Club 80-90 Forums

Hi, I’ve been rebuilding my van for the last 12 months, it got delivered on a trailer and I’m almost ready for its first test.

But I’m having an issue with the cooling system. Apologies this is my first t25 and I definitely jumped in at the deep end!
Originally a 1.9 petrol, converted to 1.9 1Y diesel.
Work done by previous owner only described as dodgy at best. See below.

viewtopic.php?t=182077

So I’ve swapped all the hoses and everything is looking like it’s meant to look.
From this
To this

I’ve not taken it on the road yet. But had the engine up to temp by holding the revs at around 2k rpm with occasional busts of full throttle. Temp guage goes to where I expect it should.
And holds there nicely fan kicks in it goes back down again. However, I’m not getting any hot air through my blowers. And the unpressurised tank does not seem to be doing anything. The blue cap on the pressurised tank is new so “should” be working. But I seem to get no coolant being pushed into the unpressurised tank. Or sucked back.

I assume the two issues may be linked. System not getting pressurised properly because the heater matrix isn’t bled. But I’ve followed brickwerks’s instructions and just can’t seem to get it bled! Any suggestions?


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Pressurised tank is full to the brim.
Unpressured tank just sits there with new clean coolant not doing anything.


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Have you checked your heater valve is actually opening?

No, I haven’t. Is it easy to find out?


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Probably not very easy. At least you can try to see if the cable moves the lever as it should. It is somewhere above the spare wheel. Perhaps try to pull a hose off somewhere behind the valve, start the engine with it closed and slowly open it to see if fluid starts to flow?

All the levers move with the appropriate level of resistance.


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The gate valve all seems to operate externally anyway. Shame you can’t get to where the hose joins the matrix inside the cab, would loosen the hose there and let any trapped air out.


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Sounds like you're doing the right things, so probably something is broken.

The heater matrix is supposed to bleed itself automatically. I've had it out and didn't have to bleed afterwards.

I'm assuming your interior fan is working.

Perhaps a silly test, but maybe you can try to pop off the hose at the rear of your cilinderhead and just blow in it with the heater valve open. See if it's blocked.

Yeah the fan is working grand. I don’t want to dump all my coolant. But yeah, thinking maybe sticking a hose though it and seeing if it comes out the other end!!


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Heater valve can break internally, lever and cable move normally but the valve may not be opening at all. Messsy wet job to remove and check.

silverbullet wrote: ↑05 May 2026, 12:23 Heater valve can break internally, lever and cable move normally but the valve may not be opening at all. Messsy wet job to remove and check.

Yeah I think this could be my issue. Just got to bit the bullet and empty all that brand new coolant on to the floor!

No you don't and you shouldn't because coolant is toxic. It causes rapid renal failure, a horrible death for small animals.
One of those big round sump drain pans with a spout hold about 15 litres. You're not doing a full drain down so it will hold the contents of the radiator easily.
Front end on ramps or jack it up (and support on stands!) tgives you space to work and helps to minimize the drain down.
Hose down any spills afterwards to reduce the concentration of whatever does hit the ground.

silverbullet wrote: ↑05 May 2026, 17:27 No you don't and you shouldn't because coolant is toxic. It causes rapid renal failure, a horrible death for small animals.
One of those big round sump drain pans with a spout hold about 15 litres. You're not doing a full drain down so it will hold the contents of the radiator easily.
Front end on ramps or jack it up (and support on stands!) tgives you space to work and helps to minimize the drain down.
Hose down any spills afterwards to reduce the concentration of whatever does hit the ground.

THAT