13 replies to this topic

[theoldmini]

Have a 2000 MPI with a coolant loss.  Have replaced radiator, expansion bottle. expansion cap, heater matrix and water pump.  Done a pressure test which held pressure.  Loosing coolant but cannot see any external signs.  All help and pointers appreciated.  Thank you

[Midas Mk1]

Coolant system fully bled? Rad cores can have the smallest of leaks under pressure too

[theoldmini]

Have replaced rad but still loosing coolant

[Quinlan minor]

How full do you top the header tank to?

If you fill it to the 'Max' mark, it will vent fluid until it reaches its natural level.

Mine settles about 3/8 of an inch below the back seam of the header tank.

Try leaving it, without topping it off. Monitor the level and see if it remains stable.

[theoldmini]

Will try that thank you

[Steam]

Is that not what the expansion bottle is for, to allow for overflow when hot then replenish on cooling down?

[68+86auto]

Connect the pressure tester and run the engine. Rev it up. If pressure builds up, you've got combustion gasses entering the cooling system. This will over pressurise the system and result in coolant loss.

[theoldmini]

This then would point to head gasket issues perhaps.

[Blumeanie]

Have a 2000 MPI ...

Pictures please! (I also have a 2000).
Best of luck with finding and sorting the leak. I hope your level settles and nothing more complicated is the issue.

[slidehammer]

Have you checked in the car at the pipes to and from the heater, I see you have changed the matrix but is all the piping sound?

[68+86auto]

This then would point to head gasket issues perhaps.

Most likey the gasket but it could be a cracked head.

[sonscar]

It could be a porous hose if the leak is small,look at the ends of the hoses for signs of antifreeze when it is cooled.If there are any cloth covered hoses they are prone to this.Just a thought before removing a head which is still not condemned.Steve..

[Steve220]

Start with the basics. Never fill to the max level in the tank, go 10mm below it.

How much coolant is it losing?

[theoldmini]

Will check later. Waiting for a good day. Mini does not go out in bad weather