Overheating/coolant issue

[alistairc]

can anyone help me my bmc1.5 overheated while idling in dock it stopped on its own accord, i left it a day to cool down properly it started straight away no problem but it doesnt keep its fresh water it is not going into the sump i think its going out the exhaust in the stern, but i put in fresh water into the heat exchanger today filled it up without starting the engine and it dissapeared in minutes any help would be gratefully recieved

[aa3jy]

When was the last time your heat exchanger saw service?Might be overly due..

[alistairc]

cant thank you enough for replying, boat was laid up for couple of years before i bought her and been a year fitting her out is it a big job to overhaul or brtter getting a recon one do you think i could have done other damage my engineering knowledge is nil

[aa3jy]

Originally Posted by alistairc

cant thank you enough for replying, boat was laid up for couple of years before i bought her and been a year fitting her out is it a big job to overhaul or brtter getting a recon one do you think i could have done other damage my engineering knowledge is nil

Hard to tell from your earlier description..but if it started up after waiting the period that you had mentioned..should be good to go. But I'd definitely have your engine serviced properly.

[alistairc]

thank you very much for replying i will have it serviced as soon as i can get an engineer cheers

[chucklesR]

Sounds to me like your heat exchanger is toasted - leaking into the raw water side.
It works by holding the water/anti freeze mix in a tank, and the raw water is pumped through it via a bunch of little tubes. If one or more of those tubes is corroded through it's shot.

To replace it isn't that hard, but if you truly have no experience it might be better to pony up the bucks and have a mechanic do it, and while he's there also check the rest of the engine.

[alistairc]

thankyou chucklesr really appreciate will sleep tonight imagining all sorts before you both replied cheers

[chucklesR]

No problem --
If you want a simple check - put a gallon of water with a squirt or three of dishsoap in the exchanger, then start the engine and check your exhaust flow for bubbles.

Works every time.

That's also a good way to check if a raw water impeller is working for folks where the exhaust is under water and they can't see the flow - put a squirt of soap in the impeller chamber
Helps to slide it in too.

[MarkofSeaLife]

It may be a simple fix for a mechanic. It could be the little gasket thingy between the raw water and fresh water at the black of the heat exchanger.

A mechanic will pull it out and unbolt the front and back and push out the fresh water tube pack... Checking the little verticals gasket at the back, cleaning all and putting it back on. If its a big problem it's a recon job or a new one which is not cheap.

It's a full hour for a good mechanic to pull it off. A tad quicker to reinstall. But estimate 2 hours off and on.

[Rockter]

Alistair :

It sounds very much like your heat exchanger has breached and you have overheated. I liked the idea of the washing-up liquid and check for bubbles trick. Take off your heat exchanger and have a wee look. It should be apparent where the breach is.

When your motor stopped from overheating, you will almost certainly have picked the pistons up and scored the bores a bit. The bottom end of the motor should be OK though as it was not an out-and-out lubrication failure.... that is much more damaging scenario. I have been there with that one... twice.... and survived it without too much damage.

Keep an eye on your oil consumption for a while.

If you are starting OK, and the revs are stable, then I would just live with it. Just keep topping it up and carry plenty of spare oil.

An oil and filter change after you have fixed it all would be an idea, too.

The BMC 1.5 is a sound and orthodox motor.

It has been running in London taxis for decades.
.