BMC 1.5 smoking at higher revs

[magnetman]

11 hours ago, David Mutch said:

Thanks Magnetman. I have checked valve clearances and had a good listen to the top end and tappet chests, so I don't think it's that, although the sound kind of fits.

 

Curious to know what you mean by the screws being soft?

 

I guess something else in the top end could be the cause of the smoke, e.g. valve stem oil seals, but the smoke is definitely more white than blue, and it's only at high revs, so that one is lower down the list of suspects. 

The ball ends were not properly hardened and had mushroomed over. In one case you couldn't even see that it had once been ball shaped. 

 

Also some of the screws had less thread than others. Signs of previous removal of the rockers so I guess just bad quality parts. 

 

Apparently soft screws is a known problem in the classic car world too. 

 

They are the same as MGB tappet screws so I bought from mgbhive website rather than random eBay made in china job. 

 

Difficult to know without doing a hardness test on them but probably ok. 

 

 

Edited January 17, 2022 by magnetman

[john.k]

Skid over a file is a simple hardness test

[magnetman]

This topic got me going so I took off the rocker assembly. 

 

To find this: 

 

So now I know what was wrong! New rocker shaft ordered and a new arm rather than just the bush. That's quite nasty. 

 

[Tony Brooks]

12 minutes ago, magnetman said:

This topic got me going so I took off the rocker assembly. 

 

To find this: 

 

So now I know what was wrong! New rocker shaft ordered and a new arm rather than just the bush. That's quite nasty. 

 

 

 

I found that when that happened the oil all leaked out of the arm bush so none or very little ran through the rocker drilling to lubricate the adjuster ball and push rod cup. I found this mainly on the A series petrol engines with fabricated rockers but no reason for it not to apply to the B series, petrol or diesel. I wonder if the soft adjuster balls were a misdiagnosis in some cases with the real problem being lack of lubrication.

[magnetman]

Does seem likely yes. 

 

The screws which were nackered were shorter than the standard ones which was a bit odd. Less threads on them. 

 

Sorry if I've hijacked the thread a bit but this problem did cause a very significant knocking sound and that was one of the complaints the OP had. 

Edited January 17, 2022 by magnetman

[David Mutch]

10 hours ago, Tracy D'arth said:

Arrange a separate fuel supply from a small tank and use clean diesel or better still clean diesel with 25% kerosene. see if it smokes on that. If its OK you have some degraded fuel in the tank.

Thanks Tracy. I've had a lot of diesel fills in the time it's been happening, and even run out once, so I don't suspect bad fuel (unless my supply is consistently bad, but then I'd expect others locally to have similar complaints)

10 hours ago, Tracy D'arth said:

Arrange a separate fuel supply from a small tank and use clean diesel or better still clean diesel with 25% kerosene. see if it smokes on that. If its OK you have some degraded fuel in the tank.

Thanks Tracy. I've had a lot of diesel fills in the time it's been happening, and even run out once, so I don't suspect bad fuel (unless my supply is consistently bad, but then I'd expect others locally to have similar complaints)

10 hours ago, Tracy D'arth said:

Arrange a separate fuel supply from a small tank and use clean diesel or better still clean diesel with 25% kerosene. see if it smokes on that. If its OK you have some degraded fuel in the tank.

Thanks Tracy. I've had a lot of diesel fills in the time it's been happening, and even run out once, so I don't suspect bad fuel (unless my supply is consistently bad, but then I'd expect others locally to have similar complaints)

10 hours ago, Tracy D'arth said:

Arrange a separate fuel supply from a small tank and use clean diesel or better still clean diesel with 25% kerosene. see if it smokes on that. If its OK you have some degraded fuel in the tank.

Thanks Tracy. I've had a lot of diesel fills in the time it's been happening, and even run out once, so I don't suspect bad fuel (unless my supply is consistently bad, but then I'd expect others locally to have similar complaints)

10 hours ago, Tracy D'arth said:

Arrange a separate fuel supply from a small tank and use clean diesel or better still clean diesel with 25% kerosene. see if it smokes on that. If its OK you have some degraded fuel in the tank.

Thanks Tracy. I've had a lot of diesel fills in the time it's been happening, and even run out once, so I don't suspect bad fuel (unless my supply is consistently bad, but then I'd expect others locally to have similar complaints)

10 hours ago, Tracy D'arth said:

Arrange a separate fuel supply from a small tank and use clean diesel or better still clean diesel with 25% kerosene. see if it smokes on that. If its OK you have some degraded fuel in the tank.

