My overheating problems.

[blackrose]

I've now ruled out the thermostat being the cause of my engine overheating problems and I got in touch with the owners of a 60ft x 12ft LB widebeam (3ft longer than mine) with the same engine and same size skin tank who haven't managed to get their engine over 85C despite two trips at max revs (2000rpm) for an hour on the Severn estuary. So does that rule out the skin tank?

 

Tony Brooks mentioned that I might have a small head gasket leak, but the engine's been the same since it was new and it's only done about 600 hours. All engine services have been carried out as per the owner's manual.

 

I'm really running out of ideas how to solve this problem now - any help appreciated.

 

Mike

[RLWP]

The head gasket leak check is non-destructive and reasonably easy to do. It would confirm or eliminate one of the variables

 

Naturally, I can't find a kit on Ebay now

 

Richard

[Grace and Favour]

I've now ruled out the thermostat being the cause of my engine overheating problems and I got in touch with the owners of a 60ft x 12ft LB widebeam (3ft longer than mine) with the same engine and same size skin tank who haven't managed to get their engine over 85C despite two trips at max revs (2000rpm) for an hour on the Severn estuary. So does that rule out the skin tank?

 

Tony Brooks mentioned that I might have a small head gasket leak, but the engine's been the same since it was new and it's only done about 600 hours. All engine services have been carried out as per the owner's manual.

 

I'm really running out of ideas how to solve this problem now - any help appreciated.

 

Mike

 

Welllllll......The two skin tanks may be the same size - but that doesn't mean they are equally effective, it could be affected by the rate at which water passes over the swim (?)

Is there any crud/mineral build-up on the inside of the skin-tank?

[bizzard]

I've now ruled out the thermostat being the cause of my engine overheating problems and I got in touch with the owners of a 60ft x 12ft LB widebeam (3ft longer than mine) with the same engine and same size skin tank who haven't managed to get their engine over 85C despite two trips at max revs (2000rpm) for an hour on the Severn estuary. So does that rule out the skin tank?

 

Tony Brooks mentioned that I might have a small head gasket leak, but the engine's been the same since it was new and it's only done about 600 hours. All engine services have been carried out as per the owner's manual.

 

I'm really running out of ideas how to solve this problem now - any help appreciated.

 

Mike

Erm right.

Are you over propped ?

Is the temp gauge reading correctly?or it could be a dodgy transmitter sender on the engine.

Those engines are not known to have head gasket issues.But does it ever boil over?

Try running the engine whilst stationary at normal temperature with the header tank cap off,blipping the throttle up and down,the water level should remain reasonably stable with no large surges up and down,'which would mean the coolant is riding on a pocket of trapped air''. No bubbles or continuous streams of bubbles should appear at the filler.Also if combustion gases were escaping into the cooling system via the head gasket you would smell the fumes and probably see them emitting also at the tanks open filler.Also check for any white oil-water emulsion at oil filler and dip stick.

[blackrose]

Welllllll......The two skin tanks may be the same size - but that doesn't mean they are equally effective, it could be affected by the rate at which water passes over the swim (?)

Is there any crud/mineral build-up on the inside of the skin-tank?

 

It's the same boat, same swim.

 

I changed the coolant about 4 months ago - I didn't notice any crud from the tank. Flushed the engine and tank out with a hosepipe because I changed from blue antifreeze to red.

[bizzard]

Welllllll......The two skin tanks may be the same size - but that doesn't mean they are equally effective, it could be affected by the rate at which water passes over the swim (?)

Is there any crud/mineral build-up on the inside of the skin-tank?

Or Vortexes.

[Chalky]

Head gaskets can go due to an early life failure as well as due to old age. I'm aware of kits that are available that are used to test coolant for combustion products and will tell you if the gaskets gone.

 

Is the engine coolant pump running correctly - nothing stupid like the impellers dropped off etc. Is the system de-gassed (it was this that killed the Triumph Stag v8 engine). Are the hoses ok internally? Do you have some interesting plumbing or does the tank connect straight to the engine? Does the tank have its internal baffles? Are any of the tank connections obscured by steelwork and restricting the flow?

