Complete Coolant Loss

[Guest Peter07]

Oct 2005 2.2 C5 VTR HD estate 43,000 miles

 

Yesterday 6 miles into a trip the warning message saying STOP and Overheating were displayed. Luckily was able to pull off within 1/2 mile. On opening the bonnet there was the unmistakable smell of hot water, corrosion and antifreeze (once smelled, never forgotten) Eventually found that the cooling system was completely empty but there was no obvious leak either from the main radiator/hoses or internally from the heater matrix. When cool I filled the system and looking underneath there was a steady drip from somewhere running off the plastic sumpguard (undertray) so not able to see where it was actually dripping from. Starting the engine increased the flow to a fast dripping and no difference noted whether filler cap was on or not; there were no bubbles coming up through the expansion tank and the level fell quite quickly.

 

Those are the symptoms, what about the diagnosis?

 

To cut a long story short I hadn't a clue what was happening but eventually found that there was a leak from a fitting going through the bulkhead and heading in the general direction of the heater. (Climate Control fitted). This is where I need some help. On the engine side there are hoses running from both fittings each into one side of the block, low down. (I am presuming these are flow and return from the heater matrix?) On one of them just before in disappears through the bulkhead is a right angled black plastic fitting maybe 1/2 inch diam.and on the top of this is a small plastic outlet about the size and shape of a tyre valve and it was from here that water was coming. There was what looked like a valve cap covering it and when I touched it the top of the cap came away. I screwed off the remainder and it did indeed look exactly like a valve cover so I replaced it with a new one and the leak stopped. I have only driven it for a journey of 24 miles since doing this and there is no further leak and the coolant level remained right on the mark.

 

Can someone help me to identify this part. Facing the engine bay from the front the fittings concerned are just to the right of centre and a few inches down on the bulkhead. It is very difficult to see and is partially covered by other pipes and cables running in front and above. If anyone would like a photo of the offending part to help identify it I can forward them if you email me.

 

I think it may possibly be some sort of pressurising/filling/draining etc valve but I am only guessing. If that is the case then the "valve" itself has failed and the only thing keeping it from leaking is the valve cap!

 

The other thing I have noticed, and I don't know whether it has any significance or not, is that there doesn't seem to be any pressure build up in the cooling system and even after I had driven for 20 odd miles the filler cap came off without any hint of pressure.

 

Sorry for such a long text but if nothing else it may point somebody in the right direction in future if they have an unexplained loss of coolant. If someone could enlighten me though it would be good.

[coastline taxis]

The part your describing is a bleed valve for bleeding the cooling system. sounds like its just come loose when engine is cold pour water into filler and slacken the valve of again till you hear and see all the air come out then a bit further down the engine theres another bleed screw on one of the main water hoses slacken that one of till you hear and see all the air come out again. Now start engine up and allow to idle till you hear the fan cut in 3 times. Allow to cool and check level in expansion tank and top up if needed. Sound like its just been one of them daft thing and nothing to really worry about

best regards

steve

[Guest Peter07]

Thanks for the quick response Steve.

I think you are spot on with your answer but the only other bleed point I can see is on top of the thermostat housing, the only difference is that the cap is blue rather than black, but I assume this is the one you mean.

 

Just to make it clear though the cap on the bulkhead bleed valve had not come loose, the top of it had sheared right off (If you took a Stanley knife to a valve cap and sliced off the closed end, that is what I had.)

Although it now seems to be holding water I am wondering if there was an underlying problem that made the top shear off (high pressure?) or whether it was a faulty cap, perhaps cracked by overtightening when the car was built, or just an unlucky chance. Any view on that?

 

The other question I now have is I now have a cooling system full of 100% water and I am going to the agents today to get antifreeze. Is there a way to drain (half) of the water from the system using these valves or do I need to undo the radiator hose as I have in other cars?

 

Many thanks, Peter.

[coastline taxis]

Im not saying the following is what caused it but its plastic and heats up and cools down so it could of just become britile and failed or could just be defective. just noticed yours is 2005 so that will be the other bleed screw as for draining just undo the bleed nipple on the bottom of the radiator and remove the expansion bottle top. Then just top up and bleed

[Guest Peter07]

Thanks for that Steve, that is what I expected you would say, but I thought I would make sure.

 

Because it is Citroen I probably needn't ask, but why on earth don't they use METAL valve caps - given that the consequences could be serious. I will change both mine to metal anyway, about 5p versus the cost of a warped head, no contest.

[coastline taxis]

there is no valve inside of it so if you use a matal cap onto a metal casing chanches are youl get a leak as metal to metal dosnt seal so your stuck with the plastic one. also theres the corrosion issue with the cap seizing on

[Guest Peter07]

there is no valve inside of it so if you use a matal cap onto a metal casing chanches are youl get a leak as metal to metal dosnt seal so your stuck with the plastic one. also theres the corrosion issue with the cap seizing on

 

It is actually a plastic housing so it was plastic to plastic.