Thanks Tracy. I've had a lot of diesel fills in the time it's been happening, and even run out once, so I don't suspect bad fuel (unless my supply is consistently bad, but then I'd expect others locally to have similar complaints)

[David Mutch]

Aarg! Seemed to be a bit of an issue with the submit button on that last one! 😆

[David Mutch]

9 hours ago, john.k said:

Another possible cause of  white smoke/unburnt diesel in the exhaust (which should be obvious -eyes watering fumes) is engine running stone cold....which can happen in marine engines...............in any case,what is the fumes/smoke?.......oil/diesel /or water/?.......you should be easily able to smell the difference.....if not ,run the exhaust thru a rag over the outlet for a minute......and smell that.

Will do, although I'm not sure it really smells like any of those. If it's oil, where could it be coming from, given that compression is good, so presumably the rings are ok? Valve stem oil seals? But from what I've read (no experience myself) that would tend to cause smoke on startup, but then clear? Fairly sure it's not steam, as it doesn't lose coolant. It does lose some oil, but so did my previous 1.5 (presumably mostly out of the breather), and it didn't smoke like this.

 

The engine does seem to run coldish, although I'm not sure I'd describe it as stone cold. I don't think my temperature gauge is very accurate, but have measured the stat housing with an infra red thermometer before, and I seem to recall it was a bit below the stat rating ( which is I think is a low temperature stat - 72 degrees?). However, it's always run at the same temperature, and the smoke is new, so I doubt that's it, TBH

7 hours ago, magnetman said:

Does seem likely yes. 

 

The screws which were nackered were shorter than the standard ones which was a bit odd. Less threads on them. 

 

Sorry if I've hijacked the thread a bit but this problem did cause a very significant knocking sound and that was one of the complaints the OP had. 

No worries. Thanks for the explanation

[TNLI]

On 16/01/2022 at 12:46, David Mutch said:

Hi all,

 

My BMC 1.5 is has started producing large amounts of white smoke (with a very slight blueish hue) at high revs. 

 

It starts OK (although takes more heat than my previous BMC), and There's no smoke at idle, or at tickover or just above, but only when gunning it a bit. Can be slightly lumpy for 30 seconds or so after starting, if put immediately to idle.

 

There's also something that sounds a little like knock, but it's fairly subtle, and it seems to come and go to an extent.

 

My first thoughts were pump timing, compression or injectors.

 

So far I have:

 

1. Replaced injectors with recon ones from Calcutt

2. Checked compression (all between 360-380psi) 

3. Advanced pump timing as far as I can/dare

4. Checked valve clearances

 

The engine is regularly serviced (oil and all filters). And oil pressure is good (at least 50psi at idle).

 

I'm now wondering what's next. I'm thinking:

 

1. Recon fuel pump

2. Timing chain (although decent compression makes me doubt valve timing)

3. Head gasket?

4. New harmonic balancer (crank pulley). I've had similar noises in cars caused by that going, but not sure it explains the smoke

 

Any comments/suggestions would be most welcome!

 

It's often I good idea to ask in this forum before spending a lot of dosh guessing at what might cause the smoke. So looking at your list, It's rare for white smoke, (Grey possibly), to be caused by a fuel injector or HP pump problem.

It could well be burning oil, (Sniff test the exhaust, as water and oil getting into the cylinders both cause white smoke), due to broken rings or duff valve guide oil seals, BUT the compression check if done correctly should help decide if it's that type of fault or not. 

Nothing wrong with checking the timing, but I definitely would not adjust it unless it's in error.

  Valve clearances are definitely worth looking at, BUT that is about the end of the first list, and as regards the second 4 points on the second list, only the HG seems a potential problem worth more attention. If the crank pulley or associated bearings are involved, I don't think they would cause smoke.

  Finally my best 2 guesses are HG failure or worn out main block requiring a full rebuild!

 

PS: what are you using for oil, and does it seem thin if you run used oil between your fingers. 

[john.k]

Oil actually burnt in the cylinder wont cause (much ) smoke........I had a supply of free aviation kerosine..... mixed 50/50 with used hydraulic oil,R&O68 to be exact.......When the Gardner was cold ,there was a bit of oil  smoke when the motor was opened up,but as soon as things got hot,completely smoke free.....go 400 miles in a weekend ,free !.......unfortunately the govt cracked down on the disposal of aviation fuel,because a lot of people were using it in cars and trucks.

