My overheating problems.

[alan_fincher]

Agreed on most counts,however I think that an engine of that size in a widebeam on rivers with a strong current may well not be powerful enough..

That's a different issue, surely ?

 

Whatever the rights and wrongs of what engine is most suitable in this sized wide-beam,experiencing that kind of use, the fact is that Mike does do things with it that others might find scary, (such as taking it up and in to Limehouse).

 

My contention is that he is undoubtedly using more of his 55 horses, and for longer, than most other people with a similar boat engine combination ever tend to normally do.

 

Most would get away with a skin tank theoretically too small, because they will not use enough power for long enough to push things to the limit. The fact is Mike has a 55HP motor he is probably working quite hard. The indicated skin tank size for that by even the most optimistic calculations is probably 12 square feet, with Tony Brooks' argument indication more like 18 square feet is safest. Mike is some considerable way short of 12 square feet. If the tank is "good" in all other respects he may get away with it. If something like lack of baffles is also an issue, I think he almost certainly will continue to struggle.

[Albion]

 

Now we know the size, to me the next most important thing is to know "does it have any baffles?".

 

I'd decide if there are any baffles at all, before getting in to a lot of spot temperature readings.

I'm prepared to say that if the tank is the size Mike says, but proves to have no baffles, then that alone is perfectly sufficient explanation for the overheating at high power levels.

 

If it proves to be properly baffled, then it is worth investigating flow patterns, I agree.

 

However, despite having been through all this myself, I'm starting to feel like a lone voice, not making much headway with winning people over. Perhaps I'll just wait until someone solves it, but it must be at least a year ago that Mike started making references to overheating or suspected inadequate tanks, (including ultimately plans to have another one added), so it has been going on a while now!

 

Having originally proposed the concept of there being no baffles in the tank back at post #9 I entirely agree that it is a diagnosis that should be made before any other diagnostic measures are taken for two reasons

1. It is a crucial factor in poor cooling.

2. It is very simple to do via the vent plug and will confirm or eliminate any doubt on the subject.

However, to be fair to Mike he has said he will do it asap so there seems little point in people throwing in all sorts of further esoteric solutions until we know that the basics are right.

 

No, you're not a lone voice for the reasons that I have outlined above and there are others, in addition to me, who are supporting the basic concept but we have to cut Mike some slack until he can get the diagnosis done (at the weekend IIRC).

Roger

[blackrose]

Mike's boat, I suspect would be fine all day long if pottered up and down the Grand Union in the manner that stretches them no more than a lot of owners ever do.

Correct - I can go all day long on the canal without any problem.

 

I genuinely suspect Mike expects more of this engine sometimes than most owners of similar boats ever do.

 

I just expect it not to overheat when I'm pushing it at 1800rpm against a slight current on the Thames. I don't think that's too much to ask.

 

I'll check that skin tank this evening and also the water pump if I have time.

 

...but it must be at least a year ago that Mike started making references to overheating or suspected inadequate tanks, (including ultimately plans to have another one added), so it has been going on a while now!

 

After reading something on the Beta website I just came to the conclusion that the skin tank was under-sized and although I had plans to get another one welded in I don't have money to burn. When I came across another "identical" boat with apparently an identical setup then it got me thinking that perhaps it wasn't the size of the skin tank. Although you might have found this frustrating Alan, I'm glad I waited. The worst outcome for me would be to pay out hundreds of pounds to have another tank installed but still have the same problem.

 

Agreed on most counts,however I think that an engine of that size in a widebeam on rivers with a strong current may well not be powerful enough.The larger sized engines have a much bigger skin tank.

 

60' x 12' Liverpool Boat with Isuzu 55, PRM150, 19" x 13" Vetus r/h prop and 9.5 ft sq skin tank. Engine running at 2000rpm from Portishead to Sharpness - temperature never rose above 85C. If I tried this with my boat the engine would overheat for sure.

 

 

Here are a couple more:

 

 

This one looks a bit worrying!

 

Edited May 31, 2012 by blackrose

[alan_fincher]

When I came across another "identical" boat with apparently an identical setup then it got me thinking that perhaps it wasn't the size of the skin tank. Although you might have found this frustrating Alan, I'm glad I waited. The worst outcome for me would be to pay out hundreds of pounds to have another tank installed but still have the same problem.

No, Mike - I only get "frustrated" by the bits where people make suggestions that science can't actually support.

 

As has been said already "identical" may not be, even if the external dimensions are both the same.

