Hi Guys,
A few weeks ago I re-entered the world of XM owenership - I have in the past owned two XM 2.0i, but this time I have bought myself a 1992 XM 3.0 V6si. It is showing 75000 miles on the clock and has a full service history up until June 2000.
When my wife was driving it home she realised after 20 miles that it was overheating (needle has JUST gone into the red), so we pulled over and got the AA to take us home.
After gleaning information from this forum I removed the radiator and back flushed it with a hose - this removed a serious amount of gunk! I also flushed the engine coolant system, and refitted the radiator.
I tried to refill the system in accordance with the Haynes manual and after a long search was unable to find the bleed screws as indicated! At this point I noticed the Haynes manual doesn't cover the 3.0 V6 engine!![:I] So filled the system as best as possible using trusty header tank method.
Everything seemed to work fine but on our first journey over 20 miles we noticed it was VERY SLOWLY creeping up on the temperature gauge.
This time went to check thermostat (fun job![xx(]) on inspection found that there was no thermostat fitted!!! so fitted one and filled the system again.
This time we got an hour away from home and yes ... you guessed it ... it slowly began to overheat!
Have now checked cylinder compression - all is fine. So removed water pump but cannot see any obvious damage.
So at this point I would REALLY appreciate any suggestions for anything else to check as I have run out of ideas.
Help me please.....
Moderator: RichardW
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VisaGTi16v
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I had a similar thing with my Visa before. Overheating constantly, back flushed radiator etc. However it turned out to be the radiator. After Carefully investigating when it was hot, only the top 1/3 was hot, the bottom 2/3 of the radiator was stone cold. So even though I had back flushed it, it was still blocked internally. New radiator fixed it (after head gasket went oops). I suggest feeling all over the radiator when its hot bearing in mind be Careful!! 
Well, you either have an air-lock, or a water leak !
Would a V engine have two bleed screws - one per bank ?
My Xantia currently drinks 4L of coolant ( currently water ) per day ( 90 miles ), I cannot yet find the source of the leak ( I can see it dripping ), although I don't believe the HG has gone.
Is there a puddle of water under your car ( don't confuse with aircon ) - check while stationary for a few hours ( turned off ), and then run it ( with plenty of water ) for a while, looking under the car for puddles.
Your symptoms are very strange, and would not point me in the direction of a missing themostat - I would expect the car to be constantly cold. Although, perhaps you have a shot radiator or top/bottom hose ?
Would a V engine have two bleed screws - one per bank ?
My Xantia currently drinks 4L of coolant ( currently water ) per day ( 90 miles ), I cannot yet find the source of the leak ( I can see it dripping ), although I don't believe the HG has gone.
Is there a puddle of water under your car ( don't confuse with aircon ) - check while stationary for a few hours ( turned off ), and then run it ( with plenty of water ) for a while, looking under the car for puddles.
Your symptoms are very strange, and would not point me in the direction of a missing themostat - I would expect the car to be constantly cold. Although, perhaps you have a shot radiator or top/bottom hose ?
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blueboy2001
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The missing thermostat is a classic sign that this has been an ongoing, and probably costly problem with the car and was more than likely the reason the car was sold. Somebodies obviously had a go at fixing the problem and decided its not worth the cost.
Get the car down to a garage and get the to pressure test the cooling system. About half an hours work or so, but it will show leaks or head gasket problems up quickly.
If that shows nothing, then you're looking at the radiator, an air lock or water pump trouble. The removed thermostat suggests its more sinister than an airlock. Its possible the previous owner had thrown a load of radweld or similar into the cooling system to stop it leaking, and has in fact blocked it up. Does the heater work inside the car? If not the matrix may be completely blocked.
Get the car down to a garage and get the to pressure test the cooling system. About half an hours work or so, but it will show leaks or head gasket problems up quickly.
If that shows nothing, then you're looking at the radiator, an air lock or water pump trouble. The removed thermostat suggests its more sinister than an airlock. Its possible the previous owner had thrown a load of radweld or similar into the cooling system to stop it leaking, and has in fact blocked it up. Does the heater work inside the car? If not the matrix may be completely blocked.
Have to back up on blueboy.
The radiator is not exactly cheap - but then again not a catastrophic expense.
I'd certainly spend a weekend running over ALL the coolant hosing/piping - ensuring none of these are kinked/blocked by gunk.
Especially when engine is warm - the rubber hoses gets soft and may kink.
It's known that the HG itself over the y's tends to gunk up in the coolant flow holes - causing much too low coolant flow through the cylinder head.
Was clearly seen on my latest HG replacement on a n/a 19diesel - and the obvious reason for the overheating problem failing the HG in the end.
If no damages yet - there is a chance the HG can be freed up in the flow holes - using a cleaning coolant like 50/50 water & household vinegar.
This requires the engine is never taken to the red for quite some time (weeks) - untill the system is cleaned out - and running the engine WITHOUT a thermostat.
The radiator is not exactly cheap - but then again not a catastrophic expense.
I'd certainly spend a weekend running over ALL the coolant hosing/piping - ensuring none of these are kinked/blocked by gunk.
