How to Cool an Overheating Narrowboat Engine!

Do you have issues with an overheating engine? We have had that problem on and off for the last three and a half years. This year, after much research and chatting to various engineers, we think we may have the solution. Watch the video to find out if it is solved and how!
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[@peterodonnell5820]

This video just popped up in my You Tube feed, how long ago it seems! The Feb 2024 update is - the radiator didn't work in the end, it caused all kinds of problems it was disconnected after a few months. I did fit a coolant header tank but still had to bleed air out of the skin tank every day while cruising. Finally in October 2023 the boat was taken out the water and an external skin tank was fitted to replace the original tank. It was fitted with an automatic air bleed valve. It was an instant fix and now I can cruise all day at 1400 - 1500 rpm instead of anxiously creeping along at 1050 - 1100. A big thank you to Andy and the team at Andicraft in Debdale Wharf Marina.

[@PartTimeBoater]

I’m really pleased to have finally reached a solution! The stress it caused was not great. Andy and his team did a great job! 🙂

[@ronnieuwstad4820]

What a lovely presentation.

[@PartTimeBoater]

Thank you. Glad you enjoyed it Ron. 🙂

[@timothycarljones4551]

Fabulous presentation. I note some excellent comments on the height of the calorifier. As an Oftec/Gas Safe heating engineer and ex REME engineer, I would like to respectfully add some points for consideration. The first thing is to check the dynamic coolant flow rate this will prove the correct opening of the thermostat and cleanliness of the cooling system and water pump. Ensure the correct water pump is fitted. Use the correct grade of coolant and viscosity levels. Avoid acute bends on pipework to the calorifier which will lessen the risk of air bubbles/cavitation. It is worth noting that If the engine coolant hasn't been maintained it is possible that cavitation has damaged the engine cylinder bore liners. Complete an engine compression test and look for a high reading! Hope this helps.

[@PartTimeBoater]

Thank you for your comment and suggestions. I will ask Peter to take a look at this and get him to reply as things have moved on since this video. 🙂

[@peterodonnell5820]

Hello from one ex REME technician (Radar 1966 - 1978) to another ex REME man! Thank you for taking the time to reply, you might see from my comment in this thread that the radiator experiment eventually failed and I finally found an engineer to make an external skin tank in October 2023. That has transformed the performance of the cooling system. The original tank was too thick and the inlet and outlet points were on the same end so coolant could avoid the internal baffles and flow straight in and out of the tank. I have also replaced several coolant hoses and rerouted them to avoid pinch points as you suggest here. Three core plugs on the engine - out of a total of 25 - failed so they were replaced and the rest were checked. The cooling system was also flushed. When a coolant hose failed very early on I changed the coolant to the red OAT type as I read that it performs better. In all the subsequent work and routine servicing no-one commented on my choice, but earlier this year when the third core plug failed the engineer who did the repairs explained that I should use the blue IAT coolant on my engine - and the red could cause corrosion. I checked with Beta Marine and they confirmed that they now recommend using the blue coolant because of the metals used in the construction of the Kubota diesel engine that is at the heart of a Beta Marine installation. So I have changed back to the recommended product and now everything is working just fine. Once again, thanks for adding to the discussion, I know other readers find these comments useful for their own boats. Peter

[@lesnicholas2433]

I had the same problem when crossing to the Lancaster canal on the tidal river Douglas,on my brand new narrow boat.I found out the propeller was to big,so Crowder marine made me a high efficiency propeller that solved the problem by letting the engine rev better putting more coolant through the skin tank.I also changed to a Crowder prop on my new boat worth every penny.I have done the Wash Boston to Denver sluice twice,Sharpness to Bristol,tidal Trent,River Mersey,Limehouse to Teddington,and Tarelton to Savick Brock onto the Lancaster canal.Coming out of Tarelton river Douglas is the most powerful current that I have come across but my 40hp Yanmar does it with ease but I do have twin skin tanks on my narrow beam river barge NB The Viking.

[@PartTimeBoater]

Wow! Your journeys sound amazing! We are holding off from doing such trips because of the overheating. I will show Peter your comment and see if it will help him! Thanks so much for sharing your experience! 🙂

[@markjewell911]

Similar problem with mine. Regularly used to dump the domestic hot water. That cooled it down for a while

[@PartTimeBoater]

We have fixed the problem by fitting an external skin tank recently. Peter doesn't have to worry about it but he tried everything else that was suggested first. This proved to be a false economy because he ended up with the skin tank anyway. Have you solved the problem?

[@markjewell911]

Yes all solved. New thermostat. All the best to you sir 👍

[@gailmatthews2964]

Hi I have a Beta 43 with a calorifire and because the pipe work to the calorifire is higher than the coolant filler cap on your engine ( as I think I can see on yours is) you are getting air into the pipe work that circulates through the calorifire. Causing the engine to overheat. As mine used to. I got round this by installing a expansion tank bottle ( similar to one in a car) higher than the calorifire I cut the rubber pipe on the return pipe to the engine from the calorifire and went up to the expansion tank( sited hire than the calorifire) then back out of the expansion tank back to the engine. So you fill your engine coolant from the expansion tank and not from the cap on the engine. You can not open the engine cap after doing this or the coolant will poor out from the higher expansion tank. As soon as I installed the expansion tank the air from the system bubbled out into the expansion tank. And also the coolant circulates around the expansion tank cooling the water down. It was an immediate success Cost very little to do as well I wish you luck in which ever way you attempt to solve this problem Gail

[@gailmatthews2964]

Hi just to add I cut the pipe highest on the calorifire ( mine was the return) so that when you put coolant in it goes in at the highest point forcing air round and out of the system Gail

[@PartTimeBoater]

Hello Gail. Thank you for taking the time to give such an in depth reply. I have shown Peter your solution and he will take a look at the engine to check it out. Glad to hear it solved your issues. 🙂

[@gailmatthews2964]

Hi I am glad you are now ok after your dreadful accident. If don't mind just to explain when you fill the engine via the filler cap you can't make the coolant go up hill into the Calorifire. So every time you you turn your engine off the water drains out of the calorifire down into the engine leaving air in the calorifire and pipe's Gail

[@johnpalfreyman8290]

So you don't have a skin tank because I've got a similar problem of plumbed the engine into the spiral in the clarifier so if I put an expansion tank on will that make sure that my engine stays cooler is that what you're saying because that would be a cheaper option for me

[@gailmatthews2964]

@@johnpalfreyman8290 Hi John I have 2 skim tanks either side of my stern to keep my engine cool. But I had a over heating problem. I found my calorifire was installed higher than my engine. So water ran round the calorifire when the engine was running As it is higher than the engine And when I switch the engine off. The water drained from the calorifire back into the engine and skim tanks The water ran round the calorifire because it was pumped up out of the engine and skim tanks when the engine was running Leaving less in the engine and skim tanks This caused the overheating when the engine was running So I put a expansion tank above the calorifire And made this the water filling point. So the whole system was filled water. Whether the engine was running or not. And I have never had over heating again. Only difference is you must not undo the water cap on the engin. As the water will drain down from the calorifire and poor out of the cap Just fill water using the cap on the expansion tank. Gail

[@martinnorthfield9358]

Did you use a car radiator

[@PartTimeBoater]

Hello Martin. It was a domestic radiator that was fitted. I don’t know if a car radiator would have been better or not. We think the problem may have been that it was positioned incorrectly due to a lack of space. Ratty, who fitted one on his boat, had it fitted in a different style of engine room but it just didn’t work on NB Bandoneon. Thanks for your question. 🙂