Heater matrix
Moderator: martauto
- Brianmoooore
- E30 Zone Team Member
- Posts: 49358
- Joined: Mon Jan 10, 2005 11:00 pm
Didn't realise that your problem was no heat at all. It's unusual for a valve to fail shut, unless the heater hoses are the wrong way around, when the flow of water can hold it closed. Do you know that the problem is with the valve and not the matrix?
The purpose of the diaphragm is to block the hole that the coolant flows through when required, and cut off all flow to the matrix. It also has the secondary purpose of keeping coolant out of the motor.
When I first got the car the heater hoses from the engine were on the wrong way around and the aux water pump had expired so maybe this could account for it ?Brianmoooore wrote: ↑Tue Oct 13, 2020 9:54 pmIt's unusual for a valve to fail shut, unless the heater hoses are the wrong way around, when the flow of water can hold it closed.
Mart.
Only the E46 cab left now.
Just got too old.
Just got too old.
Thank you,Sanchez wrote: ↑Tue Oct 13, 2020 11:47 amIirc 45mm length required for bolts.loogie1 wrote: ↑Thu Oct 08, 2020 11:09 amThinking these may fit. will strip my valve to measure o-ring size, when i get near a garage.
https://www.ebay.co.uk/itm/M3-3mm-A2-ST ... SweChcrf~5
30mm large oring and the 2 smaller 17.9mm required.
"2 smaller" Thought there was only one?
Ahhh, My diaphram is shot (non existent), i was hoping I could reassemble the unit and it would remain water tight but you say the diaphram keeps the "coolant out of the motor". Am i still going to have a leek? I hadn't considered coolant entering the motor! I was lloking at a nice flush face for the oring to seal against was forgetting the diaphram plunger opening to the motor! Damn. Will need to source a replacement valve afterall?Brianmoooore wrote: ↑Tue Oct 13, 2020 9:54 pmDidn't realise that your problem was no heat at all. It's unusual for a valve to fail shut, unless the heater hoses are the wrong way around, when the flow of water can hold it closed. Do you know that the problem is with the valve and not the matrix?
The purpose of the diaphragm is to block the hole that the coolant flows through when required, and cut off all flow to the matrix. It also has the secondary purpose of keeping coolant out of the motor.
Better to find out now i suppose.
- Brianmoooore
- E30 Zone Team Member
- Posts: 49358
- Joined: Mon Jan 10, 2005 11:00 pm
A flat plate bolted in place of the motor will keep the coolant in.
Yes, just read your previous comment, with Gasket/oring. Utilising the o ring would require some machining of a plate? be neat but flat plate and gasket would suffice?Brianmoooore wrote: ↑Fri Oct 16, 2020 2:22 pmA flat plate bolted in place of the motor will keep the coolant in.
Thank you.
- Brianmoooore
- E30 Zone Team Member
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- Joined: Mon Jan 10, 2005 11:00 pm
It's possible, I suppose, You could try adding a bit of pressure to the flow by disconnecting the heater hoses at the bulkhead (pull them off quickly, and tie them up to a piece of string from the wiper spindle). You won't loose much coolant, then hold a garden hose onto the bottom stub pipe, and see if water flows readily out of the top stub. Don't go above 2 bar or so of pressure.martauto wrote: ↑Wed Oct 14, 2020 1:06 pmWhen I first got the car the heater hoses from the engine were on the wrong way around and the aux water pump had expired so maybe this could account for it ?Brianmoooore wrote: ↑Tue Oct 13, 2020 9:54 pmIt's unusual for a valve to fail shut, unless the heater hoses are the wrong way around, when the flow of water can hold it closed.
Mart.
Good day. I have a problem with my 325is. I did a full restoration. All items were replaced. Radiator. Thermostats. Heater valve. Heater core. All piping.
