Posted: Tue Aug 26, 2008 8:01pm

my mother and father have just bought a cruiser with a 1.5 bmc engine which keeps over heating,its had a new water pump and thermostat but still overheats.what i thought was a heat exchanger just seems to be a exspansion tank bolted on to the manifold,the raw water pump works fine but this only goes to the exit of the exhaust via a small copper pipe,i can't work out how the engine maintains it's running temp with nothing to cool the engine water,i'm very very new to all this a would really appreciate some help as i'm starting to pull my hair out!

Posted: Tue Aug 26, 2008 9:35pm

Dear Dickie, Ideally I think you need to take a training course where you can actually look at cooling systems and make sure you get it explained to you. If the alternator belt only runs over two pulleys then the engine is direct cooled. If it runs over three pulleys it is probably heat exchanger cooled and you can not normally see the heat exchanger core. If you are correct about there being nothing inside the expansion tank/manifold then the boat has to be keel cooled. However I have no way of knowing which you have. I suggest you do two things. First of all read the cooling system notes in the Maintenance course notes on my website (www.tb-training.co.uk) so you understand the differences. Then take some digi-pics of the engine, including where all the cooling pipes join the engine and where they run to. I will the be able to work out what system you have and may be able to advise further. Please send the pictures to Tony@TB-training.co.uk between NEXT Sunday & Friday because I will be on wired broadband for that time. I do not want to receive pictures on my mobile connection. Thanks, Tony Brooks

Posted: Tue Aug 26, 2008 9:35pm

Dear Dickie, Ideally I think you need to take a training course where you can actually look at cooling systems and make sure you get it explained to you. If the alternator belt only runs over two pulleys then the engine is direct cooled. If it runs over three pulleys it is probably heat exchanger cooled and you can not normally see the heat exchanger core. If you are correct about there being nothing inside the expansion tank/manifold then the boat has to be keel cooled. However I have no way of knowing which you have. I suggest you do two things. First of all read the cooling system notes in the Maintenance course notes on my website (www.tb-training.co.uk) so you understand the differences. Then take some digi-pics of the engine, including where all the cooling pipes join the engine and where they run to. I will the be able to work out what system you have and may be able to advise further. Please send the pictures to Tony@TB-training.co.uk between NEXT Sunday & Friday because I will be on wired broadband for that time. I do not want to receive pictures on my mobile connection. Thanks, Tony Brooks