How are you measuring the temperature? Do you have the correct voltage regulator / gauge / thermistor combination etc?

 

A friend of mine is a Rally driver and he was going to pull out of a rally in Abingdon last year due to the engine running hot. A quick look round the engine revealed a poor connection to the thermistor. A quick fix and he went on to win his class.

Edited May 28, 2012 by Chalky

[blackrose]

Erm right.

Are you over propped ?

Is the temp gauge reading correctly?or it could be a dodgy transmitter sender on the engine.

Those engines are not known to have head gasket issues.But does it ever boil over?

Try running the engine whilst stationary at normal temperature with the header tank cap off,blipping the throttle up and down,the water level should remain reasonably stable with no large surges up and down,'which would mean the coolant is riding on a pocket of trapped air''. No bubbles or continuous streams of bubbles should appear at the filler.Also if combustion gases were escaping into the cooling system via the head gasket you would smell the fumes and probably see them emitting also at the tanks open filler.Also check for any white oil-water emulsion at oil filler and dip stick.

 

Yes, it's over-propped, but that shouldn't cause the engine to overheat should it? The other widebeam also has the same 19" x 13" prop and his doesn't overheat.

 

Temp gauge is reading correctly according to the readings I've taken with an IR thermometer.

[Albion]

Yes, it's over-propped, but that shouldn't cause the engine to overheat should it? The other widebeam also has the same 19" x 13" prop and his doesn't overheat.

 

Temp gauge is reading correctly according to the readings I've taken with an IR thermometer.

An out-of-the-box reply but could it be that the welding team that built your shell didn't bother to put baffles in the skin tank whereas another gang on the other shell did?

Roger

[blackrose]

Head gaskets can go due to an early life failure as well as due to old age. I'm aware of kits that are available that are used to test coolant for combustion products and will tell you if the gaskets gone.

 

Is the engine coolant pump running correctly - nothing stupid like the impellers dropped off etc. Is the system de-gassed (it was this that killed the Triumph Stag v8 engine). Are the hoses ok internally? Do you have some interesting plumbing or does the tank connect straight to the engine? Does the tank have its internal baffles? Are any of the tank connections obscured by steelwork and restricting the flow?

How are you measuring the temperature? Do you have the correct voltage regulator / gauge / thermistor combination etc?

 

A friend of mine is a Rally driver and he was going to pull out of a rally in Abingdon last year due to the engine running hot. A quick look round the engine revealed a poor connection to the thermistor. A quick fix and he went on to win his class.

 

How do I check the coolant pump?

 

De-gassed? My dad used to have a Triumph Stag in the early 70s. I remember as a kid the car overheating and breaking down during a traffic jam on the Westway going into London.

 

The plumbing between engine and skin tank is the same as any other Liverpool Boat as far as I know.

 

How would anyone know if their skin tank was baffled unless they were there during the build?

 

Voltage regulator? Now I am getting confused! I have the Isuzu panel - revcounter, start battery voltmeter, temp gauge and oil pressure. I've checked the temp gauge with an infra-red thermometer and it seems ok.

 

An out-of-the-box reply but could it be that the welding team that built your shell didn't bother to put baffles in the skin tank whereas another gang on the other shell did?

Roger

 

Possibly, but if it was your skin tank would you cut into it with an angle grinder to have a look?

[Guest]

I've now ruled out the thermostat being the cause of my engine overheating problems and I got in touch with the owners of a 60ft x 12ft LB widebeam (3ft longer than mine) with the same engine and same size skin tank who haven't managed to get their engine over 85C despite two trips at max revs (2000rpm) for an hour on the Severn estuary. So does that rule out the skin tank?

 

Tony Brooks mentioned that I might have a small head gasket leak, but the engine's been the same since it was new and it's only done about 600 hours. All engine services have been carried out as per the owner's manual.

 

I'm really running out of ideas how to solve this problem now - any help appreciated.

 

Mike

Just a thought; how does your prop size compare with theirs?

 

Edit sorry should have read the whole thread....

 

I think overpropping can affect temp though?

