EJ20 Engine Overheating - Solutions?

[Basilakios]

Last year I bought my T25 which has an Subaru EJ20 engine conversion.  I don't know much about the engine but it was done by Steph at Mac VW and I understand uses RJES parts - so in theory all good.

However I've hardly driven it anywhere because I had a nightmare with the gear linkage which took an age to get to the bottom of - turned out the back linkage bar was bent.  All working okay now.

When I have come to drive it though I've noticed that it keeps overheating.  I take it on a short run and the temperature gauge goes up and eventually I can hear bubbling from the header tank so turn it off and let it cool down.

The issue appears to be the thermostat not opening as the bypass pipes get warm but not the one off the thermostat and the radiator doesn't get warm.  I took out the old thermostat and bought a new one.  The old one opened in hot water but the new opened more.  Fitted the new one and no change.
The coolant is full.  Can't see any leaks.  The radiator did have a little air in it but I've topped it up again.
The oil shows no signs of goop so hopefully not a head gasket.

I presume it is just some trapped air still in the system?  Do I just need to keep driving short trips until it clears?  How many of these trips should do the trick before I have to conclude it's something else?

Is there anything else to check or try?

Now Steph at Mac VW has retired, does anyone know of a mechanic in the north west who knows about these engines?

 

[Aidan]

When you say bubbling from the header tank do you mean the overflow/top-up tank behind the rear flap ? Is it full of coolant (ie above max/full level) when this happens with sign of coolant coming out of the three holes in the top of it ?
Or do you mean the expansion tank which is pressurised with the Blue (or black) Darlek cap on the top ?

[Basilakios]

Expansion tank with the blue Blau cap on top. I replaced the cap when this all started a while back but didn't make a difference. You think it might be a pressure issue?

I might be being a bit thick but I don't appear to have a top-up tank...

[slowcoach]

Expansion tank with the blue Blau cap on top. I replaced the cap when this all started a while back but didn't make a difference. You think it might be a pressure issue?

I might be being a bit thick but I don't appear to have a top-up tank...

The hose that comes off your blue cap, must lead somewhere- to a top up tank?

Also, the thick rubber hose elbow coming off the thermostat is actually the return from the radiator. Feel under the van for the two big coolant pipes, see if one of those feels hot.

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[Basilakios]

The hose from the blue cap just leads away towards the ground. No other tank. Presume I should have one therefore...

I'll have to run it again and check those pipes. The radiator stays cold for sure.

[slowcoach]

The hose from the blue cap just leads away towards the ground. No other tank. Presume I should have one therefore...

I'll have to run it again and check those pipes. The radiator stays cold for sure.

Yes, you should definitely have the stock water tank behind the number plate. Otherwise that pipe going to ground will just be siphoning off hot coolant onto the ground when hot... And then sucking in air to the system when it cools down. And that's not a good combination

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[Basilakios]

The hose from the blue cap just leads away towards the ground. No other tank. Presume I should have one therefore...

I'll have to run it again and check those pipes. The radiator stays cold for sure.

Yes, you should definitely have the stock water tank behind the number plate. Otherwise that pipe going to ground will just be siphoning off hot coolant onto the ground when hot... And then sucking in air to the system when it cools down. And that's not a good combination

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Right, I've bought one and will get that fitted as soon as possible.

Guessing though that is not the cause of my current issue.  I'm going to run it again tonight if possible and double check which pipes get hot or not.
 

[slowcoach]

Sucking in air every time you do a warm up & cool down cycle (which you are currently doing) could certainly hurt your cooling ability. Very worth fixing as step 1

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[Basilakios]

Just for absolute clarity: the header tank should be full to the brim, right? Mine wasn't so topped it up and it kept dropping slowly although no obvious leaks. Potentially just had a load of air in the system?

Once it had stopped dropping (I think - it was very slow) I took it for a short drive but ran of time to investigate fully. The temperature gauge got up to about three quarters but I understand that doesn't necessarily mean it's oveheating and the temp gun wasn't particularly high when I tested it after parking up.

As for the pipes, the two smaller pipes running up to the front of the van were warm. Of the two big pipes only one got warm and not further than the rear axel. I don't know whether this was just because I had to cut it short. Radiator was cold.