 

Obviously the biggest difference would be if that one had baffles, and yours proved not to. But even if they both have, it is unlikely that they are welded to both skins of the tank, and manufacturing tolerances might mean yours has bigger gaps down the side where they are not welded, and hence the water is more easily able to take a short-cut, and not exploit even all the cooling surface you do have.

 

Clearly a lot of people do get away with tanks that are a lot smaller than the usual guide figures say they should be, although they may well not even realise that really the temperature should never rise above thermostat temperature. Many people's attitude may be that if its not actually boiling, it is not a problem, and in some degree that's not an unreasonable line to take.

 

However, as I'm sure you realise, if on the margins, it is not just about what current you are pushing against, and at what revs. How long you attempt to do it for will also come into play.

 

EDITED TO ADD:

 

Only just seen those great pictures.

 

Could the problem be the additional weight of your shell due to having all portholes instead of some windows ?

 

Coat,please!

Edited May 31, 2012 by alan_fincher

[Guest]

You forget that on this forum, nobody replies except if they disagree/want an argument! FWIW I am in total agreement with your points. Unfortunately a few do pop in and out of the thread with the odd throwaway un-thought-out comment such as "flow rate may be too low" to add to the confusion! Ultimately Mike will have to decide who to believe and who to ignore. Water, horse, drink etc.

 

One tiny point possibly not well known is that a coolant's ability to transfer heat is related to the strength of the antifreeze mixture. A 25% mix is capable of transporting about 10% more heat than 50%, and about 45% more heat than 100% antifreeze.

Also presumably a very rusty tank interior could reduce heat transfer from coolant to cut/river.

IIRC rally drivers add yet another fluid to the rad which transfers heat even more efficiently than coolant alone?

[larkshall]

IIRC rally drivers add yet another fluid to the rad which transfers heat even more efficiently than coolant alone?

 

 

Yes and so do F1 engineers, but I can't remember what it is ! (duh)

[saltysplash]

My old Gardner 4L3W was sea water cooled, there was no heat exchanger, the raw water was pumped directly into the block, also there was no thermostat which meant generally she took a a long time to warm up and even after a 12 hour crossing to Ostend would still be running nice and warmish, never hot.

 

Would Mike removing the thermostat from his engine cause any major problems at all? Im not very up on modern diesels but apart from not having overly hot water in the domestic tank, would it cause any other problems?

 

I used to run many old cars without thermostats without any problem but would refit the thermostat in the winter to give a bit of warmth in the heater....that was on the cars that had heaters of course

[Eeyore]

IIRC rally drivers add yet another fluid to the rad which transfers heat even more efficiently than coolant alone?

That would be this then? or something similar.

I wonder if any one has tried this on a boat, or is it just "snake oil"

Interesting thread, I've been reading from the start, but nothing new to add I'm afraid.

Steve

[RobinJ]

Would Mike removing the thermostat from his engine cause any major problems at all? Im not very up on modern diesels but apart from not having overly hot water in the domestic tank, would it cause any other problems?

When I ahd a problem it didn't help (apart from proving the thermostat was ok), removing the radiator cap (unpressurised) got me home and we eventually cocnluded that air locks were causing the problem.

Removing the cap can help in a couple of ways i) confirm water flow ii) demonstate how much expansion there is (gasses from leaking gasket etc.).

[larkshall]

On a modern engine with a thermostat and skin tank you simply can't have "too much cooling" - its a common misconception.

 

Other than needing more antifreeze than you might, and needing to cope for potentially greater expansion, there are no downsides to having an overly large area skin tank (or tanks), as the thermostat operation should prevent "over-cooling". What a nice big area tank does give you is a lot more margin that the engine should never overheat, even if thrashed hard - no bad thing!

 

agreed

[smileypete]

If there are no baffles I'd expect the skin tank cooling capacity needs derating 30-60% depending on shape.

 

And if there's a thick hull coating derate by 10-30% depending on coating thickness.

 

In Blackrose's case it's probably a combination of both.

 

Getting the coolant to flow more evenly across the skin tank instead of diagonally might just squeeze enough cooling capacity out of it.

 

cheers,

Pete.

[David Mack]

There's a lot of folk clutching at straws here!

 

From other posts on this thread the recommended skin tank area in square feet per HP is variously given as:

 

0.24 (Barrus recommendation quoted by Flyboy)

0.25 (Beta recommendation quoted by ditchdabbler)

0.3 (normal figure from Tony Brooks, quoted by Alan Fincher)

0.31-0.35 (Bizzard)

0.5 (example from Tony B, quoted by Alan F)

All of these figures are presumably based on having effective baffles in the tank.

