28 replies to this topic

[lippo]

 

 

 

I've removed the heater, turns out the newish pipe to the heater valve was blocked with crud from the heater matrix.

 

All cleaned and matrix properly flushed through then topped up with de-ionised water. Bluecol used 50/50 with the de-ionised water to fill the radiator. I could still only get around 2.5 litres in there in total, I guess there's a lot of water in the block that's difficult to drain.

 

 The car is getting to temp and staying there, the heater is hot to the touch, and no overheating whilst idling.

As we have discussed on another thread, yesterday I got the heater out of the car and flushed it.  I put it back in, but empty of water.  Should I try filling it at the higher inlet as much as possible?  Or will air find its way out again when the entire system is refilled?

 

 Yes, I filled mine with de-ionised water prior to connecting it back up to the head/upper rad hose. Saves any issues further down the line with air pockets.

 

Coming back to this.  Now it is winter the internal heater is in need.  Although the general engine heating issue is well controlled (which included the flushing of the internal heater filled with vinegar for some hours, which seemed to blast hot inside the car for purposes of testing), the internal heater blows pretty cold.  Unless driving fast.  Again, the general engine heating is fine.  But not the internal heater.  Pipes to/from are cold.  Pulling and pushing in the heater knob changes nothing.  Is the issue the valve in the engine compartment (connected to the push/pull knob) or just a need to replace the entire internal heater unit?

 

 I would guess it's the heater valve on the cylinder as if the engine/radiator is getting warm but the heater pipes are cold then it could be because of the valve not opening.

 Did you flush and reverse flush the matrix? Did the water flow through easily? If so, then there's nothing wrong with the heater. 

[mullet]

 

 

 

 

I've removed the heater, turns out the newish pipe to the heater valve was blocked with crud from the heater matrix.

 

All cleaned and matrix properly flushed through then topped up with de-ionised water. Bluecol used 50/50 with the de-ionised water to fill the radiator. I could still only get around 2.5 litres in there in total, I guess there's a lot of water in the block that's difficult to drain.

 

 The car is getting to temp and staying there, the heater is hot to the touch, and no overheating whilst idling.

As we have discussed on another thread, yesterday I got the heater out of the car and flushed it.  I put it back in, but empty of water.  Should I try filling it at the higher inlet as much as possible?  Or will air find its way out again when the entire system is refilled?

 

 Yes, I filled mine with de-ionised water prior to connecting it back up to the head/upper rad hose. Saves any issues further down the line with air pockets.

 

Coming back to this.  Now it is winter the internal heater is in need.  Although the general engine heating issue is well controlled (which included the flushing of the internal heater filled with vinegar for some hours, which seemed to blast hot inside the car for purposes of testing), the internal heater blows pretty cold.  Unless driving fast.  Again, the general engine heating is fine.  But not the internal heater.  Pipes to/from are cold.  Pulling and pushing in the heater knob changes nothing.  Is the issue the valve in the engine compartment (connected to the push/pull knob) or just a need to replace the entire internal heater unit?

 

 I would guess it's the heater valve on the cylinder as if the engine/radiator is getting warm but the heater pipes are cold then it could be because of the valve not opening.

 Did you flush and reverse flush the matrix? Did the water flow through easily? If so, then there's nothing wrong with the heater. 

 

Thanks.  Yeah, flushed several times up both holes, all positions imaginable.  Plus filled with vinegar for hours, a couple of times in warm summer weather outside.  Came out clean and was careful not to airlock on refilling system.  Then I turned my attention to the internal heater.  So worth getting a new valve it seems.  Cheaper of the two options/process of elimination.  Will update once installed and tested.

Edited by mullet, 02 March 2026 - 07:28 PM.

[Quinlan minor]

So worth getting a new valve it seems.  Cheaper of the two options/process of elimination.  Will update once installed and tested.

 

Be careful with the replacement valve!

There were some poor quality ones going around. A friend had one fail under pressure, while he had his head under the bonnet, scalding him quite badly.

Edited by Quinlan minor, 02 March 2026 - 07:52 PM.

[Lplus]

 

 

 

 

 

I've removed the heater, turns out the newish pipe to the heater valve was blocked with crud from the heater matrix.

 

All cleaned and matrix properly flushed through then topped up with de-ionised water. Bluecol used 50/50 with the de-ionised water to fill the radiator. I could still only get around 2.5 litres in there in total, I guess there's a lot of water in the block that's difficult to drain.

 

 The car is getting to temp and staying there, the heater is hot to the touch, and no overheating whilst idling.

As we have discussed on another thread, yesterday I got the heater out of the car and flushed it.  I put it back in, but empty of water.  Should I try filling it at the higher inlet as much as possible?  Or will air find its way out again when the entire system is refilled?

 

 Yes, I filled mine with de-ionised water prior to connecting it back up to the head/upper rad hose. Saves any issues further down the line with air pockets.

 

Coming back to this.  Now it is winter the internal heater is in need.  Although the general engine heating issue is well controlled (which included the flushing of the internal heater filled with vinegar for some hours, which seemed to blast hot inside the car for purposes of testing), the internal heater blows pretty cold.  Unless driving fast.  Again, the general engine heating is fine.  But not the internal heater.  Pipes to/from are cold.  Pulling and pushing in the heater knob changes nothing.  Is the issue the valve in the engine compartment (connected to the push/pull knob) or just a need to replace the entire internal heater unit?

