over heating mk1

hi am having trouble with my1.8 carbed mk1 it keeps boiling up have checked water pump impeller fitted new thermo switch new thermostat new rad but still runs at three quater then red light flashes fan kicks in but still seems to run at three quater temp any ideas thanks

Could be a few things:

- Blockage of some kind in the engine block's cooling channels - have you done a flush of the cooling system, if so, what did the old coolant look like? Any solid bits of crud, significant rust, bits of rubber or remnants of stuff such as K-Seal come out?
- Timing out - poor timing would cause overheating

Can't think of much else, you've already checked the basics.

flushed out with hose pipe nothing untowards  will try new cap for expansion tank people seem to think blue cap is best thanks

I had terrible overheating problems too my friend but all is sotted now thanks to Golf owners club. What I learned is that whenever you have cooling problems you must start with the small cheap parts so I will also advise you to put a new expansion cap.
The cap has a rubber gasket inside that holds the pressure. If that rubber is gone (which is usually the case when the cap is opened and closed more gradually than its suppose to i.e when u keep refill) then you need a neew cap. You will see the difference when you are comparing the caps.

thanks for that have changed cap but still running a bit high will try temp sender next

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