Jump to content
Strawberry Orange Banana Lime Leaf Slate Sky Blueberry Grape Watermelon Chocolate Marble
Strawberry Orange Banana Lime Leaf Slate Sky Blueberry Grape Watermelon Chocolate Marble
dizzyknits

BMC 1.5 engine, what to do for the winter

Featured Posts

Hello can any help please

We have the above engine in our Colvic, and we think it is raw water cooled ( the last BMC 1.5 we had in Tartan Witch, was keeled cooled). There is definatly water coming out of the exhaust hole for a better word!!, (and blue smoke when we first start up).

Someone has told us we have to put Anti Freeze into this system. I have included a photo of the top of engine, so that hopefully you who are much more knowledgable will steer us in the correct direction, we try to go down every couple of weeks to start engine up, but if we drain it down I don't think we can do this (reading several posts). We won't be going anywhere till spring at least any help will be appreciated

20190802_112001.jpg

Share this post


Link to post
Share on other sites

There is direct raw water cooled and indirect raw water cooled.

Direct,canal water is pumped around the engine waterjacket.

Indirect,the canal water is pumped through a heat exchanger and exits either through the exhaust or a hull fitting.

The cooling water for the engine is on a seperate circuit and circulates through the heat exchanger and is sealed like a car system.Antifreeze is usually added to the sealed system so there is no need to drain the engine coolant in winter.

You system looks to be the indirect raw water cooled type.

It may be necessary to drain the heat exchanger if leaving the boat for any length of time in below zero temperatures.The heat exchanger will probably drain itself through the exhaust and it may be prudent to drain the raw water pump by temporarily removing the inlet hose.

Be sure to turn the water inlet seacock off,because on some installations water can syphon to the pump.

Share this post


Link to post
Share on other sites

You will need to drain the engine of coolant unless you know what the present state of the coolant is. On my BMC 1.5 I did this by taking the bottom hose off and allowing the old coolant to drain into a bucket. My heat exchanger had a radiator cap and that was where I refilled the coolant. Your radiator cap is on that tank at the rear of of the rocker cover.

 

After draining the old coolant you then need to mix up the correct ratio and type of anti freeze and water and fill that blue tank at the rear of the rocker cover (that is actually the front of the engine but looking at that picture that tank is at the rear of the rocker cover). This after reconnecting all the hoses of course. Then run the engine for a few minutes to circulate the new coolant and, being careful of removing that filler cap if the engine is hot, top up the tank with new coolant. If you are going to leave the boat for any length of time I would turn the raw water inlet sea cock off until you return.

 

I have to say that that engine does not look particularly easy to get at the relevant bits. I would also suggest that if you don't understand what we saying that you get someone to show you how it is done. On my BMC 1.5 I never drained the coolant unless I was doing it as part of a service but I was checking my boat and engine, more or less, every day and I had a heater in the engine compartment.

Share this post


Link to post
Share on other sites

Agree with Harold but add:

 

The thing with the radiator cap on the front of the engine is a heat exchanger, the main body of it contains or should contain between 20% and 50% antifreeze mixture. Test it with an antifreeze hydrometer and if within spec its frost safe BUT that does not mean it has not lost its corrosion inhibitors so if in any doubt at some time in the near future drain the whole engine and refill. The heat exchanger has two domes ends on it held in place by a long bolt and nut on the right had n side. Don't touch any of this. One of the domed end plates may well have a drain plug in it, this is the one to undo to drain the  raw canal water from the tube stack of the heat exchanger. There mat well be another drain pug in the main body of the thing, this one drains the antifreeze coolant from the body so leave that one well alone. If there is no drain on an end cover remove the lowest hose on the left hand side cover.

 

The exhaust manifold almost certainly is full of raw canal water in your case so that should also have a drain plug on it. It is important to drain that as well, I doubt you will find a replacement if that one freezes and splits.

 

I would suggest that rather than just removing a hose from the brass raw water pump that I think you will find lowish down on the left front side of the engine you turn the raw water inlet valve off and take the pump's end cover off, remove the rubber impeller (that you need to inspect anyway) and place it in an old tin filled with water or glycerine. The raw water inlet is the brass thing you can see at bottom right of the photo, the valve is probably a simple lever but may be a gate/wheel valve.

 

A rather dirty way of prepping  for winter if you are not going to run the engine is to close the raw water inlet valve and remove the cap from the strainer, mix up a 30% to 50% antifreeze mixture in a bucket . Get someone to hold a bucket under the exhaust outlet to catch for proper disposal the antifreeze mixture that will be ejected. The run the engine at fast idle while you our the mixture into the raw water inlet. Stop when blue/red/green/yellow water comes from the exhaust. It woudl be less pouting if you took the hose off the water injection elbow at the back of the manifold and directed that into a bucket.

 

 

 

Share this post


Link to post
Share on other sites

Thank you Harold, Pete and Tony for your replies...i will have to re read several times to get my head around what you have all said 

 Is the system an indirect raw water cooled one then as harold says.

We are off there today so will look at the various things you have said to see if we can identify them...thank you

Share this post


Link to post
Share on other sites
9 minutes ago, dizzyknits said:

Thank you Harold, Pete and Tony for your replies...i will have to re read several times to get my head around what you have all said 

 Is the system an indirect raw water cooled one then as harold says.

We are off there today so will look at the various things you have said to see if we can identify them...thank you

Yes unless mementoes has done horrible things to the inside of the heat exchanger but that woudl be very, very rarer. Take a very small sample of the liquid under the filler cap and put the merest smudge on your tong. If its bitter or sweet then its definitely indirect raw water cooling.

Share this post


Link to post
Share on other sites

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.