Wierd Coolant Loss !

mbunting · Post by **mbunting** » 21 Feb 2003, 17:46

Over a month ago, I replaced the thermostat and coolant on my Xantia 1.9TD.
On Tuesday, after a particularly cold night, I noticed a mark on the driveway. Got in the car, and drove to work.
On my way to work ( about 20 mins into the journey ), I noticed the car wasn't warming up particularly well.
Heater Matrix, I though <img src=icon_smile_evil.gif border=0 align=middle>. Anyway, got to work, and at lunchtime, topped up the water at the local garrage ( proper tap stuff, none of this essential stuff you're supposed to use ! ).
When I say 'topped up' please read 'filled from empty'.
Expecting to hear a flood of water underneath the car as I'm filling up, I hear nothing. There is also nothing underneath when the engine is running ( apart from oil from the plug <img src=icon_smile_wink.gif border=0 align=middle> ).
Since then, I 'only' seem to be loosing about a litre per 36 hours or so, and getting nice and warm in the car. The temp stays where it should be, and all 'seems' well ( as well as normal )
What the hell happened, do you recon ?

tomsheppard · Post by **tomsheppard** » 21 Feb 2003, 18:21

Water loss on the TD seems to have but one cause. Assuming that the system is properly bled, the radiator is nice and warm all over and that the new stat has not failed or started leaking at the joint which you will have checked then I would guess that the coolant loss is our old adversary the head gasket. There are enough threads on this subject to reconstruct the Bayeux tapestry, certainly I have been bothering people with similar sounding problems since last December. Look a few over and compare notes. The classic test is the Start from stone cold, run for 30 seconds and lift the rad cap. water under pressure? head gasket for sure. At least the problem doesn't seem too severe on yours. If it is the gasket, you have a good chance that the head is undamaged because you spotted it right away .

mbunting · Post by **mbunting** » 21 Feb 2003, 19:50

Tom,
If it was the head gasket, where would all the water have gone [?]
Bearing in mind it dumped the water when the engine is turned off, and OVERNIGHT, where would the water below the gasket level have got out ?
I'm going to do the test in a moment, and I'll post back soon.
Mat.

rory_perrett · Post by **rory_perrett** » 21 Feb 2003, 20:13

Had something similar on a 95 1.9TD. From the amount of coolanft I was loosing I would have expected to see pools under the car but there weren't any. I was convinced it was the head gasket. Turned out to be a hole in front of the radiator which I couldn't see as the intercooler was in the way. The previous owner had obviously had a problem and dumped in a load of radweld which finally started to fail.
Unclip the rad and have a look before you start having sleepless nights over a head job.
Best of luck
Rory

tomsheppard · Post by **tomsheppard** » 21 Feb 2003, 20:43

Well, if it isn't there then it has to go somewhere. I suspect that the pressure building up in the system is blowing the water out through an overflow at the filler. Potentially the pressure cap may have failed. Remember that the level in a hot engine will seem higher than that in a cold one because the water expands to take up some of the air space. That being said, How certain are you that the water only leaks away at night? BXs to my knowledge for instance force steam down the by pass hose to the opposite side of the radiator and inhibits the circulation. the steam pressure forces the water out as its expansion ratio is so huge. This can push all the water out of the cooling system, even below the gasket face.Stop the engine and the absence of circulation causes water near boiling point to boil. Steam pressure does the rest.

mbunting · Post by **mbunting** » 21 Feb 2003, 21:54

Well, I released the cap, no pressure. Put it back on and started the engine. Left it to run for approx 2 mins, stopped it, and removed the cap. There was no pressure hissing.
I have a suspision that the radiator is up the duff. My reasoning is that a few months ago, I noticed a slight build-up of what looks like calcium at the bottom of the radiator.
I'll fill it back up again before I leave work, and secure a bottle to collect any stuff from the expansion tank overflow.
Let you know later.

sooty · Post by **sooty** » 21 Feb 2003, 23:50

A simple way of testing whether you think you are losing water through the overflow with a suspected head gasket fault.
Place a plastic bottle/container of a size to fit under the bonnet somewhere safe and secure, then place your overflow pipe into it.
Its best not to do this when you have freshly filled the rad as you may get excess coolant anyway till it settles down. Try running the engine till the thermostat opens and a few minutes, then place your pipe into the container and go for a run as you did when the coolant loss occurred and see if any coolant of a large amount is in the bottle, this would indicate a pressured system by a head gasket failure.
This I learn't years ago in the heavy haulage trade.
Good Luck
sooty

mbunting · Post by **mbunting** » 04 Mar 2003, 01:00

Quick update.
No overflow from exp tank into bottle.
Topping up 1.5l per week.
High speed running tonight, dumped the lot. Didn't notice. Temp @ 100.
- Both fans working.
- Radiator stone cold all over.
- Top hose HOT.
- Exp cap COLD.
- No water on-board ( will be now ! ) - limped 3m home and filled.
I think first thing on my list will have to be the water pump ( during cam belt change ). Any other thoughts ?
There doesn't appear to be leakage through visible hoses, and when full, the heater matrix is working, no leaks inside the car.

