Rover 200 & 400 Owners Club

This is a new one on me, but perhaps it’s something you all can help me with.
1996, 216 Kseries.
Starts first time. Runs sweetly. Temperature gauge appears to work fine, and doesn’t indicate any sort of overheating issue. Nothing really amiss….except.
On tickover, or in start-stop traffic, the water in the header tank beigins to boil just before the cooling fan starts. As soon as the fan starts the water cools enough to stop the boiling and all is well again - except by then a cup-full (or so) of water has come through the header tank valve. A couple of cycles of this and the coolant level is beginning to get very low.
Either the cooling fan is switching on too late, or the system isn’t pressurised enough to raise the boiling point to enable the fan to cycle on first. I’ve replaced the cap recently.
Only happens in the summer. Winter weather keeps everything cool enough.
So my questions.
Are there different versions of header tank cap set for different pressures?
Is it possible that the thermostat on the cooling fan has gone rogue and a replacement would sort it out Switching the fan on at a lower temperature?
Anything else?
I’m inclined to rewire the fan to run continually (I can change it when cool weather returns) but I’d rather see if I can sort it out properly.
Doesn’t appear to be HG, none of the usual signs - but with the K series theres always that possibility of course.

Did you mean 216 or 214 K-Series? Is it possible that the thermostat is defective? Sounds like the engine is running a bit hot. Is the radiator in good condition? All issues that the K-Series doesn't like.

Cheers,
Hugh

Are all of the hoses equally hot when the engine is warm?

My initial thought is the thermostat being stuck shut, or the water pump impeller has failed, so it’s not circulating coolant efficiently. Either that or there’s a blockage in the cooling system somewhere - has the car had regular coolant changes?

Both good shouts. The cambelt was changed during the winter along with the thermostat and water pump (so pump or stat could be the problem). I hardly used the car last year so not much history to go on.

Next thing I’m going to try is remove the rad, and as many hoses as I can and flush through with a hose. Stat is a bugger on these but I’ll try and get to it as well.

g259fsg wrote: ↑Thu Jun 27, 2024 11:04 am Did you mean 216 or 214 K-Series? Is it possible that the thermostat is defective? Sounds like the engine is running a bit hot. Is the radiator in good condition? All issues that the K-Series doesn't like.

Cheers,
Hugh

A 1996 216 will be a K-series. The Honda D-series stopped being used in 200s with the introduction of the R3 in 1995.

Sounds like it could be a faulty thermostat which is opening too late causing localised over-heating - hence the inital "boiling" before the system settles down. Alternatively, perhaps your first port of call would be to flush the cooling system.

To do this properly you will need to re-mortgage your home and but a product called Irontite Thoro-flush, which is rated as the very best, but you do have to adhere to the strict yet simple instructions regarding its use.

Is the thermostat the right way round in its housing?