 

Mike's engine is 55 HP, but can rev only to 42 hp, and has a skin tank area of 9.5 square feet, so 0.22 sq ft/HP based on the 42 HP figure, or 0.17 on the full 55 HP.

 

So whichever way you look at it, Mike's tank is undersized. Adding baffles (if indeed it has none) may make a difference, but you can't get away from the fact that there is simply too little cooling available if this engine is going to be used for anything more demanding than pootling up the cut.

 

Adding baffles to the existing skin tank is going to be difficult and messy. The access for a welder to get in and do the work alongside the engine is not great, and there would seem to be plenty of scope for a poorly accessible weld to leak once the system is pressurised. And the tank would still be too small.

 

So I think Mike's best bet is to do nothing to the existing tank and to install a second skin tank (with baffles) and plumb it in series with the existing - hot water from the engine to the top of one tank, out of the bottom, across to the top of the other tank, and then from the bottom to the oil cooler and back to the engine. The second tank could be installed on the inside of the swim on the other side if there is room - I guess this could be done with the boat afloat if you are prepared to accept some local heat damage to the blacking until the boat is next docked. Otherwise you could fit an external tank on the other side of the swim (or even the same side if there is room clear of the existing tank). If the front and back edges of this are faired into the hull side there shouldn't be much effect on handling. I sure there are photos of an external tank somewhere on the forum.

 

David

[Albion]

There's a lot of folk clutching at straws here!

snipped

Adding baffles to the existing skin tank is going to be difficult and messy. The access for a welder to get in and do the work alongside the engine is not great, and there would seem to be plenty of scope for a poorly accessible weld to leak once the system is pressurised. And the tank would still be too small.

snipped

So I think Mike's best bet is to do nothing to the existing tank and to install a second skin tank (with baffles) and plumb it in series with the existing

David

Not clutching at straws, trying to get an accurate diagnosis of root cause as a first step.

Why do you think that getting access to fit a new large tank on the other side of the engine is going to be any easier and less risk prone than adding baffles to the existing tank and, if required, adding another small tank to the other side? Access to weld a small additional tank (if it proves to be necessary) has to be easier than adding a complete large one.

Roger

[blackrose]

Would Mike removing the thermostat from his engine cause any major problems at all? Im not very up on modern diesels but apart from not having overly hot water in the domestic tank, would it cause any other problems?

 

I already tried running without a thermostat last weekend and it still overheated.

[David Mack]

Not clutching at straws, trying to get an accurate diagnosis of root cause as a first step.

Why do you think that getting access to fit a new large tank on the other side of the engine is going to be any easier and less risk prone than adding baffles to the existing tank and, if required, adding another small tank to the other side? Access to weld a small additional tank (if it proves to be necessary) has to be easier than adding a complete large one.

Roger

 

Clutching at straws? Arcane arguments about the possible effects of too low or two high a flow rate, operating withou the thermostat, suggestions that the temperature measurements are wrong and so on. All of these could be contributory factors, but I was trying to set out that even if they do play a part, by the conventional wisdom (as quoted from various other sources) the main (and perhaps only) problem - the root cause - is that the existing tank (baffles or no baffles) is just too small for the size of engine and type of boating Mike is doing. Just tinkering with the existing tank will not solve the problem, and an additional tank is needed. And so the precise reasons behind the existing tank's underperformance are not terribly helpful in solving the problem.

 

I agree that access to the other side, to fit a new tank, may not be easy - I did say "if there is room". But assuming that the space available on the other side is similar to that shown in the photo posted earlier, I would have thought it would be easier (but not necessarily easy) for a welder to get in and fit a new tank than to try and mess about with an existing tank. No cutting out to be done for example, and no awkward welds on the underside of a baffle plate inserted into a slot in the existing tank. And there is more chance of planning the work to fit around obstructions or access limitations.

 

It may only be possible to fit a small additional tank, in which case calculating the total cooling requirement and then deducting the cooling capacity of the existing tank would be important. But on the basis that (with a thermostat in place) you can't have too much cooling, I would just fit the largest (baffled) tank that can reasonably be accommodated, to give an overall tank area of (say) 0.4-0.5 sq ft per HP to be on the safe side. For a job like this the cost will not vary very much with the size of the tank. Ease of access and simplicity of construction will be the main factors.

 

David

[smileypete]

One thing I'd consider is to try to even up the flow across the skin tank by adding another inlet at the bottom below the existing, using a 28mm cylinder flange which can be fitted from the outside of the skin tank.

