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no cooling of BMC 1500 with Lancing direct cooled manifold


Frank30

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Gents - I am bewildered by the 'cooling' circuit of my recently acquired boat. The 'cooling circuit' does not include passing water through the block and head!! Surely enough, the thing overheats...  Someone has mounted the Jabsco pump 'backwards' on a steel blanking plate that covers where the car engine water pump used to go. This plate was not a quick bodge, includes a welded-on boss for mounting the alternator etc. The usual Jabsco pump cover is missing and the pump face is screwed to the plate from the inner side. I can not for the life of me understand how the water was meant to circulate in the block. As you see in the photos the Jabsco pump sucks in raw water and pumps it to the bypass end of the manifold. The large boss on the front of the manifold is routed to the thermostat housing, but from there the whole engine is a dead end!! When I took off the pump/blanking plate no water came out. Before I get and old car pump to provide hose access into the block (without using this pump to pump coolant) and construct a bracket to mount a new Jabsco near the timing cover - can anyone think what might have been a logical reason for blanking-off the normal engine water input? 

 

I will add that the vendor had the impeller replaced and the mechanic splice/re-routed the hose from the Jabsco to go into the small bypass boss on the back of the manifold - from wherever it went before (but not the usual coolant input on the front of the block). Of course the whole system looks OK- lots of water coming out of the exhaust!!

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I am not sure this helps but on the official BMC direct raw water cooled marinisation the Jabsco was mounted all but under the manifold and driven by a separate belt from a small pulley mounted in front of the normal crankshaft pulley. It fed its outlet into a blacking plate that covered the water pump hole with a spring ball bypass vale and pipes so raw water would be delivered to the exhaust with the engine thermostat closed.

 

I can see a hose at the back and low down in the engine photo that looks as if it might supply water from the back of the manifold into the plastic silencer box so if only water could get into the  engine block you would seem to have full circuit but I can't see enough details to see how that is supposed to work.

 

I can only see one hose on the Jabsco but normally it needs two, and inlet and an outlet.

 

One thing that looks a bit strange is the large washer on the back of the water pump blanking plate and it looks as if the block has been machined to accept this washer and still allow the plate to make a waterproof seal on the block face.

 

What follows is completely "off the wall" but with only one Jabsco connection its all I can think of. To be sure I would like to see the back of Jabsco body and the other side of that plate.

 

If that washer is blanking a hole in the plate that coincides with the area in the Jabsco body where the impeller vanes are bent to expel the water then water would be forced through that washer into the block and from what I can see there would be a complete circuit. The washer might be some kind of restrictor where the water flow is controlled by the size of the centre hole. I can't see why a hole in the plate would not do just as well and I certainly can't explain why the block looks as if its been machined. --------- as I said off the wall.

 

Lancing marine is still in  existence so a phone call may help if they still have staff that knows what was done in the 1960s.

 

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Whilst it looks like a very bad system to me, with direct cooling, if you have water coming out and therefore water going in it should work. I suspect the thermostat has been removed otherwise there will be too much back pressure for the jabsco. Check the flow of water out of the thermostat housing and into the manifold. If you have direct cooling you can't use the circulation pump because it is not self priming. You won't need much flow to give the engine cool. Water comes out of the jabsco and into the block somewhere, it then exits via the thermostat housing and through the water cooled manifold and into the exhaust. The repairer may have put the outlet of the jabsco into the manifold so no water though the block. The output of the jabsco must go directly into the block for it to work.

Hope this helps

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Maybe I am particularly thick this morning but I can only see one hose going to the pump! Assuming that there are two then I expect its possible to put the jabsco back on the floor where it will happily do its job with a belt from the pulley and plumb it into some sort of pipe fitting welded to the plate where the Jabsco is now. Sounds easy enough but as we all know plumbing and stuff is the devils work.

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5 minutes ago, Bee said:

Maybe I am particularly thick this morning but I can only see one hose going to the pump! Assuming that there are two then I expect its possible to put the jabsco back on the floor where it will happily do its job with a belt from the pulley and plumb it into some sort of pipe fitting welded to the plate where the Jabsco is now. Sounds easy enough but as we all know plumbing and stuff is the devils work.

 

Apart from a few difficulties that need solving that is what I would do but there seems to be no second pulley for the Jabsco and if you tried to use the existing belt run there would probably be insufficient wrap on the crankshaft pulley. If the jabsco was to be fitted in the conventional position another bracket would need fabricating and  a second crankshaft pulley would need obtaining. Then ideally a bypass for when the thermostat is closed would be needed.

 

Doing it with an electric pump would be easier.

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5 minutes ago, Tracy D'arth said:

As you see in the photos the Jabsco pump sucks in raw water and pumps it to the bypass end of the manifold. 

 

I don't see that at all, where is the other pump connection?

 

I don't think that is correct, I suspect the open metal pipe you can see at the front of the manifold may be a non-standard crankcase breather. The OP needs to clarify what that pipe is and how it relates to the cooling system.

 

Not enough photos to work out how the Jabsco is/was connected. I agree its the lack of the second connection that I find baffling.

