Overheating ZX TDI

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sooty
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Overheating ZX TDI

Post by sooty »

With this warm weather my 1996 ZX 1.9tdi overheats (according to the Temp. Gauge, to a point where the fans should be working)at High speeds(70+), but its OK otherwise. I have washed out the Rad. honeycomb and the intercooler Honeycomb, but no difference. In the Owners Handbook, it says if you are towing, you must fit an air deflector to prevent overheating??
Anyone got any clues to what or where I can find any info about this Deflector or the over heat problem. *Could the Rad. need flushing?*
Edited by - sooty on 31 Jul 2002 20:43:49
Dave Burns
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Post by Dave Burns »

ZX TDI, are you sure, never seen any such animal, didn't know it existed, are you having us on.
If it's overheating when being driven fast I would look at the stat next.
Fan's cut in at about 90c, but the moving car should already be getting plenty of cooling air, which is why the water circulation may be suspect.
Is there any water loss and have you tried bleeding it.
Dave
sooty
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Post by sooty »

I think you must be having us on, about the ZX TDI.
It has not lost any water in three months, I've bled it as per the Manual. The gauge shows only graduations. At normal running, winter or summer its approx. Midway to just below. But as it stands in traffic, it rises to approx. 3/4 as when the fans come in, but at speeds 70+ it approaches this point.
On cooler days its Ok, alot higher than 70 (on private roads of course).
Any clues about this Citroen air deflector for towing.
I was told if I raised my boost and fuel pressures etc to gain 110bhp +, which I've not done yet. Was to fit a larger Intercooler to the front of the car, because of the inefficiency of the Garret Turbo at higher boost levels. Could this be the answer at high speeds when the boost is at its max.???
Dave Burns
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Post by Dave Burns »

Hehe ZX TDI (Turbo Direct Injection) I don't think so, ZX TD (Turbo Diesel) I do think so, I stand to be corrected but Iv'e never heard of it in a ZX, nor HDI (High pressure Direct Injection).
There's got to be a restriction somewhere either in the movement of water or the exchange of heat, the obvious place to look is the stat, to make sure it open's fully, and flush the rad to see if anything nasty looking comes out.
Air deflector's for extra cooling while towing are fitted to the front under side, the Xantia has one moulded in to the front under tray, it causes air to be sucked from the engine compartment, thus getting more in through the rad.
Increasing the power output of the engine will use more fuel and generate even more heat.
If the fan cut's in while in traffic but not at speed even though the gauge rises, at least you know that engine damaging temp's are not being reached.
Dave
hardmanm
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Post by hardmanm »

If you can't find anything wrong with the cooling system, it might be time to start suspecting the head gasket.
A previous car of mine only overheated when driven hard, this was a mystery for several months until it deteriorated to the point where I parked at work after my usual 15mile trash, turned off the engine, and could hear running water. There was a 4 ft high geyser of water shooting out of the radiator cap.
If the head gasket has failed you are causing damage all the time that you drive it.
Try removing the radiator cap (CAUTION - WITH THE ENGINE COLD!) and look for escess gas in the water when you rev the engine, a little is normal.
Mark
sooty
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Post by sooty »

Thanks for Tips,
But with previous cars I've had with Gasket trouble whether petrol or diesel, as you say the combustion pressures get into the cooling system. It has always made funny noise's, but always blows the water out as well and taken a long time for the pressure to disappear when the engine is left for a couple of hours.
But it is not the case with mine, Its used no water in three months and I can safely remove the cap approx. 15mins.
I think Dave's Tip is more likely with the Rad. core being partly blocked needing a good flush out and a new Thermostat.
Thanks for all your tips.
It it developes any worse I'll let you know (hopefully not)
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