[David Mutch]

On 17/01/2022 at 22:36, TNLI said:

It's often I good idea to ask in this forum before spending a lot of dosh guessing at what might cause the smoke. So looking at your list, It's rare for white smoke, (Grey possibly), to be caused by a fuel injector or HP pump problem.

It could well be burning oil, (Sniff test the exhaust, as water and oil getting into the cylinders both cause white smoke), due to broken rings or duff valve guide oil seals, BUT the compression check if done correctly should help decide if it's that type of fault or not. 

Nothing wrong with checking the timing, but I definitely would not adjust it unless it's in error.

  Valve clearances are definitely worth looking at, BUT that is about the end of the first list, and as regards the second 4 points on the second list, only the HG seems a potential problem worth more attention. If the crank pulley or associated bearings are involved, I don't think they would cause smoke.

  Finally my best 2 guesses are HG failure or worn out main block requiring a full rebuild!

 

PS: what are you using for oil, and does it seem thin if you run used oil between your fingers. 

Thanks. Because compression is good and there's no sign of combustion gas in the cooling system, worn rings/cylinders of failed head gasket seem unlikely. I guess there are places a head gasket could fail and let oil into a cylinder without letting combustion gas into the cooling system, but I'd have thought a failure like that would still cause lower compression.

 

I use Rock Oil MP Lite D, and I can't say it's noticeably thinner than usual. What would that make you suspect? Fuel in the oil?

 

I'm starting to lean towards the possibility of valve stem seals, as these could let oil into the cylinder without loss of compression, and it does seem it's not always just on start that you get smoke when these are gone.

 

Is there any way to confirm this, though, other than changing them? And is that doable with the head in situ?

[David Mutch]

On 18/01/2022 at 00:45, john.k said:

Oil actually burnt in the cylinder wont cause (much ) smoke........I had a supply of free aviation kerosine..... mixed 50/50 with used hydraulic oil,R&O68 to be exact.......When the Gardner was cold ,there was a bit of oil  smoke when the motor was opened up,but as soon as things got hot,completely smoke free.....go 400 miles in a weekend ,free !.......unfortunately the govt cracked down on the disposal of aviation fuel,because a lot of people were using it in cars and trucks.

That's interesting, as I guess a dodgy seal on an exhaust valve could well cause oil to get sucked into the exhaust, vaporised and blown out the tail pipe without actually combusting, which fits with the symptoms and the tests I've run so far pretty well...

[TNLI]

36 minutes ago, David Mutch said:

Thanks. Because compression is good and there's no sign of combustion gas in the cooling system, worn rings/cylinders of failed head gasket seem unlikely. I guess there are places a head gasket could fail and let oil into a cylinder without letting combustion gas into the cooling system, but I'd have thought a failure like that would still cause lower compression.

 

I use Rock Oil MP Lite D, and I can't say it's noticeably thinner than usual. What would that make you suspect? Fuel in the oil?

 

I'm starting to lean towards the possibility of valve stem seals, as these could let oil into the cylinder without loss of compression, and it does seem it's not always just on start that you get smoke when these are gone.

 

Is there any way to confirm this, though, other than changing them? And is that doable with the head in situ?

 

Mine Gott! WTF is ROCK OIL MP Lite ?? I've never even heard of it before, even in Bobs The Oil Guy forum., It's also fairly expensive: 

MP Lite D 5L Marine Diesel Engine Oil: API CC 10W-40 02200/000/005 RO0 | ChasNewensMarine (chastheboat.co.uk)

 

If you want your block to last a long time, use a major brand 15w40 or 20w50 conventional base oil made by a major oil company that has a TBN of more than 9, (Total Base Number is a measure of who much detergent additive is in the oil), AND lots of Zinc, (DZZP), based anti wear additives that reduce corrosion caused by acidic compounds, and coats the bearings and rings to help reduce direct wear. 

  My current list of major engine oil companies for the UK: Liqui Moly, Shell, Mobil and Castrol. This is the oil I'm using at present:

NEW 1x Liqui Moly 1426 Nova Super 15w-40 Mineral Motor Oil 5 L (€ 5,95/L) | eBay  (Seems to be out of stock in the UK)

 

This rather more expensive oil was recommended to me by a friend in LM R&D as the best engine oil for a BMC 1500:

Liqui Moly - Touring High Tech 20w50 - Mineral based Engine Oil - 5L - 20813 | eBay

 

Oil filters are also important, so BOSCH or MANN, both made in Germany.

