BMC 1.5 replacement. Necessary evil?

[Barfly]

I have been bench testing a BMC 1.5 to replace my existing smoker. The current workhorse suffers excessive smoke [pale blue] at low revs and black smoke at high revs and 'piston slap' as it resumes tick over. The feint 'mist' is bearable at sailing revs but not in a lock and especially with company. Starting is awkward - probably due to knackered heater plugs. I was also told that it had been rebored to it's max. and some scoring was evident - but I've not had the top off, so don't know. None of the symptoms improve as it warms up.

 

Question 1 - is the current engine beyond bothering with, other than spares? What would you do? Would an exchange of head only solve the problem?

 

My replacement's smoking is insignificant at low and tick over, a little more with higher revs and a fair amount with rev bursts. Otherwise no slap etc. I have overhauled the head on this and because the heater plugs are good, starting is virtually instantaneous. There are some mods to do as the replacement is a 'BMC Captain' and draws raw water, the current is keel tank cooled.

 

Question 2 - Is exchanging whole engines sensible, or would a head change be sufficient? I'm talking about the boat, not the owner.

 

The current engine is linked to a PRM gearbox, otherwise drive is standard via a CV joint. It is a cruiser stern and the engine needs to travel back about 250 mm before it can go up. The rest of the hull etc. is sound with a good survey.

 

Question 3 - If a whole engine change is sensible what advice do you have to make it easy. Lift with gearbox etc. or not?

 

I am a competent amateur never the less all suggestions will be warmly welcomed even those you might think are 'bleeding obvious'. I'd rather have folks remind me rather than thinking I already know.

 

Many thanks in advance.

[p6rob]

Hi Barfly,

 

I'm in the process of rebuilding my BMC 1.5 and removed the engine last weekend. It was fairly straightforward although did require some ingenuity.

The first thing I'd say, is if you have nearby access to a dry dock, use it, particularly if they have access to a lifting crane. If they charge by the hour get everything loosened off ready so you would only need the dock long enough to lift the engine out.

Having said that, we didn't have access to a dock.

 

I stripped off as much weight and ancillaries as possible, starter, alternator, water pump, lift pump, injector pump and head. It would have been nicer to remove the gearbox first, but as the rear mountings are integral to the 'bell housing' it wasn't practical. It's a big old heavy lump and we were very wary that there could be some major consequences if things went wrong.

The method we used was to get a hydraulic engine crane and mount it on the cruiser deck. To do this we had to replace the crane's legs with box section, carefully measured and designed to fit securely around the engine 'ole. We then raised the engine up, whereupon the jib got caught on the roof. We overcame this by angling the hoist backwards with blocks of wood under the front legs.

Once the engine was above deck level, we found a problem. There was no way to put the deck cover back on and there was no way to pivot the engine to a clear are of deck. So, we got two sheets of 18mm plywood that fitted across the crane legs, lowered the engine onto these, being wary about the loading. Then we pulled the top plywood sheet, with engine until it made a slope off the deck and onto terra firma.

It took three burly blokes to lift the engine from the ground and into the van.

I'm not saying this is a good way to do an engine swap, but, so far, it's worked for us and hopefully a similar procedure will work to refit the bottom half and gearbox this weekend.

[BEngo]

Remove the whole power unit, do any mods, swap the gearbox and any other ancilliaries ( alternators, starter, extra water pumps etc.) to the new engine then re-fit a complete power unit.

 

For the sake of peace of mind change the drive plate as you swop the box over, unless it's nearly new.

 

If you start on a head swop and the old engine bores are knackered then you have wasted a lot of effort and made it more difficult to lift the engine.

 

You will only know what the current engine is like when it's in bits. The B series (like the A series) can be bored over-oversize and dry linered back to size - the MGB boys are the best source of info on this. Whether this is worth it will depend on the state of the rest of the engine.

 

Easiest way to lift it is with a Hi-ab or Palfinger, if you know someone who has/drives a truck with one. If not there are various techniques involving bridge holes, deep locks or even engine cranes as suggested by P6rob.

