The MR2 Owner's Club of New Zealand

Yes it's probably from that fwd redtop beams that I got with a killed Piston

So I haven't been keeping you guys updated much but yes the engine is in the car and most stuff is connected up. I've taken it for a few not very legal drives and it's pretty ok!
I have had a play with the cam timing and launch control on the ECU.
I tell ya what it sounds pesty as, will need a quieter exhaust for sure.
Couple of coolant leaks, no air filter, bad idle control setup among some other things but it's pretty much all go.
Will need to quieten it down a huge amount but that's for later..

id love some more photos of the progress set up and how it looks in the engine bay. definitely something not often done, and an idea ive been playing around with myself

If you want to do it yourself then you need to have basically all the bits and bobs from a redtop or greytop..
I unfortunately used a RWD blacktop head gasket which means I need to use the water outlet on the left of the exhaust manifold.

I am currently running into a bit of strife with the cooling system.
I have no idea where the rear of head hoses are supposed to go and from a look online it seems that they need to be looped together in some fashion to allow the water pump to circulate the rear of the head correctly.
Basically as long as I have some revs on with minimal load then the temp measured on the head outlet is about 90c (a bit hot) but if I return to idle then it pretty much starts overheating.
I just have no idea where those hoses are supposed to be plumbed. Looks like one of the hoses directly off the back of the water pump that goes under the exhaust manifold needs to be routed.. somewhere.

Any help would be great. I have a couple of videos but I think they exceed the size limit a bunch so not sure how to post them up

I think I need to make a connection between the inner small outlet from the pump to the head outlet (marked in red)
Pictures shamelessly stolen from online and badly drawn on...

Coolant flows into the back of the water pump. Not from it.

You'd definitely be better off swapping the head gasket and setting it all up like an MR2. How are you getting coolant from the right side of the car to the radiator?

I guess this is why the blacktop swap is very uncommon. So many issues with the way it's setup in the Altezza vs MR2.

Swapping the head gasket and things like that I'd rather not do because I already have everything connected up (radiator hoses and heater core)
I have a long coolant crossover pipe from right to left of the engine bay.
I'll see if I can extract some pictures.
The only thing is that it overheats.... I have a thermal camera and basically the thermostat seems to not open until its already too hot..
I'll PM you a link to a video I took.
Everything is pretty rough but getting there. Wiring still a disaster

Fair enough. Custom projects always take a bit of thinking and learning in the process. Hindsight is a right pain in the behind.

I see, I figured you'd have done that with the radiator feed.

It should behave like the Altezza system if it's been setup like that and just had a hose run from right to left to go to the hot side of the radiator as you describe.

What thermostat did you use and how are you bleeding the coolant system? Do you have any high points in the custom system that are above the head coolant passages?

Ah yes, the wiring side of things. If you need a hand I can try help out.

The only difference to the Altezza factory setup that I can see is the small water connection to the head water outlet like I have marked out in the post a few replies back.
I am working on the wiring very slowly. Temporarily I will just continue to add a few more connections to the ECU (O2 setup, engine bay fan, knock sensor) and will then redo the under the boot part later on.
The engine loom itself I am happy with. currently
The pictures that I extracted from the video are not very helpful. I'll take some pics shortly to outline how its connected

I am using a brand new from toyota Altezza thermostat (82c) and oring
The water crossover is close to the same level as the water cap so its a little bit of a pain to get the air bled.
I am fairly confident there are no water leaks as I have pressurized the whole system to 20psi and it doesn't bleed down
I am sure there is no air in the front section of the cars cooling system (radiator and heater core)

I see what has happened. You have removed the red pipe/hose from the equation but you need this to allow the water pump to actually move (circulate) coolant around the engine with the thermostat closed. Add this back in to the system and it should work. You might be able to add a connection to the circulation pipe you capped off to the filler pipe you created. Up to you what you do but you need to add this circulation pipe back into the equation or it won't be happy ever.

Hope this helps.

Yes, I've had a look at my spare water pump (I think the original from the mr2 so it's not quite the same)
But yes looking at the hose in question it ends up flowing water into under the thermostat.
Check the pictures, the blue line is the one currently blocked and the red one goes to the heater and returns to the back of the head (from memory)
I have a plan in place that involves a welder and 15mm bit of pipe but I should be able to get it done tonight. Hopefully no more overheating

Alright everyone, that was the issue.
It appears water flows from the head outlet and into the bottom of the thermostat. This is how the thermostat knows when to open and allow cool water into the engine.
The blacktop head gasket has more restricted water flow on the front 3 cylinders (progressively tighter holes) where the redtop and I assume any other fwd 3sge has restricted water flow on the rear, as the hot water flows from the rear on the head.

I drilled a hole and welded on a 14.5mm ID pipe onto the long crossover pipe.
Found some pretty nice heater hoses at super cheap that fit great
My welds are heinous so taking the crossover pipe to a welding shop tomorrow morning

Excellent news!!

Yeah the head gasket on the BEAMS Blacktop only allows coolant to come up from the block at cylinder 4 unlike all other 3S engines that allow it at all 4 as it flows from the pump, block, head, back of head and loops around to the pump again. Then when the thermostat gets hot it opens up and loops through the radiator.

For the BEAMS Blacktop it goes, water pump, block, up through to the head at cylinder 4, along the head towards the front and to the outlet on the front of the head. Then it loops back into the water pump. Once the thermostat gets hot it opens up and flows out the front of the head to the radiator and back to the pump. Makes sense for the Transverse vs Longitudinal configuration of the engines.

Well. It's going pretty well.
I've driven around a wee bit doing some rough as guts tuning on it.
Increased the limiter to 5000 and it goes pretty well
I have a day on the dyno tomorrow so gonna get stuck in and extract all those horses. Hopefully won't blow up haha