Boiling & Leaking coolant? S1 FHC 2+2 1966 (with Video)

Hi there,
i again come to you with a beginners question… i took my Jag for a short ride (maybe 5km). When i got back and parked it, i noticed a loud ‘bubbling’ sound. I cant quite say if it sounded like something is boiling or like if you’d flip an open bottle up side down and the liquid would come out bubbling while sucking in air. Shortly after i noticed a pink fluid coming coming out from the front bottom of the car (below front axis) it stopped dripping after maybe 100-200ml.

This Video should make it pretty clear: E-Type S1 1966 2+2 FHC - YouTube

Is this boiling coolant spilling out? Why would it do that? The car was checked comprehensively just 2 weeks ago. That day i only drove 40mph max no high rpm. It was very hot outside tho 30 Celcius but that cannot be it?

  1. Is this of great concern?
  2. Should i just refill coolant? I don’t recall which was used originally, are they compatible in general?
  3. I was trying different ventilation settings on the dashboard because i noticed very warm air coming to the cabin in the leg room (which i have not noticed before). Am i right to assume that any of those ventilation settings are purely for cabin comfort and not related to the engine cooling?

I am speaking about these 3. What do these actually do exactly?

Bear with my lack of knowledge… i wish the User’s Manual would explain these things but i could not find these information.

Thanks a lot as always!

Yes the controls in the dash are for your comfort and have little effect on the engine.
I say little because they can be used to try to take heat out of the coolant if the engine temperature gets high.
With regards to coolant, DO NOT mix colours, they can turn to a gell consistency if you are unlucky.
Now to the release of coolant. Does your car have a recover tank and is it full to the brim when cold? The coolant expands as it heats up, if the system is completely full it has nowhere to go except to atmosphere/the road.

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One is the heater valve, one is the „recirculation“ flap that eliminates ram air, one is the cabin air fan. Theyre all labeled?
30C should not be a problem for the engine.

I have a 1966 2+2. To check the level in the header tank I remove the cap, and stick my finger in.

If I can just feel coolant, then all is good. The tank needs expansion room.

Does your fan kick in at around 74 C?

If you are running hot is is good to remedy the situation ASAP as you could damage the head. Is the otter switch working, is the thermostat doing it’s job? Is it the correct unit, is it installed correctly? Is your timing correct?

Now might be a good time to change your coolant.

Good luck.


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Pressure test the system. If it has a leak, and cannot hold pressure, the boiling point is lowered.

I assume the temp gauge read under 100 degrees C when you were driving? Anything over 100 degrees and things are getting dicey. The S1 4.2 is known to have cooling issues in even moderate weather (ask me how I know).

If the car was running at an acceptable temp, here’s a clue: you said you just had it serviced. If so, the coolant was likely topped off in the header tank. It is common for the system to expand and discharge the excess when you park and stop. Now that it is at the proper level, you shouldn’t have any more issues.

That said, I’d look at improving the cooling system anyway beginning with an aftermarket fan.

Did the car actually boil as measured by the gauge?

If your car was serviced a couple of weeks ago and they topped up the coolant it’s possible all you were seeing was overflow due to expansion, which is normal.

I would firstly check the coolant level and see if it is low. If not drive the car and see if it actually overheats or not.

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