BMC engine overheating

[Dean1977]

hi 

i have recently purchased a Creighton 26' centre cockpit. it has a BMC 1.5L engine, i never have an engine service done when i bought it stupid mistake but anyway. whilst moving it up the Lancaster canal to the marina i sourced it started over heating, me not being mechanically minded i opened up the engine bay and google this problem a lot of people were saying check the raw water pump which i found in eventually and had a look at the impeller which seemed fine no broken blades and rotated as it should i think. other people were saying air in the system ok not sure about that. but then i got to looking at the cooling system and it doesn't look like any of the pictures i've seen online can anybody is correct or am i missing something. any help or advice would be much appreciated.

[Tony Brooks]

This is very much a "fred in a shed" marinisation an I can not work out what sort of cooling system it has.  It has a raw water pump plus an engine cooling pump so it is unlikely to be direct raw water cooled. It may be a heat exchanger system except I can not see a conventional heat excharger. I can see whet looks like soem form of heat exchanger secured to a wooden cross member by a U clip but it does not look large enough to cool the engine plus I can not see four (two large and two small) pipes on it.

I can see what looks like a crude self fabricated expansion tank with another "old car type"connected to it. This suggests it may have a weird tank/keel cooled system that is used to coll a small heat exchanger.

I feel I need more photos or a  circuit diagram but first see if that brass water pump is connected to a hole in the hull and if so make sure whatever is fixed in the hole os clear. It probably ahas a strainer in it.  The make sure  the small car type header tank plus the cylindrical thing connected to it are full of coolant.

Sorry not to be much help.

 

[RLWP]

8 minutes ago, Tony Brooks said:

I feel I need more photos

 

Please, it would really help

Can you reach down and take pictures of the sides and front of the engine

I don't think I've ever seen 'Austin' on a boat rocker cover before, must have come from something like an Austin 1800

Richard

[Mad Harold]

My boat too has a BMC 1500 but it looks nothing like your installation.Yours looks to be a "one off"and to be honest looks a bit of a plumbers nightmare.

I have had my engine overheat,and I found that the raw water inlet was blocked with leaves.Also there should be a water filter in the water inlet line,and this should be checked.

A long shot but,if your boat has been standing for a while,the water inlet seacock may have been turned off.

[RLWP]

7 minutes ago, Furness said:

.Also there should be a water filter in the water inlet line,and this should be checked.

I think I can see one, without being able to piece together the whole circuit it in't easy to tell

Richard

[Tony Brooks]

I think I might a well but it seems to be made up out of sundry brass fittings with a hexagon nut on top with a pipe coming from it but it also looks as if there might be a rubber elbow below it.

[Mike Hurley]

Header tank cap is missing, did you take it off?

[Tony Brooks]

14 minutes ago, Mike Hurley said:

Header tank cap is missing, did you take it off?

But that should not allow it to boil unless there is another fault. However if what I think may be a heat exchanger really is one then it looks very undersized to me so it just might let it run hotter without boiling with the cap on.

[Dean1977]

hi Guys i totally agree its a heath Robinson affair, i thought it had some old type heat exchanger but i cant work out how it could possibly work like this. im now thinking i need a bowman heat exchanger, any ideas where  i attach what photos ive got.

any ideas where i could get a used heat exchanger from??

[WotEver]

Just a thought but if it has a raw water inlet is the sea cock open?

[Mad Harold]

May I describe the cooling system on my boat,it may give you some guidance although I will defer to more experienced boaters.

BMC 1500 cooled directly by canal water. Seacock in the swim plate with home made strainer in it [1ft of 15mm copper pipe with lots of 1/4inch holes ] goes to standard type water filter,[plastic with see through top].Then to foot mounted water pump which looks the same as yours.The engine water pump has been removed and a blanking plate with a water inlet has been fitted.The outlet pipe from the water pump goes to the blanking plate water inlet and has  a "T" in it for the bypass.Bypass has a "T" in it connected to the thermostat pipe and then to the water outlet on the side of the hull.

Don't know how to post photos but the system is very simple,and does away with the need for heat exchangers,skin tanks etc.

The only downside is that it has to be drained if the boat is to be left in below zero temperatures,but I have fitted a drain valve in the feed side of the pump so this is easily done.

The temperature needle has never exceeded 80 degrees even when giving the engine some "pastie"

[Dean1977]

sea cock is wide open but i do think their is a blocked as i have taken the jabsco pipe off on the sea cock side and nothing came out, not sure how to check whilst its still in the water. but its just the fact that i dont understand the rest of the cooling system that's annoying.

[Tony Brooks]

Now I can see the exhaust manifold properly it seems to be a wet exhaust boat.

There is a blue heat exchanger but I think its an oil cooler for the gearbox.

There is also what looks like a vertically mounted heat exchanger in the first two photos that could be the engine heat exchanger.

If the Jabsco inlet pipe is taken off and held below the water;le water should flow out of it now we can  see its a wet exhaust boat but if any part of the inlet piping top the raw water pump rises above the water line this may not be the case.

Try blowing back down the pipe that runs into the Jabsco. If with a  bit of effort you can blow down it and hear bubbles outside the hull then the raw water side is clear. If not its blocked.

If the face plate gasket to the Jabsco pump is missing torn or too THICK then it may well not prime. Likewise if the cylindrical ends of the impeller vanes have worn away. Likewise if there is a loose connection or a so=plit in the suction side hose.

Heat exchangers and oil coolers on raw water boats can and do block at the ends of the core. Typically under the cover held on by three bolts in the top two photos but I do not know which is the inlet and which the outlet end. Ditto the blue oil cooler. Do not take the oil pipes off, only the pipes at each end and then try back  flushing it.