 

Tony will know if the valve stem oil seals can be changed easily, BUT you will need a head gasket set as far as I'm aware. Don't get the valves mixed up, as they are all different in terms of how they were seated, and the inlet and exhaust valves are normally different anyway. A head gasket set will normally include valve guide oil seals:

Head Gasket Set BMC1.5 T90 Cup Valve Seals (asap-supplies.com)

Might be better to buy the HG only if you do not know the type of valve seats fitted:

Parts Identifier | ASAP Supplies (asap-supplies.com)

 

Tony might know how you can tell the difference without pulling the head off first and sending pic's to ASAP.

Edited January 19, 2022 by TNLI

[Tony Brooks]

40 minutes ago, David Mutch said:

Thanks. Because compression is good and there's no sign of combustion gas in the cooling system, worn rings/cylinders of failed head gasket seem unlikely. I guess there are places a head gasket could fail and let oil into a cylinder without letting combustion gas into the cooling system, but I'd have thought a failure like that would still cause lower compression.

 

I use Rock Oil MP Lite D, and I can't say it's noticeably thinner than usual. What would that make you suspect? Fuel in the oil?

 

I'm starting to lean towards the possibility of valve stem seals, as these could let oil into the cylinder without loss of compression, and it does seem it's not always just on start that you get smoke when these are gone.

 

Is there any way to confirm this, though, other than changing them? And is that doable with the head in situ?

 

First of all as diesels like most of ours do not have a carburetor venturi or throttle butterfly there is way less depression in the inlet manifold to suck oil down the guides. The main thing that might cause a depression is  a paper element or foam air filter so unless your air filter (if you have one) is foam then as you said above, the main time stem oil seals cause smoke is after standing for a while so gravity pulls oil down the seals, especially after an oil change when the oil has flooded the rocker cover. You could try running without an air filter and also lead the breather pipe into a bottle sitting in the engine tray.

 

A far as doing the valve stem seals in situ. If you have a suitable valve spring compressor then it may well be. The piston on a diesel comes to within a few 10s of one thousandths of an inch of hitting the cylinder head so with a bit of luck if you set a piston to TDC it should prevent the valves dropping into the cylinder. However I have never tried it on a BMC but did do it on my Bukh successfully. That was also chasing smoke and made no difference. The Bukh is direct injected while the BMC is indirect but if there is a difference in bump clearance (piston to head at TDC) I would expect it to be marginally greater on the Bukh. I can not guarantee it will work on a BMC but can see no reason why it won't.

 

If you give it a try then once the spring is off lower the valve slightly and wobble it about to assess the  degree of wear in the stem and guide. I also have a feeling the  exhaust valves did not have stem seals when I was rebuilding them but that may be wrong or has changed.

Edited January 19, 2022 by Tony Brooks

[john.k]

A bad stem  seal on an exhaust valve leaks oil directly into the exhaust......where it burns with maximium odour and smoke................However ,if you have a  muffler,or something else to produce a certain back pressure ,this resists oil running down the guides to some extent.......The worn rockers indicate that valve stem to guide clearance may also be excessive.............Despite good compression ,oil rings may also be worn to the point of inefficiency.

Edited January 19, 2022 by john.k

[TNLI]

Good point from john there, and if the head has to be removed cos the seals are bad, it's almost certainly time to do the rings unless they were done by some previous person who decided they could not be bothered to do the valves.

 

 

[David Mutch]

4 hours ago, TNLI said:

 

Mine Gott! WTF is ROCK OIL MP Lite ?? I've never even heard of it before, even in Bobs The Oil Guy forum., It's also fairly expensive: 

MP Lite D 5L Marine Diesel Engine Oil: API CC 10W-40 02200/000/005 RO0 | ChasNewensMarine (chastheboat.co.uk)

 

If you want your block to last a long time, use a major brand 15w40 or 20w50 conventional base oil made by a major oil company that has a TBN of more than 9, (Total Base Number is a measure of who much detergent additive is in the oil), AND lots of Zinc, (DZZP), based anti wear additives that reduce corrosion caused by acidic compounds, and coats the bearings and rings to help reduce direct wear. 

