Morning all, hear's a puzzeler for you, I'am haveing cooling issue's ....mid engine car engine is toyota mr2 so is fitted transverse) thermostat housing on right side,so cooling pipe goes to the right a few inches turns 90deg down for 14ins 90deg then pipe goes forward to the front of the car through the sill where it then goes up 25deg to 1 of the front rads these lay at 25 deg so 1 pipe in and 1 out a cross pipe to the rad on the other side and a return journey back to the other side of the engine, so where would you best site the expansion bottle and where would you put any bleed pipes ?, I had a good run to Brighton and back the other weekend but after a short run yesterday I keep getting what I think is air locks, at speed its seems fine as there is more water flow but low speed the temp shoots up the twin fans do cut in but can"t cope, maybe an electric water pump and control ? what do you thing.........thanks for reading all this.

It sounds like a fan problem are the fans rotating in in the correct direction of rotation?
Also do you have a proper bypass connection.

You relatively cheap mod you might want to consider is to use a mod used by MGF owners who remove the original thermostat and fit an external thermostat in the front of the car.
These thermostats are Land rover units and simply tee into the rad pipe work.

[Edited on 23/6/14 by britishtrident]

Where is the header tank, have you a small pipe to bubble off steam from the head, if it's all just large bore you will get air locks front to back.

Hi thanks for your thoughts the fans are correct as you can hold a piece of paper in front of the vents and it will be pulled towards the rads so the fans do suck, header tank is in the engine compartment with a bleed into it feeding water in the direction of flow ie towards the 1st rad.....

The pump on your engine will be more than adequate for a front rad.
I take as read you have bled air from the top of the rad on filling and after the first few runs.

It might be worth double checking the coolant is flowing through the rad the right way -- ie in at the top connection and out at the bottom.

Some other things you might want to check are the fan blades facing the correct way relative to the air flow, to work efficient the fan blades should scoop the air and an turn it through almost 90 degrees to accelerate it it in the desired direction of flow.
Also the thermostat ISTR Toyota used a few different designs of thermostat but most were of the double type that partly closes the by-pass/heater connection when the thermostat is fully open, this to encourage the coolant to take the long route through the rad rather than short circuiting through the by-pass.

[Edited on 24/6/14 by britishtrident]

I found the problem and thanks for your thoughts it was the diameter of the leak off pipe going back to the expansion bottle, I have reduced it to 8mm and have a good run down to goodwood last weekend from home a round trip of 285miles.......