BMC 1.5 question

[turnbuttonboy]

I have bought an overheating alarm to fit to a friends 1.5 BMC. It has arrived with a 3/8th-18 NPTF thread and I was wondering if anyone could tell me what thread the water jacket plugs should be on a BMC - he is moored in the middle of nowhere and it would be a lot easier to arrive with the right adaptor!

 

Many thanks Giles.

[Rob Brierley]

Hi Some of the threads on the BMC engines used to be Whitworth, if this is case you can substitute sizes 1/4,5/16,3/8,and1/2 to UNC the only difference is the spanner size they are slightly smaller and you will need an AF set.

Rob

[PeterIsbister]

I have bought an overheating alarm to fit to a friends 1.5 BMC. It has arrived with a 3/8th-18 NPTF thread and I was wondering if anyone could tell me what thread the water jacket plugs should be on a BMC - he is moored in the middle of nowhere and it would be a lot easier to arrive with the right adaptor!

 

Many thanks Giles.

 

 

Hi Some of the threads on the BMC engines used to be Whitworth, if this is case you can substitute sizes 1/4,5/16,3/8,and1/2 to UNC the only difference is the spanner size they are slightly smaller and you will need an AF set.

Rob

 

Hi just a thought, if it's a water jacket fixing won't they be a B.S.P. thread? usually denoted by the head form either a square or a female hexagon and 1/2" U.N.C will be difficult to use in a 1/2"Whit tapping as the threads per inch are different by 1.

Good luck, please let us know how you get on.

[mikevye]

I have bought an overheating alarm to fit to a friends 1.5 BMC. It has arrived with a 3/8th-18 NPTF thread and I was wondering if anyone could tell me what thread the water jacket plugs should be on a BMC - he is moored in the middle of nowhere and it would be a lot easier to arrive with the right adaptor!

 

Many thanks Giles.

 

If you mean the core plugs they are usually a press fit in the block and head all other tapping points are usually spoken for so a T piece will probably be required.

[turnbuttonboy]

If you mean the core plugs they are usually a press fit in the block and head all other tapping points are usually spoken for so a T piece will probably be required.

 

 

Thanks for the advice guys, I have been to the boat armed with a T piece which I hoped would allow me to put both the existing temp sender and the new alarm sender into the existing tapping. Of course that would be far too easy - the temp sender is between cylinders 3 and 4 and adjacent to the fuel pump and its plumbing so no chance there. The existing fitting appears to be in a core plug and there is one free between cylinders 1 and 2 but I also suspect that this will be a 'knock in' rather than a threaded hole. More research required!

 

Cheers Giles.

[alan_fincher]

I may be misunderstanding completely, but......

 

Would a temperature sender normally be fitted to the block ?

 

Our BMC 1800 has it's sernsor on the head, just below the thermostat housing.

 

 

Not a brilliant picture, but you can see it here, with a blue wire attached just below the upper fan belt.

 

Presumably most BMCs have an easily accessed tapping there, so can you not just leave the existing arrangements for one fitting, but introduce the new one at the point shown ?

 

Apologies though if I've misunderstood the problem!

 

 

OOPS: Edited to add the image!

Edited February 24, 2009 by alan_fincher

[PeterIsbister]

Thanks for the advice guys, I have been to the boat armed with a T piece which I hoped would allow me to put both the existing temp sender and the new alarm sender into the existing tapping. Of course that would be far too easy - the temp sender is between cylinders 3 and 4 and adjacent to the fuel pump and its plumbing so no chance there. The existing fitting appears to be in a core plug and there is one free between cylinders 1 and 2 but I also suspect that this will be a 'knock in' rather than a threaded hole. More research required!

 

Cheers Giles.

Hi Giles

Going back a few decades when we used to do the same thing to mini engines (a similar top end set up to the 1500 BMC diesel) we made up a male 1/8" bspt tee piece with a 3/8"nptf female and a female 1/8" bsp to take the original fitting from a brass tee fitting made by a firm called "enots",making pneumatic fittings, not sure if they are still in business but somebody should be.

On my 1500 bmc diesel the sender is tapped in near to the thermostat housing, which could be removed and perhaps tapped to suit the sender. could you get a housing from a car recyling plant and rework it?

I don't fancy the tapped core plug idea at all as they are only 1 mm thick at most and as they are pressed in under pressure and sealed, drilling would in my opinion alter/weaken their function, which i think is to bust out before the block cracks due to pressure.

Best of luck, Peter

[TerryN]

I have also recently purchased a boat with a BMC 1.5 engine. I have never seen a BMC with this type of Heat Exchanger fitted onto the Thermostat housing. Although I did initially notice waterloss in the Heat Exchanger I thought I should manage to sort this out. After Purchase I dismantled the heat exchanger but for the life of me can not get the heat exchanger lifted off. It seems to have rusted itself onto the three studs holding it in place.