 

Another edit: I once read about a skin tank where the outer skin had pulled away from the hull a little causing a gap at the back of the baffles. This resulted in a short circuit and the engine overheated. A scissor jack to force the outer skin back made the baffle work again and the engine cooled properly.

Edited May 28, 2012 by Guest

[Albion]

How do I check the coolant pump?

 

De-gassed? My dad used to have a Triumph Stag in the early 70s. I remember as a kid the car overheating and breaking down during a traffic jam on the Westway going into London.

 

The plumbing between engine and skin tank is the same as any other Liverpool Boat as far as I know.

 

How would anyone know if their skin tank was baffled unless they were there during the build?

 

Voltage regulator? Now I am getting confused! I have the Isuzu panel - revcounter, start battery voltmeter, temp gauge and oil pressure. I've checked the temp gauge with an infra-red thermometer and it seems ok.

 

If you feel the skin tank in the corners where the inlet and outlet are not then they will be pretty cool if there are no baffles because the coolant flow will be going straight across from inlet to outlet. With a baffled tank the temperature will be much more evenly spread getting cooler as it gets closer to the outlet.

Roger

[bizzard]

How do I check the coolant pump?

 

De-gassed? My dad used to have a Triumph Stag in the early 70s. I remember as a kid the car overheating and breaking down during a traffic jam on the Westway going into London.

 

The plumbing between engine and skin tank is the same as any other Liverpool Boat as far as I know.

 

How would anyone know if their skin tank was baffled unless they were there during the build?

 

Voltage regulator? Now I am getting confused! I have the Isuzu panel - revcounter, start battery voltmeter, temp gauge and oil pressure. I've checked the temp gauge with an infra-red thermometer and it seems ok.

 

 

 

Possibly, but if it was your skin tank would you cut into it with an angle grinder to have a look?

Some temp gauges are of a lower voltage than the boats 12v supply caused by a voltage stabilizer,this is to steady the gauges needle and stop it from flickering about. But i think your gauge is internally stabilized.

[Arthur Brown]

The IR thermometer will tell you what the temperature pattern is over the area of the skin tank, from this you should see exactly where the water flows.

[blackrose]

If you feel the skin tank in the corners where the inlet and outlet are not then they will be pretty cool if there are no baffles because the coolant flow will be going straight across from inlet to outlet. With a baffled tank the temperature will be much more evenly spread getting cooler as it gets closer to the outlet.

Roger

 

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

[alan_fincher]

No two skin tanks are ever likely to be completely identical, even on a production Liverpool boat.

 

Even if an attempt has been made to make both identical, and with same number of baffles in the same positions, the baffles will probably only be attached to one side of the skin tank, with the other side forming as tight a contact with them as possible, but unlikely to be welded to them.

 

Depending on how successfully any particular build went together, there may be just very small gaps where water could take a short circuit route avoiding the baffles, or very big gaps that permit this to happen. Obviously the more any baffles can be bypassed the greater the chance that the whole area of the skin tank is being used to best advantage.

 

Also I know it is a bit of a cliché, but even the amount of blacking applied over the skin tank area can apparently make quite a difference.

[bizzard]

The baffles welding penetration marks would still be on the tank sides or (swim flank which i doubt)depending on how they were put together.If you buzzed the paint off you would almost certainly see them.

[Chalky]

The stag cooling system had 1 pipe that was too small and did not allow all of the air out of the coolant. Changing this pipe size fixed the problem and solved all of the issues. If you've got a standard Liverpool build it won't be that.

 

If the coolant pump isn't working you won't get any flow other than by convection. A pump failure where the impeller comes loose is very rare, but not unknown.

 

Was the problem there before the coolant change?

[alan_fincher]

If you feel the skin tank in the corners where the inlet and outlet are not then they will be pretty cool if there are no baffles because the coolant flow will be going straight across from inlet to outlet. With a baffled tank the temperature will be much more evenly spread getting cooler as it gets closer to the outlet.

Roger

You should more or less be able to work out where the baffles are by the order it warms up. It would be unusual for them not to be horizontal, I'd say, and if your inlet and outlet are at opposite ends of the tank, I'd assume just 2 horizontal baffles, giving three horizontal compartments that the water should flow around in a kind of elongated "S" shape. So you should see the top third warm up from one end, then the middle third from the opposite end, then finally the bottom third warm up from the same end as the top third.

