My BMC 1.5 is chucking out white smelly smoke and misfiring with very little power

[Aqbrum123]

Hi, new to the forums. I have a problem with my engine, it’s a 1.5 BMC. It started to smoke really bad and was very low on power with a misfire blowing clouds of white and bluish smoke like a 50 a day smoker but maybe worse, occasionally a hoop or two as it makes a popping noise from the exhaust. It kind of dies down when moving and under load but comes back as soon as it’s put in neutral then the misfires start again and clouds of smoke from the exhaust, smells a bit like paraffin. I have to be honest, the engine wasn’t running very well for the 3 years I’ve had the boat and it has always kind of smoked, black smoke mainly so I believe to much fuel but it didn’t really bother me as it seemed to chug along fine. I’d like to add that I knowingly added the wrong oil, I think it was 5/30 fully synthetic about 6 months ago, only because the oil level was low and it’s all I could get (I think 2 litres) I haven’t bothered servicing it since.

 

I checked the engine and the head gasket was leaking water and oil so presumed it was the head gasket. I’ve stripped the head off, checked for cracks (no need for skimming), checked the cylinders (seem fine to me no scratches) visually inspected the pistons and all seemed ok, replaced the valve stem oil seals, grinded and polished the valves because there was a lot of pitting on the sealing faces, set the tappets and replaced the head gasket. Put it all back together and it’s still the same. I have noticed a tapping noise that gets louder as you rev the engine that makes me think there may be an oil supply issue (possible blocked oil filter as I haven’t changed it yet because I could not get the engine to operating temperature to drain the oil using a pump) the tapping goes away if I apply full throttle and rev the engine then reappears occasionally but I’m still left with the misfire and the clouds of smoke polluting the environment. 

 

I was hoping someone on here could point me in the right direction as I’ve spent a few days trying to figure out what the fault could be. Could I be right in assuming maybe the timing chain tensioner or chain are to blame and messing up the injector timing, possibly faulty injectors or am I just hoping it’s an easy fix and the engine needs a full rebuild ? 

 

If anyone else has experienced the same problem or symptoms and managed to sort it I’d be happy to hear from you

 

Cheers Andy 

[Tony Brooks]

The oil filter has a bypass valve in it so when it blocks unfiltered oil bypasses it straight into the engine oil ways, so not that.

 

No mention of the idling and revving oil pressure hot & cold so no way to assess bearing wear.

 

1.5s have been known to slip a tooth when the timing chain & tensioner block get worn and if you have not been cleaning the injector pump skew gear lubricator and its associated strainer the camshaft and skew gear drive may well be worn. That would mess with the timing. The tapping may well be the timing chain thrashing about.

 

Pitted valve seats suggest water may have got into the cylinders regularly and if so goodness knows whet state the injectors are in.

 

You imply you are using rather than gaining engine oil so that tends to rule out a leaking main injector pump shaft oil seal or a leaking lift pump.

 

No bore measurements just a visual inspection with no mention of the size of the lip so cant comment on how badly they are worn (taper, ovality and maximum wear). Likewise no data for the straight edge checks on the head and block face.

 

The long term black smoke might be associated with an oversized prop especially if it got worse as the engine revved in gear.

 

Whitish smoke for a short while after starting 1.5s is not that rarer but  oit when its hot. I expect the auxiliary spray holes in the injectors are blocked but they only have a significant effect when cranking.

 

You can draw the skew gear drive shaft after taking the injector pump off but take great care to get it back in exactly the same place, it has a master spline. In theory you can get the timing cover off in situ but in many narrowboats you don't really have the space in front of the engine so taking the engine out may be easier.

 

Edited to add: I assume that you have drained any water from the fuel tank and ensured the fuel filter(s) are clean.

Edited July 26, 2020 by Tony Brooks

[Bee]

Crumbs! that's quite a list! The smoke that smells like paraffin might be badly or unburnt fuel, the tapping could be a broken ring which could be the same problem. In my experience timing chains tend to rattle or clatter when worn but you could have multiple problems or it could indeed be all down to timing. If this was my engine I think I would start with a relatively easy and non invasive look at the timing chain, I think (not too sure) that there are timing marks (punched dots) on the various sprockets that the chain drives so you could check that all in situ and eliminate that before moving on to pump and injectors. Tony knows much more about these engines.

