Club 80-90 Forums

If it helps any guage paranoia, mine reads approx 3/4 when warned up, and has done for years- it's normal for this van. I've an rjes converted loom too.

It sounds a lot like you've a lot of air in the system, if it's not coming out the radiator bleed when hot. Get the overflow tank fitted and filled!

You should have the original vw gauge sender on that header tank connection yes. That just drives the VW gauge in the dash. The Subaru temp sender you photo'd drives the ECU only, and should control the rad fan- if it is indeed an rjes original setup

Sent from my Pixel 4 using Tapatalk

Get a Haynes manual and full the system as though it had a VW engine. You have to raise the rpms to get the coolant circulating and fill the system via the blue "dalek" cap, not via the radiator bleed screw (its designed to be accessible through the grille slats with a suitable open spanner)
The heater must be set on hot to purge any air in that loop.
Bleeding the radiator has to be done once you can't get any more in the header tank. Then top it up again and have a small amount of coolant in the overspill tank.

slowcoach wrote: ↑15 May 2026, 15:57 If it helps any guage paranoia, mine reads approx 3/4 when warned up, and has done for years- it's normal for this van. I've an rjes converted loom too.

It sounds a lot like you've a lot of air in the system, if it's not coming out the radiator bleed when hot. Get the overflow tank fitted and filled!

You should have the original vw gauge sender on that header tank connection yes. That just drives the VW gauge in the dash. The Subaru temp sender you photo'd drives the ECU only, and should control the rad fan- if it is indeed an rjes original setup

Sent from my Pixel 4 using Tapatalk

I think you're right. I'll push it further once I've got that overflow tank fitted.
I believe I do have an RJES loom as the square metal box with all the wires looks the same as the one on the RJES website.
Don't know why I don't have the head tank sensor wire. Can't see it anywhere. I'll have to look at running a new one at some point maybe. For now I'll be keeping a close eye on the coolant levels.

Get a Haynes manual and full the system as though it had a VW engine. You have to raise the rpms to get the coolant circulating and fill the system via the blue "dalek" cap, not via the radiator bleed screw (its designed to be accessible through the grille slats with a suitable open spanner)
The heater must be set on hot to purge any air in that loop.
Bleeding the radiator has to be done once you can't get any more in the header tank. Then top it up again and have a small amount of coolant in the overspill tank.

I've got a VW Haynes manual although between the different VW variants and the Subaru bits it's not straightforward to navigate. I could also do with a Subaru manual but hard to know which one to get.
I understood the radiator was the high point in the system so the last bit of filling has to be done by the radiator but I've been focusing on keeping the header tank full for now anyway. Just went to check it and coolant starter coming out as I was unscrewing the dalek cap so it's defo full at the moment.
The fact the radiator is now getting warm is a big relief.

The rad is the high point but you bleed the air out and fill from the tank.
The wiring harness that connects the header tank contact probe is part of the original VW engine harness, so it has probably been removed as part of the conversion.
Should connect via one of the two 7-pin white round connectors in the engine bay junction box.
Or, its coiled up behind the LH rear light because it no longer reches the new hear tank location.

"Metal box with all the wires" do you mean the engine ECU?

you can fill the radiator using some 4mm washer hose syphoning from a coolant bottle on top of the cab, as long as you remove the bleed screw, don't lose the washer if fitted and have them to hand when it is full, works really well - Dai taught me that trick

I've been using a bit of the tubing from a brake bleed kit. Works okay but tricky to get in the screw hole while you're trying not to lose the syphon.
Still waiting for the overflow tank to arrive. Will probably be Monday

Possible some useful info....

My way of bleeding the cooling system was to use my cooling system pressure tester, Fill the header right up, Apply pressure, Open the bleed on the radiator until the header tank was near empty and repeat until all the air was gone, Then you can of course test the system for leaks while you're at it. Took me maybe 20 mins and it's been spot on since. It's worth having a cooling pressure tester anyways and I don't think they are expensive.

Aidan wrote:you can fill the radiator using some 4mm washer hose syphoning from a coolant bottle on top of the cab, as long as you remove the bleed screw, don't lose the washer if fitted and have them to hand when it is full, works really well - Dai taught me that trick

Yeah I've had some interesting contraptions set up for that- thin tubing, stepped up to a bigger diameter tube, taped into a funnel and that taped onto the top of some step ladders. Got loads in through that, and found it less stressful. Hate filling these things.

Mine is long overdue really.

Sent from my Pixel 4 using Tapatalk