 

Also beach the boat on a tidal bit and remove coatings on the outside of the skin tank, replacing with 1 thin layer of epoxy.

 

cheers, Pete.

~smpt~

Edited May 31, 2012 by smileypete

[blackrose]

There's a lot of folk clutching at straws here!

 

From other posts on this thread the recommended skin tank area in square feet per HP is variously given as:

 

0.24 (Barrus recommendation quoted by Flyboy)

0.25 (Beta recommendation quoted by ditchdabbler)

0.3 (normal figure from Tony Brooks, quoted by Alan Fincher)

0.31-0.35 (Bizzard)

0.5 (example from Tony B, quoted by Alan F)

All of these figures are presumably based on having effective baffles in the tank.

 

Mike's engine is 55 HP, but can rev only to 42 hp, and has a skin tank area of 9.5 square feet, so 0.22 sq ft/HP based on the 42 HP figure, or 0.17 on the full 55 HP.

 

So whichever way you look at it, Mike's tank is undersized. Adding baffles (if indeed it has none) may make a difference, but you can't get away from the fact that there is simply too little cooling available if this engine is going to be used for anything more demanding than pootling up the cut.

 

Adding baffles to the existing skin tank is going to be difficult and messy. The access for a welder to get in and do the work alongside the engine is not great, and there would seem to be plenty of scope for a poorly accessible weld to leak once the system is pressurised. And the tank would still be too small.

 

So I think Mike's best bet is to do nothing to the existing tank and to install a second skin tank (with baffles) and plumb it in series with the existing - hot water from the engine to the top of one tank, out of the bottom, across to the top of the other tank, and then from the bottom to the oil cooler and back to the engine. The second tank could be installed on the inside of the swim on the other side if there is room - I guess this could be done with the boat afloat if you are prepared to accept some local heat damage to the blacking until the boat is next docked. Otherwise you could fit an external tank on the other side of the swim (or even the same side if there is room clear of the existing tank). If the front and back edges of this are faired into the hull side there shouldn't be much effect on handling. I sure there are photos of an external tank somewhere on the forum.

 

David

 

Thanks, yes, I agree with this. There's definitely enough room to install a second skin tank on the inside of the other swim.

 

I took the bleed screw out of the skin tank this evening and shoved a wire coat hanger inside. It didn't hit anything until it hit the baseplate, which leads me to conclude that there are no baffles.

 

Clutching at straws? Arcane arguments about the possible effects of too low or two high a flow rate, operating withou the thermostat, suggestions that the temperature measurements are wrong and so on. All of these could be contributory factors, but I was trying to set out that even if they do play a part, by the conventional wisdom (as quoted from various other sources) the main (and perhaps only) problem - the root cause - is that the existing tank (baffles or no baffles) is just too small for the size of engine and type of boating Mike is doing. Just tinkering with the existing tank will not solve the problem, and an additional tank is needed. And so the precise reasons behind the existing tank's underperformance are not terribly helpful in solving the problem.

 

I agree that access to the other side, to fit a new tank, may not be easy - I did say "if there is room". But assuming that the space available on the other side is similar to that shown in the photo posted earlier, I would have thought it would be easier (but not necessarily easy) for a welder to get in and fit a new tank than to try and mess about with an existing tank. No cutting out to be done for example, and no awkward welds on the underside of a baffle plate inserted into a slot in the existing tank. And there is more chance of planning the work to fit around obstructions or access limitations.

 

It may only be possible to fit a small additional tank, in which case calculating the total cooling requirement and then deducting the cooling capacity of the existing tank would be important. But on the basis that (with a thermostat in place) you can't have too much cooling, I would just fit the largest (baffled) tank that can reasonably be accommodated, to give an overall tank area of (say) 0.4-0.5 sq ft per HP to be on the safe side. For a job like this the cost will not vary very much with the size of the tank. Ease of access and simplicity of construction will be the main factors.

 

David

 

There's plenty of room for a welder to get in there. To cut costs I'm going to make a cardboard template of the curve of the swim and have a 3 sided 4mm wall thickness baffled skin tank made at a sheet steel fabricators (the bottom of the tank will be the baseplate and the forward side will be the watertight bulkhead between the engine space & cabin). Then I'm going to pay a welder at work to weld it in for me. He should be able to tack it in place and then just fully weld it in. Hopefully the fabrication should cost no more than about 100 - 150 quid and welding it in about 80 - 100 quid?

[alan_fincher]

I took the bleed screw out of the skin tank this evening and shoved a wire coat hanger inside. It didn't hit anything until it hit the baseplate, which leads me to conclude that there are no baffles.

