Citroen Zx Diesel Engine OVerheating - alexander
I have an L reg citroen ZX 1.9 diesel and after driving for about 5 minutes the engine oile temperature guage gradually sneaks up to the red. In addition, NO heat is coming out of the air fan heaters for the inside of the car.

I've checked that there is enough oil in the engine, and enough water in the radiator and there is. The radiatior gets warm when the engine first starts, and all the pipes too and from it get warm as the engine heats up, but once it gets into the top end of the temperature scale, the radiator gets very cold (fans come on too, but I'd expect a little residual heat in there coming off from the cooling fans?) The big pipe at the top of the radiator gets VERY hot and the other pipe on the other side that comes into the bottom (on the side where you pour the water in the radiator) just goes cold.

I guess its blocked, but I cannot work out where or how, does anyone have any clues at all please?

Citroen Zx Diesel Engine OVerheating - wemyss
I would check the obvious to begin with.
Disconnect the top and bottom hoses and see if you get a good water flow through the radiator with an hosepipe.
Remove the thermostat and test or perhaps even replace as a matter of course.
Check out the archives on this site regarding the re-filling of the cooling system as apparently this engine is prone to airlocks through not being refilled correctly.
Citroen Zx Diesel Engine OVerheating - Big Cat
The 1.9 engine is notoriously difficult to bleed air out of. Make sure you get this seen to quickly, the cooling system on these engines is marginal, any overheating can easily lead to a blown headgasket.
Citroen Zx Diesel Engine OVerheating - FFX-DM
The matrix on ZX's is also a well known trouble spot. You could try thoroughly flushing the system out to see if it's sludge that's the problem. The O-rings and connectors to the matrix go a bit hard and flat and can leak. If you are not loosing coolant but you have no heat, that's what I would suspect.

If you have major air locks in the coolant, in my experience, this causes the system to pressurise and blow coolant out of the cap. If you are not loosing coolant, this does not seem as likely. If you want to try properly filling the system up to avoid airlocks, a usual Citroen dodge is to create a header tank out of something like a plastic bottle with a tube attached, which wedges in the filler hole. Fill the system until air stops coming out of the bleed valves (I think there are 2) and then close them off. My tame mechanic did something similar by bunging a hose in the hole and running the hose until only liquid came from the bleed valves.

Also, check for head gasket symptoms - murky oil, oily sludge on inside of filler cap, coolant system remaining pressurised after car has cooled down, car overheating... I am afraid that head gasket problems are also common in ZX's. :-(
Citroen Zx Diesel Engine OVerheating - M.M
OK guys some fair points is chapter and verse..

Posted by David W on June 3, 2001, 4:38 am , in reply to "Re: Possible faults.

"Years ago cooling systems were simple and filling them just meant pouring in cooolant to the rad and a few minutes running would self-bleed any small air residue. My 1970 diesel tractor is like this, big old radiator mounted higher than all the other waterways, no complicated narrow hose runs curving over the engine - no problems.

But like many other modern cars Citroen's can be a real problem to fill and bleed. Models with the cap on the radiator are the worse as there is almost no head of water when filling, even those with the expansion tank aren't much better.

So the method is......

First locate all the bleed points on your particular engine. These may include one on the radiator opposite the filler cap, two on the thermostat housing, one on the small hose that leaves the thermostat housing, one on the metal heater feed pipe just behind the camshaft cover, one on the heater hose just to the rear of the engine, one on a small hose running just behind the radiator. I do not want to be specific to a particular model/year as I have seen cars with odd combinations of the normal set-up, just carefully look for them all.

With the engine cool remove the filler cap and fabricate some sort of header tank that will give about an extra 300mm head of water. Mine is very simple. It is a large plastic funnel for filling up tractor fuel that has a nozzle about the same size as the filler hole and holds 3 litres of coolant. I cut the nozzle at a point so that the taper just goes into the radiator/expansion tank filler hole and a firm push will keep it wedged there. I have seen loads of other clever solutions to this with little tanks held on a stand and filler hoses that connect to a modified radiator cap boss, I used mine because it was lying about at the time and has worked OK for 7 years now.

Now top up the system with coolant and allow the funnel/header tank to fill about 2/3rds. Bleed each coolant bleed point in turn until bubble-free coolant is seen. Close them all firmly. Start the engine and allow it to run at a fast idle until the thermostat opens and the radiator becomes fully hot. During this period you should see loads of small bubbles appear in the funnel/header tank, and as the thermostat opens a huge amount of air often bubbles up. Now stop the engine and bleed each point in turn again. Use great care as the coolant will be scalding. Top up the funnel as needed during this to keep it about 2/3rds full at all times. Close all bleed points finally and re-start the engine. Allow it to run for up to another five minutes for all the remaining small air bubbles to bleed off.

When you are happy stop the engine and remove the funnel. Put the radiator cap back on with the coolant still right to the top (ie overfilled by cold standards). Allow the car to cool completely then check the level and add/remove coolant as needed. Give the car two days normal use then check the level again when completely cold. Again add/remove to get the level spot on. Only now consider this an accurate level to monitor from.

Why is this bleeding crucial? Well the thermostat and coolant temperature warning sensors (and fan switch on some models) are in a position that is easily left air-locked if this procedure isn't properly carried out. And these do not work properly in air, only if the water is in contact with them. So it is possible after a water loss, and re-filling without bleeding, for the engine to go above the thermostat opening temperature without it allowing coolant to the radiator. Then because the temperature senders are also in the air lock they don't indicate a problem. Result engine cooks and the head gasket/head are damaged.

Many Citroen diesel head gasket problems follow a simple loss of water. It is my belief this is often due to the problem of bleeding the system rather than the initial fault damaging the head/gasket."

Updated by MM 20-11-02

Hope that helps.

Citroen Zx Diesel Engine OVerheating - 105Gary

i know it is going back a couple of years but i wondered what the eventual outcome of your problem was ?

i have a y reg picasso with an identical list of symptoms has been into a couple of citroen experts and i am still no closer to getting the problem solved....


Citroen Zx Diesel Engine OVerheating - JGwynne
I have what seems to be a similar probem with a Citroen ZX. Are these things especially difficult to bleed air out of the cooling system?

I've taken it back to the garage twice and there still seems to be air in the system somewhere.

Anyone have any thoughts?

Citroen Zx Diesel Engine OVerheating - veggie
hi all
ive had this same problem with my zx.
as above and water being pushed out the header tank by large amounts of air.
new head gasket has sorted it.


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