[Aidan]

some good pics of the installation would really help understand what your set up looks like
The pipework from the reversed Subaru waterpipe is important, as is getting the radiator send and return pipes correct, using RJES stuff works well but it may need the rad connections swapping over depending on how it has been connected at the back - certainly on mine that's how it is, the easy front to back connection from the manifold is the wrong one but it's not difficult to swap them over at the front.
Also the Subaru sender for the temp gauge is calibrated differently to the VW set up the gauge is designed to work with so a pic of the wiring from the manifold will also help, usually an additional resistor is added in to make the gauge read correctly, RJES probably does that when he does the loom work, but it maybe the loom isn't his work.
You might find contacting Richard helpful, he really understands it all in super detail, will be able to check what Steph bought from him and provide better support than we can.
Did you get any paperwork, instructions, or explanation of the installation when you bought the van ? The lack of a top up tank would be a red flag to me, either somebody doesn't understand the T3 cooling system or was deliberately trying to hide a issue when selling the van

[Basilakios]

I'll try to get some pics but too dark and late now.

I've considered contacting RJES but haven't yet. Might be time.

Easy to spot red flags when things go wrong. Previously I had an air cooled so I'm unfamiliar with the coolant system. When I bought it it drove well and had been converted by a reputable outfit so assumed that was all okay. It wasn't overheating then.

I'd be surprised if the pipework was mucked up but you never know. The conversion was done a couple of years ago and as far as I'm aware was running fine. Apparently Mac VW used to deal with any issues as they knew the van so well.
The missing overflow tank is very strange as it's a VW part so why would it be missing. The exhaust fits below where the tank should be so I'm wondering if the tank fixings came loose and the welded on exhaust bolt knocked it off at some point unnoticed. One of the exhaust fixings sticks up so might have clashed with the tank. Might become apparent once I've got the overflow tank.

[silverbullet]

Don't forget the heater bypass H-pipe mod that all EJ's need because the Subaru heater is a full-flow blended air system unliike the VW which throttles the hot water flow to regulate air temperature.
Without this mod, when you close the heater valve the coolant can recirculate in a stagnant loop causing warm-up problems, which then affects fuel economy and can also cause overheating (assuming that the temp sender and/or gauge have the resistor mod to make the gauge read properly!)
Little detail things but EJ's have a different coolant flow path and thermostatic bypass arrangement to wbx engines.

[Basilakios]

I don't know whether any of these will be useful.

Not sure where this resistor should be but the wire connection to the thermometer:


Header tank.  I've ordered an overflow tank and will fit as soon as it arrives.  
There is no wire/plug to the header tank.  Seems to have been taken out.  Not sure if that is why the red light on the temp gauge constantly flashes.


A hard place to see let alone photograph.  Can just about see the H pipe.

 

[Basilakios]

Also I don't know if this is connected but the blowers aren't working.  This maybe just an electrical contact issue as I've been having issues all over with poor contacts. 
(I've had to clean up the earthing points next to the glovebox and replace the connectors.  I've also replaced the fusebox because lights and other electrics would stop working suddenly - all working fine now thankfully.  The temp gauge stopped working at one point until I cleaned the contact.)
The radiator fan works fine though.  Tested it by shorting the plug behind the grille.

[Basilakios]

Update: took the van for a quick run just now (I'm squeezing in bits of time after work and on lunch breaks to chip away at it) - just a mile or two.  Basically I'm following the instructions on the RJES website for filling the system.  

Again the temperature gauge rose up to about three-quarters but I don't know what is normative for this van.  I'll feel more confident once I understand that.  It might have gone higher if I'd continued but I don't know.  The engine temperature was generally reading 70/80/90 degrees but I did get the odd 101 degrees which concerns me slightly.

The good news is the radiator was beginning to get warm which it hasn't previously.  The coolant in the header tank keeps dropping slightly but no sign of a leak and there was a release of pressure when I opened the cap so I'm thinking its just working air out the system.
I undid the bolt on top of the radiator and it released some pressure but not coolant.  I tried filling it up at this point but it's not easy to tell if it's overflowing or I'm just making a hash of the filling.  Once I get coolant coming out when I remove the bolt I'll be happier.

I'm expecting my replacement overflow tank to arrive today/tomorrow so that should help make sure the coolant is always topped up.  Cautiously optimistic.