Auxillary engine cooling system

[LEO]

I love how the forum as a whole knows rather a lot about my boat and its problems!

 

 

 

Yes, there is no thermostat due to the previous raw-water cooled nature of the cooling. There is a debate as to whether it matters or not, though; Alnwick is very firmly of the opinion that it doesn't.

 

I could fit a thermostat, as the housing is there, I'd just have to drain the coolant, I think, in order to do it.

 

 

 

 

 

It doesn't have a thermostat currently fitted, as it never had one in it's indirect raw water days (as in, water sucked in through inadequate mudbox by Jabsco impeller pump, circulated through heat exchanger, then expelled into exhaust) although it could have.

 

As I mentioned, I'm in two minds whether to fit a thermostat or not. Even running hard on the river, the engine doesn't get near to temperature, according to the gauge.

 

It certainly would have no hope of getting anywhere near whilst at canal speeds.

 

I suppose I'd better borrow an IR thermometer! I used to have great fun, back when I was 15 and working at Safeway, taking an IR thermometer outside on my lunchbreak and, whilst wearing a hi-vis jacket, pointing it at passing cars.

 

Hi,

 

I had a BMC 1.5 cooled through a heat exchanger - water pulled from the canal by a Jabsco, through a gearbox oil cooler and an oil cooler for the engine, then through a heat exchanger before discharging via the exhaust. Engine block cooled by water containg antifreeze and circulated by the engine pumps.

 

I used an 82C 'stat and had a calorifier fitted - all worked a treat and engine never overheated.

 

I might have a suitable one somewhere if you want it (can't guarantee this as I changed engines 5 years ago and got rid of various spares).

 

LEO

[blackrose]

Hi,

 

I had a BMC 1.5 cooled through a heat exchanger - water pulled from the canal by a Jabsco, through a gearbox oil cooler and an oil cooler for the engine, then through a heat exchanger before discharging via the exhaust. Engine block cooled by water containg antifreeze and circulated by the engine pumps.

 

I used an 82C 'stat and had a calorifier fitted - all worked a treat and engine never overheated.

 

I might have a suitable one somewhere if you want it (can't guarantee this as I changed engines 5 years ago and got rid of various spares).

 

LEO

 

If you're talking about an old heat exchanger, I'm interested. Let me lknow if you find it.

 

Mike

[Radio-Ga-Ga]

It's not completely ridiculous though, is it?

 

If you have overloaded a diesel engine so that the governor cannot maintain the speed you set the throttle for, it will overfuel. You can see this effect as unburnt fuel coming out the exhaust as black smoke. In the combustion process, unburnt fuel gets heated up, lowering the temperature of the charge in the cylinder, and robbing the engine of power

 

Whether that makes a scrap of difference to the coolant temperature is a whole different question

 

Richard

the post as a whole is ridiculous, and your right about the smoke, but suggesting that an overloaded engine gains some sort of benefit from chucking expensive pollution out is something else, if its smoking due to overloading the load is too heavy so you shouldn't even be there, let alone be thinking ah well at least all those pound notes will keep it cool.

[ChrisPy]

As I mentioned, I'm in two minds whether to fit a thermostat or not. Even running hard on the river, the engine doesn't get near to temperature, according to the gauge.

I don't understand your logic. The reason it will not get near to temperature is because you don't have a thermostat.

If you fitted one it will get up to temperature before the thermostat valve opens and allows coolant to flow.

It can't be good practice to run your engine cold. All the clearances, oil viscosity, etc. are designed for normal operating temperature.

[RLWP]

the post as a whole is ridiculous, and your right about the smoke, but suggesting that an overloaded engine gains some sort of benefit from chucking expensive pollution out is something else, if its smoking due to overloading the load is too heavy so you shouldn't even be there, let alone be thinking ah well at least all those pound notes will keep it cool.

 

I agree

 

Richard

[blackrose]

If you have overloaded a diesel engine so that the governor cannot maintain the speed you set the throttle for, it will overfuel. You can see this effect as unburnt fuel coming out the exhaust as black smoke. In the combustion process, unburnt fuel gets heated up, lowering the temperature of the charge in the cylinder, and robbing the engine of power

Since there is no black smoke from my exhaust at any engine revs can I take that as a sign that my engine is not particularly overloaded?

[WotEver]

Since there is no black smoke from my exhaust at any engine revs can I take that as a sign that my engine is not particularly overloaded?

Yes.

[Radio-Ga-Ga]

Since there is no black smoke from my exhaust at any engine revs can I take that as a sign that my engine is not particularly overloaded?

 

But you already know the engine is overloaded, it's overpropped. there seems to be some myth on here that overpropped is somehow right. overpropped means what it says and correctly propped means what it says.

 

edited due to lost signal leaving a blank reply

Edited July 2, 2010 by Radio-Ga-Ga

[colin stone]

As I mentioned, I'm in two minds whether to fit a thermostat or not. Even running hard on the river, the engine doesn't get near to temperature, according to the gauge.

