BMC diesel engine problems

[SimonA]

I have a BMC 1.5 engine on my boat. Recently I have had a new gearbox fitted, along with a new shaft seal, prop and other bits. My engine was not developing it's full power in gear and it was found the old gearbox was worn and the prop shaft was out of line.

Now this has all been fixed it seems the engine is still not developing it's full power.

The problems include the engine stalling when put in gear. This happens with the revs set to about 700rpm in idle, if the revs are increased to about 1200 rpm it does not stall but as soon as it goes into gear the revs drop down to about 500rpm.

When in gear it seems to take a while for the full revs to build up. I'm told it should develop the power instantly.

Out of gear it will rev fine.

The boatyard have suggested that it could be a fuel blockage / faulty injectors / faulty governor / poor compression. Having already spent a lot on the gearbox I can't really afford to change all of these.

Any ideas where to look first?

 

[Gordonmc]

Just a thought...
Did you change the size and/or pitch of the prop or the gearbox ratio?
The symptoms described could be the result of a oversized or over-pitched prop.
There may be nowt wrong with the motor, but more info needed.

 

[SimonA]

The gearbox ratio changed from 1:1 to 2:1 and the prop from 12x7 to 12x14.

The lack of power was present before the gearbox change as well, but was put down to the gearbox being very worn and everything being out of line. I couldn't source a replacement 1:1 box, hence the 2:1 and new prop.

 

[PCUK]

How long before the new gearbox was fitted was the lack of power discovered because neither the gearbox or shaft misalignment would have that effect on the engine.
Does the engine start easily from cold?
Does it smoke when under load?
Is the prop' shaft turning freely?
We'll sort it out by a process of elimination!

 

[SimonA]

The engine has been getting worse over the past couple of years, when I first had the boat it would do 2500rpm in gear, last year I was lucky to get 2000 rpm.

The engine does not start very well when cold. In the summer it starts first time, in the winter it takes a while to get it started.

The engine has white smoke that smells when running under load.

The prop turns freely now, it didn't before they did the work.

I have changed the fuel filter recently, it didn't have any dirt inside.

 

[Saddletramp]

[ QUOTE ]
The gearbox ratio changed from 1:1 to 2:1 and the prop from 12x7 to 12x14.


[/ QUOTE ]

Seems a large increase in prop pitch. The drop in revs maybe partly due to a worn engine, but you can live with that. Any chance you can try the old prop again.

 

[ms1]

I suspect that a 14inch pitch prop is rather taxing for a not so young BMC 1.5 .. hence the stalling . I would also suggest a plan to have injectors serviced in the longer term.
Canal narrowboats have been big users of the BMC 1.5 for years so there is no shortage of experience with these engines.

 

[PCUK]

Mac, halving the prop revs with the new box will more than accommodate the new prop' pitch. I would have said it was undersize.
Sounds like the problem is with the engine itself.
My next step would be to have the injectors overhauled at the local truck diesel injection specialist. (find them in Yellow pages).

 

[SimonA]

[ QUOTE ]
I suspect that a 14inch pitch prop is rather taxing for a not so young BMC 1.5 .. hence the stalling .

[/ QUOTE ]

It's a 12" prop, the pitch is 14. The boatyard told me 12" was the biggest prop they could fit.

 

[Saddletramp]

I dare say your right re the injectors, probably a bit of lost compression as well. I still think the pitch is too high. Ok for motorsailing but It will be awkward trying to control the boat at low speed.

 

[SimonA]

BTW, the boat isn't a sailing boat, it's a river boat. I posted on here as there seems to be more practical knowledge than on the other forums.

It sounds like I need to get the injectors looked at. The boatyard have suggested a price of around £400 for these to be serviced (£100 each). Does that sound about right?

 

[Saddletramp]

arghhh.... I paid £37 each for mine and a friend had his done in Pompey for £25 each.
Watson Diesel, Wimbledon may be too far from you but will give you a benchmark price.

 

[SimonA]

Just had a call from the marina.

Diesel Bug!


Apparantly my fuel lift pump was full of it. This has been cleaned and the boat is now running much better. They have suggested cleaning all of the fuel system and treating the fuel tank.

I'm sure the injectors also need looking at.

 

[Saddletramp]

Good to know that. Try it and enjoy it for a while before you spend any more money on it.
/forums/images/graemlins/smile.gif

 

[tonykerry]

A good check on the condition of the BMC 1.5 is to do a compression check on each cylinder. This can be done via the four heaters (and it may be worthwhile changing the heaters while they are out to improve starting) Compression should be over 400psi in each cylinder.
Tony

 

[PCUK]

Sounds promising on the diesel bug.
Have the fuel system cleaned. If you have the injectors serviced at some point. NEVER get them done by the boat-yard. The local truck diesel service will do it. As Mac said £100 each is a blatant rip-off. between £20 and £40 is right. Shop around. Keep us posted on developments.
Was the new gearbox something the boatyard had in stock as it would have been far better to stay with a 1:1 reduction?

 

[brianhumber]

Re: BMC diesel engine problems-

Big clue is your white smoke that smells, indicating to me unburnt fuel.
So look at fuel itself, change filters, check compression, get injectors overhauled ( cheapest will be where the local taxis get their fuel ssytems done) All fairly cheap and routine to do. Finally the fuel injection pump checked for governor response, delivery pressure etc but leave this untill ALL other combustion problems have been eliminated as its not a DIY job for you unless you have have training to check and overhaul this. Also applies to refitting unless you are happy with the timing procedure. An old seris 2A LandRover Workshop manual for engines/gearboxes cheap from ebay will tell all you ever need to know about these engines and whats inside injectors/fuel pump etc if yours has a DPA CAV system.


Brian

 

[squidge]

Re: BMC diesel engine problems-

Hi , Good old lump the 1.5 BMC. I agree with all of the above. White smoke is unburnt fuel, so check injectors. They run along the starboard side of the engine and only use 2 bolt each.Easy to remove and check or clean but you will have to blead the system after , also not hard.
As for spare parts the following link with give you most BMC parts you will ever need.
http://www.asap-supplies.com/


If you cant find what you want under BMC1.5 look under Thornycroft 90, its the same engine.
131121 INJECTOR NOZZLE ONLY BMC1.5 DIESEL EACH £10.64

 

[PCUK]

Re: BMC diesel engine problems-

I didn't know LandRover ever used the BMC 1.5. Thought it was always their own 2.25 diesel!
It sounds as if you are on the right road now. Hopefully you will be sorted for the summer!

 

[DownWest]

Re: BMC diesel engine problems-

Though I doubt you will be refitting the injectors yourself, if so . Be carefull of the little top hat bits that fit on the ends at the entry to the combustion chamber, very easy to bust them from over torquing the mounting screws. Definately sounds like they could use a look tho´from the white smoke, but also a sign of mis-timing.
A