Corsa 1.5 Diesel overheating

Yorky

I've got a 1995 Corsa 1.5 diesel (Isuzu engine) which has done 163,000 miles.The water pump and thermostat have been changed but it's still overheating. I drove about 18 miles in it today and the water temperature gauge almost reached 100 degrees so I pulled over and waited for it to cool down.

I then drove with the cabin heater fan on full which kept the water temperature around 95 degress - still a lot higher than the 90 degrees that it used to run at.

On the way home it almost reached 100 degrees again despite having the heater on full. I pulled over again and allowed it to cool. I started off again and it rose again after a few miles. Then I noticed the cabin heater fan was not quite as hot and the water temperature also dropped - for no apparent reason- to about 92 degrees.

I called my mechanic who said it may be the head gasket and to check the radiator hoses for resistance but they are quite soft and pliable.

The radiator cooling fan does not come on at all but when it was checked by shorting it worked.

Any advice would be appreciated.

Muckie

If its not the water pump, thermosat at fault. I'd have a guess as the

radiator or switch that works the fan at fault. If you get stuck on the

side of the road again, check along the wire that connects to the radiator fan,

some car makers have an emergency connector type plug on the wire.

That plugs into itself and the fan should come on(sorry about the describition:))

Connecting it will cause the fan to come on and keep running. Just remember to disconnect once you park up.

Owen

Make sure there's enough water in there too. Sounds stupid I know, but it's worth checking the basics always.

MagicMarker

Did a warning light come on?

shamwari

Those Isuzu engines are usually very good. Is the car otherwise driving ok? Is it down on power? Is it using water?

On the expansion tank on those, there's one large hose into the bottom, and one or two small hoses into the top. Are there bubbles blowing up out of the bottom one, or boiling coolant being blown under pressure out of the top ones? Also, did anyone put anything like radweld into it?

A simple test to see if the system is pressurising: drive the car till warm then stop. Open the expansion tank carefully. Start the car and hold the revs moderate for around a minute and get someone to watch the level in the tank. If it shoots up significantly or overflows out of the tank then you've a problem....

Under normal driving, the gauge should sit at about 90 degrees. It definitely should not climb the way it did on you.

Yorky

Thanks for all of the replies.

Update: The water level has not dropped overnight so it's not losing any water. Drove the car to the same spot where it overheated yesterday - about 15 miles travelling at 50-60mph approx- and the water temp. barely rose above 90 degrees and the cabin heater air was only luke warm also.

On the way back the water temp. (and cabin heat) rose quite quickly to 95 degrees so I pulled over to feel the radiator. It was mainly cold and only slightly luke warm in places!

When I got home the temp was just above 90 degrees ( urban driving towards the end of journey). I felt the radiator hose and it was under pressure which was released when the header tank cap was removed.

It seems to overheat when travelling at speed and not in slow moving traffic.

Do these problems sound like a clogged radiator or the head gasket about to go?

Thanks again.

shamwari

It's very difficult to say exactly what's wrong, or whether its head or rad. Have you tried the test I mentioned above to see if the system is pressurising or producing bubbles?

I supposed you can eliminate the rad by removing it and flushing it with a garden hose and see what the flow is like.

When the waterpump was replaced, was the alternator belt tightened properly? If you Corsa has PAS then there should be two belts: one goes around Crank / waterpump / Alternator, and the other goes around Crank / waterpump / PAS Pump. The crank and waterpump have a double pulley which drive two belts!

Yorky

Thanks for your reply. It doesn't have PAS.

I decided to flush the radiator today and followed the Haynes manual instructions: drain the system via the bottom radiator hose and remove the thermostat. ( By the way, the capacity of the car is 6 litres but only 4.5 -5 litres drained out as I didn't know where the cylinder block drain plus was so it wasn't fully drained.)

When drained, I connected the garden hosepipe to the lower radiator hose, as directed, and turned the tap on. The water just backflowed with no water coming out of bottom radiator outlet. I then tried connecting the hosepipe to the top radiator pipe and blocked the expansion tank vent hose and the water ran out of the bottom radiator outlet. The water running out was clear with no sign of rust or deposits.

So the water is not making it through the engine from the lower hose but will flow through the radiator from the top hose. Why might this be?

I saved the coolant and reused it - it took the same amount to refill it so there must have been no deposits removed. It has a self-venting cooling system according to the manual so it didn't need manually bleeding.

I left the car idling for about 20 minutes and the temperature crept up to above 90 degrees. The top rad. hose felt quite hard and then released when the expansion tank cap was removed. Coolant did not overflow but then it wasn't that hot as I hadn't driven it.

Is this a sign that the head gasket may be going?

I know the car is old but it's a Japanese diesel and has only done 163k miles.

Could you offer any more advice?

Thanks again

shamwari

Yorky wrote: »

Thanks for your reply. It doesn't have PAS.

I decided to flush the radiator today and followed the Haynes manual instructions: drain the system via the bottom radiator hose and remove the thermostat. ( By the way, the capacity of the car is 6 litres but only 4.5 -5 litres drained out as I didn't know where the cylinder block drain plus was so it wasn't fully drained.)

When drained, I connected the garden hosepipe to the lower radiator hose, as directed, and turned the tap on. The water just backflowed with no water coming out of bottom radiator outlet. I then tried connecting the hosepipe to the top radiator pipe and blocked the expansion tank vent hose and the water ran out of the bottom radiator outlet. The water running out was clear with no sign of rust or deposits.

So the water is not making it through the engine from the lower hose but will flow through the radiator from the top hose. Why might this be?

I saved the coolant and reused it - it took the same amount to refill it so there must have been no deposits removed. It has a self-venting cooling system according to the manual so it didn't need manually bleeding.

I left the car idling for about 20 minutes and the temperature crept up to above 90 degrees. The top rad. hose felt quite hard and then released when the expansion tank cap was removed. Coolant did not overflow but then it wasn't that hot as I hadn't driven it.

Is this a sign that the head gasket may be going?

I know the car is old but it's a Japanese diesel and has only done 163k miles.

Could you offer any more advice?

Thanks again

The Haynes manual procedure is a little inaccurate. Firstly there is no drain bung on the 1.5D block. There was one fitted on the old GM Opel / Vauxhall 1.7D block, but NOT on the Isuzu one.

Secondly, the best way to flush the rad is top and bottom hose off and hose into the top and water on. The procedure described in the Haynes is for flushing the entire cooling system, wheras I suggested just checking the rad. But again this seems wrong because with the thermostat closed, the water cannot circulate throughout the entire system. To flush the block, I'd remove the stat put the hose in there, and flush out through the bottom hose. You can flush the expansion tank section down from there and it will flow out through where the stat is and the bottom hose.

The system is self venting and this is what the top hose(s) do on the expansion tank. It works on this car because the system is filled from and vented to the highest point, and the air can gravitiate its way to the top. One bit of advice and this may explain why you didn't get all of the coolant out: make sure that the heater temp setting is at MAX before you drain it, and again when you are refilling it.

The way you describe the car behaving points to a circulation problem rather than a head gasket one, but I could be wrong. But you've already replaced the waterpump and the stat. Whilst this might not be possible, it is worth a mention: is the thermostat installed the correct way around?

Finally, when you open the expansion bottle, does the escaping air smell of diesel / exhaust fumes?