Rover 200 & 400 Owners Club

I've noticed a weird behaviour from my 214 cabby.
She runs fine, the coolant temperature is absolutely normal along every journey (9 o'clock, middle position), the oil is clear without any level variation.
The coolant is coloured as on the first day but when I top it at the MAX level it's blowing out of the header tank cap at the end of the day, spilling some surplus around the tank and just below.
When I top at the MIN level or even a little above (say up to mid position but never above) nothing abnormal happens.
Too much pressure? Why? anything else?
I'd never noticed before that puzzling phenomenon... and nothing had been done or modified on the car since 6 months.
Thanks a lot for your wise advice.

Could just simply be a failed pressure valve in the cap - they do become weak after a while.

Fit a new cap and see what happens.

Could be just that. If you've been driving the car and the engine is hot, then the latent heat in the engine could boil the coolant when you take of the coolant filler cap and the pressure reduces. It does warn of this on the header tank. HOWEVER, if it didn't do that before, then maybe something else is causing it. I had exactly the same symptoms last year on our 1990 214 GSi, and it was early stage HGF. A leak had developed from one of the cylinders to the coolant channel and the system was being pressurised by combustion gases. This drives the coolant up to the header tank and overflows when you take off the cap. Like you, the engine performed normally and the temp gauge read normal. Since the head gasket was replaced, this problem has completely gone away, even when the engine is very hot. I diagnosed the fault with a kit called Mr. Headgasket and at the local garage where we did a sniff test in the coolant tank with the exhaust analyser, confirming there was combustion gas present.

Hugh

Thanks a lot for your contributions guys. Very much appreciated.
I'll begin by the cap even if just in need I've bought everything to replace the HG. But I'm dubious about it.
BTW my cabby is very seldom above the 3k revs and if so around 3.5k. Never over. So...
Anyway before any journey I've an overall oversight of every levels, tyre pressure and the like. The battery is controlled by a Noco Genius intelligent charger (I know it has nothing to do with the HG! ) but to say that my Rovers are garaged. Besides the cabby (and the 75 V6 as well) are regularly in service once a month at least and more if possible.

id start planning a thermostat swap.

Thank you mate but just in case which is its reference? I don't see any at Rimmers.

For example https://rimmerbros.com/Item--i-PEL10016 . There's also a 82 degC thermostat, which is the one I fitted.

That’s interesting my 416 started displaying exactly the same characteristics after I replaced some of the hoses and the thermostat.
I’ll be interested to see what you do to resolve it. Probably need to buy a spare thermostat for when I change the coolant next time.
Did a sniff test last year and there was no hint of a HGF at that time

g259fsg wrote: ↑Sun Sep 24, 2023 7:24 pm For example https://rimmerbros.com/Item--i-PEL10016 . There's also a 82 degC thermostat, which is the one I fitted.

Thank you very much.
But the 82°C one doesn't seem to be compatible with my 214i or am I wrong?

Father in Laws 214 Cabbie did this a few years ago, luckily it was only the rubber seal on the expansion tank cap. Replaced the seal & it hasn't done it since