 

But unless you are using a lot of power as you do this, in an ideal world the bottom really wouldn't get hot at all. If it is getting significantly hot right to the bottom when you are not thrashing the engine, then it confirms either the tank isn't adequate, or (just possibly) you have always had a head gasket problem. Personally my money has been on skin tank size / design ever since you first raised this, and I still suspect that is the root cause, even if other people appear to be "getting away with it".

[Higgs]

Any chance the timing could be out and not producing full compression and possibly causing the power stroke to be weaker. Not producing sufficient torque. ?

[alan_fincher]

If the coolant pump isn't working you won't get any flow other than by convection. A pump failure where the impeller comes loose is very rare, but not unknown.

To me the question is.....

 

When it is overheating, has whole skin tank become hot right to the bottom, with little temperature gradient across it, and is water that is still very hot then being returned to the engine.

 

If "yes", then it is not an air lock of any kind, nor a failure (full or partial) of the pump, because these would prevent all the hot water heating the tank up in that way.

 

If "no", (i.e. the skin tank stays well cold at the bottom, but the engine overheats), then (and only then!) do pump failure, blockage or air-lock look worth investigating, IMO.

 

I'm sure the question has been asked before, but can't remember the answer.

 

Mike,

 

Once overheating, how hot is the skin tank at the inlet point, and how hot at the outlet, when water is being pumped back into an already very hot engine. The answer to this simple question has very distinct implications on the likely causes IMO.

[nicknorman]

You could certainly see the weld lines of the baffles on our skin tank - that was before it was spray foamed. A point so basic that this may seem a stupid post, but you have checked that the hot water enters the skin tank at the top, and exits at the bottom, haven't you?

[bizzard]

To me the question is.....

 

When it is overheating, has whole skin tank become hot right to the bottom, with little temperature gradient across it, and is water that is still very hot then being returned to the engine.

 

If "yes", then it is not an air lock of any kind, nor a failure (full or partial) of the pump, because these would prevent all the hot water heating the tank up in that way.

 

If "no", (i.e. the skin tank stays well cold at the bottom, but the engine overheats), then (and only then!) do pump failure, blockage or air-lock look worth investigating, IMO.

 

I'm sure the question has been asked before, but can't remember the answer.

 

Mike,

 

Once overheating, how hot is the skin tank at the inlet point, and how hot at the outlet, when water is being pumped back into an already very hot engine. The answer to this simple question has very distinct implications on the likely causes IMO.

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.

Edited May 28, 2012 by bizzard

[blackrose]

The stag cooling system had 1 pipe that was too small and did not allow all of the air out of the coolant. Changing this pipe size fixed the problem and solved all of the issues. If you've got a standard Liverpool build it won't be that.

 

If the coolant pump isn't working you won't get any flow other than by convection. A pump failure where the impeller comes loose is very rare, but not unknown.

 

Was the problem there before the coolant change?

 

Yes, it's been there since day 1 only I never realised because initially I was coming downstream on the Thames and never used a lot of revs. Then I was on the GU and it was fine. It was only back on the tidal Thames and now pushing against the current on the non-tidal Thames that it's a problem.

 

You could certainly see the weld lines of the baffles on our skin tank - that was before it was spray foamed. A point so basic that this may seem a stupid post, but you have checked that the hot water enters the skin tank at the top, and exits at the bottom, haven't you?

 

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

 

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

 

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.

Edited May 28, 2012 by blackrose

[bizzard]

Yes, it's been there since day 1 only I never realised because initially I was coming downstream on the Thames and never used a lot of revs. Then I was on the GU and it was fine. It was only back on the tidal Thames and now pushing against the current on the non-tidal Thames that it's a problem.

 

 

 

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.

What the other way round?

Like a vehicle,hot water sinks as its cooled. The hot water passes from the top of the engine via the top hose to the top of the radiator,(skin tank)sinks to the bottom as its cooled and then returns to the engine via the bottom hose and continues its cooling cycle again.