 

 I would guess it's the heater valve on the cylinder as if the engine/radiator is getting warm but the heater pipes are cold then it could be because of the valve not opening.

 Did you flush and reverse flush the matrix? Did the water flow through easily? If so, then there's nothing wrong with the heater. 

 

Thanks.  Yeah, flushed several times up both holes, all positions imaginable.  Plus filled with vinegar for hours, a couple of times in warm summer weather outside.  Came out clean and was careful not to airlock on refilling system.  Then I turned my attention to the internal heater.  So worth getting a new valve it seems.  Cheaper of the two options/process of elimination.  Will update once installed and tested.

 

I've had a valve on which the head came adrift from the plunger so it stayed closed even when the plunger was pushed forward.  The flow direction holds it closed.

[mullet]

 

So worth getting a new valve it seems.  Cheaper of the two options/process of elimination.  Will update once installed and tested.

 

Be careful with the replacement valve!

There were some poor quality ones going around. A friend had one fail under pressure, while he had his head under the bonnet, scalding him quite badly.

 

Hello.  How can I identify a poor quality one?  Normally I buy from minispares and pick up on trips to England (due to tax).  Unfortunately, no trips planned and I'd like this done before good weather (using heater as extra engine cooling if needed in traffic...worked well in the past....although my engine heating issue seems fixed now). 

 

A French site has also been very helpful in the past and has this.  Is it good?:

https://www.thelittl...ustin-mini.html

[Quinlan minor]

Buy one from a reputable supplier and avoid cheap marketplace ones, is the best policy.

[Lplus]

 

 

So worth getting a new valve it seems.  Cheaper of the two options/process of elimination.  Will update once installed and tested.

 

Be careful with the replacement valve!

There were some poor quality ones going around. A friend had one fail under pressure, while he had his head under the bonnet, scalding him quite badly.

 

Hello.  How can I identify a poor quality one?  Normally I buy from minispares and pick up on trips to England (due to tax).  Unfortunately, no trips planned and I'd like this done before good weather (using heater as extra engine cooling if needed in traffic...worked well in the past....although my engine heating issue seems fixed now). 

 

A French site has also been very helpful in the past and has this.  Is it good?:

https://www.thelittl...ustin-mini.html

 

Looks exactly like the minispares one.

[mullet]

Buy one from a reputable supplier and avoid cheap marketplace ones, is the best policy.

Thank you.  This is France's version of minispares.  I just wasn't sure of the specific model or if anyone would suggest another type.

[mullet]

 

 

 

So worth getting a new valve it seems.  Cheaper of the two options/process of elimination.  Will update once installed and tested.

 

Be careful with the replacement valve!

There were some poor quality ones going around. A friend had one fail under pressure, while he had his head under the bonnet, scalding him quite badly.

 

Hello.  How can I identify a poor quality one?  Normally I buy from minispares and pick up on trips to England (due to tax).  Unfortunately, no trips planned and I'd like this done before good weather (using heater as extra engine cooling if needed in traffic...worked well in the past....although my engine heating issue seems fixed now). 

 

A French site has also been very helpful in the past and has this.  Is it good?:

https://www.thelittl...ustin-mini.html

 

Looks exactly like the minispares one.

 

Thanks!  That was my impression.  I'll give it a go.

[burchy35]

Just out of interest is the pipe from the heater tap on the head that goes through the bulkhead is connected to the top spigot pipe of the matrix?
Mine was plumbed into the bottom one of the matrix and it never really got hot enough.
I swapped them over and it gets to hot now 😲

[Lplus]

Just out of interest is the pipe from the heater tap on the head that goes through the bulkhead is connected to the top spigot pipe of the matrix?
Mine was plumbed into the bottom one of the matrix and it never really got hot enough.
I swapped them over and it gets to hot now

Normally the pipe from the tap goes to the bottom pipe on the heater - at least both mine do ('80 and '84)

[burchy35]

Yes your right, my mistake. It had been plumbed in from the tap to the top hose. Swapping them to the correct position fixed my particular issue.
It was causing air locking before.

[mullet]

Yes your right, my mistake. It had been plumbed in from the tap to the top hose. Swapping them to the correct position fixed my particular issue.
It was causing air locking before.

Thanks.  I am going to check this when I get the car back from some bodywork.  I just put things back how I found them, but doesn't mean it was done right before!

[mullet]

I got a new valve for the heater (https://www.thelittl...ustin-mini.html).  Taking the old one off, it was all broken inside (but if anything, left in a heater-on fashion).

 

Pipe to heater goes in low, out at the higher outlet.  So this is correct.  I fill up rad fluid from the valve pipe before quickly connecting to the valve to minimise airlocks (to fill the internal heater up).  When running, bottom pipe gets warmish (is touchable).  Top pipe hardly warm.  Although I flushed the internal heater, achieving a clean flow (and generally, very well controlled engine temperature), I've got to wonder if the internal heater has had its day now and the flow isn't all that great?  I guess it is the original (1984) so may not be flowing very well?

 

Unless there's a last ditch thing to try?