High Pressure Coolant System/Possible Head Gasket Failure

cyclonebri1

MikeH99 wrote: »

Sounds feasible. But in that case of gasket failure between cylinder and waterway interfering with the water system pressure, wouldn't you also be experiencing difficulty starting and lumpy running due to water also leaking into the cylinder, plus constant white smoke out of the exhaust rather than just when the engine is cold? Not to mention slow but steady water loss.

If angel00079 is experiencing these things too, I'd agree it's head gasket no question.

Read what the op said about the original garage diagnosis, head gaskets can fail catostrophically or gradually.

credit_crunch_victim

the hose was split surely it is worth giving it a little run first before shelling out loads of money on it

ozvaldinho

It sounds to me like you may have a failing gasket or possibly a cracked/porous cylinder head. The chances are that the problem is around the exhaust valve area, this is why you're not seeing a leak or water in the oil...it's probably being blown out the exhaust. You may notice the white 'steam' in the exhaust fumes and possibly a smell of coolant.
If this is the case, they'll need to strip the head down, replace the gasket etc. Normally you'd need to get the head sent off for pressure testing.
I'd think carefully about the cost of all this, it can be a fair amout of labour and parts, not to mention subcontracting the pressure test out to an engineer. I wouldn't do this on a 176k Citroen.

Keith

MikeH99 wrote: »

Sounds feasible. But in that case of gasket failure between cylinder and waterway interfering with the water system pressure, wouldn't you also be experiencing difficulty starting and lumpy running due to water also leaking into the cylinder, plus constant white smoke out of the exhaust rather than just when the engine is cold? Not to mention slow but steady water loss.

If angel00079 is experiencing these things too, I'd agree it's head gasket no question.

Pressurisation of the coolant system is a sign of head gasket failure, I guess it could lead to a pipe bursting or a pipe could reach the end of it's life and a small split could lead to it bursting.

Limey

Surely a split pipe will result in air getting into the system and the coolant boiling due to this?

The best way as far as I know of diagnosing head gasket failure is to get a 'sniff test' done. This is done simply by holding the hydrocarbon monitor, that the garage use for exhaust emisions, over the warm coolant. If it registers any HC then the gasket's gone as there shouldn't be any hydrocarbons (unburnt fuel/oil) in the coolant.

jumpingjack09

Have you tried using k-seal? Its only £10 and can actually seal a head gasket as long as it not completely gone i have used it before and so have people i know and it has worked for them you can buy it from any good motor factor store. Basically you just add it to your cooling system bring the car to operating temperature and it seals it permanently.
By the way i spoke to an AA man when i broke down before and he said he had a case of it on his van so must be pretty good if they use it.

One question though is the car still overheating and did it overheat in traffic? The only reason i ask is that your radiator fan switch may be deffective so your coolong fan my not be cutting in, if its was me i would still chuck in the K-seal as a for a permanent repair for £10 cant be bad and as long as it stays in your system even if your head gasket hasnt gone if it ever does it will repair it.

MikeH99

cyclonebri1 wrote: »

Read what the op said about the original garage diagnosis, head gaskets can fail catostrophically or gradually.

Indeed. But if cylinder pressure is getting into the water, even just slightly to start with, then water will also quite likely be getting into the cylinder.

You then see rough running and extra white smoke. It only takes a small amount of water in the cylinder to cause lumpy starting and is particularly noticeable at first time starting of the day.

Let's not forget that the coolant system is always a high pressure system when the engine is running, and hose failures on older cars are not unusual.

I remain far from convinced there's anything more wrong with the op's car than has already been fixed.

credit_crunch_victim

i am with you mikeH99

cyclonebri1

Mike I corrected you on the technicalities of head gasket failure, not whether I thought the gasket had gone or not.

This came up in post last week regarding how long/how much work is required to diagnose a failed head gasket, (or something more serious that required the engine to be split anyway).

The answers the same, 1/2hr is enough time/cost to do a compression test and a snifter test on the car. The compression test tells you where the problem is and the snifter confirms combustion fumes in coolant. Therefore no major cost and no scatter gun approach needed.
Any garage that can't do that in that time should be avoided;)

Quote;
"But if cylinder pressure is getting into the water, even just slightly to start with, then water will also quite likely be getting into the cylinder."


Not true, unless it's a complete failure, and from the symptoms the op has described it clearly isn't. The combustion and compression pressure are much greater and will ensure the water system is pressurised. Even if a minute amount of water entered the compression chamber under induction, it would actually aid combustion and cooling. Which is why high performance cars make use of water injection.

MikeH99

cyclonebri1 wrote: »

The combustion and compression pressure are much greater and will ensure the water system is pressurised. Even if a minute amount of water entered the compression chamber under induction, it would actually aid combustion and cooling. Which is why high performance cars make use of water injection.

I'm reading your comments with interest, and I've certainly learnt here about the 'snifter test' which I hadn't heard of before.

In relation to the above, however, I could understand this may be the case when the engine is running, but can I ask what about the situation when the engine stops? Surely pressure in the cylinder drops almost immediately, yet water pressure remains high for some time - or at least a longer time - until it cools. This is when, if there were a gasket breach, water would find its way into the cylinder and make itself evident in the ways I've described.

Also, we're talking about a diesel Citroen Xsara on 176k here ... not a "high performance car" that I agree probably wouldn't be bothered by a little water in the cylinders. It would, however, be noticeable in the Xsara. If there were a head gasket problem.

all the best,