Coolant blowing out!

[Citroen Surf Bus]

Hi, my coolant is over-pressurising and escapes at the filler cap (tried new cap).

Can this be caused by an air lock (bled the bleed screw) or does it indicate head gasket failure? (Don't coolant/combustion leaks usually push coolant into the chamber and out the exhaust rather than the reverse?

2003 Relay van 2.2hdi turbo.

[RichardW]

Cooling systems don't spontaneously get air locks...

Check for HG fail: Engine cold - is there pressure in the system still? Start engine, run for 30s, stop and check - pressure in the system? If answer to these is yes, then HG is away I'm afraid - and I'm pretty much certain this is what you will find.

[ekjdm14]

Sorry to say, but I do think this is likely HGF symptoms It's possible for the gasket to fail in many different ways with differing symptoms, some will burn oil or coolant through the engine, others will mix oil and coolant, others still will just pressurise the cooling system (this is likely the early stages of a breach between cylinder/water jacket, eventually it'd begin ingesting coolant as well).

Just to confirm it though, as well as Richard's pressure check you can either have a friendly local garage put their emissions probe into the header tank (not into the actual coolant, just the airspace) and "sniff" for combustion gases, or you can buy "block tester" kits online that you add to the coolant & it changes colour if exhaust gases are present in the coolant. If you're familiar with how your coolant usually smells you can even sniff test it yourself, I've found this easier with petrol engines but it's possible to smell diesel exhaust fumes in the header tank too.

(I had a Supra a while back with a particularly early HGF symptom, I could fill the coolant & bleed it & the engine would idle/rev gently forever without the level changing or making any airlocks, but as soon as I opened the throttle wider and made any sort of boost the coolant would just well up and fountain out of the radiator cap in seconds. I kidded myself that it was a cracked turbo for about a week before accepting I was having the head off. I'd bet the HDi is an easier job than a 7MGTE though so don't be too upset, I rebuilt that on the driveway over winter single handed and it turned out fine)

[dumpvalve]

hello ive had a early c5 2.2hdi with the same issue and deffo was the head gasket, you can try steel seal its worth a go , it dident work on my c5 but has saved my Audi 2ltr tdi and worked 100% for around 2 years now

[Citroen Surf Bus]

Not good news but great replies all the same, thankyou!
Steelseal is interesting, but Im pretty sure it can only work if coolant is escaping INTO the combustion chamber.

[Citroen Surf Bus]

Dumpvalve - what were the symptoms that Steelseal cured on your Audi?

[dumpvalve]

If you know anything about Audi there are certain models that Audi new had porous cylinder heads.. Namely the 2lt 2003 PD engine,, so one day the wife phoned to say the engine would not turn over, I went and new that one of the pots had filled with coolent, this fix is brilliant... Put in 5th gear very very slowly rock the car backwards and forwards slowly pushing the coolent out of the cylinder.. The car should then start and it did.. Buy steel seal.. Follow the instructions on the steel seal.. In 3 years I've had to do it again but if you put up the expense of a cylinder head from a later year Yr talking thousands of pounds against 40 quid steel seal.. On of c5 I got my money back from steel as it did not work

[Gibbo2286]

SteelSeal is snake oil as far as Citroen are concerned, I've had a few customers try it and it simply doesn't work, it also leaves a white crust on the paintwork under the bonnet when it boils out that's really difficult to remove completely.

[Peter.N.]

I had a Citroen CX diesel with a porous block and the only thing that would work with that was a new head gasket about every 15k. I did that for 150k +.

Peter

[dumpvalve]

It didn't work on my 2.2 hdi,, but it has 100% worked on my Audi it was a case of scrap valve or try steel seal,, if it doesn't work and you have the receipts for the new head gasket you can get Yr money back as they say money back guarantee.. They sent me a cheque once I sent them proof of new head gasket

[dumpvalve]

On the Audi it went at 115000 and now has 135000 so that's not bad for steel seal and uses absolute no coolent

[Citroen Surf Bus]

As I suspected. The leak has to be coolant into combustion chamber for SS to work: as the coolant is pulled in the flame crystallises the silica to block the leak.
Maybe the Citroen had the 'wrong' type of leak?

[Peter.N.]

Sounds interesting, wonder if it would have worked on my CX, that was over 20 years ago mind.

Peter

[dumpvalve]

just to be honest about this guys I'm not telling people to use SS just in the odd case it does really work, so in 20000 miles ive had to repeat the SS at a cost of just £80 for 2 bottles, but you have to take into consideration that I would of have to buy a later date complete cylinder head and evidently the cost of a mechanic then doing the outways the cost of a 53 plate Audi A3 TDI ... please be aware of buying any AUDI/ VOLKSWAGON, with the engine code BKD... I wish some one had told me before I bought mine , my local garage tells me that they have more issues with these engines than any other, Audi new about it but will not do anything about it , my C5 PSA 2.2 hdi is a brilliant engine compared to so called bullet proof Audi engines, this does not apply to the early 1.9 PD, I believe its only 16v 2ltr BKD from 53 to around 55, I'm on the Audi forum and everyone knows about it

[Peter.N.]

All the Hdi's are brilliant engines - except possibly the 1.6.

Peter