Discovery 4 heater

niffty10 said:

Where would i find the fbh control valve, the guy who looked at it for me was suspect of the of what looks like a pump that mounted behind the fbh, it has two hoses connected to it, i was thinking about connecting the two pipes to bypass the unit to see if it allowed a flow.

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hi @niffty10

have searched through some of my manuals for u

ur find that valve between ur main battery box and FBH where it’s bolted to the side

plse don’t quote me on this but I believe that valve has one water connection that leads onto ur cabin heater , have been reading through many manuals to try and find out more details for u , but with the engine running indeed feel the 2 x bulkhead water pipes that go into ur cabin heater

also a good idea as suggested by @lynall regarding a infra red thermometer off eBay

hope it’s useful and will try and find out more details for u

lynall said:

Surely feeling the hoses or using an infra red heat gun (cheap off ebay) would tell you if coolant was flowing?
All that elec water pump does is allow the hot water to be pumped around the system mainly in preheat mode, ie engine off, I dont know if it runs with the engine running? I suspect it does.

But and here may be the thing to look into, I think the d4 allows the interior heater to run when the fbh is running so the car is warmish when you start it up, but I dont know how it controls the flow of coolant?

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hi mate

indeed I believe if that 3 way control is faulty it stops heat getting into the cabin heater , just going through some of my manuals etc

think ur able to remove the rubber seal that’s inside to then allow heat to get into the cabin matrix , plse don’t hold me to that, just what I’ve been reading over several hours etc , just wished to pass it on in case it’s useful to u

or with the engine running to carefully tap the top of that 3 x way valve with a screwdriver to see if the pipe gets hot

plus assume you’ve tried all the vent points to ensure no air is the system

@niffty10

also found this which I hope is useful to u, YAH, managed to now post pics


Distribution motor self-test

The motor and flap operation can be checked using the on-board distribution motor self-test function.

The self-test can be initiated by pressing and holding the CON and RECIRC buttons while turning the ignition switch to the ON position.

The control module will then compare the current motor position with the values stored in the module and will indicate an error by flashing the ECON LED (light emitting diode).

If there are no errors, the LED will go out and the system will function normally.

To confirm that there are no errors, turn the ignition switch to the OFF position, then back to the ON position.

Observe the operation of the programmed defrost LED.

If there are errors present, the programmed defrost LED will flash and the system will attempt to calibrate itself.

3 x way control valve location

There’s also a canbus test u can do with a multimeter to see if there’s any issues , plse let us know what u find

Really hope all of this is useful to u

Both battery leads disconnected

Multimeter set to ohms, ( TP Is just short for test probe from ur multimeter)

TP to pin 6 other TP to pin 14 , read ohms

TP to pin 3 other TP to pin 11, read ohms


Reconnect battery, ign off , meter set to Vdc

TP to pin 6 other TP pin 4 Read Vdc

TP to pin 6 other TP to pin 5 Read Vdc

TP to pin 14 other TP to pin 4 Read Vdc

TP to pin 14 other TP to pin 5 Read Vdc

gstuart said:

View attachment 279623


View attachment 279624

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Fcuk me thats looks like a plumbers nightmare!

gstuart said:

@niffty10

also found this which I hope is useful to u, YAH, managed to now post pics


Distribution motor self-test

The motor and flap operation can be checked using the on-board distribution motor self-test function.

The self-test can be initiated by pressing and holding the CON and RECIRC buttons while turning the ignition switch to the ON position.

The control module will then compare the current motor position with the values stored in the module and will indicate an error by flashing the ECON LED (light emitting diode).

If there are no errors, the LED will go out and the system will function normally.

To confirm that there are no errors, turn the ignition switch to the OFF position, then back to the ON position.

Observe the operation of the programmed defrost LED.

If there are errors present, the programmed defrost LED will flash and the system will attempt to calibrate itself.

View attachment 279621

View attachment 279622

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Not seen item 8 before, I thought he meant item 9 the pump, though earlier on in the thread the op did say all the pipes are getting hot, though thta could just be radiating heat rather than hot by water?

lynall said:

Not seen item 8 before, I thought he meant item 9 the pump, though earlier on in the thread the op did say all the pipes are getting hot, though thta could just be radiating heat rather than hot by water?

