BMC 1.8, good engine?

[Tasemu]

Hi all, i've tried searching for information before writing this but have come up blank. I am looking at a boat with a BMC 1.8 Engine, I'm still new to this and only been on the canal for 6 months now with my little springer sporting a SABB 2HG. That boat is now gone and i'm looking to buy my own, hoping to get some opinions on this engine.

 

Thanks for any and all advice!

[Tony Brooks]

Plenty in service, some in at least one hire fleet. Newer than the 1.5 so for now the spares should be easier.  I would be more3 concerned about the gearbox if it is a Hurth (avoid if possible!)

[Tasemu]

Just now, Tony Brooks said:

Plenty in service, some in at least one hire fleet. Newer than the 1.5 so for now the spares should be easier.  I would be more3 concerned about the gearbox if it is a Hurth (avoid if possible!)

Cheers mate, i'll make sure to check next time i look at the boat.

[doratheexplorer]

Downsides:  Unrefined and a bit noisy. (But far quieter than anything air cooled)

 

Upsides:  Easy to work on, cheap parts, proven reliability, every mechanic you'll find will be very familiar with it.  it may just be the most common engine ever put in a narrowboat.

 

If I was you, I'd test it by starting it by turning the key but don't hold on pre-heat first.  Just crank it straight over from cold.  If it fires up after a few seconds of cranking it's ok.  If it takes forever to start or fails to start without pre-heating the plugs, then it's probably a bit dodgy.  Also, BMCs will smoke a bit from cold, but excessive smoke is a bad sign.  Check for signs of oil or water leaks or usual things like head gasket failure.  Make sure the skin tank is a decent size.

 

I remember chatting to another boater with BMC 1.8 who said they won't start when it gets too cold, and that's normal for this engine.  It's not true.  When I first got mine I didn't even know I had to pre-heat the plugs, I used to just start it from cold.  I started it no problem in temperatures way below zero, just took about 10 seconds of cranking to fire.

[Boater Sam]

58 minutes ago, doratheexplorer said:

Downsides:  Unrefined and a bit noisy. (But far quieter than anything air cooled)

 

Upsides:  Easy to work on, cheap parts, proven reliability, every mechanic you'll find will be very familiar with it.  it may just be the most common engine ever put in a narrowboat.

 

If I was you, I'd test it by starting it by turning the key but don't hold on pre-heat first.  Just crank it straight over from cold.  If it fires up after a few seconds of cranking it's ok.  If it takes forever to start or fails to start without pre-heating the plugs, then it's probably a bit dodgy.  Also, BMCs will smoke a bit from cold, but excessive smoke is a bad sign.  Check for signs of oil or water leaks or usual things like head gasket failure.  Make sure the skin tank is a decent size.

 

I remember chatting to another boater with BMC 1.8 who said they won't start when it gets too cold, and that's normal for this engine.  It's not true.  When I first got mine I didn't even know I had to pre-heat the plugs, I used to just start it from cold.  I started it no problem in temperatures way below zero, just took about 10 seconds of cranking to fire.

Agreed, if the compressions are good it will start cold, without preheat. But be careful, the preheat will come on anyway with the starter cranking with most ignition switches.

If you want to be sure the preheat is off, disconnect the main wire to the preheat plugs first.

The main reason they smoke on starting is the extra fuel setting in the injection pump and if they run too cold normally they will smoke all the time.

Reliable engines, main problems I find are cam wear on early ones and timing chain wear due to it being longer than the 1,5D, the slipper pad and tensioner wear out causing the chain to go slack and thrash itself to death.

Cylinder heads  should be re-torqued regularly.

Use a crucifix and garlic when looking at Hurth mechanical gearboxes, spawn of the devil.

[alan_fincher]

Of course although many will start from cold without use of the heaters, (the one we had would), they are not actually designed to be used in that way.

The fact you may need to use the heaters in my view in no way makes it a bad example of the engine - that's how they are meant to work, as laid out in the users handbook.

Would all modern units from the far east with heaters pass a similar test, I don't know?

[Boater Sam]

6 minutes ago, alan_fincher said:

Of course although many will start from cold without use of the heaters, (the one we had would), they are not actually designed to be used in that way.

The fact you may need to use the heaters in my view in no way makes it a bad example of the engine - that's how they are meant to work, as laid out in the users handbook.

Would all modern units from the far east with heaters pass a similar test, I don't know?

No, they will not Alan because they run on a lean injection, emission regs, there is no over fuel for starting on the injection pump.

The comparison is like comparing a Cornish steam engine with a steam turbine, development has moved on.

My experiences with indirect injection diesels bears this out, Citroen/Peugeot engines had to have preheat, even more so with single rail injection.

But the old BMC with Ricardo chambers should always fire up without in our climate if the compression is good. They were made to run in all sorts of climatic conditions by dumping fuel in at start but in extreme conditions that fuel needs heat to help the compression ignition. That's why they will never pass any later emission testing.

[ditchcrawler]

1 hour ago, alan_fincher said:

Of course although many will start from cold without use of the heaters, (the one we had would), they are not actually designed to be used in that way.

The fact you may need to use the heaters in my view in no way makes it a bad example of the engine - that's how they are meant to work, as laid out in the users handbook.

Would all modern units from the far east with heaters pass a similar test, I don't know?

Our Vauxhall and my Rangrover wouldnt start with a heater down, the Isuzu did every time, I didnt even have the heaters connected.

[Richard T]

We have a 1.8 in our boat that has done nearly 11000hours. It does need the heaters to start but it doesn't smoke. Until something major goes wrong it will not be replaced. Ours is coupled to a PRM 260 gearbox which is an excellent bit of kit.

[Boater Sam]

A very good pairing, solid old engine and a bomb proof gearbox working well within its ratings.

 

PRM 260 and the later 280 are probably the best canal boat gearboxes you could have. The earlier PRM 160 was good but had slightly weaker clutch linings, any water in the oil caused problems.

[doratheexplorer]

15 hours ago, alan_fincher said:

Of course although many will start from cold without use of the heaters, (the one we had would), they are not actually designed to be used in that way.

The fact you may need to use the heaters in my view in no way makes it a bad example of the engine - that's how they are meant to work, as laid out in the users handbook.

Would all modern units from the far east with heaters pass a similar test, I don't know?

I'm not recommending a BMC is always started from cold, it's just a simple way of identifying a knackered engine when buying.  Especially if you're not a n expert.

[Stilllearning]

6 minutes ago, doratheexplorer said:

I'm not recommending a BMC is always started from cold, it's just a simple way of identifying a knackered engine when buying.  Especially if you're not a n expert.

I agree, and might add that if you are looking at a boat to buy, whether it has a 1.8 BMC or any other engine, always check the engine is stone cold, then start it. That way you find out how it starts, rather than a cunning owner getting it nice and warm before you arrive, ready to be fleeced.

[doratheexplorer]

2 minutes ago, Stilllearning said:

I agree, and might add that if you are looking at a boat to buy, whether it has a 1.8 BMC or any other engine, always check the engine is stone cold, then start it. That way you find out how it starts, rather than a cunning owner getting it nice and warm before you arrive, ready to be fleeced.

Yep.  True with second hand cars too.  As I found to my cost when buying my first car.