The heater rotary knob on the dash panel was also defective , and replaced (this knob alone was USD250)
When I leave the temperature control knob on full cold , I get environmental temperature air into cabin. When I turn on full heat , I get hot air
The problem is in between. I do not get “blended” air temperature. What can the problem be ? It’s either too hot or too cold , and I cannot regulate it to give the desired temperature
The heater rotary knob on the dash panel was also defective , and replaced (this knob alone was USD250)
When I leave the temperature control knob on full cold , I get environmental temperature air into cabin. When I turn on full heat , I get hot air
The problem is in between. I do not get “blended” air temperature. What can the problem be ? It’s either too hot or too cold , and I cannot regulate it to give the desired temperature
- Brianmoooore
- E30 Zone Team Member
- Posts: 49358
- Joined: Mon Jan 10, 2005 11:00 pm
When the temperature knob is at fully cold, an electrical switch is closed, supplying power to an electric water valve, which shuts off all flow through the heater matrix.
When the knob is turned just a few degrees from fully cold, the switch opens,, the water valve opens, and full flow passes through the heater matrix.
The rest of the rotation of the knob operates a Bowden cable, which should control an air diverting flap inside the heater body. With the flap fully one way, air passes from the fan directly to the vents without passing through the heater matrix. With the flap fully the other way, air from the fan is all forced through the matrix before exiting the vents. At flap positions in between these extremes, some air bypasses the matrix and some flows through it, mixing it to the desired temperature.
It sounds like your flap is permanently in or near the position where all air is forced through the matrix, so you need to check whether the inner and outer of the cable are fixed and adjusted correctly, and whether the flap control is broken or stuck in any way.
The above assumes you do not have the rare climate control option, which controls temperature in a different way.
When the knob is turned just a few degrees from fully cold, the switch opens,, the water valve opens, and full flow passes through the heater matrix.
The rest of the rotation of the knob operates a Bowden cable, which should control an air diverting flap inside the heater body. With the flap fully one way, air passes from the fan directly to the vents without passing through the heater matrix. With the flap fully the other way, air from the fan is all forced through the matrix before exiting the vents. At flap positions in between these extremes, some air bypasses the matrix and some flows through it, mixing it to the desired temperature.
It sounds like your flap is permanently in or near the position where all air is forced through the matrix, so you need to check whether the inner and outer of the cable are fixed and adjusted correctly, and whether the flap control is broken or stuck in any way.
The above assumes you do not have the rare climate control option, which controls temperature in a different way.
You're back
we were all wondering where you went
Did aircon cars have this fitted too? I have one aircon set with the numbers round the dial where the others don't, it seems to be very different and I am struggling to fathom it out.


I have one that I am looking to put back instead of my old one. If you are back long-term I might give it a go!Brianmoooore wrote: ↑Sun Aug 13, 2023 10:20 pmThe above assumes you do not have the rare climate control option, which controls temperature in a different way.
Did aircon cars have this fitted too? I have one aircon set with the numbers round the dial where the others don't, it seems to be very different and I am struggling to fathom it out.
I thought it was cleverer than that?Brianmoooore wrote: ↑Sun Aug 13, 2023 10:20 pmWhen the temperature knob is at fully cold, an electrical switch is closed, supplying power to an electric water valve, which shuts off all flow through the heater matrix.
When the knob is turned just a few degrees from fully cold, the switch opens,, the water valve opens, and full flow passes through the heater matrix.
The rest of the rotation of the knob operates a Bowden cable, which should control an air diverting flap inside the heater body. With the flap fully one way, air passes from the fan directly to the vents without passing through the heater matrix. With the flap fully the other way, air from the fan is all forced through the matrix before exiting the vents. At flap positions in between these extremes, some air bypasses the matrix and some flows through it, mixing it to the desired temperature.
It sounds like your flap is permanently in or near the position where all air is forced through the matrix, so you need to check whether the inner and outer of the cable are fixed and adjusted correctly, and whether the flap control is broken or stuck in any way.
The above assumes you do not have the rare climate control option, which controls temperature in a different way.
At about the mid setting it is supposed to put cooler air through the face level vents and warmer at foot level.
Ben
- Brianmoooore
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- Joined: Mon Jan 10, 2005 11:00 pm
That's done by positioning the outlets in the heater box for the face vents closer to the bypass side of the flap than the outlets for the floor .
Interesting, Thanks, Brian.Brianmoooore wrote: ↑Mon Aug 14, 2023 7:13 pmThat's done by positioning the outlets in the heater box for the face vents closer to the bypass side of the flap than the outlets for the floor .
Good to see you back.
Ben