My overheating problems.

[alan_fincher]

80 degs in and 70 degs out. Mike told us at the beginning of the thread.

 

Sorry Alan,it was on his other thread on the same problem.

So the skin tank is only managing to drop the temperature of the water 10 degrees by the time it comes out the bottom.

 

That means water is being pumped back into an already hot engine only 10 degrees cooler than it is leaving it, so not really surprising the engine wants to go well above thermostat temperature, if worked hard.

 

Only two explanations I can see are.....

 

1) Skin tank not up to task being asked of it.

2) Engine has a fault (like head gasket) that means it is producing more excess heat to produce a given power than the manufacturer expected.

 

My money remains firmly on (1), I'm afraid.

 

I can't see it can be....

 

3) Blockage (full or partial)

4) Air lock(s)

5) Faulty or inefficient pump

6) Thermostat

 

all of which would not produce a symptom of the skin tank getting too hot all the way down, with insufficient temperature gradient across it.

 

Yes, at idling it was 80C at the bottom of the tank where the pipe is connected, and 70C at the other end of the tank (at the top) where the pipe is connected. I'll post a picture tomorrow.

Forget everything I just said.

 

If you are serious that the skin tank is hotter at the bottom than the top, then surely the engine has been plumbed in with connections reversed.

 

Yes, pictures, please !!

[nicknorman]

 

Actually I thought it was the other way round? I'll check it again tomorrow.

 

I mentioned it in a different thread - sorry for the confusion. Yes, at idling it was 80C at the bottom of the tank where the pipe is connected, and 70C at the other end of the tank (at the top) where the pipe is connected. I'll post a picture tomorrow.

 

If your plumbing is the other way round, this absolutely explains the problem. If you put the light hot water in at the bottom, it just wants to rise straight to the top and exit the tank without passing much of the surface area and hence doesn't cool much. Meantime there will be lots of "dead" water filling the tank not doing anything. Whilst baffles help this a bit, as has been said they tend not to be a perfect seal and so the light and bouyant hot water will finds its way around them.

 

By putting the hot in at the top, the water tends to move progressively down through the whole tank, maximising the cooling.

Edited May 28, 2012 by nicknorman

[bizzard]

So the skin tank is only managing to drop the temperature of the water 10 degrees by the time it comes out the bottom.

 

That means water is being pumped back into an already hot engine only 10 degrees cooler than it is leaving it, so not really surprising the engine wants to go well above thermostat temperature, if worked hard.

 

Only two explanations I can see are.....

 

1) Skin tank not up to task being asked of it.

2) Engine has a fault (like head gasket) that means it is producing more excess heat to produce a given power than the manufacturer expected.

 

My money remains firmly on (1), I'm afraid.

 

I can't see it can be....

 

3) Blockage (full or partial)

4) Air lock(s)

5) Faulty or inefficient pump

6) Thermostat

 

all of which would not produce a symptom of the skin tank getting too hot all the way down, with insufficient temperature gradient across it.

 

 

Forget everything I just said.

 

If you are serious that the skin tank is hotter at the bottom than the top, then surely the engine has been plumbed in with connections reversed.

 

Yes, pictures, please !!

The ratio should be roughly say 80 degs in and 40-50 degs on returning to the engine.

[RLWP]

If your plumbing is the other way round, this absolutely explains the problem. If you put the light hot water in at the bottom, it just wants to rise straight to the top and exit the tank without passing much of the surface area and hence doesn't cool much. Meantime there will be lots of "dead" water filling the tank not doing anything. Whilst baffles help this a bit, as has been said they tend not to be a perfect seal and so the light and bouyant hot water will finds its way around them.

 

By putting the hot in at the top, the water tends to move progressively down through the whole tank, maximising the cooling.

 

If this were a 1930's thermocycle car radiator system, you could be right.

 

As this is a pumped system I remain to be convinced I'm afraid

 

Richard

[nicknorman]

If this were a 1930's thermocycle car radiator system, you could be right.

 

As this is a pumped system I remain to be convinced I'm afraid

 

Richard

It is your privelege to remain unconvinced, however you would remain wrong! I just checked the Beta Installation manual and it clearly shows hot in at the top. Alan and Biz seem to agree with me!

[by'eck]

If this were a 1930's thermocycle car radiator system, you could be right.

 

As this is a pumped system I remain to be convinced I'm afraid

 

Richard

 

Pumped or not, it makes sense to buck the odds. The laws of physics will still hold true

[bizzard]

Vehicle type belt driven water pumps are not true powerful pumps as such but waterflow circulation assistors similar to domestic central heating pumps.

[alan_fincher]

Alan and Biz seem to agree with me!

Not sure what I agree with, TBH.

 

I thought Mike's boat was supplied direct from LB, with its Isuzu already fitted. Given the huge number they built, and that the Isuzu was very much a standard, it takes some believing they plumbed his example "upside down", unless they had some school kid on a work experience placement that particular day, (and obody checking!).