[Tracy D'arth]

Dirty fuel, water in the fuel. Draw off a sample.

How easily does it start from cold?

TD'

[Sir Nibble]

The noise sounds like piston slap and the symptoms sound like poor compression could be to blame. I would look at the spray pattern of the injectors in case it's a diesel knock and if there isn't one squirting or dribbling move on to a compression test.

[Tony Brooks]

57 minutes ago, Sir Nibble said:

The noise sounds like piston slap and the symptoms sound like poor compression could be to blame. I would look at the spray pattern of the injectors in case it's a diesel knock and if there isn't one squirting or dribbling move on to a compression test.

 

Exactly why I asked about the cylinder lip and the bore measurement.  The intermittent "whoop or two" might be an injector sticking open but it could also be the timing (pump and/or valve) thrashing abut.

[Tony Brooks]

Sad I know but been thinking about this and hoping for more info from the OP but I wonder if the engine is suffering from well blocked exhaust like a silencer falling apart inside. Not at all common but once the obvious things have been eliminated maybe worth considering.

 

Confirming Bee's comment, yes the crankshaft sprocket and camshaft sprocket have dimples in then that allow you to use a straight edge to line them and the centre of the camshaft up.

[Tracy D'arth]

Heavily carboned up valves is another possibility but he has had the head off, would have found out.

Silencer is a good thought.

Sounds like it is a very sick and poorly maintained engine, owner admits he can't be bothered to change the oil.

TD'

[Flyboy]

A blocked and/or collapsed air filter maybe ?

[Tony Brooks]

4 minutes ago, Flyboy said:

A blocked and/or collapsed air filter maybe ?

I thought about that but for old BMCs the filter was a wire gauze so not so likely to callops or even block. Newer ones had open cell foam and they could block.

[Tracy D'arth]

I do know of one boat with a BMC, 1.5D I think, that digested a paper air filter that someone fitted.

It is a moot point as to whether a canal boat engine needs an air filter, most Isuzus don't it seems.

TD' 

[TheBiscuits]

18 minutes ago, Tracy D'arth said:

It is a moot point as to whether a canal boat engine needs an air filter, most Isuzus don't it seems.

 

Having seen the dust and dry leaves my air filter collects, I'll keep it. 

 

It does help that I can get cheap knockoffs as the aftermarket suppliers have finally caught up with the new shape filters Beta introduced in 2012!

[Tracy D'arth]

Just now, TheBiscuits said:

 

Having seen the dust and dry leaves my air filter collects, I'll keep it. 

 

It does help that I can get cheap knockoffs as the aftermarket suppliers have finally caught up with the new shape filters Beta introduced in 2012!

You have trees in the engine room? Palm trees?  That's more than keeping up with the Jones's?

 

Mine is ducted to under the cabin floor. it keeps the cabin bilge ventilated as there are vents at the bow into the floor. Reminds me that it must be 6 years since I checked the foam filter in there!

[Troyboy]

3 hours ago, Tracy D'arth said:

I do know of one boat with a BMC, 1.5D I think, that digested a paper air filter that someone fitted.

It is a moot point as to whether a canal boat engine needs an air filter, most Isuzus don't it seems.

TD' 

 

I've owned my BMC 1.5 diesel engined narrowboat for 34 years and never had an air filter on it . Any spiders that climb in face a quick demise once it starts up .

[Tracy D'arth]

22 minutes ago, Troyboy said:

 

I've owned my BMC 1.5 diesel engined narrowboat for 34 years and never had an air filter on it . Any spiders that climb in face a quick demise once it starts up .

Best ending yet for spiders, hate the little blighters, they c#ap on the curtains.

TD'

[Up-Side-Down]

16 hours ago, Tracy D'arth said:

Best ending yet for spiders, hate the little blighters, they c#ap on the curtains.

TD'

They also maintain the fly population at acceptable levels. As an old Yorkshire farmer once said to me : " I fosters spiders ............" and I can very well understand why!

[Aqbrum123]

On 26/07/2020 at 09:31, Sir Nibble said:

The noise sounds like piston slap and the symptoms sound like poor compression could be to blame. I would look at the spray pattern of the injectors in case it's a diesel knock and if there isn't one squirting or dribbling move on to a compression test.

