Christina732

Gave the engine a good test on a cruise today and it was faultless! Maybe even ran very slightly cooler than usual, maybe just the cold weather but maybe a little air has been trapped for years?! Very happy and sorted for now but definitely planning to enlarge the hoses in the spring to keep temps and oil viscosity happy

Interestingly when changing the oil with a very experienced engineer we did really struggle to suck the old oil out and this took us a great deal of time due to the viscosity which makes a lot more sense now!

So we went with the bodge for today and managed to drill a hole in the u shaped pipe and clip some spare hose over it once the air cleared. The bleeding from the calorifier produced a very meagre flow even with good revs which made us doubt we had the correct pipe, checked the other and definitely had it right the first time. Decided to have a test before attempting to bleed further and the engine was not overheating anymore whilst out of gear with some revs and produced some warm water!! The acid test will be a short move this weekend so fingers crossed but looking like it's enough to get me from A to B while I order some larger hose to hopefully improve the flow overall and have a much happier engine. And yes you're right the overheating tends to happen in higher revs/very hot days/if a piece of weed even thinks about my propshaft so hopefully that will improve things. Thank you so much Tony for your time and very well explained steps I would have been in quite a pickle otherwise! Hugely appreciate your efforts and very relieved!!!

Ah brilliant that's extremely helpful Tony thank you. Almost at the boat so I will give bleeding the top hose and redirecting the cooler hose a go. All seemed to work well before my fiddling so hopefully that will be enough to rectify things but switching to larger hoses and checking for remaining heat exchanger core does sound like a very good idea as I have always had problems with overheating so that would be amazing if that would finally sort those issues!! Thank you so much for the detailed guidance for those bits too. Also that makes sense with the raw systems. Thank you for bearing with through my somewhat confused descriptions! Wish me luck! Will let you know how it goes! And here is the diagram my lovely OH has made in the interim!

Hi Tony, That's incredibly kind and helpful thank you for such a detailed reply. I will go to the boat and draw up the pipe diagram shortly but to answer your questions in the mean time. -I will check what the 2nd oil cooler is connected to. I did think it was odd I'd never seen another engine with 2! -The engine used to be raw water cooled but at some point has been converted (perhaps not very optimally!) to a closed system (sorry not sure if that's the right term) at some point before I owned the boat. - Yes it was the skin tank I bled - sorry I'm a bit of a novice! - I have owned the boat for a couple of years but this is the first time I have completely changed the coolant so unsure if this is a repeat issue but have had some sporadic issues with overheating at various points so perhaps the system explains that! -The cable ties were in fact my bodge after the fuel pump bracket sheared off recently but will make sure to find a better solution (especially as my bss is coming up!) So thank you for pointing that out! I will bleed the top hose as suggested today thank you for explaining that so clearly. In regards to the other potential issues, would replacing the rubber end caps on the oil coolers and replacing the thin hoses with larger ones be a good idea? Or would removing the coolant and flushing the system be likely to help in the meantime? Is the U shaped pipe likely to serve an important purpose or could I potentially remove and bridge with straight pipe? Thank you so so much for the guidance, so appreciated. I will report back!

Hello all, I would really appreciate some guidance. Last weekend I emptied the coolant on my BMC 1.8 and refilled with fresh antifreeze solution. I bled the main tank and ran the engine for a while with cap off. But when cruising the engine started to overheat after 20-30 mins and after a short break and weed hatch check it happened again the calorifier also hadn't seemed to make hot water so I fear there is air in the system. I have tried massaging the (fairly firm) hoses while the engine runs and leaving it to run capless a bit longer but this doesn't seem to have rectified things. One of the hoses did seem higher than the header tank so I've pushed that lower and run engine and there is a kind of u-shaped pipe that could be holding air? Any advice very gratefully received! Christina