 

I'll reserve judgement until I see pictures that prove this to be the case.

 

Clearly if it is wrong it is not even worth speculating about how much worse it might

make things. If it proves to be incorrect, to me it is a no-brainer to plumb it up correctly first, then see what the situation is.

[RLWP]

Pumped or not, it makes sense to buck the odds. The laws of physics will still hold true

 

All the way through those baffles, effectively making a system of square tubes? Well, if Mike's cooling system is so critical, no wonder that it overheats

 

Are the baffles really horizontal? I suppose it makes it easier to bleed. Without thinking about it, I would have put the baffles vertical. Oh well

 

Richard

 

MORE: Mike, this is all jolly stuff from a bunch of SAEs* - myself included - but you need data. Like the temperature distribution across the tank, and Bizzards suggestions for checking if your head gasket has gone by examining the header tank

 

*Self Appointed Experts

Edited May 28, 2012 by RLWP

[blackrose]

All the way through those baffles, effectively making a system of square tubes? Well, if Mike's cooling system is so critical, no wonder that it overheats

 

Are the baffles really horizontal? I suppose it makes it easier to bleed. Without thinking about it, I would have put the baffles vertical. Oh well

 

Richard

 

I think my baffles (if they exist) must be vertical because the tank is plumbed in/out at each end, rather than the top and bottom at the same end (like in the Beta diagram).

 

Anyway, I'll take some pictures tomorrow evening and post them on this thread.

 

Edit: Wait a minute - I've just found a picture. Will this do?

 

Edited May 28, 2012 by blackrose

[bizzard]

Not sure what I agree with, TBH.

 

I thought Mike's boat was supplied direct from LB, with its Isuzu already fitted. Given the huge number they built, and that the Isuzu was very much a standard, it takes some believing they plumbed his example "upside down", unless they had some school kid on a work experience placement that particular day, (and obody checking!).

 

I'll reserve judgement until I see pictures that prove this to be the case.

 

Clearly if it is wrong it is not even worth speculating about how much worse it might

make things. If it proves to be incorrect, to me it is a no-brainer to plumb it up correctly first, then see what the situation is.

It may be possible that Mike has inadvertantly reversed them,as he did once try to couple up the engines cooling circuit with his central heating circuit to try to solve the problem, but on the other hand it must have been giving this trouble before he did this,erm cos that's why he did it.

[nicknorman]

Not sure what I agree with, TBH.

 

 

That hot water should enter at the top and exit (cooler) at the bottom.

[ditchcrawler]

Ok, I'll try that. I'll map out the temperatures in various positions using the IR thermometer and report back.

if you have an IR thermometer have you tried recording the water return temperature ex scin tank, per engine to see if it is being cooled. If its slow flow rate I would expect it to be very cool but poor skin tank quite hot,

[smileypete]

Only two explanations I can see are.....

 

1) Skin tank not up to task being asked of it.

2) Engine has a fault (like head gasket) that means it is producing more excess heat to produce a given power than the manufacturer expected.

 

My money remains firmly on (1), I'm afraid.

+1

 

Either very bad design, or welded up by someone who didn't quite follow the (any?) design. IR readings please!

 

You could certainly see the weld lines of the baffles on our skin tank - that was before it was spray foamed.

Yes, better to have any gaps on the outside where leakage goes past the hull side. I wouldn't be surprised if it was the other way round on Mikes boat.

 

cheers, Pete.

smpt

Edited May 28, 2012 by smileypete

[nicknorman]

 

I thought Mike's boat was supplied direct from LB, with its Isuzu already fitted. Given the huge number they built, and that the Isuzu was very much a standard, it takes some believing they plumbed his example "upside down", unless they had some school kid on a work experience placement that particular day, (and obody checking!).

 

Not that hard to believe really - a simple mistake that doesn't immediately reveal itself.

[blackrose]

It may be possible that Mike has inadvertantly reversed them,as he did once try to couple up the engines cooling circuit with his central heating circuit to try to solve the problem, but on the other hand it must have been giving this trouble before he did this,erm cos that's why he did it.

 

Yes, that's partly why I did it - also because my Eberspacher died and I had 4 unused rads inside the boat. But my engine central heating system circuit runs indirectly through a heat exchanger. I don't think it changed the engine cooling system. It goes from the engine to the heat exchanger and calorifier. It hasn't altered the cooling system radically.

 

 

That hot water should enter at the top and exit (cooler) at the bottom.

 

I'll have to take some more temp readings again tomorrow.

Edited May 28, 2012 by blackrose

[alan_fincher]

I think my baffles (if they exist) must be vertical because the tank is plumbed in/out at each end, rather than the top and bottom at the same end (like in the Beta diagram).

Not necessarily.