That's a bummer!

 

One really might have hoped anyone who built as many boats as they did at least managed to get that right.

 

Although it would not be the only "volume" builder to mess up on this - ours didn't have them either, (Evans & Son), but apparently the "legendary" Mike Heywood was particularly "legendary" for thinking skin tank design didn't matter, and anything small and vaguely box shape would do.

 

It will not help you, obviously, but it would be interesting to know if the "identical" LB boat is also without them, or whether that is actually a big difference between the two.

 

At least now you know.

[Guest]

That would be this then? or something similar.

I wonder if any one has tried this on a boat, or is it just "snake oil"

Interesting thread, I've been reading from the start, but nothing new to add I'm afraid.

Steve

Not familiar with that name, but it certainly is the type of thing I have seen being added to competition engine cooling systems. No personal experience but I am led to believe that there are additives which help to transfer the waste heat away from the system in a more efficient manner.

[blackrose]

One thing I'd consider is to try to even up the flow across the skin tank by adding another inlet at the bottom below the existing, using a tank connector/essex flange bolted to the skin tank.

 

So, drill and tap threads to hold the flange on? How would I make that watertight?

 

Presumably you mean that the feed from the engine should be Td to go to two inlets in the skin tank?

Edited May 31, 2012 by blackrose

[bizzard]

Evening shift clocking in.

Ahoy Mike,

Assuming you've carried out all the checks mentioned.

Thermostat;--yes. Gauge and sender checks. Head gasket waterpump and drive belt checks. Air lock check. Blockage check. Not to big a concentrate of anti-freeze check,certainly no more than 50/50. Was the coolant nice and clean when you removed the thermostat ?no gunge or rust?I would use nothing but distilled or deionized water in an engine or central heating.

So we've more or less decided that your skin tank is inadequate for sustained high power use against strong currents and probably strong winds.

So the cheapest test is probably the S/hand car radiator with 12v cooling fan attached simply fitted temporarily to preferably your engines hot water outlet hose.Pipe from engine into top port of car rad, bottom port of car rad to skin tanks inlet port.Couple up fan with crocodile clips to battery and go for a high speed run,but with your engine deck cover off though so as not to just recirculate all the hot air around the compartment and so make the experiment almost void.

This ultimate test i'm certain will be successful.

If this is the case that Bowman heat exchanger would probably be your cheapest and definitely successful solution,as you would only need to bring it into use by turning a little 12v pump on when the engine temperature creeps up too high.

My notes on gaining the use of pumped raw water are available to you in my two Watery Wheeze posts 1&2,which i dedicated to you.No2 is quite serious and more attractive as it does not require drilling anywhere below the waterline and quite inbstrusive.Though No1 is pucker would be a little bit of a challenge.

[RLWP]

So, drill and tap threads to hold the flange on? How would I make that watertight?

 

Presumably you mean that the feed from the engine should be Td to go to two inlets in the skin tank?

 

Can't see that will make a scrap of difference

 

Richard

[alan_fincher]

Can't see that will make a scrap of difference

 

Richard

At this stage we appear to know the tank is both severely undersized for any normal recommendation for the engine size. And the wrong design - no baffles. And that Mike probably uses the boat more "enthusiastically" than many - or at least would like to.

 

Plus he goes on the more "interesting" bits of the Thames - hardly the kind of place you want to boil over, if you end up working it harder than he expected.

 

He seems to now accept he needs to spend some money, and have evolved a plan to make the improvements as economically as possible. I'm kind of bemused that people think it worth tinkering further with current arrangements.

[nicknorman]

... apparently the "legendary" Mike Heywood was particularly "legendary" for thinking skin tank design didn't matter, and anything small and vaguely box shape would do.

 

the boat we have routinely "borrowed" for the past 18 yrs was a Mike Heywood. A ridiculous skin tank, incredibly fat so a huge volume of water to expand, but almost certainly not baffled and the Lister 4pot could not be run over about 1600 long term without overheating.

[smileypete]

So, drill and tap threads to hold the flange on? How would I make that watertight?

 

Presumably you mean that the feed from the engine should be Td to go to two inlets in the skin tank?

Yes. A flange fits though a hole with 4 slots then is turned and tightened up. That way it can be installed from outside without inside access to the tank.

 

 

Maybe do a trial using the bilge pump to pump cold bilge water over the inside of the skin tank to see how much extra cooling it gives. If it makes all the difference, then baffles or more even flow across the tank will probably do it.

 

cheers, Pete.

~smpt~

Edited May 31, 2012 by smileypete