KV6 Thermostat on Rover and Freelander

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Re KV6 Thermostat - I have just taken the decision to butcher it (well cut carefully around the glue line joining both halves). Here are some piccies fur ya to peruse. It is interesting to note that the thermostat operates in two sections -there is the usual thermostat section in the main section, but there is also a small spring closed blanking plate at the bottom, which effectively stops any water flow through to the head, without the thermostat being opened. It can also be seen that it is next to impossible to drill holes through the main thermostat valve whilst it is inside its casing. The only choice would be to drill a hole/holes in the spring loaded plate - which is free floating and therefore also very difficult to drill with conventional equipment (spark eroding might be possible.

The good news is that I believe that it might be possible to reassemble witha PVC "pipeweld" adhesive, although I havent tried it yet ;).

It is also clear (I hope )that on the top of the thermostat housing is a small oblong panel, which gives the part number and its opening temperature - I have spray painted this in one of the pics and it can be seen that it reads "Temp 82C".
A rubber "sealing washer" can also be seen around the periphery of the thermostat itself. Not sure why this is so critical.

It would be interesting to try removing the bottom spring loaded blanking section, so that the bypass water can go into the head, but I am not sure how this would affect the flows.
Enjoy!
 

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The Mad Hat Man said:
It is interesting to note that the thermostat operates in two sections -there is the usual thermostat section in the main section, but there is also a small spring closed blanking plate at the bottom, which effectively stops any water flow through to the head, without the thermostat being opened.

It would be interesting to try removing the bottom spring loaded blanking section, so that the bypass water can go into the head, but I am not sure how this would affect the flows.
Enjoy!
Click to expand...

So my propose bypass would make much different then?! because the bypass has valve controlling the flow.
I think removing th bottom spring loaded blanking section is a good idea and I am too not sure how this would affect the flows as I dont understand how it actually works.
 
Yup - its a very complicated and difficult flow pattern with the Hippoo - int the olden days:D - it was simple - hot water gets pumped out of the top of the engine - into top of radiator and cooled water flows from bottom of radiator into bottom of engine. Not sure how much can be improved without thermodynamic involvement. i still maintain an ewp will even out the temps a bit more and with a temp sensing system monitoring the hottest temp is the best that can be achieved without going for a dual cooling system - one for the engine and one fur the IRD, heater etc.
 
yu might have to wait awhile till i can check it in some hot water, but the bottom plate moves up the bottom shaft against the spring, so if the PRESSURE in the head is higher than in the thermostat, the plate will lift slightly, against the spring, and allow flow up into the thermostat housing.

I believe, but have not confirmed yet, that as the main thermostat opens, it will lift the bottom shaft and thereby lift the bottom plate up at the same time.

I will endevour to see how it work in some hot water and take some pics if i can.

Just dont hold ya breath ;)
 
What do you think about shorten those springs? What sort of affect will it has?
i think it will open allow the thermostat to open earlier than the stated temp seting.
 
not sure yu can do that without destroying the Thermostat.
it will not open earlier, because I believe that it is a function of the liquid inside the thermostat bulb.
 
Here yu go - an ickle video of the thermostat closing (easier to video than it opening)

It can be seen that the main thermostat closes, and reduces the pressure on the bottom pressure valve. This leads me to believe that this valve is always closed and is kept shut when the thermostat opens by increasing the spring pressure on the bottom plate. It will only open with a positive pressure differential between the head and the thermostat housing. I cant understand how that works. Maybe someone can enlighten me?
It would be interesting to follow the flow around the engine and see if removing this valve would change very much.
 
The Mad Hat Man said:
yu might have to wait awhile till i can check it in some hot water, but the bottom plate moves up the bottom shaft against the spring, so if the PRESSURE in the head is higher than in the thermostat, the plate will lift slightly, against the spring, and allow flow up into the thermostat housing.

I believe, but have not confirmed yet, that as the main thermostat opens, it will lift the bottom shaft and thereby lift the bottom plate up at the same time.

