7 replies to this topic

[orac69]

Hi,  1994 SPi, I have been having trouble with the heater, after following a load of threads here, Im now 99% sure the issue is with my heater core, so Im going to replace with one of the higher quality brass pipe ones..  

https://thecarheater...x-1992-onwards/

 

Anyway, while "servicing" the heater valve, the floating type which sits up by the wiper motor, I noticed that on operating the cable/plunger the gate which restricts the water flow doesnt fully close.  It looks like the valve is always allowing approx 20% of water through.   I dont think the plunger is jammed, seems pretty free, didnt want to force it, but I just wanted to check if this is normal or if I should replace the valve too.

 

If anyone knows Id appreciate it.

 

Thanks!

[MikeRotherham]

Is it the correct cable?

I'd start by checking the action of the hot/cold pull knob to see if it has full movement.

 

Assuming it's still working, there's a locking mechanism so you twist it a 1/4 of a turn before pulling and pushing then twist the opposite way to lock it.

Pull it out for heat and push it in for no heat. (On older models the knob works the other way round)

[orac69]

Yes, I dont have an issue with the cable, in/out etc - it was an observation with the valve removed from the car.

 

If you look down the pipe hole on the valve and actuate the little in/out lever manually, the plunger seems quite free, and I can see the flow hole opening / closing, but it only blocks the flow to about 80% when closed.  I wondered if this was normal is all.  I would have expected it to be 100% blocked/closed - hence my question!

[Ethel]

I think it's a short of sliding shutter (haven't got one, but have had similar on other vehicles), so it will be prone to silting up if it's not operated frequently. I don't see why you couldn't attempt to  clean the slider grooves with an angled  dental pick sort of thing. There's a similar valve if you're looking for an alternative & plenty of others on fleabay. That one looks like it's for a Bowden cable, with a loop on the end to go over the pin on the lever, but shouldn't be hard to botch modify.

[MikeRotherham]

It should block the all the hole.

 

I have the same heater valve on mine.

 

Ethel made a good suggestion about making sure the channel the shutter slides in is clean.

[orac69]

Hi all, an update for you - in case anyone is searching for this info in future...

 

I removed the heater valve again, took it all apart, and it was indeed just full of crud.  A good scrub, pick, clean out, then some lube, and actuate it dozens of times and its now operating like butter - and as Mike said, the valve SHOULD fully open and close the flow - see the pics for info.  As you can see, mine wasnt fully closing at first but is now.

 

I also replaced the bad heater matrix - mine was in really rough shape, the in/out pipes were nearly completely blocked, and the fins were all corroded, and I got a ton of crud out (shown in the red pot)

 

A shout out to "The Car Heater Shop" in the UK.  The new matrix arrived ultra fast, and is of excellent quality. Its easy to change. 

 

- Put some towels down and have a shallow pot ready to catch the crud. Not much comes out, but its really dirty.

- In the passenger footwell, just 2 small phillips screws hold the heater matrix in - 1 up to the top left of the back pipe, and 1 at the bottom right of the front pipe.

- Undo the 2 jubillee clips on the pipes.  The rubber pipes will likely be quite seized on due to corrosion.  Take your time, wiggle, wiggle, prise - dont split the rubber if you can help it...

- Catch all the crud in the bowl as the pipes come off.

- Pull out the matrix - again there will be a load of dust, bits, dead spiders probably.

- Refit the exact same way.

 

A top tip for refilling so you dont get an airlock in the system... 

Under the bonnet you have the feed pipe to the matrix (the pipe attached to the open/close valve) and next to it on the left is the return pipe from the matrix.  Undo the jubillee clip on the return pipe, unplug the pipe and holding it up a bit, use a hose with a funnel stuck in the end of the pipe and back fill the new matrix using new coolant/water mix.  It doesnt take that much, maybe a pint / 500ml or so at a guess.  This is the highest point and filling it this way should prevent an airlock.

 

mmm. toasty.

 

Attached Files

•  closed.jpeg   49.05K   0 downloads
•  partial.jpeg   25.92K   1 downloads
•  heater-pipes-blocked.jpeg   77K   1 downloads
•  poorly-heater-matrix.jpeg   93.26K   2 downloads
•  crud.jpeg   45.46K   1 downloads

Edited by orac69, 29 July 2025 - 01:22 PM.

[croc7]

Hi all, an update for you - in case anyone is searching for this info in future...

 

I removed the heater valve again, took it all apart, and it was indeed just full of crud.  A good scrub, pick, clean out, then some lube, and actuate it dozens of times and its now operating like butter - and as Mike said, the valve SHOULD fully open and close the flow - see the pics for info.  As you can see, mine wasnt fully closing at first but is now.

 

I also replaced the bad heater matrix - mine was in really rough shape, the in/out pipes were nearly completely blocked, and the fins were all corroded, and I got a ton of crud out (shown in the red pot)

 

A shout out to "The Car Heater Shop" in the UK.  The new matrix arrived ultra fast, and is of excellent quality. Its easy to change. 

 

- Put some towels down and have a shallow pot ready to catch the crud. Not much comes out, but its really dirty.

- In the passenger footwell, just 2 small phillips screws hold the heater matrix in - 1 up to the top left of the back pipe, and 1 at the bottom right of the front pipe.

- Undo the 2 jubillee clips on the pipes.  The rubber pipes will likely be quite seized on due to corrosion.  Take your time, wiggle, wiggle, prise - dont split the rubber if you can help it...

- Catch all the crud in the bowl as the pipes come off.

- Pull out the matrix - again there will be a load of dust, bits, dead spiders probably.

- Refit the exact same way.

 

A top tip for refilling so you dont get an airlock in the system... 

Under the bonnet you have the feed pipe to the matrix (the pipe attached to the open/close valve) and next to it on the left is the return pipe from the matrix.  Undo the jubillee clip on the return pipe, unplug the pipe and holding it up a bit, use a hose with a funnel stuck in the end of the pipe and back fill the new matrix using new coolant/water mix.  It doesnt take that much, maybe a pint / 500ml or so at a guess.  This is the highest point and filling it this way should prevent an airlock.

 

mmm. toasty.

That much crud makes me wonder about the condition of the radiator/cooling system.  Any issues with overheating or running hotter than normal?

[orac69]

The radiator was new a year or so ago, and the system was flushed through then - although im guessing as the heater valve wasnt working properly the heater matrix didnt get flushed through then. My bad.  Lesson learned.

 

No problems with cooling - no overheating, running nice and cool according to the needle.   Actually I must plug in the mems and see exactly what its reading...  Another job.