 

If it has an odd number of horizontal baffles, it will normally result in top and bottom connections being at opposite ends of the tank.

 

Only with an odd number of baffles, (hopefully at least three, not just one!), both top and bottom connection will be at the same end.

 

Horizontal baffles are far more sensible, as natural convection will do what you want. Vertical baffles would be very poor practice, as in "alternate" compartments, gravity would be doing the exact opposite of what makes sense. Can't believe LB would do that, TBH.

 

My guess is you have two horizontal baffles, if top and bottom connections are at opposite ends. My guess is that is the most common arrangement of all.

 

Like this.....

 

 

Should still be hot water in at the top though, and cooled water out at the bottom.

 

Absolutely, definite, for certain, no arguments!

[ditchcrawler]

Not that hard to believe really - a simple mistake that doesn't immediately reveal itself.

Do you think going the wrong way would make that much difference to its efficiency ?

[nicknorman]

I think my baffles (if they exist) must be vertical because the tank is plumbed in/out at each end, rather than the top and bottom at the same end (like in the Beta diagram).

 

Certainly hope they are not vertical! If the entrance and exit are at opposite ends, that just (hopefully) means there is an even number of horizontal baffles.

 

Do you think going the wrong way would make that much difference to its efficiency ?

Yes, a huge amount, though to some extent dependant on how effective the baffling is. Since the baffling is generally only welded at one side, and leaky at the other side, and bearing in mind the flow rate is not that high, the water (being lazy like the rest of us!) will find the easiest route through, aided by gravity in this case. With the "right way round" it has to fight gravity and so does not tend to take short cuts.

 

Consider the case with no baffles - hot water entering at the bottom would go vertically straight up to the top in a narrow path (thus not losing much heat), then maybe or maybe not (depending on which side the exit was) run along the top, again in a very narrow path, before exiting. You have reduced the effective area massively. As we said, baffles help but are usually far from perfect. By contrast pushing the hot down from above will fill the whole tank with hot water, so the whole surface areas is used to dump heat.

Edited May 28, 2012 by nicknorman

[bizzard]

I think my baffles (if they exist) must be vertical because the tank is plumbed in/out at each end, rather than the top and bottom at the same end (like in the Beta diagram).

 

Anyway, I'll take some pictures tomorrow evening and post them on this thread.

 

Edit: Wait a minute - I've just found a picture. Will this do?

 

That rusty elbow looks like its reduced in diameter where it screws into the tank,quite restrictive i would think.

[nicknorman]

That rusty elbow looks like its reduced in diameter where it screws into the tank,quite restrictive i would think.

Not familiar with Isuzu - can you tell which is the "send" and which is the "receive" pipes to the skin tank?

[alan_fincher]

Not sure what I agree with, TBH.

 

That hot water should enter at the top and exit (cooler) at the bottom.

Yes, OK, obviously I agree with that !

 

But, despite his description of the skin tank being hotter at the bottom than the top, I'm struggling to see Mike's Isuzu as plumbed "upside down".

 

Not completely clear from his picture where everything goes, but here.....

 

 

the pipe with a wire attached to it with three zip ties appeatrs to come from the bottom of the tank, (towards front of boat) and clearly connects to the gearbox oil cooler. In any normal engine that would be the inlet for the cooled water, so to my mind the plumbing looks CORRECT!

 

But if so, Mike's assertion that that pipe is connected to a hotter bit of the tank than the other one, (connected at the top, towards the rear of the boat) just sounds plain wrong.

 

Something isn't right with the story here, to my way of thinking.

[nicknorman]

 

the pipe with a wire attached to it with three zip ties appeatrs to come from the bottom of the tank, (towards front of boat) and clearly connects to the gearbox oil cooler. In any normal engine that would be the inlet for the cooled water, so to my mind the plumbing looks CORRECT!

 

 

Unfortunately I am inclined to agree! Curses, I thought we had the problem there. Still worth Mike checking which is the hotter bit of the tank though!

[alan_fincher]

That rusty elbow looks like its reduced in diameter where it screws into the tank,quite restrictive i would think.

I'm convinced this is not a problem of restricted flow!

 

Do you think looking at the pictures it is plumbed the right way around, or the wrong way around.

 

A clue here, possibly....

 

(Picture from Ashby boats site).....

 

 

May be not identical engine, but an Isuzu with that top mounted gear box oil cooler, just the same. Note it also connects to the lower part of the tank, just like Mike's.

 

If Liverpool Boats got it wrong with Mike's then Ashby surely got it wrong with this one too.

 

I cn't see how the top connection can't be hotter than the bottom, I'm afraid - no explanation I can see at all as to how bottom could conceivably be hotter than the top.

[bizzard]

The pipe with the gearbox oil cooler attached should be the cooler return water.

So the other on the rusty elbow should be the hot inlet into the tank,and it looks as if it enters at the top.