Especially when engine is warm - the rubber hoses gets soft and may kink.
It's known that the HG itself over the y's tends to gunk up in the coolant flow holes - causing much too low coolant flow through the cylinder head.
Was clearly seen on my latest HG replacement on a n/a 19diesel - and the obvious reason for the overheating problem failing the HG in the end.
If no damages yet - there is a chance the HG can be freed up in the flow holes - using a cleaning coolant like 50/50 water & household vinegar.
This requires the engine is never taken to the red for quite some time (weeks) - untill the system is cleaned out - and running the engine WITHOUT a thermostat.
I wish I lived closer, that way I reckon I could win myself a lottery ticket here.[:D]
Here's a crystal ball diagnosis, based on experience and almost repeating what others have said.
My guess is that you have a partially blocked radiator which is causing the problem and this partial blockage has been caused by a leak in the system that has come possibly from the heater matrix; the weakest link in the chain.
I would suggest that someone in their wisdom has then poured a bottle of sealer into the system and this muck has done what it always does; coated the insides of your cooling system and is now acting as an insulator & not allowing the heat to penetrate the walls of the core of the radiator or the cool to make proper contact with the water....six of one/half dozen of t'other.
Have the radiator cleaned or replaced & that may solve <b>one</b> problem.
Next one is, will the matrix then leak? Assuming it doesn't at first, is it something that is going to need doing? MOST importantly though, is the head gasket slightly leaking & is this why the matrix leaked in the first place, due to increased pressure within the system??
I'm not trying to be a Jobs comforter, but that was the sequence of events that I discovered on a Ford/Mazda I owned which was showing identical symptoms.
A word of advice, again based on painful experience; get that radiator done ASAP as in my case, unbeknowns to me, my son took it for a reasonably long drive & that was when the head gasket failed properly; whether it was initially leaking, we never did get a chance to find out. That part for us became hypothetical so in your case, fixed soon enough, you may be lucky.
Alan S
Here's a crystal ball diagnosis, based on experience and almost repeating what others have said.
My guess is that you have a partially blocked radiator which is causing the problem and this partial blockage has been caused by a leak in the system that has come possibly from the heater matrix; the weakest link in the chain.
I would suggest that someone in their wisdom has then poured a bottle of sealer into the system and this muck has done what it always does; coated the insides of your cooling system and is now acting as an insulator & not allowing the heat to penetrate the walls of the core of the radiator or the cool to make proper contact with the water....six of one/half dozen of t'other.
Have the radiator cleaned or replaced & that may solve <b>one</b> problem.
Next one is, will the matrix then leak? Assuming it doesn't at first, is it something that is going to need doing? MOST importantly though, is the head gasket slightly leaking & is this why the matrix leaked in the first place, due to increased pressure within the system??
I'm not trying to be a Jobs comforter, but that was the sequence of events that I discovered on a Ford/Mazda I owned which was showing identical symptoms.
A word of advice, again based on painful experience; get that radiator done ASAP as in my case, unbeknowns to me, my son took it for a reasonably long drive & that was when the head gasket failed properly; whether it was initially leaking, we never did get a chance to find out. That part for us became hypothetical so in your case, fixed soon enough, you may be lucky.
Alan S
Mbunting,
If you have a bleed screw for your coolant system, warm the engine and then take off the bleed screw (carefully) put on an electric tyre pump and pressurize the system to about 20psi, I think you will find water will pump out of your radiator. I had a similar problem with my Xantia td, did the above and water pumped out. Cost a new radiator, but car runs better.
Paul
If you have a bleed screw for your coolant system, warm the engine and then take off the bleed screw (carefully) put on an electric tyre pump and pressurize the system to about 20psi, I think you will find water will pump out of your radiator. I had a similar problem with my Xantia td, did the above and water pumped out. Cost a new radiator, but car runs better.
Paul
Many thanks to everyone so far on this problem[:D].
I have now removed the radiator from the car and as a simple test I ran hot water through it and sure enough the majority of the radiators surface was cold to the touch[:I]. At first I could not even get water to come out of the drain plug at the bottom, now after much flushing and back flushing when I fill the radiator up with hot water it feels uniformly hot across its entire surface.
I now intend to refit the radiator to the car, then I am going to follow AndersDK's advice and fill the system with a vinegar water solution for a week or two. Flush the system again and re fill it with a 50/50 coolant water mix.
If anyone out there has any other suggestions then please let me know as I am still very open to new ideas.
Once again thanks to everyone so far for their advice.
I have now removed the radiator from the car and as a simple test I ran hot water through it and sure enough the majority of the radiators surface was cold to the touch[:I]. At first I could not even get water to come out of the drain plug at the bottom, now after much flushing and back flushing when I fill the radiator up with hot water it feels uniformly hot across its entire surface.
I now intend to refit the radiator to the car, then I am going to follow AndersDK's advice and fill the system with a vinegar water solution for a week or two. Flush the system again and re fill it with a 50/50 coolant water mix.
If anyone out there has any other suggestions then please let me know as I am still very open to new ideas.
Once again thanks to everyone so far for their advice.