Cold ZX TD (ongoing)

Snid · Unread post by **Snid** » 30 Jan 2003, 14:00

I have just bought an old ZX TD (K-reg). Whilst the car starts and drives beautifully, what I failed to notice on the test drive is that the temperature guage never reaches 'normal'. The needle reaches about a quarter of its travel then wavers a tiny bit as I drive. The heater pumps out luke warm air at the best.
The oil and water show no evidence of head gasket failure and it isn't losing coolant. I have not seen the electric fans running. I fitted an new thermostat yesterday and it has made no difference. After driving for a while the top hose is quite hot and the expansion-tank type bit on the O/S of the radiator is cool, and coldest at the bottom.
Does anybody know what the problem might be?
Edited by - Snid on 02 Feb 2003 17:57:23
Edited by - Snid on 03 Feb 2003 19:01:58

Andyman · Unread post by **Andyman** » 30 Jan 2003, 16:39

It could be air in the system, Have you bled it out? There are three caps, One on top of the radiator opposite the filler cap, A cap near the thermostat housing on a return hose, And one on the Drivers side of the bulkhead on the end of a small hose, That bleeds out the heater. Run up the engine start expelling air from the radiator first, Then the thermostat return hose and finally the heater, Keep topping up and don't let the water level drop as you bleed the system, Make sure you replace the anti freeze at the same time,
Run it up the road for a few miles then repeat opening up the caps again, To make sure there is no air, It is possible for the head gasket to expel a little air enough to cause an air lock it doesn't take much, So bear that in mind. Have fun Chris.
Edited by - Andyman on 30 Jan 2003 11:56:33
Edited by - Andyman on 30 Jan 2003 11:57:28

Snid · Unread post by **Snid** » 30 Jan 2003, 23:07

Thanks for the advice Chris. I looked in the Haynes book at this procedure, they suggested using a temporary header tank made from a plastic bottle to keep it topping up while idling at 2000 revs. I did all this and bled the three valves.
The gauge reached the ninety-odd degrees necessary to fire the electric fans. All went well until I took to the road and the temperature dropped again. Doh! The water level has dropped an inch or so but nothing serious.
Maybe the head gasket is leaking a bit then...bugger.
Snid.

sooty · Unread post by **sooty** » 31 Jan 2003, 01:12

I know its a bugger, if you are not using any water on a weekly basis it may not be the gasket, (I do approx. 250 mile a week and do not put any in over a month). But it maybe that your heater matrix is partly blocked and may need cleaning with either rad flush if you are lucky or get a service exchange/new unit.
One other thing to check is your heater controls, are they operating correctly?
Sooty
Edited by - sooty on 30 Jan 2003 20:15:36

Andyman · Unread post by **Andyman** » 31 Jan 2003, 04:48

Pahaps it might be worth getting the radiator flow tested at a local radiator specialist, In case its partially blocked, Don't won't to be all doom gloom and dispair but the heads are prone to cracking on xud engines, The heater wouldn't change anything even if you blocked off both ends, Apart from shivering your t*ts off, But the easy way of testing the heater matrix for blockage is to remove both the heater hoses on the bulkhead, Careful cos they are held in with a flimsey plastic clip and a couple of 'O' rings, Get a hose pipe run water through one end and observe how much comes out the other end, But don't put to much pressure through it in case you pop the matrix.
Chris.

jmd · Unread post by **jmd** » 31 Jan 2003, 05:08

I would be inclined to suspect a faulty thermostat, it's worth renewing for the sake of £10/£12.If there is no improvement then you can worry about other things.

Snid · Unread post by **Snid** » 02 Feb 2003, 22:56

Thanks to everybody for the advice.
<u>The Story So Far:</u>
I have changed the thermostat, refilled and bled the system (several times). Today I cleaned out the cooling system using a two part heavy duty rad flush from Halfords. This was a long process including draining and refilling six times and back flushing. It is now refilled with new antifreeze.
There is no change...
Unless anybody has any other suggestions it's off to the garage on Tuesday.
Cheers, Snid.

sooty · Unread post by **sooty** » 03 Feb 2003, 01:32

Have you checked the heater controls on the dash are operating correctly ??. IE: are the flaps directing full heat, when the temperature control is turned to max. and not staying partly opened allowing cold air through.
Last hint before the garage job/Tuesday
sooty

Dave Burns · Unread post by **Dave Burns** » 03 Feb 2003, 02:37

It sounds like the gauge is accurate enough to be believed from what you say about the indicated temperature when the fans cut in with the car stood, does the heater also put out hot air at this time or does it remain merely warm.
If the temp then goes down when you drive and cold air passes through the rad, this means that the stat is not regulating the temperature correctly or water is bypassing it somehow though unlikely, or the head gasket is leaking but then you are going to lose water.
Not very often we get one that doesn't get hot enough, usually they get too hot.
Dave

jeremy · Unread post by **jeremy** » 03 Feb 2003, 16:57

As a matter of ineterst does your tehrmostat have a gasket in the housing or does it rely on an O ring type of gasket fitting round the circumfrence of the thermostat?
We have an ordinary diesel ZX (94) and when I changed the thermostat I was sold an 83 degree one which I understand is current practice to fit. The gauge is amazingly accurate and the thing goes to the line just below the 1/2 way mark. The gasket supplied was a thin one and is used for sealing. I believe the older engines as in BX's use a paper gasket to seal the system but a rubber gasket round the thermostat which un turn is held in with a circlip. Is the gasket in place and the right size? If not it would allow water to bypass the thermostat and give the problems you are experiencing.
There isn't much heat output on these engines due to their inherent efficiency and on ours there was an o ring gasket on the thermostat valve itself that had broken and become displaced - allowing the thing to leak internally and fail to warm up properly.
jeremy

Snid · Unread post by **Snid** » 04 Feb 2003, 00:01

Jeremy,
The only gasket supplied with the thermostat was a rubber ring with a groove around the inside. It is identical to the one I took out. It seems to be a nice snug fit in the 'stat housing and gets nipped up when the three bolts on the plasic front section are tightened up.
I am suprised at your comments about the XUD commonly not getting hot, this is the third ZX TD I have had (my wife has the second one) I've also owned a BX TD and two Pug 306 TD's. All of them have run nice and hot. Maybe my lucky streak has just run out!
Thanks for your comments,
Snid.
P.S. I have to admit to visiting my local garage today which is a real old fashioned place and also a Citroen dealer. There was a lot of head scrathing and teeth sucking when I told the story! The end result being "erm, you'd better bring it in on Friday" I have been very impressed with their service in the past so watch this space...

sooty · Unread post by **sooty** » 04 Feb 2003, 00:31

Reference: the rubber ring you mentioned. Has it been fitted onto the outer rim of the thermostat (fitting into the groove of the ring), that then fully seals the assembly from any by-passing that may occur.
Sooty

jeremy · Unread post by **jeremy** » 04 Feb 2003, 03:43

From experience if you have the plastic thermostat housing and use the wrong rubber ring it will leak - so that's not your problem.
I suppose the possibility of someone in the past having plumbed the engine wrongly can be dismissed which leaves the waterpump?
When you bleed it can you get any sign of suction or movement in the system to suggest the pump is working? I seem to remember that I could get water to come out of a couple of bleed points when I revved the engine.
jeremy