Coolant Type for Subaru EJ20 Engine Conversion
Posted: 17 Sep 2025, 11:45
Another week and another new problem to deal with.
I've not had this T25 campervan for long and barely driven it anywhere due to an ongoing issue with the gear linkage. I've managed to fix it to a point where I could at least get it MOT'd (which it thankfully passed) but in driving to & from the garage (about a mile drive) I noticed an issue with the coolant / temperature.
It's a 1985 T25 with a Subaru EJ20 NA engine converted for the previous owner by Mac VW (who I understand are not trading anymore) about 5 years ago.
I'm in the process of trying to fix two issues - probably related but possibly not:
The first is the temperature light is continuously flashing right from the turning the engine on. My suspicion is the issue is at the relay as I've been having electrical issues due to poor contacts on the fuse box thanks to a leaking windscreen which I need to get sorted when funds allow. The coolant level is fine (or at least was).
The second issue is the engine is overheating (although I'm not sure where the needle usually sits). I ran the engine at the weekend and the thermostat didn't appear to be opening so I've removed it and ordered a new (genuine Subaru) one.
I of course lost a bit of coolant in doing this although I managed to capture some of what came out. I was surprised though to see that the coolant was pink when I was expecting it to be green or blue from what I've read on the RJES website (if anyone else has a Mac VW conversion I've be interested to know if they used RJES parts and systems? Any information would be appreciated).
Should the coolant be pink? Or am I right in thinking it should be the Subaru Super blue coolant?
I'm guessing I shouldn't mix them but is it wise to flush and replace the coolant?
I've not had this T25 campervan for long and barely driven it anywhere due to an ongoing issue with the gear linkage. I've managed to fix it to a point where I could at least get it MOT'd (which it thankfully passed) but in driving to & from the garage (about a mile drive) I noticed an issue with the coolant / temperature.
It's a 1985 T25 with a Subaru EJ20 NA engine converted for the previous owner by Mac VW (who I understand are not trading anymore) about 5 years ago.
I'm in the process of trying to fix two issues - probably related but possibly not:
The first is the temperature light is continuously flashing right from the turning the engine on. My suspicion is the issue is at the relay as I've been having electrical issues due to poor contacts on the fuse box thanks to a leaking windscreen which I need to get sorted when funds allow. The coolant level is fine (or at least was).
The second issue is the engine is overheating (although I'm not sure where the needle usually sits). I ran the engine at the weekend and the thermostat didn't appear to be opening so I've removed it and ordered a new (genuine Subaru) one.
I of course lost a bit of coolant in doing this although I managed to capture some of what came out. I was surprised though to see that the coolant was pink when I was expecting it to be green or blue from what I've read on the RJES website (if anyone else has a Mac VW conversion I've be interested to know if they used RJES parts and systems? Any information would be appreciated).
Should the coolant be pink? Or am I right in thinking it should be the Subaru Super blue coolant?
I'm guessing I shouldn't mix them but is it wise to flush and replace the coolant?