I have a 1997 hijet van 993cc which has recently begun overheating. Started with occasional boiling sound after engine stop, and getting hot while stuck in traffic. I have had a slight noise from the front of the engine for some time which I assumed meant either alternator bearing going or water pump. Took it for mot the other day and they said they couldn't complete test as it boiled over. Swapped fan switch (as fan had been temperamental occasionally) in rad today and still same although fan came on as it should. Re-filled rad with clean water to test, and as engine warmed up began running slowly back into expansion bottle but was frothy(?), no obvious sign of oil in water, or leaks anywhere, and engine seems to run ok, but seemed as though air in system or water boiling although correctly filled with bleed rubber above rad removed.

Methinks water pump probably gone, although would also like to replace engine side cap to be certain that is ok. Rang local dealer who quoted nearly £30 for just that cap! Will check if play at the end of the water pump pulley tomorrow and got friendly mechanic coming to look sunday. Anyone know what might fit as engine side cap that I can get elsewhere, and where to get a water pump if indeed it's that.

I know my local dealer just thinks of a price then trebles it for everything, but £30 for what is essentially a radiator cap (and have only just paid another £30 for the rad fan switch)!

Blown gasket.

Overheating could just be a thermostat stuck closed so the coolant boils.
Possibly a water pump problem but that can be checked by removing the radiator cap and reving the engine ... the water lifts up the radiators neck when the water pump 'drives' the coolant. However you have coolant being expelled into the overflow bottle and this suggests an expensive repair.

Coolant leaking back into the expansion bottle is usually due to a cylinder leaking through a head gasket into the coolant. The pressure leaking from compression of a cylinder forces the coolant from the engine block into the radiator and the excess is pushed into the overflow bottle. Oil may not be present since the leaky head might not be postioned across an oilway. Hopefully it is only a broken head gasket and not a cracked cylinder head. Don't drive knowing it is overheating .. a hot spot could develop and blow a hole in the cylinder head.

Smell the overflow bottle ....... does it stink of petrol or exhaust fumes? A certain sign is bubbles escaping from the overflow bottle .... bubbles smell of petro/exhaust fumes.

Overheating Hi Jet.

2003 Sirion SL 1300. And I love it.
Don't like the new shape much.

Fingers crossed.

Sounds like stuck thermostat valve to me.

Change it.

2003 Sirion Rally 4. And I love it.
Don't like the new shape Sirion much.Sorry.

Thanks very much for the

Thanks very much for the helpful replies.

I changed the thermostat when I first bought the van, about 2.5 years ago, should be ok as water seems to get around the system when warmed up.

I might have found the fix - coolant cap nearest the engine may not have been sealing properly, slight bump from weld and corrosion, removed this and smoothed down, temporarily stuck extra piece of rubber over rubber on cap and seems ok. If this was the problem then system was loosing pressure allowing water to boil and create air pockets. Can't test drive yet as got to wait till bled brakes and arranged another mot (mot run out). Took alternator drive belt off to feel water pump pulley, feels fine but slight noise/roughness at alternator so that probably source of noise.

Will let you know how it goes.

Well it's been fine for

Well it's been fine for about 40 miles and then suddenly gone tits up again, losing coolant, bubbles into expansion tank (small ones but bubbles all the same). Am changing engine side coolant cap then calling in my friendly mobile mechanic. Still no sign of oil contamination, or other except for air apparently getting into cooling system. Coolant doesn't seem to smell especially of petrol or exhaust, so if it is a bad gasket can't be a huge hole.

Hijet Kettle

A common problem with Hijet engines and you are right t see if the caps are sealing properly. There are 2, one on top of the ad and as you say the other beneath the passenger seat. If they are sealing the pipes will pressure up and become hard.

It sounds as if you may have a head gasket problem alowing super heated exhaust gases to enter the water ways. Failed Head gaskets do not always manifest themselves with oil and water contamination. The Super heated gases boil the water and make it froth as you have said. You could try a sealant like bars leaks but I expect any improvement would be short lived. The first thing is to see if the system is pressurising by checking that the pipes are hard when the engine is warm. Hopefully the cap seals have gone.

Daihatsu dealerships quote stupid prices and if you shop around the Motor Factors of Jap suppliers on Google or even ebay you should get one a lot cheaper than from the dealer.



Hot Hi Jet.

2003 Sirion SL 1300. And I love it.
Don't like the new shape much.

Oh Dear, sounds like Head Gasket now!!



2003 Sirion Rally 4. And I love it.
Don't like the new shape Sirion much.Sorry.