 

Fit the thermostat. Engines can overheat because there is no thermostat - the cooling water goes through so quickly that there is no cooling. My Fischer Panda genset with a Kubota engine, 2/h ex BBC tx wagon, was rejected by BBC as it was overheating. They had had an overheat problem, removed the thermostat, and continued with the overheat issue. I fitted a new thermostat and no problem at all. Hot engines are more efficient. My Golf engine runs at 90C, no reason why a boat engine should not do similarly.

[smileypete]

It doesn't have a thermostat currently fitted, as it never had one in it's indirect raw water days (as in, water sucked in through inadequate mudbox by Jabsco impeller pump, circulated through heat exchanger, then expelled into exhaust) although it could have.

 

As I mentioned, I'm in two minds whether to fit a thermostat or not. Even running hard on the river, the engine doesn't get near to temperature, according to the gauge.

Ex hire boat?

 

cheers,

Pete.

[blackrose]

But you already know the engine is overloaded, it's overpropped. there seems to be some myth on here that overpropped is somehow right. overpropped means what it says and correctly propped means what it says.

 

edited due to lost signal leaving a blank reply

 

But you already know that an overloaded engine produces black smoke from the exhaust. Since mine doesn't I think we can assume any overloading is not that significant.

[Radio-Ga-Ga]

But you already know that an overloaded engine produces black smoke from the exhaust. Since mine doesn't I think we can assume any overloading is not that significant.

It depends how many symptoms you need to have and what you call significant, I know your boat is a widebeam and I seem to think from a post in another thread its a 57'? if thats right you have an engine that is at best adequate, on top of that you have a skin tank that is less than adequate and to top it it off its overpropped enough to limit its rpm significantly. Its just overheating waiting to happen! if you need to see smoke as well just take it for a good run at full throttle.

 

Regardless of what others have said, correctly propping the engine will have an impact on the overheating problem, and the proper way forward is to start with the prop, you will then get the right performance from the engine and can decide if the improvement is enough to live with amd if not what to do about increasing the skin tank area.

 

If you just want to fix the overheating just add more skin tank and live with the performance limitation.

[blackrose]

It depends how many symptoms you need to have and what you call significant, I know your boat is a widebeam and I seem to think from a post in another thread its a 57'? if thats right you have an engine that is at best adequate, on top of that you have a skin tank that is less than adequate and to top it it off its overpropped enough to limit its rpm significantly. Its just overheating waiting to happen! if you need to see smoke as well just take it for a good run at full throttle.

.

You obviously know more about the performance (and my use) of the boat I have owned for the last 5 years than me?

 

Why do you assume I've never run the engine at full throttle? I have taken it for a good run at full throttle several times on the Thames and as I already said, there's no black smoke at any engine revs.

 

There must be a flaw in your theory somewhere.

Edited July 3, 2010 by blackrose

[bargemast]

QUOTE (Radio-Ga-Ga @ Jul 2 2010, 04:28 PM)

the post as a whole is ridiculous, and your right about the smoke, but suggesting that an overloaded engine gains some sort of benefit from chucking expensive pollution out is something else, if its smoking due to overloading the load is too heavy so you shouldn't even be there, let alone be thinking ah well at least all those pound notes will keep it cool.

 

 

I agree

 

Richard

 

 

I have to agree too, you can't overload a properly (rightly calculated) propped engine, unless there's something wrapt around your prop or shaft that's stops it from going round freely.

 

Peter.

[ChrisPy]

http://www.mvdirona.com/TechnicalArticles/...ineOverload.htm

 

this seems to be a very definitive article. note the following extract:

 

Characteristic signs of an overloaded diesel engine are excessive black smoke at cruising speed, exhaust temperatures beyond those specified by the manufacturer, and most importantly, an inability to reach full rated RPM at wide open throttle on a fully loaded boat with fuel and water tanks at capacity. Most boat and engine manufacturers do not supply adequate information regarding the potential for damaging the engine through overloading, and many in fact deliver boats that are likely to end up in this situation. Further, few provide gauge packages that would allow you to detect this problem. The instructions from boat manufacturers and from many diesel engine producers are to run the engines at cruise at no higher than 200 RPM off the maximum rated RPM. However, this advice is only correct if the propeller pitch is correct. When the pitch is excessive, this advice to “just run 200 RPM below the maximum rated RPM,” can lead to serious damage and expensive overhauls.

 

so if you ignore the black smoke issue, it would seem that over-propping will overload and damage your engine.

Edited July 3, 2010 by ChrisPy

[soldthehouse]

Found this easy to use calculator, might help with regards prop suitability.

 

http://www.castlemarine.co.uk/pitch.htm

[Timleech]

'Overpropping' can be just another name for 'derating' and is often done from choice.