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1 hour ago, Tony Brooks said:

 

If that washer is blanking a hole in the plate that coincides with the area in the Jabsco body where the impeller vanes are bent to expel the water then water would be forced through that washer into the block and from what I can see there would be a complete circuit.

I think you've got it here. The Jabsco was installed as a direct replacement for the original circulating pump, pushing water straight into the block through that hole in the blacking plate. But for some reason someone has closed off the hole with the washer, with the result that the block is now dry.

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I think the OP might have just disconnected the second connection. Someone may have tried to feed the jabsco from the back housing,which wouldn't work hence the blanked up hole. I suspect all that has to be done is connect the output of the pump LH side, looking at the top, to the block input which may be that pipe sticking up. A case of the 'engineer' not knowing what he was doing. Simple fix.

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1 hour ago, Mike Adams said:

I think the OP might have just disconnected the second connection. Someone may have tried to feed the jabsco from the back housing,which wouldn't work hence the blanked up hole. I suspect all that has to be done is connect the output of the pump LH side, looking at the top, to the block input which may be that pipe sticking up. A case of the 'engineer' not knowing what he was doing. Simple fix.

 

Pending more photos and more info from the OP I would strongly advise that he does not connect a water pipe to that open pipe unless he traces it. If t is  a breather pipe he could easily end up filling the sump & crankcase with water. I am sure I have seen an application on a B series engine where the breather turned up like that but can't remember what it was on. Could have been diesel or petrol.

 

We need all round photos of the Jabsco and a good clear shot of whatever is below the manifold at the least plus more info about what the OP has disconnected from where.

 

I can assure you that if the hole in the Jabsco backplate is in the correct place water will be pumped through it. However, to maximise the flow I think some machining would be needed to the Jabsco body or to the other side of the plate the pump is mounted on -  which we can not see. We use a hole in and intermediate plate with a hole between back to back Jabsco pumps on the wooden hire boats so one pump supplied the raw water cooling  and the other pumped the bilge. The hole ensured the bilge half did not run dry.

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Surely,there should be two pumps on an indirect cooling system. The engine driven one on the front of the engine to circulate water through the block,and a Jabsco type usually belt driven to suck water in and pump it through the heat exchanger.

If the Jabsco pump has rubber vanes it will not be suitable for pumping hot water.

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1 minute ago, Mad Harold said:

Surely,there should be two pumps on an indirect cooling system. The engine driven one on the front of the engine to circulate water through the block,and a Jabsco type usually belt driven to suck water in and pump it through the heat exchanger.

If the Jabsco pump has rubber vanes it will not be suitable for pumping hot water.

 

It is apparently an indirect raw water cooled system. The OP says its a direct raw water cooled manifold but time will tell if he is correct or not, I suspect he is.

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8 hours ago, Mad Harold said:

Surely,there should be two pumps on an indirect cooling system. The engine driven one on the front of the engine to circulate water through the block,and a Jabsco type usually belt driven to suck water in and pump it through the heat exchanger.

But is that box marked Lancing Mariner a heat exchanger or just a water cooled exhaust manifold?

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Thankyou to all the contributors. I see some clever thoughts here.

Just to summarise my lengthy post - there is no water circuit through the engine at the moment. The Jabsco pumps water directly to the bypass connection at the back of the manifold (small black hose) and thence out the exhaust.

The washer on the back of the blanking plate is down tight at the moment and nothing would go past it. I'd initially guessed it was something to do with one of the pump mounting holes having a stripped thread, but I think Tony et. al. are right - it may have been an adaptation of the pump into a THREE WAY version. The hole could have been a specific size to limit the flow through the block in order to allow for the engine temperature to get to somewhere near normal. There is no thermostat fitted and I don't know if there ever was. The output side of the pump (not in photos) goes only to the back of the manifold (I had to take off that hose connection in order to get at one of the mounting bolts on the blanking plate). Obviously the output side of the pump allows much of the water to go down the bypass and prevents pump damage. Given the main pump output being a bypass I don't see a reason why a low temp thermostat could not be fitted. Any thoughts?

 

I'm thinking of removing the washer, seeing what's underneath and if a hole does align with the pump output side I'll try the engine without the blocking washer. Possibly whoever replaced the impeller very recently was not familiar with the 3-way option and decided to block it off.... Can anyone think of any other options?

Apologies for incomplete photos. Initially I took them for my own purposes. As the boat is 2.5 hrs drive away it's not too easy to get more....

 

Thanks, Chris

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Direct raw water are ace at furring up the internal hot spots and cracking heads so I would leave the thermostat out, especially with a much restricted raw water flow. I did that to the direct cooled hire boats we had and solved  a lot of problems.  Naturally the engine will be a tad less efficient and there is no chance of running a calorifier but that's the price you pay for an automotive engine with direct raw water cooling.

 

You really need to see where abouts in the pump body that hole comes through to. If its not where the vanes are being compressed it won't work - remember the use of the hole is only guesswork.