Hi, I dropped my phone in the canal so sorry for my late reply.

You hit the nail on the head (thanks) I have had the head off again and the piston in cylinder number 4 has a lot of movement, slipped or extremely worn bearing I believe. I didn’t run the engine much after failure so hoping the crank will be ok after a bit of polishing.

How do I know what size bearings to get, are they stamped on the old ones? 

I changed the injectors for a new set and the diesel smell went away but then could smell oil instead and the smoke (apparently) turned blue (I can’t tell because I’m slightly colour blind so relied on friends and passers by). I also changed the timing chain as this to was extremely worn. Thanks for your help it’s appreciated. 

Im planning on attempting a repair in situ as I have a lot of room under the engine as I only have a small rear door that the engine would just about fit through so seems to hard to bother removing it.

Again thank you 

[Tony Brooks]

To be honest if you can find play in the bearing I suspect just fitting new bearings will end up a temporary fix. I would expect to find the bearing oversize value on the back of the shell parallel to and close to the split but I would always prefer to measure the crank because it could be worn tapered or oval.

 

Worn bearings on their own should not cause blue smoke, I suspect your bores, pistons and rings are also badly worn. How large is the lip at the top of the bore?

[Tracy D'arth]

Be easier in the long run to pull it out, its going to need more than bearing shells. Bearings don't cause blue oil smoke, rings and pistons and bores need measuring.

Plenty of engineers in Brum with accurate micrometers, which you are going to need.

Shell over sizes are on the steel backs. 

You may be extremely lucky if the piston oversizes are still readable on the crowns.

[Alan de Enfield]

I think you are going to a lot of expense and work and will still end up with a 'bodged' (possible knackered) engine, that will just fail on the next  'thing down the line' - can you not pick up a 'short engine' and transfer the marinisation and ancillary parts and have, in effect, a 'new engine' ?

[ditchcrawler]

6 minutes ago, Alan de Enfield said:

I think you are going to a lot of expense and work and will still end up with a 'bodged' (possible knackered) engine, that will just fail on the next  'thing down the line' - can you not pick up a 'short engine' and transfer the marinisation and ancillary parts and have, in effect, a 'new engine' ?

Can you buy new BMC 1.5 short engines? I would rather rebuild it myself than buy a painted reconditioned one

[Tony Brooks]

15 minutes ago, ditchcrawler said:

Can you buy new BMC 1.5 short engines? I would rather rebuild it myself than buy a painted reconditioned one

I agree but I would not have a clue these days where to go for the machining.

 

I see vendor of many s/h marine engines in Dorset has a rebuilt 1.5 but its over £1000, Lost the link now.

[Tracy D'arth]

I have had good experiences with Crewe Engines.

[Aqbrum123]

On 26/07/2020 at 09:31, Sir Nibble said:

The noise sounds like piston slap and the symptoms sound like poor compression could be to blame. I would look at the spray pattern of the injectors in case it's a diesel knock and if there isn't one squirting or dribbling move on to a compression test.

Hi, I dropped my phone in the canal so sorry for my late reply.

You hit the nail on the head (thanks) I have had the head off again and the piston in cylinder number 4 has a lot of movement, slipped or extremely worn bearing I believe. I didn’t run the engine much after failure so hoping the crank will be ok after a bit of polishing.

How do I know what size bearings to get, are they stamped on the old ones? 

I changed the injectors for a new set and the diesel smell went away but then could smell oil instead and the smoke (apparently) turned blue (I can’t tell because I’m slightly colour blind so relied on friends and passers by). I also changed the timing chain as this to was extremely worn. Thanks for your help it’s appreciated. 

Im planning on attempting a repair in situ as I have a lot of room under the engine as I only have a small rear door that the engine would just about fit through so seems to hard to bother removing it.

Again thank you 

[wandering]

On 26/07/2020 at 09:06, Tracy D'arth said:

Dirty fuel, water in the fuel. Draw off a sample.

How easily does it start from cold?

TD'

When I bought her, ages. . Now quite quickly 

 

oops ignore me 

Edited April 6, 2023 by wandering