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Looking for heat exchanger core (tube stack) for old marine diesel engine
January 31, 2009 08:32AM
I have a 1970's BMC 1.5 Marine Diesel that needs a new tubestack and am having trouble sourcing one (either on island or off). It looks possible that a tube stack for a Perkins might work, assuming it meets the dimensions below. Any help would be appriciated!

The unit in questions old part# is BG7 and it is 2" diameter by 22 7/8" long, tubes and outer tube (body?)

-Dave
Re: Looking for heat exchanger core (tube stack) for old marine diesel engine
January 31, 2009 05:20PM
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I have a 1970's BMC 1.5 Marine Diesel that needs a new tubestack and am having trouble sourcing one (either on island or off). It looks possible that a tube stack for a Perkins might work, assuming it meets the dimensions below. Any help would be appriciated!

The unit in questions old part# is BG7 and it is 2" diameter by 22 7/8" long, tubes and outer tube (body?)

-Dave

Is it just the inner bundle(uses rubber end caps or end plates)
Is it intergrated into the manifold?
Or does it also have a outer shell?
Re: Looking for heat exchanger core (tube stack) for old marine diesel engine
January 31, 2009 05:41PM
It is a bundle of straight through copper tubes with an outer (brass?) sleeve, no end caps. Its a core that runs through the cooling system with salt water going through the inner copper tubes and the fresh water system flowing around the outer sleeve. I've been told that older Perkins engines use a similar unit. I'll take a picture tomorrow and add it to the post after I'm at the boat...
Re: Looking for heat exchanger core (tube stack) for old marine diesel engine
January 31, 2009 07:21PM
It sounds like a Boman heat exchanger that is used on Perkins engines.
The Boman uses rubber end caps, does your heat exchanger have this?
Is the BMC some sort of Leyland or other diesel?, So you can determine who marinized it.
Sounds like some European?British engine.
I`ll see if I can help, don`t know.
Re: Looking for heat exchanger core (tube stack) for old marine diesel engine
February 01, 2009 08:18AM
You're exactly right DUN, I guess it was originally made by Polar then taken over by Bowman. No rubber end cap, instead uses a double clamped elbow at each end to control where the waters go and to keep them separated. Again you're right, the BMC (British Motor Company) engines were originally diesel taxi cab engines from the UK and other parts of Europe. Not sure who marinized them. I've been told the part I'm looking for is a match for the Perkins pieces too though all the Perkins ones I've been able to find so far are either too long or too short. I'll grab a couple pics today at the boat and re-post later. Thanks for all the help! -Dave
Re: Looking for heat exchanger core (tube stack) for old marine diesel engine
February 01, 2009 03:45PM
Here are images of the tubestack by itself and it again on top of the engine (it goes through the radiator to the right and is connected to the elbows at each end).




Re: Looking for heat exchanger core (tube stack) for old marine diesel engine
February 01, 2009 06:56PM
Yes. that does look like a Boman heat exchanger/manifold/header tank.
The 90 degree black end caps are indeed rubber(may be old & brittle).<<These are delicate, be easy (you can get new ones from V.I. Techno diesel, he may even have a new bundle too, best to test yours first as he won`t take it back).
I don`t see much electrolysis in the pics, but are you looking for the bundle BC your getting salt water in your header tank(the radiator cap part).?
If so, it may be that one of the end caps are not clean/smooth) on the inside, it`s VERY important the bundle is in the exact middle & the outer clamps are sealing the rubber end completely, this is what keeps you from mixing(unless your bundle is indeed corroded & has a hole leaking between).
The larger clamps seal the outer fresh cooling water & if that was incorrect you would see a external leak.
You can test the assembled heat exchanger with a automotive cooling system tester & pressurize to say 16 lbs.
If the system looses pressure, install 2 hoses to the input & discharge(the small hoses that connect to the rubber end caps) these hoses are for this test:
Put those same 2 hoses in a bucket of water & re-pressurise the fresh water system.
If you see bubbles in the bucket, you know that is how the water is mixing.
If you put this back together to test, sand clean the ends of the bundle & you can (optional) apply a thin layer of silicone(providing the inner rubber surface is good).<<If it`s not, you need new ones anyway.
Re: Looking for heat exchanger core (tube stack) for old marine diesel engine
February 01, 2009 07:04PM
The engine LOOKS like a Perkins 4.09, it came out before the 4.107(Westerbake) & the 4.108...but, I could be WRONG, just looks like one!
Re: Looking for heat exchanger core (tube stack) for old marine diesel engine
February 01, 2009 11:21PM
When I run the engine all my fresh cooling water is getting pushed out through the exhaust, there is no external leaking, this problem has just recently developed in the last week or so. The 90 degree end caps are new, and the rest of the system recently disassembled and cleaned, the heat exchanger has some electrolysis but not much (compared to some I've seen) but looks to be the oldest part of the system, here is a closeup of the electrolysis (rim is corroding and breaking off in places)



I will clean and check the end caps for smoothness again and re-test, I was pretty careful the first couple tries but who knows I may have missed something. I called Hector at VI Techno and described it to him, he said he didn't have anything remotely like that, but I may just drive up there and show it to him in person to make sure.
Re: Looking for heat exchanger core (tube stack) for old marine diesel engine
February 02, 2009 07:49PM
If things don`t go well with Hector, I put a inquiry with one of my suppliers with your dimensions(did you use a caliper to measure the Outside diameter of the bundle)?
The length could go to 23", it would just be 1/6" deeper into the endcaps at both ends.
What I`m saying that measurement doesn`t need to be exact, you could measure with a tape.
The O.D. is more precise.
Yes, now with the close up I agree, you do have electrolysis(does your heat exchanger use zinc anodes?
The aluminum manifold (that`s the material...right?)
looks pretty good in the pic(then again, my ex looked good at a distance too!).
Dun
Re: Looking for heat exchanger core (tube stack) for old marine diesel engine
February 03, 2009 09:57AM
Dave, if you have internet try www.asap-supplies.com or 0845-1300-870 in suffolk, england. I believe they can help with about anything bmc.
Re: Looking for heat exchanger core (tube stack) for old marine diesel engine
February 03, 2009 10:16PM
Thanks DUN, scubado,

I've gotten ahold of the company that makes the parts now (Bowman) and will hopefully be able to order the nessisary parts from them... couldn't run anything down locally that was an exact fit. Appreciate the help...

Dave

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