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Hi, I was wondering if anyone had a diagram of the cooling system of the BMC Captain engine in my MacWester Malin. I know the raw water inlet and stop cock is front left, looking at the engine through the saloon inspection cover, but where should the strainer be located. I don’t see it. And I can see the raw water pump driven by a v belt, top right of engine. I presume it has an impeller located behind a cover in the rear. Also, how do I adjust the v belt? What bolts do I need to loosen? And where is the internal water pump for the engine cooling? Does it have an impeller too? A diagram of the complete system would help. Sorry for the newbie questions. Thanks in advance.
One more question. When I signed up and paid my dues you said you would send a burgee. Still not arrived. Would be nice to put on the boat. Paul
This is the primary water pump that is on the front of the engine block, to circulate the antifreeze solution around the cylinders, cylinder head etc. to send it to the heat exchanger which is combined with the exhaust manifold. The “impeller” on that is cast iron, and does not require servicing. This setup is very similar to Austin Mini engines, and even closer to MGA 1500. That is driven by the same belt as the altenator. More to follow with extract from the parts manual.
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More details of the engine block pump. There are different models: see the listings from ASAP
Spares are available, notably from ASAP supplies : https://www.asap-supplies.com/search?query=BMC+1.5d+water+pump
As for the raw water strainer, that has usually attached to the inlet seacock. Over the years, that could have been removed or replaced by something else. Next reply will show you what I have on my MW 27.
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This (IMHO) is the best type of strainer : Vetus , with nice big strainer, and transparent cover to see the water flow, and any weed , etc. that may have been sucked up.
https://www.asap-supplies.com/search?query=vetus+water+strainer
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Hi Paul, the strainer should be right above the inlet (as Bob said connected to the inlet). It’s hard to miss, so if you don’t see it, it must have been removed. We used to have one and it was then removed on advice of a service engineer (he said it was redundant as there was a gauze at the inlet). Curious what people here would recommend.
Hi Paul,
I am so pleased you have mentioned about your ‘missing’ New Members Pack. Because I this, it has come to light that a glitch in our system earlier in the year resulted in the fact that I did not receive notice that you had joined our Association.
You are not alone. Five new members were missed and I am now working to rectify the situation. I apologise profusely for this problem, and assure you that your New Members Pack and burgee will be winging it’s way to you this week. Better late than never, I hope!
Linda – Membership Secretary
Thanks for all your replies. I’m going down to the boat tomorrow and I’ll take some photos and post them. I was confused about the absence of a water strainer which most boats have, like the one in your boat Bob. I’ll look into that. So the diagram of the pump you’ve posted, Bob, is located behind the pulley on the crankshaft, Johnson F5B8, I think. I won’t have to look at that, I hope. The raw water pump on my boat is a Jabsco 4900 and is run by the other v belt, not the alternator one, and takes an impeller at the back of the pump. It doesn’t seem to be in great shape. I’ll take a picture and show you. Again, thanks for the replies and I look forward to getting my burgee this week.
Ok. Went to the boat today. In the first photo you can see the raw water inlet with a nut on the top, underneath which is a gauze filter, which I cleaned. Not great. Sort of out of sight out of mind. The second photo shows the raw water pump, which looks to be needing servicing or replaced. And the third photo is the engine pulley running the internal water pump, which it is behind, and is not leaking, so should be ok. Thanks for all the help. I think I’ve got the gist of it now, and Bob’s idea of a separate see through strainer is obviously the best way to go, because you can see it visually every time you check the engine and it’s quite large, so would take a lot to block it, unlike mine. Paul
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