thermostat conversion for raw water cooling

[BWM]

Due to my Jp3 never getting hot, particularly the middle cylinder, I am considering a thermostat conversion. Any advice on the wisdom of this, and where to buy the kit or components would be useful. One thing that concerns me is the water pump-it is the original piston type which seems quite happy to leak slightly most of the time, would the thermostat generate pressure in the system causing the pump to leak more?

[by'eck]

Have a word with Martyn at MPS, he fits them to his marine conversions.

 

Regarding the piston raw water pump you have. I have heard they are prone to leaking a tad and probably designed for the same high raw water flow that comes from the original gear type pump on my JP2M. I suspect that pressures within the thermostatically controlled close circuit system I have are higher than others designed for such. In over 1300 hours use though this has presented no more problems that a slight weep from one joint.

Edited November 11, 2015 by by'eck

[RLWP]

Are you using the changeover valve at the end of the exhaust manifold?

 

Richard

Edited November 11, 2015 by RLWP

[by'eck]

Are you using the changeover valve at the end of the exhaust manifold?

 

Richard

 

???

[RLWP]

 

???

 

The JP2M I'm working on has a positive displacement pump and has a changeover valve on the end of the exhaust manifold to regulate the temperature. It is labelled something like cold and warm

 

Part number 11-13-468 'Cylinder Head Water Temperature Regulating 3-way Cock'

 

Richard

Edited November 11, 2015 by RLWP

[by'eck]

 

The JP2M I'm working on has a positive displacement pump and has a changeover valve on the end of the exhaust manifold to regulate the temperature. It is labelled something like cold and warm

 

Part number 11-13-468 'Cylinder Head Water Temperature Regulating 3-way Cock'

 

Richard

 

Sorry Richard misunderstood

[RLWP]

 

Sorry Richard misunderstood

 

No problem.

 

I wouldn't expect a thermostat with a positive displacement pump. One way round, the pump would push the thermostat open. The other way, it will stick shut and cause leaks elsewhere

 

And yet - the Gleniffer has a thermostat, a positive displacement pump and a bypass valve.

 

Richard

 

MORE: This is a current job:

 

 

New sealing washers, new gudgeon pin, new leather buckets

Edited November 11, 2015 by RLWP

[MtB]

That's not my Gleniffer is it? I don't recognise those bits.

 

I have a positive displacement pump on the Kelvin too, along with a three port thermostatic bypass valve. Works excellently.

 

There is a thread on here seven or eight years old discussing the design and installation of it, should you be able to work the search facility better than me...

[RLWP]

That's not my Gleniffer is it? I don't recognise those bits.

 

No, that's a combined main and bilge pump from a JP2M

 

Richard

Edited November 11, 2015 by RLWP

[BWM]

Are you using the changeover valve at the end of the exhaust manifold?

 

Richard

Yes, I have tried this valve in both positions but have noticed no change in the temperature of number two cylinder. The pump is the one you pictured above, are they easy to rebuild?

[by'eck]

 

No problem.

 

I wouldn't expect a thermostat with a positive displacement pump. One way round, the pump would push the thermostat open. The other way, it will stick shut and cause leaks elsewhere

 

And yet - the Gleniffer has a thermostat, a positive displacement pump and a bypass valve.

 

Richard

 

MORE: This is a current job:

 

 

 

New sealing washers, new gudgeon pin, new leather buckets

 

Take your point but I'm sure I have seen JP's with thermostat controlled cooling systems fed by the more common piston displacement pump.

 

Yes just checked Martyn's site and there is an original JP2M and a JP3M which he rebuilt with piston pump and later fitted with thermostat..

[BWM]

Have a word with Martyn at MPS, he fits them to his marine conversions.

 

Regarding the piston raw water pump you have. I have heard they are prone to leaking a tad and probably designed for the same high raw water flow that comes from the original gear type pump on my JP2M. I suspect that pressures within the thermostatically controlled close circuit system I have are higher than others designed for such. In over 1300 hours use though this has presented no more problems that a slight weep from one joint.

Thanks for the info.

[RLWP]

Yes, I have tried this valve in both positions but have noticed no change in the temperature of number two cylinder. The pump is the one you pictured above, are they easy to rebuild?

 

Yes, not too bad. I found near-enough leather buckets and recut holes to match the pump rods. Mind you, I haven't reassembled it yet, and I can see getting the bilge pump washer in being challenging

 

Richard

[BWM]

On Wednesday, November 11, 2015 at 19:59, RLWP said:

 

Yes, not too bad. I found near-enough leather buckets and recut holes to match the pump rods. Mind you, I haven't reassembled it yet, and I can see getting the bilge pump washer in being challenging

 

Richard

I was told by someone that it wasn't a good idea to replace the bottom seals for the bilge part of the pump unless it was being used, as it may damage the pump? 

I found the cause of the cold running middle cylinder, it turned out to be the liner had been installed too low in the block, with obvious consequences!

[monkeyhanger]

On 11/11/2015 at 09:27, RLWP said:

 

No problem.

 

I wouldn't expect a thermostat with a positive displacement pump. One way round, the pump would push the thermostat open. The other way, it will stick shut and cause leaks elsewhere

 

And yet - the Gleniffer has a thermostat, a positive displacement pump and a bypass valve.

 

Richard

 

MORE: This is a current job:

 

 

New sealing washers, new gudgeon pin, new leather buckets

I did the same job on my JP2 pump many years ago. The original bronze (I think) gudgeon pin was very warn, so I made a replacement up out of stainless steel. Several years later, when I came to replace the leather washers, I found that my new gudgeon pin had done a nice job of wearing 4 vertical grooves inside the bore. After having the bore re-sleeved, I reduced the length of the gudgeon pin slightly and machined up a couple of nylon plugs to fit in the ends. Hopefully this will prevent premature bore wear, but only time will tell. You may wish to consider something like this, as your gudgeon pin in the photo looks like it could be made of stainless.

[monkeyhanger]

On 11/11/2015 at 10:10, by'eck said:

 

Take your point but I'm sure I have seen JP's with thermostat controlled cooling systems fed by the more common piston displacement pump.

 

Yes just checked Martyn's site and there is an original JP2M and a JP3M which he rebuilt with piston pump and later fitted with thermostat..

I have run a thermostat on my JP2 for a few years now, and it works well. I bought mine from Tony Redshaw.