Edited by Tony Brooks
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The core of the issue is finding the input and output of water from the block. It clearly goes out of the engine via the thermostat housing so it must go in somewhere. This could have originally via the back of the jabsco or some other route via a pipe for example into the base of the block  coolant. The problem of overheating may have been due to internal corrosion. It may have originally worked with a hole in the backplate but eventually internal corrosion led to overheating and someone may have blanked off the backplate and fed the water in though some other point at the other end of the engine in an attempt to solve the problem. You could try and find a bowman cooler on ebay, a original coolant pump and refit the jabsco driven by the fan belt and have indirect cooling but this will not help if the block is badly corroded. 

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If its been running hard and hot it may well be a cracked head but they usually just crack the pre-combustion chamber inserts at first.

 

Unless a core plug has been doctored the only other place you could get water into the block is via the thread for the block drain tap/plug.

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PS - in another thread I posted a reply from one of the engineers at Lancing involved in the design of their direct cooled conversions. He gives an overview of the cooling circuit with a caveat that he can't remember it well over 50 years later. The description given of their standard water circuit does not tally with what I have. So mine might be an experiment from the Lancing works (given the half moon machined into the block under the water pump blanking plate); or a third party conversion.

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Thanks Tony. In the original Lancing designer's (vague) description he mentions having a Jabsco mounted on the port side under the front of the manifold (presumably driven by a second crankshaft pulley) and water going into the block via the usual front water pump cavity and out via the thermostat housing into the big boss on the front of the manifold (using standard size radiator hose). For the initial period when the thermostat was closed they had a small gauge hose going from some extra orifice in the block (are there more than the standard drain-down hole which apparently is near the engine oil filter??) to the small boss at the back of the manifold.

 

From memory my rig only has the one front pulley driving pump and alternator. I had a quick scout round for what may have been a recently disconnected small bore water jacket access, but saw nothing obvious. However on the port side at the back there are as many as 3 bolt heads going into the block and I don't know what they are to do with.... They're rather low down - possibly oil pressure relief?

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Quickly on the matter of the little open pipe by the front of the manifold - to my knowledge it is the crankcase breather pipe. Interestingly there's no obvious place for it to go. The air inlet manifold is not present and there is no hole/boss to connect to on the rocker cover. The main good thing about it is that no smoke/fumes seem to be coming out. It either shows that the underside of the engine is still in very good shape; or it has been blocked to make things look good. After a warm-up period the engine exhaust look pretty decent for an ancient engine.

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2 minutes ago, Frank30 said:

Quickly on the matter of the little open pipe by the front of the manifold - to my knowledge it is the crankcase breather pipe. Interestingly there's no obvious place for it to go. The air inlet manifold is not present and there is no hole/boss to connect to on the rocker cover. The main good thing about it is that no smoke/fumes seem to be coming out. It either shows that the underside of the engine is still in very good shape; or it has been blocked to make things look good. After a warm-up period the engine exhaust look pretty decent for an ancient engine.

The breather pipe has a coarse mesh filter/oil catcher in the forward tapped chest cover which is possibly blocked with gunge.

 

Oil pressure release valve is under an oddly shaped hex cap about 28mm AF down on the port side rear if I remember right.

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33 minutes ago, Frank30 said:

Thanks Tony. In the original Lancing designer's (vague) description he mentions having a Jabsco mounted on the port side under the front of the manifold (presumably driven by a second crankshaft pulley) and water going into the block via the usual front water pump cavity and out via the thermostat housing into the big boss on the front of the manifold (using standard size radiator hose). For the initial period when the thermostat was closed they had a small gauge hose going from some extra orifice in the block (are there more than the standard drain-down hole which apparently is near the engine oil filter??) to the small boss at the back of the manifold.

 

From memory my rig only has the one front pulley driving pump and alternator. I had a quick scout round for what may have been a recently disconnected small bore water jacket access, but saw nothing obvious. However on the port side at the back there are as many as 3 bolt heads going into the block and I don't know what they are to do with.... They're rather low down - possibly oil pressure relief?

 

If they are largish bolt heads then the horizontal one is the skew gear oil jet strainer that needs removing eventually t make sure its clean and not fallen apart. The vertical one is the oil jet that needs checking to see its still clear. The third one, a much larger one as Tracy said covers the oil pressure relief valve.

 

I am sure Lancing would have supplied those manifolds to anybody who wants to buy one so this may well be a" Fred in a shed" conversion, nothing to do with Lancing Marine. Mounting the Jabsco under the front of the manifold on a bracket fixed to the front engine foot was the standard way to do it on a range of marinisers like J G Meaks, Tempest, Thorneycroft and Newage. I expect some Broads outfits did the same. Trouble is you need a small pullet to mount in front of the engine pulley plus the pump and bracket. I don't know if Calcutt can supply what you need

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Thanks Tony. It was those biggish bolt heads I was thinking of. So no good putting water in there..... I'll check what happens under the washer and the three-way pump!!?? It may work as presumably it did work at some point over time. Otherwise I'll be in the market for a mountable cooling pump and a small pulley.

 

Thanks everyone for their input. I'll go up there in the next few days and do some tests and will report back. Regards, Chris

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