27 replies to this topic

[AVV IT]

I'd try the "air lock" route first. As previously described take the radiator cap off & run the engine until it is up to temperature & the thermostat opens to see if that cures the problem. But if you now have overheating problems too (especially in this weather), then I'd be more concerned that your water pump may be the problem.

[asmith88]

i have already tried the method of leaving the cap off and running the engine, it did no use,

the engine has not overheated in a long time, even 2 days ago on a long drive, it didnt overheat until the morning after i pulled the matrix and pipes out (this morning). if i dont get into work tomorrow, i will give it another go.

[bmcecosse]

I've never known a Mini heater to 'airlock'......... Make sure the pipes aren't kinked shut, and I would remove the valve and fit a stub of copper pipe instead to make sure full flow. It could be that the impeller has rotted away on the water pump, so if all else fails - remove the pump for inspection.

[asmith88]

any quick way of checking the water pump rather than pulling it off.

[AVV IT]

any quick way of checking the water pump rather than pulling it off.

Not that I've ever discovered, unfortunately it tends to be a case of drain the system & take the radiator out & fan belt off just in order to get to it. Make sure that you have a new gasket for refitting it (even if you put the old pump back in) & take the opportunity to replace the bypass hose (if you have one) whilst you have the water pump off!

[asmith88]

good news, took all the pipes of again this morning, blew them through, bled it all up and shes blowing hot air.. better than before.

[union jack]

I've got no heating either.I Took the hose off the righthand side (as you look at it) off the after market inlet manifold & blew down the pipe & water came out of the manifold. So i take it that the pipes aren't blocked. I can't run the car yet as i'm awaiting rocker cover parts. Anything else i can check till i can get the car running? cheers

[union jack]

I took the thermostat out & tested that in a bowl of boiled water & it opened up. I Got the parts i needed for the rocker cover so i went out for a drive about 6 miles, but still no heat! When i got home I checked the hoses to see how they felt. The heater hoses in the car felt a little warm. The hose with the valve on under the bonnet felt warmer than the 1 without. The hose on the left hand side (driver's side) of the inlet manifold didn't feel very warm at all.

[AVV IT]

I've got no heating either.I Took the hose off the righthand side (as you look at it) off the after market inlet manifold & blew down the pipe & water came out of the manifold. So i take it that the pipes aren't blocked.

That really depends on how your manifold has been plumbed in (which could be in a number of ways, if it is an aftermarket item & also depending on the age of the car & position of the standard plumbing). Presuming your heater matrix is actually plumbed in between the pipe you have disconnected & the end of the manifold, then it is still possible that you have a partial obstruction somewhere in the heater circuit that is allowing some air to pass through, but not a significant enough amount of water to provide any real heat. It might therefore be worth flushing the heater circuit anyway if only to fully "rule that out" as the problem.

[dave-88_123]

i had a the same problem a couple of months ago and had to replace the water pump as it was no longer circulating waterand if stuck in traffic the car would begin to overheat

[union jack]

Ok thanks. What's the best way to flush it through? Cheers

[AVV IT]

Ok thanks. What's the best way to flush it through? Cheers

Disconnect the heater inlet & outlet pipes at the bulk head, connect a garden hose to one and a spare piece of pipe leading to a bucket into the other, turn the garden hose on and flush through, then reconnect the heater pipes again.... Simples!!! (Just don't turn the garden hose on fully though, as full mains water pressure may well blast holes in your heater matrix if it is old!!)

See this pic: Note that your heater inlet/outlet hoses may well be in a different location on the bulkhead, as this is a late HIF 38 mini & earlier models had different plumbing:

[union jack]

Finally got a warmish (14deg) dry day, so i did what you suggested. And i've got heating many thanks