 

Any suggestions on how I might be able to loosen this without cracking the heat exchanger?

 

Alternatively, Any suggestion where I can perhaps get hold of a second hand (or new) heat exchanger of the same type. (Then I can smash the current one to bits.)

 

It is a Bowman Heat Exchanger

 

Edited February 25, 2009 by TerryN

[turnbuttonboy]

I may be misunderstanding completely, but......

 

Would a temperature sender normally be fitted to the block ?

 

Our BMC 1800 has it's sernsor on the head, just below the thermostat housing.

 

Not a brilliant picture, but you can see it here, with a blue wire attached just below the upper fan belt.

 

Presumably most BMCs have an easily accessed tapping there, so can you not just leave the existing arrangements for one fitting, but introduce the new one at the point shown ?

 

Apologies though if I've misunderstood the problem!

 

 

Thanks Alan,

 

The problem is not helped by my not being familiar with the engine and its being in the smallest of very dark spaces! I will have a look at my it to see if there is a tapping in the same place as yours (and Peter's by the sound of it) - I was surprised to find the sender for the temp gauge installed where it is but, given the history of this engine, anything is possible. I am hoping to go again on Friday and will update accordingly.

 

Cheers Giles.

[PeterIsbister]

I have also recently purchased a boat with a BMC 1.5 engine. I have never seen a BMC with this type of Heat Exchanger fitted onto the Thermostat housing. Although I did initially notice waterloss in the Heat Exchanger I thought I should manage to sort this out. After Purchase I dismantled the heat exchanger but for the life of me can not get the heat exchanger lifted off. It seems to have rusted itself onto the three studs holding it in place.

 

Any suggestions on how I might be able to loosen this without cracking the heat exchanger?

 

Alternatively, Any suggestion where I can perhaps get hold of a second hand (or new) heat exchanger of the same type. (Then I can smash the current one to bits.)

 

Hi Terry mine is not like yours but you could try to remove the studs using two nuts locked together on each stud then twist the box off, this sometimes works better than a staight pull.

Calcutt engines may be able to supply a new/used one but without any marinisers name plate it is a bit of a lottery but it may be best not smash anything!

Ive only been boating two years but if its got BOAT on it that means Bump On Another Thousand,

Best of luck

Peter

[TerryN]

I have managed to contact AMC who advised that this is a Bowman Captain Heat Exchanger. The heat exchanger is no longer available unless secondhand off another engine. These engines are now being replaced like for like with Mitsubishi engines.

 

That said, they were able to source a new core for this heat exchanger which I have ordered at £209 (phew, I see what you mean) and new rubber seals for it. So I might just be able to save the current unit.

 

Now if I can just remove those studs. I tried on the weekend but no luck. Have soaked it with some paraffin and will have another go this weekend.

[PeterIsbister]

I have managed to contact AMC who advised that this is a Bowman Captain Heat Exchanger. The heat exchanger is no longer available unless secondhand off another engine. These engines are now being replaced like for like with Mitsubishi engines.

 

That said, they were able to source a new core for this heat exchanger which I have ordered at £209 (phew, I see what you mean) and new rubber seals for it. So I might just be able to save the current unit.

 

Now if I can just remove those studs. I tried on the weekend but no luck. Have soaked it with some paraffin and will have another go this weekend.

Hi Terry

I think maybe we are off topic slightly from the original question, you may get more relative experienced advice by asking a specific question again?

Anyway at least you have some spares on order.

It sounds like the whole box and the studs are well stuck so if the paraffin doesn't work perhaps you could try levering with timber on a broad edge or a small hydraulic car type jack underneath if that's possible? spreading the lifting point to be as large as possible.

If you repost you may get some relative answers from some one who has done the job?

Where abouts are you,and showing my ignorance, who's AMC?

Good luck, keep us posted,

Peter

[TerryN]

AMC, well, when I bought the boat and received all the paperwork, there was some catalogues for parts within. The latest one dates back to 1996 so I was very surprised when I called the number and somebody answered and the company still had the same name. (What with all these telephone code changes in the past 15 years I thought this to be quite surprising).

 

I got the new core for the Captain Heat Exchanger, looks fantastic, but slightly dear at £209 (I presume because it had to be made up). Anyhow Got some other bits and bobs also and fitted all only to fine I now have a water leak between the engine and the heat exchanger. Probably damaged the original cork gasket whilst trying to get it off.

 

Decided to do a bit of a botch job so I can simply get the boat to the boatyard where I have access to better tools as I am about to do a refit anyway. So I just filled the hole with some cardboard and gasket sealer. Unofrtunately I now managed to strip the stud in the core, but that should not be too difficult to get sorted.

 

Yes, sorry I know I went a bit off topic here. I just wanted to add some photos to show the temperature sensor. I have now also replaced mine with a new electrical sensor and guage.