 

Before you start pick a point- say the crankshaft pulley- and then work systematically round the engine one way disconnecting things. Take pictures and make notes of every connection- Throttle, alternator, oil pressure, water temp sender, starter etc. etc. Refit the connections to the new one in reverse order.

 

Fit new nylock nuts to the mountings.

 

Start with the water tank fairly low- otherwise you will be nose down with the engine out and that is usually the wrong way for sleeping!

 

Get the starter battery well charged- it has a lot of work to do to bleed the fuel system.

 

Don't forget new antifreeze.

 

Cat litter, sawdust and disposable nappies are very handy for clearing the bilge once the engine is out. Allow time to give the bilge a repaint if you can.

 

Change the stern gland packing whilst the engine/box is out. It's at its easiest then.

 

N

[Barfly]

Hi Barfly,

 

I'm in the process of rebuilding my BMC 1.5 and removed the engine last weekend. It was fairly straightforward although did require some ingenuity.

The first thing I'd say, is if you have nearby access to a dry dock, use it, particularly if they have access to a lifting crane. If they charge by the hour get everything loosened off ready so you would only need the dock long enough to lift the engine out.

Having said that, we didn't have access to a dock.

 

I stripped off as much weight and ancillaries as possible, starter, alternator, water pump, lift pump, injector pump and head. It would have been nicer to remove the gearbox first, but as the rear mountings are integral to the 'bell housing' it wasn't practical. It's a big old heavy lump and we were very wary that there could be some major consequences if things went wrong.

The method we used was to get a hydraulic engine crane and mount it on the cruiser deck. To do this we had to replace the crane's legs with box section, carefully measured and designed to fit securely around the engine 'ole. We then raised the engine up, whereupon the jib got caught on the roof. We overcame this by angling the hoist backwards with blocks of wood under the front legs.

Once the engine was above deck level, we found a problem. There was no way to put the deck cover back on and there was no way to pivot the engine to a clear are of deck. So, we got two sheets of 18mm plywood that fitted across the crane legs, lowered the engine onto these, being wary about the loading. Then we pulled the top plywood sheet, with engine until it made a slope off the deck and onto terra firma.

It took three burly blokes to lift the engine from the ground and into the van.

I'm not saying this is a good way to do an engine swap, but, so far, it's worked for us and hopefully a similar procedure will work to refit the bottom half and gearbox this weekend.

 

 

 

Many thanks for your reply. Please read my post.

Many thanks - and my apologies for not replying sooner.

 

I made the decision to change engines. It's not easy as it's a case of better the devil you know - at least while it's working! I small fee I was able to use the 'hook' above connected to a block and tackle which gave better control on extraction. The lump came out with everything attached - except the boat. The only problem was enough clearance for the bolts on the CV joint. I solved this by releasing the bearing and shifting the prop etc, rearwards. I placed the engine alongside it's replacement and began to examine the differences. This is when you begin to realise no two blocks are identical although separately you would swear they were. There is a deal of doubt at this stage and questions arise like, 'Why didn't I test the replacement more and for longer?' 'Was the amount of smoke and rattle really that irritating?' 'Maybe it was only the injectors?', and, of course, 'Do I really need a boat?'

 

The first problem of crank pulley wheel pulling loomed because I had to change the timing cover and the existing pulley was smaller. Not even back at home could I say I had the appropriate tool. An angel appeared called Andy who was an ex-fitter and had the right tools. This sounds like nothing but at the time no angel's appearance could have been more timely. While I was helping a couple of lads with their own 'rust bucket', Andy had removed the front bolts, one pulley wheel, and was using a couple of wooden wedges to remove the other - all in the space of ten minutes. The God's do smile sometimes. Everything else was pretty straightforward. There were many occasions when I had to improvise, a stud used on one block and a bolt on the other etc.