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Must confess also hadn’t seen that ( 8 ) until a little while ago where I was looking at the FBH layout on the D3 Vs the D4

cant find any resistance values for that 3 x way valve, but seen where some have carefully hit the solo iid with a screwdriver and some removed the internal rubber diaphragm

indeed regarding ghost flow on the pipes , as u suggested a thermometer would be perfect if a differential meter with 2 x clamps putting one at either end of the pipe

Did find this below which Ive been trying to understand


PRESSURE RELIEF THERMOSTAT (PRT)

The thermostat is closed at temperatures below approximately 82°C (179°F). When the coolant temperature reaches approximately 82°C the thermostat starts to open and is fully open at approximately 96°C (204°F). In this condition the full flow of coolant is directed through the radiator. The thermostat is exposed to 90% hot coolant from the engine on one side and 10% cold coolant returning from the radiator bottom hose on the other side. Hot coolant from the engine passes from the by-pass pipe through four sensing holes in the flow valve into a tube surrounding 90% of the thermostat sensitive area. Cold coolant returning from the engine, cooled by the radiator, conducts through 10% of the sensitive area.

In cold ambient temperatures, the engine temperature is raised by approximately 10°C (50°F) to compensate for the heat loss of 10% exposure to the cold coolant returning from the bottom hose.

The by-pass flow valve is held closed by a light spring. It operates to further aid heater warm-up. When the main valve is closed and the engine speed is at idle, the coolant pump does not produce sufficient flow and pressure to open the valve.

In this condition the valve prevents coolant circulating through the by-pass circuit and forces the coolant through the heater matrix only. This provides a higher flow of coolant through the heater matrix to improve passenger comfort in cold conditions. When the engine speed increases above idle, the coolant pump produces a greater flow and pressure than the heater circuit can take. The pressure acts on the by-pass flow valve and overcomes the valve spring pressure, opening the valve and limiting the pressure in the heater circuit. The valve modulates to provide maximum coolant flow through the heater core and yet allowing excess coolant to flow into the by-pass circuit to provide the engine's cooling needs at higher engine speeds.

gstuart said:

Must confess also hadn’t seen that ( 8 ) until a little while ago where I was looking at the FBH layout on the D3 Vs the D4

cant find any resistance values for that 3 x way valve, but seen where some have carefully hit the solo iid with a screwdriver and some removed the internal rubber diaphragm

indeed regarding ghost flow on the pipes , as u suggested a thermometer would be perfect if a differential meter with 2 x clamps putting one at either end of the pipe

Did find this below which Ive been trying to understand


PRESSURE RELIEF THERMOSTAT (PRT)

The thermostat is closed at temperatures below approximately 82°C (179°F). When the coolant temperature reaches approximately 82°C the thermostat starts to open and is fully open at approximately 96°C (204°F). In this condition the full flow of coolant is directed through the radiator. The thermostat is exposed to 90% hot coolant from the engine on one side and 10% cold coolant returning from the radiator bottom hose on the other side. Hot coolant from the engine passes from the by-pass pipe through four sensing holes in the flow valve into a tube surrounding 90% of the thermostat sensitive area. Cold coolant returning from the engine, cooled by the radiator, conducts through 10% of the sensitive area.

In cold ambient temperatures, the engine temperature is raised by approximately 10°C (50°F) to compensate for the heat loss of 10% exposure to the cold coolant returning from the bottom hose.

The by-pass flow valve is held closed by a light spring. It operates to further aid heater warm-up. When the main valve is closed and the engine speed is at idle, the coolant pump does not produce sufficient flow and pressure to open the valve.

In this condition the valve prevents coolant circulating through the by-pass circuit and forces the coolant through the heater matrix only. This provides a higher flow of coolant through the heater matrix to improve passenger comfort in cold conditions. When the engine speed increases above idle, the coolant pump produces a greater flow and pressure than the heater circuit can take. The pressure acts on the by-pass flow valve and overcomes the valve spring pressure, opening the valve and limiting the pressure in the heater circuit. The valve modulates to provide maximum coolant flow through the heater core and yet allowing excess coolant to flow into the by-pass circuit to provide the engine's cooling needs at higher engine speeds.

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I think it would be 5 litres of finest and some matches time!

lynall said:

I think it would be 5 litres of finest and some matches time!

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here u go, sorted , lmao

lynall said:

Surely feeling the hoses or using an infra red heat gun (cheap off ebay) would tell you if coolant was flowing?
All that elec water pump does is allow the hot water to be pumped around the system mainly in preheat mode, ie engine off, I dont know if it runs with the engine running? I suspect it does.

But and here may be the thing to look into, I think the d4 allows the interior heater to run when the fbh is running so the car is warmish when you start it up, but I dont know how it controls the flow of coolant?

Click to expand...

It appears you’re not far wrong, we can’t work out if it stops the flow around the heater matrix. I haven’t got a hint of any heat in any heater pipes. I think it’s the matrix blocked. I’m going to bypass the fbh and isolate it, then try back flushing the matrix.

niffty10 said:

It appears you’re not far wrong, we can’t work out if it stops the flow around the heater matrix. I haven’t got a hint of any heat in any heater pipes. I think it’s the matrix blocked. I’m going to bypass the fbh and isolate it, then try back flushing the matrix.

