Perkins + Calorifier?

[philthane]

I've just bought an old Trentcraft GRP cruiser with a Perkins 100 series 3 cyl diesel engine. It has a heat exchanger that incorporates the exhaust manifold and uses canal/river water to cool it (and spits it out of the exhaust). There's a separate clean water supply via a header tank on top of the heat exchanger and a conventional (ie car type) water pump driven by vee belt. There's a bottom hose from the heat exchanger to the water pump but whereas on (old) cars you get a thermostat housing on top of the cylinder head and a top hose to the rad on this there's nothing like that. I assume the flow is through the cylinder head straight into the heat exchanger. According to a downloaded manual (which isn't very clear)  there should be a thermostat behind the water pump, but the temp gauge varies from about 40°C on a canal to 70°C going upstream on a river so I suspect the thermostat is either jammed or missing. I'll strip it down at the end of the year and check. There are two tapping points on top of the water pump, currently plugged with threaded blanking plugs.

I would like to fit a small calorifer but can't figure our where to connect to. Are the two tapped holes on the pump usable as flow and return? If so which is which, is there some way to find out? Or should I take hot water from one of those (which?) and return to a tee in the bottom hose?

Any advice anyone?

 

[Tony Brooks]

Any chance of a photo or photos so we can see what you are describing, plus a link to the manual?

I can't see a thermostat behind the water pump would be very effective so think that you may have misread that bit.

[Tony Brooks]

Right - found a manual and on the Perama it seem that you are correct. The engien water pump will have to come off to get at the thermostat.

It seems that the water pump housing is also being used as a thermostat housing although the flow through the water pump and the flow through the thermostat are totally separate.

The water pump housing has two hose connections on it. A horizontal one and one pointing downwards at an angle. The one at an angle is the cold return to the pump from the heat exchanger (warning - a note elsewhere says Perkins "build to order" so the illustration may be different to your engine) This is the one I would plumb the return from the calorifier into.

The horizontal one is the hot supply to the heat exchanger and if needs must it will probably work if you T the hot to calorifier pipe into this section. However I would prefer to take it from the engine side of the thermostat because it will be easier to bleed or it may well self bleed. it will also give the calorifier a slightly faster warm up.

I would expect there to be a plug somewhere on the  cylinder head tapped into the water jacket that would be used to feed a cab heater. If you can find it feed the calorifier from this because its on the engine side of the thermostat.

The manual I found also shows a version with a separate thermostat housing bolted onto the front of the cylinder head, hence my request for photos etc.

[philthane]

Thanks Tony, I'll investigate more next time I'm onboard. Major jobs like taking the pump/thermostat housing off can wait until winter. There's certainly a cold return from the bottom of the heat exchanger to the pump, but not a 'top hose'. I guess since the header tank and heat exchanger is a single unit bolted onto the cyl head and incorporating the exhaust manifold the water flows internally, no hose needed. The only possible take-off points I've found are both on top of the pump housing. It's quite a small engine, often used to drive a generator, pump or refrigeration unit on a truck, so it won't ever have needed a take off for 'cab heating'.

On a related matter, come winter should I close the 'sea cock' and try to drain the cooling system? The engine side can have anti-freeze like a car but the raw water side could freeze?

 

[Tony Brooks]

The problem is that it is all too easy to leave some raw water in the system that then freezes and damages something. Just turning the sea inlet of is no way enough. You will need to ensure all the raw water is drained from the heat exchanger core. This is easier said than done when you have rubber end caps that seal to both the core and the fresh water side. The raw water pump will need its cover taking off and the impeller removing (place it in a tin of water).

If you have  helpers you could turn off the sea inlet and take off the cap. mix a 0% antifreeze mixture in a bucket/can. Get someone to hold an empty bucket under the exhaust. Start engine, run at fast idle while the antifreeze mixture is poured into the sea inlet. keep going until the anti-freeze mixture comes from the exhaust. Stop and put the cap back on.

 

The manual I found showed a fitting running downwards into what looked like the water pump inlet chamber and if thsi is the case it will make an ideal return.

[WotEver]

1 hour ago, Tony Brooks said:

If you have  helpers you could turn off the sea inlet and take off the cap. mix a 0% antifreeze mixture in a bucket/can. Get someone to hold an empty bucket under the exhaust. Start engine, run at fast idle while the antifreeze mixture is poured into the sea inlet. keep going until the anti-freeze mixture comes from the exhaust. Stop and put the cap back on.

What a neat idea!

[Scholar Gypsy]

I think you mean something other than 0% antifreeze ??

[Tony Brooks]

Well spotted - I did type a 5 honest. 50%

[philthane]

Sounds like a good plan.