alan s · Post by **alan s** » 04 Mar 2003, 02:03

This is starting to sound like one of two things;
An air lock is the most likely or secondly a dodgy thermostat but my guess is the air. Somee of these things can be absolute dogs to get the air out of and I think yours would have to be one. Chances are it has a problem that caused the air in the first place which may become more evident once the air is out of the system, but I once struck this on a CX we had years ago & it almost drove us beserk until one day, right out of the blue we cured it & the problem has never resurfaced.
Amongst tips for ridding a stubborn system of air is to park on an angle or incline so as to get the filler cap higher than the heater matrix top, overfill initially & keep it that way until you are finished bleeding & then adjust coolant level via the bleed screws, using a makeshift header tank so as to increase the height of the coolant being fed into the system, squeeze the hoses when you think the system is almost bled so that they create a pumping action & eject the air/coolant mix & tighten bleeder whilst squeezed in, followed by further squeezing until nothng but solid coolant without bubbles is felt in the hoses particularly top & bottom hoses. Be sure that the heater control is set in the hottest position throughout the whole bleeding & refilling procedure!
Give that a try before you engage in any major surgery; you might save yourself a lot of time & money or at worst, find out what caused the problem in the first place.
Whoops nearly forgot; you say you replaced the thermostat, was there any good reason for this & was this problem evident before you started? If not I suggest you remove that thermostat & test it before you start. This is done by placing into a pan of cold water & bringing to the boil. Just before boiling, the thermostat should start to look like it's trying to turn itself inside out. Themostats are a notoriously unreliable antiquated piece of machinery and buying a dodgy one isn't unusual. When I was working in a Jap car franchise years ago, I saw the foreman wade through boxes of them looking for one that wasn't faulty. He found on average, 3 to the box that were 100% Things have improved since then but the principle is still the same.
Alan S

sooty · Post by **sooty** » 04 Mar 2003, 03:12

Matthew,
You say that, you have lost no coolant into a bottle from the overflow pipe from the filler cap doing as I suggested. Yet you say you are putting about 1.5 ltrs into the rad. Your sure you have no external leaks or signs on the floor etc. You may have a Water pump seal failure leaking when the motor is running and the system under pressure. As for yor radiator being stone cold, yet the top hose is hot and the bottom cold, suggests the radiator is partially blocked, not allowing flow through.
As for bleeding the 'Haynes' method has always worked for me. Get a bottle/container with a neck thats a good fit with some tape around it to seal it into the header tank, cut the base of the bottle so its about 6"/ 150mm above the filler neck. Fill the bottle and then open the three bleed screws one at a time, one on top right of the rad, one on the heater hose at the left rear of the engine compartment and one on the hose to the right of the fuel filter, but all times the bottle must be at least half full. The engine has to be running to do this, from cold the best for safety. One thing, its makes no difference on a ZX, whether you turn your heater up or not when bleeding the system because there is no heater valve. The heat is controlled by flaps within the heater unit controlling the air flow through the matrix as you adjust the Temp. control for the heat you reqiure.
To check whether your thermostat may be at fault, try removing it for while to see if there is any improvement with the water loss, but the water should overflow into the bottle at the end of your overflow pipe with or without the thermostat if you have a fault within your system causing the system to pressurise/overheat and blow the water out.

mbunting · Post by **mbunting** » 04 Mar 2003, 18:32

When there is water in the system, the thermostat and radiator work perfectly.
Filled it up last night, bled the system.
Dumped the water on the motorway - temp shot up ( previously OK for miles and consistent ).
Pulled into services, filled and bled as much as I could sensibly ( Suit on ! ), level stabilised, but getting small bubbles.
Sounds to me like the HG has gone, although it could be air getting in from wherever the leak is ??
I may get some talk powder, and sprinkle it over the hose joins to see if there is anything obvious, otherwise I plan to do the Belt, Water Pump, and HG in one weekend.

jeremy · Post by **jeremy** » 04 Mar 2003, 21:21

You could try this product
http://buy.snapon.com/catalog/pro_det.a ... ir=catalog
probably cheaper to buy another car!

mbunting · Post by **mbunting** » 04 Mar 2003, 21:58

The option I had thought of was to try and get a tight seal between my pressure washer and the filler cap, or to put a footpump onto the top bleed point with a one way valve, and pump air in under pressure, and see where the water is forced out.

Dave Burns · Post by **Dave Burns** » 04 Mar 2003, 23:43

Don't like the sound of that Mat, whatever you do don't go above 15psi or you will probably damage the rad and matrix.
Also note, if the H/G is a gonner and you pressurise the cooling system, forcing water into a cylinder, you may cause a hydraulic lock, if you then turn the engine over on the key in this condition you can end up having a much more miserable time of it than just changeing the gasket, bent conrods and damaged pistons are easily obtainable this way.
I suggest you do the standard cold start test for confirmation of gasket failure rather than risk damage elsewhere.
Dave

NiSk · Post by **NiSk** » 04 Mar 2003, 23:46

Take a compression test of the four cylinders, just to eliminate the worry about the head gasket!
//NiSk