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hi mate

is always appreciated for the updates , many thks and hope the above information may be of use to u , including the canbus testing etc

did u manage to find that 3 x way valve please as see it’s also called a park heating valve assembly , think I read somewhere about it having a separate remote but depends on which model it is

likewise as not 100% sure , have spent hours reading through many manuals etc to no avail about that 3 x way valve , I’m wondering if one part of the valve is closed then slowly opens as the engine warms up and then as that port starts to open it allows heat into the matrix

May I ask please have u tried tapping the 3 x way solenoid with a screwdriver to see if it starts to work or the body , or maybe take it apart to see if the rubber diaphragm has become stuck

trouble is because you’ve never seen it working it can be like opening a can of worms seeing you’ve got to go through the entire system

will keep trying to find out more information for u , plus thks again for the updates

ps, what model have u got plse

Forgot to say , will also be interesting to see of ur findings with regards to the heater matrix

Just read that indeed that valve gives priority to the engine first then the cabin, but of course only when it’s cold , ie below 7c, which I think then should go round the bypass

that’s if u have this parking valve fitted as was an option

hope u get on ok

Hi guys
I finally got time to have another look at this heater problem yesterday.
Flushed all the hoses and the matrix, they all run fine.
We found a thermostat housing o/s lower engine that has very hot hoses one side and cold hoses the other side, also the 3 way valve behind the FBH has one hot hose and 2 cold hoses.
It appears either this thermostat or the valve are stopping the flow, coolant must be going around the engine because the temp gauge sits right in the middle.

Could that housing have 2 thermostats in it, 1 engine and 1 heating or am i assuming right from what i have read, that 3 way valve does that job.
I have ordered a new a thermostat unit and i have found a local 4x4 breaker who has several FBH units.

Niffty said:

Hi guys
I finally got time to have another look at this heater problem yesterday.
Flushed all the hoses and the matrix, they all run fine.
We found a thermostat housing o/s lower engine that has very hot hoses one side and cold hoses the other side, also the 3 way valve behind the FBH has one hot hose and 2 cold hoses.
It appears either this thermostat or the valve are stopping the flow, coolant must be going around the engine because the temp gauge sits right in the middle.

Could that housing have 2 thermostats in it, 1 engine and 1 heating or am i assuming right from what i have read, that 3 way valve does that job.
I have ordered a new a thermostat unit and i have found a local 4x4 breaker who has several FBH units.

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I have no idea on the d4 but assuming it is much the same as the d3, the only reason the stat housing has a few hoses is the bypass is built into the stat housing itself.
Sounds posh, but all it means is when cold the coolant bypasses the rad to speed up the engine warming up process, then when it gets to temp the stat opens and closes the bypass circtuit sending all the coolant via the rad.
Modern coolant systems are way more complicated than the old stuff.

I reckon Gary was on the right track and it is that 3 way valve.

lynall said:

I have no idea on the d4 but assuming it is much the same as the d3, the only reason the stat housing has a few hoses is the bypass is built into the stat housing itself.
Sounds posh, but all it means is when cold the coolant bypasses the rad to speed up the engine warming up process, then when it gets to temp the stat opens and closes the bypass circtuit sending all the coolant via the rad.
Modern coolant systems are way more complicated than the old stuff.

I reckon Gary was on the right track and it is that 3 way valve.

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I dont think he is far wrong, Kent 4x4 breakers have some but they are closed until the 9th.
I might get the valve off and see if it comes apart, bits of rust come out of it when i flushed it, might be lucky and find its just jammed shut.

Niffty said:

I dont think he is far wrong, Kent 4x4 breakers have some but they are closed until the 9th.
I might get the valve off and see if it comes apart, bits of rust come out of it when i flushed it, might be lucky and find its just jammed shut.

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Got to be worth a try.
How much are they new versus used?

Niffty said:

I dont think he is far wrong, Kent 4x4 breakers have some but they are closed until the 9th.
I might get the valve off and see if it comes apart, bits of rust come out of it when i flushed it, might be lucky and find its just jammed shut.

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hopefully it is indeed that 3 x way valve , from what I’ve been reading it does indeed go round the engine first then opens allowing hot water to pass into the cabin heater

not all had that 3 x way valve , it’s basically a park heater and read that it can sometimes work if u tap the solenoid , or the rubber diaphragm inside becomes stuck , maybe if u lift off the solenoid there might be junk in it

of course my only concern is if u fit one and it doesn’t work, have u tried using a multimeter to see if there’s any voltage on it plse , or can the diaphragm be easily removed in the mean time to allow some heat to get into the cabin

also been checking on wiring diagrams as there must be a thermostat to tell it when to open like what @lynall has also mentioned

will read up some more and see what I can find for u , ie what the ohms should be on the thermostat and VDC readings on the solenoid etc , also plse let us know if u have in the mean time any update , thks