 

Edited to add - Before trying to source parts you need to work out how the system works and what runs to where. My guess is that the gearbox oil cooler is on the suction side of the Jabsco. In my view a bad idea. Once I had sorted out how your system works and got it running I would be altering that so only a single length of hose/pipe is on the suction side. This gives longer pipe/hose runs but minimises the opportunity for sucking air into the system.

Another thought. Sometimes the exhaust hose burns through the inner layers of hose when the raw water is lost. This can be cumulative. The teh exhaust flow can force a flap of inner lining across the hose, esecially at higher speeds. This blocks the exhaust flow, creating back pressure and preventing the Jabsco from pumping enough. This is usually accompanied by a lot of hissing, steam and water SPRAY from the exhaust rather than the gurgle and glugs that are normal on wet exhaust systems.

 

Edited January 22, 2018 by Tony Brooks

[Bee]

Whoa! Before you take any more bits off it or buy any more parts to connect to it sit down with a cup of tea and try to work out a) where the water comes into the boat b )how it is supposed to get out of the boat then c) what on earth it does in the middle. I reckon you will end up with about 20 lbs of old brass left over if you can simplify the whole shebang.

[Tony Brooks]

13 minutes ago, Bee said:

Whoa! Before you take any more bits off it or buy any more parts to connect to it sit down with a cup of tea and try to work out a) where the water comes into the boat b )how it is supposed to get out of the boat then c) what on earth it does in the middle. I reckon you will end up with about 20 lbs of old brass left over if you can simplify the whole shebang.

Except I am all but sure there are two lost of water involved, raw water & coolant. Still good advice though. He must work out how its supposed to work before doing anything else.

Can we have a photo of where the water comes into the boat?

[RLWP]

Nice paper trimmer

This is a water cooled manifold, water comes on the right and leaves the jacket on the left, being injected into the exhaust.

Bit of a waste of heat there

This blue thing at the top is the oil cooler for the gearbox (Velvetdrive). Water from the raw water pump should pass through this

This looks like a large header tank. Are there any other connections to this?

Richard

Edited January 22, 2018 by RLWP

[Mad Harold]

1 hour ago, Bee said:

Whoa! Before you take any more bits off it or buy any more parts to connect to it sit down with a cup of tea and try to work out a) where the water comes into the boat b )how it is supposed to get out of the boat then c) what on earth it does in the middle. I reckon you will end up with about 20 lbs of old brass left over if you can simplify the whole shebang.

Lighten and simplicate.

[Attributed to Sir Geoffrey De Haviland,of Tiger Moth and Mosquito fame]

[David Mack]

Tony Brooks is too modest to mention his own website which covers this at http://www.tb-training.co.uk/15cool.htm

It looks like your installation should be similar to the diagram below, except you have separate exhaust manifold and header tank (as identified by RLWP). Do you also have a calorifier fitted?

 

 

[RLWP]

46 minutes ago, Furness said:

Lighten and simplicate.

[Attributed to Sir Geoffrey De Haviland,of Tiger Moth and Mosquito fame]

"Perfection is achieved not when there is nothing more to add, but when there is nothing left to take away" - Antoine de Saint-Exupéry

[Dean1977]

43 minutes ago, David Mack said:

Tony Brooks is too modest to mention his own website which covers this at http://www.tb-training.co.uk/15cool.htm

It looks like your installation should be similar to the diagram below, except you have separate exhaust manifold and header tank (as identified by RLWP). Do you also have a calorifier fitted?

 

 

I have seen this online it does have a calorifier but has been disconnected for some reason you may see in the photos 2 pipes with white ends that I think went to it. 

[RLWP]

It looks to me like this system used to work at one time, probably for whoever made up the parts. Then something went wrong when the boat was in the hands of a later owner. Since then, it looks like it might have been somewhat bodged, changed and messed about

Richard

[Dean1977]

1 hour ago, Tony Brooks said:

Except I am all but sure there are two lost of water involved, raw water & coolant. Still good advice though. He must work out how its supposed to work before doing anything else.

Can we have a photo of where the water comes into the boat?

The raw water comes up out of the hull to a sea dock up to a tee from the tee straight to the raw water pump. The other end of the tee is blanked. To that cylinder thing in picture 2 then up to that manifold affair.

[RLWP]

3 minutes ago, Dean1977 said:

The raw water comes up out of the hull to a sea dock up to a tee from the tee straight to the raw water pump. The other end of the tee is blanked. To that cylinder thing in picture 2 then up to that manifold affair.

Which is fine (well, not really, let's do some more searching)

On the front of the engine is another water pump driven by the vee belt that also drives the alternator. What is that piped up to?

Richard

[David Mack]

3 hours ago, Dean1977 said:

 

any ideas where i could get a used heat exchanger from??

New Bowman heat exchangers are available from ASAP Supplies. If all you need is a simple tubular heat exchanger an EC100 will suit an engine up to 54hp and cost less than £200.

Second hand ones come up regularly on eBay.

[RLWP]

13 minutes ago, David Mack said:

New Bowman heat exchangers are available from ASAP Supplies. If all you need is a simple tubular heat exchanger an EC100 will suit an engine up to 54hp and cost less than £200.

Second hand ones come up regularly on eBay.

https://www.asap-supplies.com/engine-spares-gearboxes/heat-exchangers-exhaust-manifolds/tubular-heat-exchangers/bowman-tube-heat-exchanger-ec100

https://www.asap-supplies.com/engine-spares-gearboxes/heat-exchangers-exhaust-manifolds/heat-exchanger-manifolds-manicoolers/bowman-marine-heat-exchanger-bl180-3318

We have several of the BMC ones, none have the heat exchangers though. They have come from skin tank cooled boats

Richard