I would appreciate informed opinions on the possible causers of a loss of cooling water only when the engine is running. The car is an 8 value 2Li Cavalier. So far the car has had the cylinder head gasket changed plus a new header tank all hoses & radiator checked in an effort to solve this problem, yet the car still users about 300 ml of water in 25 miles.
The car can stand for a week without water loss. There is no evidence of any exturnal leak during and after a run. The system appears to be under full pressure when hot and stays so until cool! The car runs well, but continues to use water! I should perhaps mention that flushing and RadSeal has been tried.
Has any one out there experience a similar problem?
Any suggestions as to the possible cause and or investigations that might reveal the reason or culprit would be much appreciated. My thanks in anticipation Nikki
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ONly way to check this is to run the car for 25 miles, pull over while its still hot and try and see where the leak is coming from. If the car has proper antifreeze mix in it you will smell the hot fluid if its ;eaking. Keep the engine running to see if it only leaks when running, but KEEP CLEAR OF HOT PARTS, BELTS and FAN
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Was the head gasket changed due to overheating? If so; was the head skimmed at the same time? If not then I would still suspect the head is slightly warped. If the gasket was chanegd for some other reason then another favourite on most cavaliers is the water pump bearing (hidden behind the plastic cambelt cover).
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Ideally when head is off it should have a skim and pressure test (about £60).
Take it to a local MoT test station and let them wave their 4-gas analyser probe over the header tank. If HC is detected then combustion gas is getting into the system and you have a head blow/crack. If no gas detected then you are looking for external leaks (w/pump, heater matrix, rad. etc. etc.).
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"The system appears to be under full pressure when hot and stays so until cool! "
If the cooling system is still under pressure when cold (try it in the morning, but do not open it the night before - you might be confusing sucking in for blowing out) then the head gasket is still leaking, or there is a crack in the head or block. You will probably find there are lots of little bubbles rising into the header tank when the engine is running also.
RichardW
Is it illogical? It must be Citroen....
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Richard:- Plus al the others who came up with good ideas about my cooling problem. I have now established that it is a cracked cylinder head that is causing the cooling circuit to suffer from over pressure and water to be blown out of the exhaust!
The leak is only at the rate of a cup full per 50 miles.
A colleague who works at a transport company tells me of an additive that cures \'cracked heads\' on Diesel engines and suggests that it might also work on petrol engines.
The material is called DAVMAC and they, the Transport Company, have some success in using it on two trucks but not on a third. Does any one out there have any experience of the material and method?. If so I would appreciate your comments since I am reluctant to take off the cylinder head for a third time. Regards NIKKI
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If the head is not off, how have they 'established' that it is cracked. The only sure fire way of knowing is by pressure testing and / or visual / x-ray inspection. If they have changed the gasket again without testing, found it still leaking and pronounced the head cracked I would find another garage!
I have not heard of anything that might 'mend' a cracked casting - at best it would be a temporary measure. It might be possible to have the head cold stitched or welded, depending on where the failure is and how serious it is. I do not know the cost of this, and how it relates to the cost of a new / re-con head. Your ultimate route might be to replace the whole engine - I'd imagine you could pick up a used Cavalier engine with some sort of warranty for not all that much money.
RichardW
Is it illogical? It must be Citroen....
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nikki
If you don't top it up, does the car continue to lose water?
It's common for cars to shed excess coolant before stabilising at a level. My BMW does just this. Top it above the mark, and it makes its way down to the mark over a couple of trips, and then stays there.
Regards
John S
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The 'Dynamic cooling problem' has gone off the page, therefore befor I for get my manners. Many Thanks for your suggestions, they have been taken on board! Nikki
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My I remember to say a sincere Thank You! to the five'experts' who took the trouble to reply to my question on 'Dynamic Cooling'
Once again Thanks Nikki
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John S's point reference to systems 'finding' their levels is one not to be ignored. I can recall two or three cars on which this happens, with no ill-effects whatsoever. FYI, all are PSA Diesels!
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Don't forget the pressure release valve on the radiator cap (the cap that sits on top of your expansion bottle). If steam is coming out of this, then you may simply have an airlock in your system or it may be over pressurised for some other reason.
H
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Nikki,
Only just got to see this. One of my previous Cavaliers kept losing coolant only while driven. It would drain the header tank on a 25 mile journey. No evidence of fluid on the ground or around the engine block. It turned out to be a leaking head gasket and the coolant was being blown straight out the exhaust pipe. I drove the car 3 weeks like this before the garage could fix it. In that time the pressure of the coolant cut a small channel into the aluminium head, thus needing it skimming. The thing I did notice was an increase of steam out of the exhaust (it was winter) and a small increase in performance which is the last thing you want when trying to drive steadily until the garage could fix it. The increase in performance was down to the water being pushed into the exhaust system. It cooled the exhaust gasses and acted like a simplified turbo.
Anyway, the garage diagnosed a head gasket problem by measuring carbon monoxide in the cooling system.
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Dynamic Dave
Many thanks for taking the trouble to interrogate the 'nearly archived pages' particularly mine about the Dynamic Loss of Coolant. your description exactly matches my proble on my Cavalier. It's nice to have a evidence of a directly analogous situation and its cure.
Obviously the head has to come off again and an investigation be carried out to ascertain the if I to have a grove in the cylinder head.
My thanks for replying Regards regards Nikki
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Nikki,
The simplest way is to get the garage to test the coolant to see if carbon monoxide, (exhaust gasses), are present. That was how mine was diagnosed as a head gasket failure.
With regard to the cylinder head, there *could* be a hairline crack between an exhaust port and cooling duct.
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Its difficult to detect CO in the coolant - it goes into solution with the water to form carbonic acid. Ask the garage to test for hydrocarbons (HC) - they should show up on the 4-gas analyser.
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Carbon monoxide (CO) is insoluble in water, carbon dioxide (CO2) is soluble and forms carbonic acid.
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Dynamic Dave. The object of this note is to report the solution to the loss of coolant whilst driving. It took three attempts, the last one involved changing the cylinder head for a S/H one from a scap yard. Unfortunately this head needed some work, one of the valve spring was broken and it must have been running on poor fuel the valves were crudded up and in bad condition.
No matter alls well that ends well and at 8 pm this evening I took the car out for test drive -- Its now back to its old self running as sweet as a nut. The way I proved that exhaust gas was being forced into the \'water circuit\' was to over fill the header tank and watch the bubbles leap out. At the standard level fill the venting pipe is about the water level!
When the old head was examined the chamber nearest the distributor showed small white spots on & around the valves. No visible crack could be detected, but the car now goes fine and no bubbles emerge from the header tank. Total cost to repair £54.plus the cost of a torque wrench. My thanks to all those who took the trouble to give me their opinion. This matter is now closed Regards Nikki
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