I will endevour to see how it work in some hot water and take some pics if i can.

Just dont hold ya breath ;)
Click to expand...

If your theory its correct that means the flows doesnt go into the head but out from the head mix with the water from radiator and bypass path through the water pump.

If you lift the bottom plate up, does the main thermostat open?
 
The Mad Hat Man said:
Re KV6 Thermostat - I have just taken the decision to butcher it (well cut carefully around the glue line joining both halves). Here are some piccies fur ya to peruse. It is interesting to note that the thermostat operates in two sections -there is the usual thermostat section in the main section, but there is also a small spring closed blanking plate at the bottom, which effectively stops any water flow through to the head, without the thermostat being opened. It can also be seen that it is next to impossible to drill holes through the main thermostat valve whilst it is inside its casing. The only choice would be to drill a hole/holes in the spring loaded plate - which is free floating and therefore also very difficult to drill with conventional equipment (spark eroding might be possible.

The good news is that I believe that it might be possible to reassemble witha PVC "pipeweld" adhesive, although I havent tried it yet ;).

It is also clear (I hope )that on the top of the thermostat housing is a small oblong panel, which gives the part number and its opening temperature - I have spray painted this in one of the pics and it can be seen that it reads "Temp 82C".
A rubber "sealing washer" can also be seen around the periphery of the thermostat itself. Not sure why this is so critical.

It would be interesting to try removing the bottom spring loaded blanking section, so that the bypass water can go into the head, but I am not sure how this would affect the flows.
Enjoy!
Click to expand...

You top man MHM! Great pics. I wonder if its the same PRT mechanism from previous posts

The PVC weld needs the ketone solvent to prime the plastic. This is butanone although acetone will do the trick
 
dearot said:
If your theory its correct that means the flows doesnt go into the head but out from the head mix with the water from radiator and bypass path through the water pump.

If you lift the bottom plate up, does the main thermostat open?
Click to expand...

not brilliant if yu get cavitation in the head!:eek:

no - it just pushes against a spring which is attached to the bottom of the thermostat plunger, so when the thermostat opens, the plunger drops and compresses the spring further, thereby increasing the pressure needed to open the valve - as I read it - that means when the temp is at its highest, the pressure needed to release water from the head is at its highest too :confused:
 
LR1796 said:
You top man MHM! Great pics. I wonder if its the same PRT mechanism from previous posts.

The PVC weld needs the ketone solvent to prime the plastic. This is butanone although acetone will do the trick
Click to expand...

It is the only thermostat i have and is the one fitted between the two banks of cylinders at the rear of the engine and i a reet bastid to get at. Luckily??? this is the "old one" replaced under HGF:eek: All of my pics are of this thermostat.
 
Am I being really obtuse here?

Referring to the cooling system flow charts, the Radiator return (cold) enters the main pipe on the thermostat - as does a couple of by-pass hoses. this water is then fed along a pipe on the outside of the heads to the back of the water pump - which then recycles the water again. The HOT water in the block can only escape via the water pump body mounted at the front of the engine and through this closed valve at the bottom of the thermostat, which only opens with a positive pressure differential between the head and the thermostat. Now, flame me if I am wrong - but if the water pump is pumping water from the block, this will reduce the water pressure in the block (and heads) so that the water in the heads is basically stuck in limbo, getting hotter and hotter until cavitation takes place and no cooling takes place at all. Is it surprising that it is common to hear water boiling inside the heads after shutdown?

What have I mis-understood?
 
thats exactly what my understanding...and if you read more closely in RAVE it says
"When the temperature of the bypassing coolant reaches
82....C (180....F), the thermostat begins to open, allowing 'cold' coolant from the radiator bottom hose into the pump inlet
and hot coolant from the cylinder block to flow to the radiator through the top hose."

maybe its better to remove the bottom plate all together...but not sure since it is still mistery on how does it actually work :confused: :confused:
 
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