 

At each stage I was expecting a crisis. I removed the bell housing, then the gearbox adaptor plate. The threaded holes in the flywheels bore no resemblance and again I began to wonder why I was putting myself through this. Then more in desperation than logic, I offered up the plate and found that what appeared to be just holes were in fact threaded and corresponded to holes in the plate, though different. Result!

 

With all ancillaries connected, several alarms and helpful advice from Kevin another fitter and boat owner, the engine was put back in. I was delighted to see that the engine mountings corresponded precisely - another fear overcome.

 

Morse cables! In themselves nothing much but trying to get them mounted on another engine was hours of fiddley frustration and warranted a trip back home to pick up any bits, nuts, bolts and brackets that could be used. Discovered that the control lever on one pump 'pulled' to accelerate, the other to decelerate. Moved the control lever round to accommodate.

 

Bleeding the engine - sounds like one is cursing it. Got to the final stage where the engine needs to turn over. Turned key - CLUNK!

 

Checked starter motor and wiring, particularly earth. CLUNK!

 

Borrowed a tool to turn the crank - ROCK SOLID!

 

'Do I really need a boat?'

 

Could only be the gearbox adaptor plate etc.

 

Loosened bell housing nuts and starter motor. Out of curiosity tried to turn the engine, and it did with difficulty.

 

Loosened more, easier.

 

Engine lifted in situ with a beam and a ratchet strap. Split the engine gearbox to find two bolts inside binding against the coupling plate. Scoring was evident - the smoking gun!

 

Reduced these and solved the problem.

 

Lessons? 1. Make sure you have all the tools you need. 2. Turn the engine over before putting it back!.

 

Engine now runs well, some minor leaks but what is a narrowboat without the smell of diesel?

 

Many thanks to those for their very helpful advice.

Remove the whole power unit, do any mods, swap the gearbox and any other ancilliaries ( alternators, starter, extra water pumps etc.) to the new engine then re-fit a complete power unit.

 

For the sake of peace of mind change the drive plate as you swop the box over, unless it's nearly new.

 

If you start on a head swop and the old engine bores are knackered then you have wasted a lot of effort and made it more difficult to lift the engine.

 

You will only know what the current engine is like when it's in bits. The B series (like the A series) can be bored over-oversize and dry linered back to size - the MGB boys are the best source of info on this. Whether this is worth it will depend on the state of the rest of the engine.

 

Easiest way to lift it is with a Hi-ab or Palfinger, if you know someone who has/drives a truck with one. If not there are various techniques involving bridge holes, deep locks or even engine cranes as suggested by P6rob.

 

Before you start pick a point- say the crankshaft pulley- and then work systematically round the engine one way disconnecting things. Take pictures and make notes of every connection- Throttle, alternator, oil pressure, water temp sender, starter etc. etc. Refit the connections to the new one in reverse order.

 

Fit new nylock nuts to the mountings.

 

Start with the water tank fairly low- otherwise you will be nose down with the engine out and that is usually the wrong way for sleeping!

 

Get the starter battery well charged- it has a lot of work to do to bleed the fuel system.

 

Don't forget new antifreeze.

 

Cat litter, sawdust and disposable nappies are very handy for clearing the bilge once the engine is out. Allow time to give the bilge a repaint if you can.

 

Change the stern gland packing whilst the engine/box is out. It's at its easiest then.

 

N

Many thanks for your advice - I have made notes!

I made the decision to change engines. It's not easy as it's a case of better the devil you know - at least while it's working! I small fee I was able to use the 'hook' above connected to a block and tackle which gave better control on extraction. The lump came out with everything attached - except the boat. The only problem was enough clearance for the bolts on the CV joint. I solved this by releasing the bearing and shifting the prop etc, rearwards. I placed the engine alongside it's replacement and began to examine the differences. This is when you begin to realise no two blocks are identical although separately you would swear they were. There is a deal of doubt at this stage and questions arise like, 'Why didn't I test the replacement more and for longer?' 'Was the amount of smoke and rattle really that irritating?' 'Maybe it was only the injectors?', and, of course, 'Do I really need a boat?'