[ando7p]

Could be just as bad. Metal to plastic. Different expansion rates and given the relative amount of heat in the area I would not be confident that a metal valve would stay tightly screwed down and not work its way loose over time.

[Guest Peter07]

Could be just as bad. Metal to plastic. Different expansion rates and given the relative amount of heat in the area I would not be confident that a metal valve would stay tightly screwed down and not work its way loose over time.

 

Thats 2 experts saying keep plastic, so good enough for me.

 

As a matter of interest you will note earlier in this thread that the offending article looked exactly like a valve cap, and I put a new one on and the problem was fixed. I was passing the local dealers today so I thought I would call in and see what they said about losing all coolant like this. The answer was "it happens" really helpful. He also said I should have used the correct replacement part and not a valve cap, though he couldn't say why, so I said OK have you got one, he had at £1.93. Had a look at it and if you asked 1000 people what it was they would say a valve cap. Honestly there is no difference at all. We are all used to main dealer price rip-offs but almost £2 for one plastic valve cap? Anyone got a better ripoff than that?

 

So, if it happens to you, you know what to use.

[coastline taxis]

I stand corrected. Also im assuming that the difference in the caps will be on the inside and would hope that it has some kind of seal in it. You should send a email to techbod as he just loves storys of dealers and will probally go and burn them down for you ha ha

[myglaren]

The plastic caps have been replaced with thin metal ones as they were found to expand and leak.

 

Mine did on it's last MOT, the tester was lucky to get out unscathed, when I collected the car the pit was full of water and they had taken the cap off one of the (new) tyres and substituted it for the missing one.

 

I suspect that they had revved the guts out of it for the smoke test then stopped the engine without allowing it a minute to settle down.

 

It continued to leak for a while afterwards and I fitted a new metal cap since which it has been fine.

[Guest Peter07]

The plastic caps have been replaced with thin metal ones as they were found to expand and leak.

 

Mine did on it's last MOT, the tester was lucky to get out unscathed, when I collected the car the pit was full of water and they had taken the cap off one of the (new) tyres and substituted it for the missing one.

 

I suspect that they had revved the guts out of it for the smoke test then stopped the engine without allowing it a minute to settle down.

 

It continued to leak for a while afterwards and I fitted a new metal cap since which it has been fine.

Very interesting, who said they had been replaced, your dealer? Mine certainly are still selling/fitting the plastic ones and said they had never heard of a metal one. I am surprised that there haven't been more incidents through this piece of terrible design.

[Guest Peter07]

The plastic caps have been replaced with thin metal ones as they were found to expand and leak.

 

Mine did on it's last MOT, the tester was lucky to get out unscathed, when I collected the car the pit was full of water and they had taken the cap off one of the (new) tyres and substituted it for the missing one.

 

I suspect that they had revved the guts out of it for the smoke test then stopped the engine without allowing it a minute to settle down.

 

It continued to leak for a while afterwards and I fitted a new metal cap since which it has been fine.

Meant to ask in my last post but does anyone have a figure for the capacity of the cooling system? Sounds daft but my handbook and service guide have no mention of it but, very useful this, tells you the capacity of the screenwasher. I asked my dealer when I went for some antifreeze to refill my empty system, bloke in parts said he didn't know and went away to ask someone, came back and said we don't know but the mechanic says he always uses 3 litres of antifreeze to completely refill a system! So, if the ratio of water to coolant fluid is 50/50 this suggests a total capacity of 6 litres? Seems a bit on the low side to me, anyone help?

As a point of interest they supplied me with Antigel as the correct antifreeze but given their track record of useless answers can anyone confirm that this is the right stuff?

[myglaren]

Very interesting, who said they had been replaced, your dealer? Mine certainly are still selling/fitting the plastic ones and said they had never heard of a metal one. I am surprised that there haven't been more incidents through this piece of terrible design.

 

Yep, the one that posts here.

[mlkey]

Yep, the one that posts here.

 

Common misconception about these valve caps... The original poster said the top of the cap had come off, leaving just the threaded body... a classic symptom of overtightening, which probably goes back to the last person that changed the coolant on his car! These caps do not need to be mega tight, just done up until they start to pinch, then a further 1/8 of a turn for good measure. If you use metal, there is every chance the same attitude to tightening will result in stripped threads on the hose or thermostat housing.

[myglaren]

True enough, as with most fasteners and threaded widgets.

[Guest Citroen CT]

ensure you use a valve cap with a rubber seal inside most valve caps don't have this seal,as this could lead not to a leak but to air coming into the system,when the system heats up then cools the pressure difference can cause poor sealing components to drag air into the system without having coolant leak out which eventually leads to a head gasket misdiagnosis.

i am speaking from experience within the dealer network.

 

there is no valve inside the component and is solely use for bleeding the system at the heater matrix the cap is the only seal

[kfk]

I would also pass comment that it isnt a good idea to use tyre valve caps on the cooling sytem except in an emergency, the part supplied by citroen to do the job has a resistance to antifreeze and will have been tested to ensure it can cope with extremes in temperature.