  My current list of major engine oil companies for the UK: Liqui Moly, Shell, Mobil and Castrol. This is the oil I'm using at present:

NEW 1x Liqui Moly 1426 Nova Super 15w-40 Mineral Motor Oil 5 L (€ 5,95/L) | eBay  (Seems to be out of stock in the UK)

 

This rather more expensive oil was recommended to me by a friend in LM R&D as the best engine oil for a BMC 1500:

Liqui Moly - Touring High Tech 20w50 - Mineral based Engine Oil - 5L - 20813 | eBay

 

Oil filters are also important, so BOSCH or MANN, both made in Germany.

 

Tony will know if the valve stem oil seals can be changed easily, BUT you will need a head gasket set as far as I'm aware. Don't get the valves mixed up, as they are all different in terms of how they were seated, and the inlet and exhaust valves are normally different anyway. A head gasket set will normally include valve guide oil seals:

Head Gasket Set BMC1.5 T90 Cup Valve Seals (asap-supplies.com)

Might be better to buy the HG only if you do not know the type of valve seats fitted:

Parts Identifier | ASAP Supplies (asap-supplies.com)

 

Tony might know how you can tell the difference without pulling the head off first and sending pic's to ASAP.

Rock Oil is a major brand, stocked and recommend pretty universally in chandleries I've visited. Used it for 10 years now without complaint (perhaps, admittedly, until now, that is!). I'm assured it's supposed to help prevent bore glazing in the kind of low load application an engine has in a narrowboat.

 

Pretty sure my oil filter is Bosch, and it gets changed at least twice a year.

 

TBH, if doing the seals, I might get someone in who's more of a mechanic than I, but thanks for the tips.

[David Mutch]

3 hours ago, john.k said:

A bad stem  seal on an exhaust valve leaks oil directly into the exhaust......where it burns with maximium odour and smoke................However ,if you have a  muffler,or something else to produce a certain back pressure ,this resists oil running down the guides to some extent.......The worn rockers indicate that valve stem to guide clearance may also be excessive.............Despite good compression ,oil rings may also be worn to the point of inefficiency.

Thanks John. I think perhaps there's some confusion between my post and magnetman's, as I'm not aware of any worn rockers in my case. 

 

I'm hoping it's not rings, as at that point, I guess it's pretty much engine out, which probably means I may as well get a new one!

 

Not quite sure how to proceed. Seems the only to confirm would be to at least have the head off...

 

I guess I'll completely rule out timing first.

 

Also still have a sneaking suspicion it may have to do with fuel delivery. I'd have thought that a tired pump could cause effectively retarded timing, if it meant the injectors didn't get to breaking pressure early enough in the cycle, perhaps? I realise that may be wishful thinking

[David Mutch]

4 hours ago, Tony Brooks said:

 

First of all as diesels like most of ours do not have a carburetor venturi or throttle butterfly there is way less depression in the inlet manifold to suck oil down the guides. The main thing that might cause a depression is  a paper element or foam air filter so unless your air filter (if you have one) is foam then as you said above, the main time stem oil seals cause smoke is after standing for a while so gravity pulls oil down the seals, especially after an oil change when the oil has flooded the rocker cover. You could try running without an air filter and also lead the breather pipe into a bottle sitting in the engine tray.

 

A far as doing the valve stem seals in situ. If you have a suitable valve spring compressor then it may well be. The piston on a diesel comes to within a few 10s of one thousandths of an inch of hitting the cylinder head so with a bit of luck if you set a piston to TDC it should prevent the valves dropping into the cylinder. However I have never tried it on a BMC but did do it on my Bukh successfully. That was also chasing smoke and made no difference. The Bukh is direct injected while the BMC is indirect but if there is a difference in bump clearance (piston to head at TDC) I would expect it to be marginally greater on the Bukh. I can not guarantee it will work on a BMC but can see no reason why it won't.

 

If you give it a try then once the spring is off lower the valve slightly and wobble it about to assess the  degree of wear in the stem and guide. I also have a feeling the  exhaust valves did not have stem seals when I was rebuilding them but that may be wrong or has changed.

Thanks Tony. Sounds like stem seals may be less likely then.

 

I think I need to have a good look at how much oil it's losing, and at what's coming out of the exhaust. If I don't know if it's oil, diesel or steam (unlikely), then I'm flying blind as far as diagnosis is concerned. 

 

I think it's probably time to get some who knows their onions to take a look!