The first problem of crank pulley wheel pulling loomed because I had to change the timing cover and the existing pulley was smaller. Not even back at home could I say I had the appropriate tool. An angel appeared called Andy who was an ex-fitter and had the right tools. This sounds like nothing but at the time no angel's appearance could have been more timely. While I was helping a couple of lads with their own 'rust bucket', Andy had removed the front bolts, one pulley wheel, and was using a couple of wooden wedges to remove the other - all in the space of ten minutes. The God's do smile sometimes. Everything else was pretty straightforward. There were many occasions when I had to improvise, a stud used on one block and a bolt on the other etc.

At each stage I was expecting a crisis. I removed the bell housing, then the gearbox adaptor plate. The threaded holes in the flywheels bore no resemblance and again I began to wonder why I was putting myself through this. Then more in desperation than logic, I offered up the plate and found that what appeared to be just holes were in fact threaded and corresponded to holes in the plate, though different. Result!

With all ancillaries connected, several alarms and helpful advice from Kevin another fitter and boat owner, the engine was put back in. I was delighted to see that the engine mountings corresponded precisely - another fear overcome.

Morse cables! In themselves nothing much but trying to get them mounted on another engine was hours of fiddley frustration and warranted a trip back home to pick up any bits, nuts, bolts and brackets that could be used. Discovered that the control lever on one pump 'pulled' to accelerate, the other to decelerate. Moved the control lever round to accommodate.

Bleeding the engine - sounds like one is cursing it. Got to the final stage where the engine needs to turn over. Turned key - CLUNK!

Checked starter motor and wiring, particularly earth. CLUNK!

Borrowed a tool to turn the crank - ROCK SOLID!

'Do I really need a boat?'

Could only be the gearbox adaptor plate etc.

Loosened bell housing nuts and starter motor. Out of curiosity tried to turn the engine, and it did with difficulty.

Loosened more, easier.

Engine lifted in situ with a beam and a ratchet strap. Split the engine gearbox to find two bolts inside binding against the coupling plate. Scoring was evident - the smoking gun!

Reduced these and solved the problem.

Lessons? 1. Make sure you have all the tools you need. 2. Turn the engine over before putting it back!.

Engine now runs well, some minor leaks but what is a narrowboat without the smell of diesel?

Many thanks to those for their very helpful advice.

[Arthur Brown]

The bit needing real care is the lift. Be very sure that you can lift the engine and gear box all the way from the engine hole to the bench before you start. Then you can look at the bores and make a decision -based on facts.

 

If you can rebore or fit liners that may be the whole solution,

[Barfly]

The bit needing real care is the lift. Be very sure that you can lift the engine and gear box all the way from the engine hole to the bench before you start. Then you can look at the bores and make a decision -based on facts.

 

If you can rebore or fit liners that may be the whole solution,

Hi, the 'old' engine is now in my workshop and I have been solving a few leaks with it's replacement. I'll have a closer look at the engine bores etc. but will need some more info then. In the mean time some research to do and a decision to make - whether I bother with trying to recondition it or let someone else have the joy. Thanks.

[Bee]

Keep whatever bits are left over. If you can rebore the cylinders or reline them you effectively have a new block. If you regrind the crank and fit new shells etc and then refit to the block with new pistons you have a reconditioned short engine - a valuable thing. If both heads are ok and not damaged you have the basis of a recon engine, call it a winter project and refit all the fiddly bits and you will have a good engine next spring.

Richard Cooper

[Barfly]

Keep whatever bits are left over. If you can rebore the cylinders or reline them you effectively have a new block. If you regrind the crank and fit new shells etc and then refit to the block with new pistons you have a reconditioned short engine - a valuable thing. If both heads are ok and not damaged you have the basis of a recon engine, call it a winter project and refit all the fiddly bits and you will have a good engine next spring.

Richard Cooper

And there was me wondering what I was going to do all winter . .. I'm certainly keen to follow your suggestion and the 'bits' are not in the way so . .. . Thanks.