If you put a 50 bhp engine in a narrowboat, as seems to be common these days, you may well get more satisfactory results all round by having a bigger propellor than that which will allow full speed and power, nobody really needs that much power in a narrowboat. It can give a cruising speed at more comfortable rpm, the bigger prop can be more efficient and give better starting and stopping, etc. There may be some trial and error involved to get just the match which suits an individual boat and its operator.

Ideally the engine pumps/governor would be set up for the reduced rpm and power, but even without that it shouldn't be possible to seriously overload a properly set up diesel engine so as to cause damage. If you're getting black smoke at full throttle and the engine is in good order, just ease back a touch until the smoke stops. If easing back a touch doesn't stop the smoke, look for another cause.

 

 

Tim

 

Edit for spilling

Edited July 3, 2010 by Timleech

[Radio-Ga-Ga]

You obviously know more about the performance (and my use) of the boat I have owned for the last 5 years than me?

 

Why do you assume I've never run the engine at full throttle? I have taken it for a good run at full throttle several times on the Thames and as I already said, there's no black smoke at any engine revs.

 

There must be a flaw in your theory somewhere.

 

I was basing it on what you have already said, that it overheats if run above a certain rpm therfore you can't run it for very long on full throtle. If thats not the case why are you messing about trying to cool it though a hose with a flow that is a fraction of the hose that is intended to cool it. you can't have both ways. I didn't specifify the smoke would be black.

 

My responses in this topic are not based on theory, but on a lifetime of of experience working with engines, the knowledge gained from that is given to you freely. choose to accept or ignore it as you will.

[blackrose]

I was basing it on what you have already said, that it overheats if run above a certain rpm therfore you can't run it for very long on full throtle. If thats not the case why are you messing about trying to cool it though a hose with a flow that is a fraction of the hose that is intended to cool it. you can't have both ways. I didn't specifify the smoke would be black.

 

My responses in this topic are not based on theory, but on a lifetime of of experience working with engines, the knowledge gained from that is given to you freely. choose to accept or ignore it as you will.

 

I can run it on full throttle for a while before it overheats, but my response is based on you telling me that there would be black smoke when in fact there isn't.

 

To be honest I don't really care how long you've been working with engines because I think you've made an assumption about my engine which turns out not to be true. Thank you for the free advice but I will have to ignore it since I belive it is based on that misapprehension.

Edited July 3, 2010 by blackrose

[nb Innisfree]

I can run it on full throttle for a while before it overheats, but my response is based on you telling me that there would be black smoke when in fact there isn't.

 

Temp aside if you get no black smoke at full throttle, 2k rpm in gear and 2.7k in neutral then I would hazard a guess your injector pump isn't fully opening. You could disconnect throttle linkage and open pump lever by hand and see if revs increase?

[alan_fincher]

Yes, there is no thermostat due to the previous raw-water cooled nature of the cooling. There is a debate as to whether it matters or not, though; Alnwick is very firmly of the opinion that it doesn't.

 

I could fit a thermostat, as the housing is there, I'd just have to drain the coolant, I think, in order to do it.

I can't think of any reason why you would choose to run at only 55 degrees a cooling circuit normally designed to operate at maybe 74 or 82.

 

It cannot be good for the engine to over-cool to that degree, as lubricating oils are designed with certain assumptions about how hot the engine will get.

 

I also assume you have no calorifier ? If you have, I'm guessing it doesn't serve much useful purpose except ballast.

 

Get a thermostat!

[Radio-Ga-Ga]

I can run it on full throttle for a while before it overheats, but my response is based on you telling me that there would be black smoke when in fact there isn't.

 

To be honest I don't really care how long you've been working with engines because I think you've made an assumption about my engine which turns out not to be true. Thank you for the free advice but I will have to ignore it since I belive it is based on that misapprehension.

 

For the second time!, I have not told you you would get black smoke, I said if you need to see smoke take it on a good run at full throttle. and I stand by that. It just depends how long you're prepared to torture it for. As it gets hotter it will start with dark blue as the rings scrape at the bores and it starts burning oil, moving to a nice shade of pigeon blue as the compression drops and partly burned fuel combines with partly burned oil, and finaly if your big end shells and con rods are very durable a few minutes of pale ivory just like morning mist will fill the river valley as the compression drops so low virtualy no fuel is burned, and you should have penty of time to cook lunch on it while you decide on re-con or new. But don't take my word for it try it for yourself, your "while" was just not long enough.

 

don't take my advice, but don't twist my words because it doesn't suit you, you often ask for help on here and regularly reject good advice because you don't like it. Gibbo gives some of the best electrical advice you could want, but I've seen you rejecting what he's told you on electrical topics, and twisting what he's said until he makes a mistake so you can argue even more.

 

Don't think for one minute I'm offended, rejecting good advice is what you do.

 

Just one last thing, for Robin3, earlier in this topic I was unkind to you, no matter what I thought of your post I should not have been so tactless and I apologise.