Skin tanks - Option of running 1 or 2

[richardf]

I have suffered an ongoing problem with my Kelvin P4 sooting up - the heads have just been decoked for the second time in a year; I have also fitted new rocker shaft bushes to aid valve stem lubrication, drilled out my silencer to stop back pressure (it is now a big straight through expansion box), fitted new valve guides in the head - the story goes on and on!

 

Another theory is that it is not getting hot enough and I have now plumbed it to work on one skin tank rather than two - this will be an experiment, but first indications seem to show that the engine runs hotter, but nearer the preferred temp of 65C. It would be an easy pipework fix to valve off the second tank and by simple use of these valves, to bring the second tank into play when running on rivers etc. Obviously I would need to be wary of flooding the hot engine with cold water and cracking something - but has anyone else ever tried this out successfully?

[WotEver]

Someone posted on here an inline temperature-actuated valve a while back. Possibly that could automate the plumbing to the 2nd tank. Hopefully whoever it was will be along shortly

 

Tony

[alan_fincher]

Richard,

 

Is this an engine that doesn't have a thermostat ?

 

I ask, because on an engine that does, you can't really have "too much" skin tank, as the thermostat should prevent over-cooling.

 

I am aware of quite a few people having the kind of arrangement you are suggesting. A mate of mine added it to a 50 foot narrow boat, for example. However, as he has a BMC 1800, where the thermostat should control the engine temperature, I feel he has over-engineered it by making it possible to shut one tank out of use. He should be able to have both permanently connected, and the engine should reach running temperature just as fast as with only one.

 

But for an engine that will simply not heat up enough if there is too much cooling, I can't see there should be a problem with what you suggest.

[Proper Job]

My JP never really got up to temp when I bought the boat (big skin tank, no thermostat).

 

I fitted one of Redshaws external thermostats fit with a 65 deg stat. Best thing I did.

 

Engine runs nice and hot (quickly) and loads of piping hot domestic water.

 

Fit a stat

[richardf]

My JP never really got up to temp when I bought the boat (big skin tank, no thermostat).

 

I fitted one of Redshaws external thermostats fit with a 65 deg stat. Best thing I did.

 

Engine runs nice and hot (quickly) and loads of piping hot domestic water.

 

Fit a stat

 

You are quite right - no stat fitted currently and temp control has always been a bit hit and miss with a manually operated ball valve dictating what proportion of water from the jabsco pump went through the engine or through the bypass.

I have the outlet from the Jabsco teed off - one leg runs straight into the block. The other (valved) leg is the bypass which runs past the top of the cylinder heads and collects the water as it exits the heads before everything runs back to the skin tank.

Where should the stat be fitted? On the leg direct to block or on the bypass. Presumably these stats open at 65C?

Thanks for your help

[RLWP]

The thermostat goes in the outlet hose from the engine, so it won't let water out until it is hot enough

 

Richard

[dor]

Someone posted on here an inline temperature-actuated valve a while back.

 

Err, isn't that a thermostat?

[BEngo]

I have suffered an ongoing problem with my Kelvin P4 sooting up - the heads have just been decoked for the second time in a year; I have also fitted new rocker shaft bushes to aid valve stem lubrication, drilled out my silencer to stop back pressure (it is now a big straight through expansion box), fitted new valve guides in the head - the story goes on and on!

 

Another theory is that it is not getting hot enough and I have now plumbed it to work on one skin tank rather than two - this will be an experiment, but first indications seem to show that the engine runs hotter, but nearer the preferred temp of 65C. It would be an easy pipework fix to valve off the second tank and by simple use of these valves, to bring the second tank into play when running on rivers etc. Obviously I would need to be wary of flooding the hot engine with cold water and cracking something - but has anyone else ever tried this out successfully?

 

 

My Kelvin J2 runs just like this. One skin tank for winter or narrow canals or lots of wide locks. Two skin tanks for summer on rivers, Milton Keynes, the long level and, (if I ever get there) big canals oop the North. I tend to decide what set up top use at the beginning of the day whilst oiling round and leave it alone until tying up, but if I forget and start off on one when I need two it is easy to gently bring in the second tank to lower the cooling water inlet temperature slowly.

 

The physical arrangement is simply a bypass connection across the second tank. Valve open- skin tank not used because it's easier for the water to use the bypass. Bypass closed- skin tank two in use. I also have a bypass on tank one which is good for quick warm up or keeping things warm in long flights of narrow locks in winter.

 

Don't forget to send the output from the botton of tank one to the top of tank two for best effect!

 

N

[WotEver]

Err, isn't that a thermostat?

Yes, but this was an inline valve that served a similar function.

 

Tony

 

I know nothing about P4s, so assumed that there must be some difficulty with fitting a 'conventional' thermostat.

[dor]

Yes, but this was an inline valve that served a similar function.

 

I've seen on a car somewhere a housing for a thermostat that fitted inline in the cooling hose to the radiator. The thermostat inside was a standared type of 'stat.

 

I've just found this one http://qedmotorsport.co.uk/qed-shop/view-all-products-in-shop?keyword1=in%20line%20thermostat%20housing%20uk

 

But there are others which are simpler/cheaper.

 

Try googling for "inline thermostat housing"

[richardf]

Sorry - my lack of technical knowledge is showing though here!

 

If I simply place the stat on the outlet pipe work from the engine, the cooling circuit will not run until the stat opens at 65C. This means the jabsco will be running, but will be unable to shift the water anywhere?

Are the thermostats you describe a 2 connection item - inlet and outlet only, or is there a third connection?

[dor]

This is normally accomodated by having a small bypass pipe.

[richardf]

This is normally accomodated by having a small bypass pipe.

 

Sorry to be a pain - but could someone give me more information on how this could be plumbed in - where does the bypass feed to for instance?

 

Thanks

[Tony Brooks]

Sorry to be a pain - but could someone give me more information on how this could be plumbed in - where does the bypass feed to for instance?

 

Thanks

 

 

I think you already have the bypass. You know your ball valve. That allows water to bypass the engine and go straight overboard/into the exhaust.

 

I think that if you just fit a thermostat into the outlet from the engine and then make sure the ball valve is in the branch of pipe that bypasses the engine (so you can restrict that if required) rather than the feed to the engine it will be fine.

 

You may well find that if you substitute a short length of iron water pipe with an OD suitable for the hose it will provide enough restriction to ensure the engine can get sufficient cooling water but that depends on the output from the Jabsco. I would keep the ball valve and remove the handle once it is set up.