp and thermo opening, no problems, some air then just solid stream of water.

Coolant at the correct level Peter went out for a drive.

Came back, same problem. Then we rebled with the nose high and the engine running hot from the blat. There was always bubbles in the system this time., I could not get a clean stream of water from the rad bleed screw.

 

Peter D will get a combustion gases in the coolant test (Rover do these test kits surprise surprise).

 

I reckon early head gasket failure on Peter D's car.

 

 

Hants (North) and Berkshire Area club site here

My racing info site

here

 

Edited by - stevefoster on 3 May 2004 00:17:15

[Nick Woods]

blatchat is great - I wasnt expecting any replies so late last night. Thanks everyone.

 

thinforth may be right - " little people did it". The cap is new but the tank isnt, I might just replace it anyway on the basis that a new tank shouldnt make it any worse. There are no signs of a leak from the tank until the boils over, which I'm assuming is the pressure valve in the cap doing its job.

 

Paul, its being filled to just over the halfway mark on the expansion tank and behaves itself when idling and after a shortish run.

 

I think Steve has summed it up perfectly, the symptoms he describes are exactly the same as mine (Peter emailed me last night to swap notes) The only puzzle is that my coolant test was negative but i'm now wondering if by checking just whats in the expansion tank they are missing the exhaust gas residues 🤔.

 

Nifty, you may be right but I'm beginning to wonder if its a very slow pressurisation because the gasket is only now starting to fail, such that on a 25 mile blat it doesnt really do anything. Only when given a longer run does it produce enough gas to blow the system up. I think I'm going to get it tested again to see of it turns up anything.

 

i inspected it at Stoneleigh after it had cooled for a few hours, fortunately I took some extra coolant with me to top it up. When I got home I took the bonnet off straight away to be confronted by it boiling over before me. There were coolant splashes all the way back to the bulkhead so it had obviously done it on the way home as well.

 

If the head was porous what would happen ? would gases get into the coolant or could coolant find its way outside the engine ?

 

 

Nick

Red and Black 1.6K supersport

visit Carrotland.co.uk

 

[Peter Carmichael]

Mr Foster, even if Peter D didn't have head gasket failure before, bringing the car up to running temperature without a pressurised cooling system is a damn good way to promote head gasket failure.

 

In this case the failure sounds like it had already occurred, but the procedure you describe is inappropriate - how many people bleed their engines to death in this way?

 

As a contrasting example, when Geoff Northcott (Miraz) completed his big engine project, I helped him bleed the cooling system - he had fitted an electric pump. We didn't have to have the engine running to circulate coolant. We filled with coolant and then switched on the pump - it was noisy with all the air bubbles and after a couple of minutes went quiet as the system self-bled.

[Nick Woods]

An update from me, and a couple of questions

 

Firstly, the coolant that had dried over the block was white, I always understood that PG coolants (comma coldstream) left no trace. Is this a clue ?

 

I bled a lot of air/gas from the radiator bleed screw, and bypassed the heater by connecting the pipe from the thermostat housing to the one that connects to the water rail. I refilled the system via the expansion tank and via the t-piece I have in the top heater hoses.

 

It may be my imagination but the excess coolant that was running out of the radiator whilst I was refilling didnt seem to look quite the same, it had a slightly milky look to it but it could just be a trick of the light and the fact that it was running over an alloy radiator making it look different.

 

Once I thought I'd filled it I started the engine with the bleed screw off and after a few burps it it started 'foaming' from the hole so I switched off.

 

I checked the coolant level via the t peiceand found it was a bit low, although I cant recall whther I double checked it before restarting so it may have been my fault

 

I refilled it again, this time i put the bleed screw back in once coolant started coming out and added more via the t-peice until it was full. I started the engine with the system sealed and left it for a couple of minutes, but definitely not until it was up to full temp, then left it a few more to cool. There was quite a bit of air in the top of the radiator when I checked it ☹️

 

I think my next step has to be to retest the coolant for exhaust gases but this time I'll get the sample taken from either the t-price or the radiator because i wonder if the coolant in the expansion tank isnt really circulating and the exhaust gases are building in the rad 🤔

 

Nick

Red and Black 1.6K supersport

visit Carrotland.co.uk

 

 

Edited by - Nick Woods on 3 May 2004 11:54:44

[stevefoster]

So Mr Carmichael, I am always willing to learn.

How do you do it?

 

The Caterham assembly guide on the Rover installation says,

f) The cooling system shoulf be filled with 33% antifreeze solution and carefully bled with the engine running and the bleed valve on the radiator loosened. The syem will hold approximately six pints. Raising the car at the front will help with the bleeding process. Fill the expansion tank approximately 1/3 full.

 

(Nothing about the temp that should be acheived of course.)

 

Plus Peter D's car was producing a lot of coolant displacement from somewhere before we tried a hot bleed as a method of diagnosis....

I should have added that we only had the bleed screw open a fraction so no great reduction in pressure.

 

I understand that there is a better Rover headgasket available that cures the frailty of this component that so many have seen. Not just a Caterham thing this, many Rovers have suffered it.

 

 

Hants (North) and Berkshire Area club site here

My racing info site

here

 

Edited by - stevefoster on 3 May 2004 13:12:12