Cylinder #4 cooling improvement

[MrDangerUS]

Cylinder 4 overheating problem can be solved permanently by adding a heater matrix bypass hose as shown in the picture.

This simple modification makes  coolant flow indifferent to the heater dial position.  Works well on any 4-cyl Esprit.

[Chillidoggy]

Does it work if the heater valve is turned off?

[Escape]

That would make sure there is always flow to cylinder 4. But the bypass would seriously reduce flow through the heater, given the long pipework. So not really suitable for those (like myself) who run their Esprit all year long and need a good heater to demist the windows and make the cabin comfortable if the weather isn't great.

Filip

[lotus-62]

get a 3way T-valve in that position, so at least you can fine tune the flow to the heater. or even better make it an electrical operated 3 way valve so you can switch on the heater flow in the winter.

 

[MrDangerUS]

You can add a NC solenoid valve in to the bypass branch, which opens up only when dial is at "off" position, easy fix.

PS. I don't drive this car in winter so "defrost" mode is not that important to me.

 

Edited February 16, 2021 by MrDangerUS

[Escape]

16 hours ago, lotus-62 said:

get a 3way T-valve in that position, so at least you can fine tune the flow to the heater. or even better make it an electrical operated 3 way valve so you can switch on the heater flow in the winter.

 

You could power the valve together with the A/C, so the bypass is only active when the heater is off.

[lotus-62]

5 hours ago, Escape said:

You could power the valve together with the A/C, so the bypass is only active when the heater is off.

me not have A/C  (I'm the poor one in the family 🙂

 

[Escape]

Me no want A/C, I ripped it out of all my cars. 😉 But in the Esprit the wiring is till there (too much effort for too little lightness to gain) so I could reuse that if fitting a bypass with a 3-way valve.

[cammmy]

I haven't heard of this issue. What causes it and how do you ensure best cooling if you haven't done this mod?

[cammmy]

So with the stock setup, is it better to run with the heater set to hot or cold?

[Escape]

You'd have to have the heater on hot, otherwise the heater valve will remain closed and there will be no flow. You can at the same time put the distribution knob to the face vents, so you will not get too much hot air into the cabin, regardless of the temperature setting.

But I'm not convinced there actually is a problem, unless the engine is worked particularly hard and/or the cooling system is not in good shape. I always drive with the temperature said as I want it and still going strong after 150k miles total (about 60k since I bought the Esprit). There is already a bypass in place, via the turbo cooling, that should suffice.

Filip

[cammmy]

Okay cool. My cooling system works fine but I am running a bigger turbo and 320bhp. If it's just a flow issue then I'll try turning it to hot but leaving the fan off and see, once my suspension is back together and road legal.

[MrDangerUS]

One can use this electric compact COOLANT CONTROL VALVE, 3 Way from Tesla 6007384-00-F, to control the flow direction.