Sylv's ZX 1.9TD needs TLC! Overheating Problem!

Unread post by **Rhothgar** » 03 Aug 2011, 16:38

Hi all,

If anyone has been following any other the topics I have previously posted on Sylvi's ZX then you'll know I have a list as long as my arm of things to do!

None serious apart from heater matrix when I get around to it.

I need some advice on this because I cannot understand what is going on with it at the moment.

1) Her water level light has been making regular appearances then going off (sometimes following top up) and then re-appearing within a day or so.

2) The water is being lost from the overflow pipe off the side of the top of the radiator (not sure if all of it is being lost this way). The engine has enormous torque and blows clean gases out of the exhaust. NO WHITE SMOKE!

3) Temperature has been running at normal until of late.

Last weekend, I took it up to my mate's to use his garage equipment following complaints from Sylv that she is having to top it up 1 - 2 litres a day.

4) Did pressure test. Cooling system holds 1 bar - neglible drop of 0.01 bar after 15 minutes or so. No cylinder head gasket problem then! PHEW!

5) Did test for combustion gas in radiator water. None found! Did a routine test and a major leak test. No combustion gases are making it into the water.

6) Took car for a spin around the block with no radiator cap on and Temp rose to 105 degrees (normally runs at 83).

7) Couldn't remember if I had changed the thermostat so took that out.

8) Flushed system through with clean water as I had used a system flush way back before winter when matrix was blocked solid. It removed some crud at that time. No crud evident on flushing last weekend. I should mention at this point that car had new radiator last year so that's new.

9) Drove home. Car ran at 105 degrees all the way home (at 60 mph mainly). Rad fans were on full tilt trying to keep engine cool. Notice water dribbling out of thermostat housing. Realised thermostat and housing design on ZX does not allow for former to be left out!

10) Put kettle on. No time for tea. Checked thermostat previously removed at point 7) above. 100% fine. Opens fully. Closes fully. Put it back in!

11) Sylv drove around the block and temp was still 105 degrees. Hills and acceleration cause overheating.

12) Sylv drove car again today for 1st time since this and temp runs fine at 83 degrees.

13) The water level light has not YET come on again.

So...

After the long detailed explanation, does anyone have any thoughts / ideas on what could be the problem.

Also, at one point during the above procedures there appeared to be specks of white 'oil' in the radiator.

This ZX has an 'oil-cooler' block to which the oil filter screws with two pipes coming off it, one of which comes to the radiator just in front of the alternator.

Many thanks in anticipation,

Rhothgar

wotwot · Unread post by **wotwot** » 03 Aug 2011, 22:34

Not something as simple as an airlock maybe.

Unread post by **Rhothgar** » 04 Aug 2011, 08:27

Can't be! Surely?

Why would it play up for months then as soon as I do a block test, stop...

Bearing in mind, I forgot to say I took the top hose off and drained the radiator as well last weekend then surely I have another airlock.

I'll check this out as I must admit that I hadn't checked the ZX for a bleed valve.

How would an airlock cause the car to lose water?

lexi · Unread post by **lexi** » 04 Aug 2011, 08:48

Eliminate airlock theory. Buid a filler in rad to create reservoir that goes above the highest bleed point. Fill in stages and open lowest tyre cap bleed niples until water comes out..........close and then do the higher one. Squeeze hoses to expel air and water.

Is your heater blowing hot air? does it pull the temps down when full on?

If answer is yes to both after bleeding then no airlock I would say. The oil in water may be from cooler and could be a coincedence?

Change rad cap too.

xmexclusive · Unread post by **xmexclusive** » 04 Aug 2011, 09:18

Hi Rothgar

Just had similar temperature/water loss problems with a 2.5TD XM.
The overheating turned out to be caused by an intemittant electrical fault with the rad fans. Took ages to pin down as at speed with low revs did not need the fans to keep temperature right. Low speed or pushing car gave variable results depending on state of fans. Temperature rise was often short and quickly reduced again. Think I failed to spot this happening to start with.
Water loss was even more difficult to understand.
Sometimes header tank would be almost empty in 30 miles, sometimes loose nothing for days. Turned out to be loss through the overflow every time the temperature went up around 110 degrees.
Once the fans were rewired both problems went away.
The false water level warning can be caused by contaminants settling on the 2 probes of the header tank sensor. Might be worth giving them a clean. Another of the 2.5's kept doing this for months after I cured an oil in coolant problem. Despite multiple flushing minute traces of oil would turn up and seemed attracted to the sensor probes. Light would be there on start up then go off once the water pump had got the coolant churning about a bit.

John

Unread post by **Rhothgar** » 04 Aug 2011, 09:37

lexi wrote:Eliminate airlock theory. Buid a filler in rad to create reservoir that goes above the highest bleed point. Fill in stages and open lowest tyre cap bleed niples until water comes out..........close and then do the higher one. Squeeze hoses to expel air and water.

Is your heater blowing hot air? does it pull the temps down when full on?

If answer is yes to both after bleeding then no airlock I would say. The oil in water may be from cooler and could be a coincedence?

Change rad cap too.

Hi Lexi.

a 2 litre plastic coke bottle screws in nicely from memory.

lower air bleed! Do you know it's approx. whereabouts? Front of engine, side, rear?

It's not blowing hot air for long because matrix is full for curd. Managed to clear some out last year with a coolant flush so it's hot for a while then cools.

I love coincidences. Something tangential ALWAYS happens when you touch a car.

I thought of changing rad cap but figured that the car was still overheating with the cap off. The spring does on the cap feels very strong.

I'm going to rule out airlock first.

Unread post by **Peter.N.** » 04 Aug 2011, 09:49

If its running at over 100C without the thermostat I would strongly suspect that the radiator is furred up and needs replacing. You shouldn't get an airlock without a thermostat present as there is nothing to restrict the flow, it should be self bleeding as the 2.1 XM system.

If you are moving at 30 mph or so you should have an adequate air suppy through the radiator without the fans operating. The temperature under those conditions should probably not exceed 50C.

The only other possible cause I can think of is failure of the water pump, although I don't think the do, do they?

Peter

lexi · Unread post by **lexi** » 04 Aug 2011, 09:49

Could also by pass heater Matrix for a test, in case this is restricting coolant flow? Can't remember now where bleed screws are..........been so long

wotwot · Unread post by **wotwot** » 04 Aug 2011, 11:13

I'm sure mine had 2 bleed nipples oooooohhh dont you just love that word.
My zx never self bled always had to burn my fingers to get it to bleed properly.
And mine did used to get very hot and run off from the overflow pipe when not bled.
I suppose the airlock causes expansion so you get the build up of pressure leading to blow off.

davetherave · Unread post by **davetherave** » 04 Aug 2011, 14:40

Ive got a spare zx rad in the loft if it turns out to be the rad, fairly new lookin 2. Not sure if there are varients though.

Unread post by **myglaren** » 04 Aug 2011, 17:42

If the head is furred up causing waterway restrictions then the coolant may be boiling and creating steam pockets = overpressure which will eject some coolant. May cause airlocks too.