[Tony Brooks]

10 minutes ago, David Mutch said:

Thanks Tony. Sounds like stem seals may be less likely then.

 

I think I need to have a good look at how much oil it's losing, and at what's coming out of the exhaust. If I don't know if it's oil, diesel or steam (unlikely), then I'm flying blind as far as diagnosis is concerned. 

 

I think it's probably time to get some who knows their onions to take a look!

 

I doubt it is any consolation but I am flummoxed as well.

 

This has little  relevance to you because the 1.5 is indirect injected but on the Bukh I noticed the longer  ran at low seed     and load the worse the smoke became. If I gave it a run on the move at 1500 rpm it would gradually improve. The inland agents confirmed smoking at light load in inland use was a known problem. I put it down to the known tendency of direct injected diesels with small cylinder capacities to suffer insufficient swirl in the cylinders at low speed to properly burn the fuel. This seemed to allow diesel and carbon to build up in the exhaust.  Although it cold started very well and did not seem to suffer excess oil consumption I do wonder if its years in a hire fleet had caused the bores to glaze but never investigated it. My smoke looked light grey rather than blue from burning oil but reading the exhaust smoke is a far from  exact art.

 

I certainly think logging the oil consumption may be a good idea, as may trying a SAE 20W50 or straight SAE 30 grade oil in API CC to CE or CF at a push. More to try to rule out low viscosity oil than much hope of a cure.

[TNLI]

1 hour ago, David Mutch said:

Rock Oil is a major brand, stocked and recommend pretty universally in chandleries I've visited. Used it for 10 years now without complaint (perhaps, admittedly, until now, that is!). I'm assured it's supposed to help prevent bore glazing in the kind of low load application an engine has in a narrowboat.

 

Pretty sure my oil filter is Bosch, and it gets changed at least twice a year.

 

TBH, if doing the seals, I might get someone in who's more of a mechanic than I, but thanks for the tips.

Chandleries have a far higher profit margin that good oil suppliers on Fleabay, Amazingzone or best of all Opie Oils. That means they tend to stock the cheapest junk oil that is not even certified in the EU by ACEA. I wonder why that is? Unless you send off a used oil sample to a company like Blackstones, you really do not know what is in the oil, or how badly your engine is responding.

 

Good you are using Bosch filters, BUT if you change them too often it will result in a far higher wear rate for the main block. A normal cardboard media air, oil, or fuel filter has a random pattern of hole sizes, but those normal hole patterns change when the filter starts to get dirty and many of them become partially blocked up. An oil filter in particular is most efficient when it is nearly blocked, exactly the opposite of what most operators think. 

  So a typical oil filter will stop 95% of 20 micron debris when new, BUT will stop 99% when nearly full. Now you might think that that is only 4% difference, BUT when you are trying to figure out how well a filter works, it's the 100 minus the 95% figure that matters, so 5% of the critical size debris. (It get stuck in bearing races, rings and oil seals), BUT when dirty it lets only 1% of that debris past. That means a dirty filter can easily be 5 times more efficient when well used.

 

Keeping track of oil consumption is a good idea, although sniffing a hot dipstick and rubbing it between your fingers to check the viscosity is worth doing. If the diesel contamination exceeds 5% the human nose should detect it. 2% is the max figure for long term wear rate implications. If it rises above 10% the exhaust will probably start to smell odd and the oil level will start to increase. Often a sign of bad HP or lift pump seals. Using a thick oil like a 20w50 defintely helps keep the viscosity in range.

[David Mutch]

Well, something to report:

 

This afternoon, to some extent out of frustration, I decided to give the old 'Italian tune up' a jolly good go, as a bit of a 'kill or cure'. I don't have a rev counter, so couldn't say exactly to what extent I gunned it, but I'd say I gave it at least 2000rpm, if not considerably higher (certainly more than I'd ever use for any longer than it takes to stop in a hurry), and just left it. The smoke was pretty appalling to begin with, but I held my nerve, and after maybe 3 or 4 minutes, it began to clear. It didn't clear completely (although my nerve didn't hold long enough to find out if it might, if left), but it reduces to what seemed to me a not completely unreasonable level for those RPMs. The temp gauge read considerably higher than I've seen it previously, and oil pressure at idle dropped below 50psi (to maybe 35-40, it's hard to tell on a dial with tick marks every 25psi), but crept back up as the engine cooled off.

 

I'm beginning to wonder whether @Mad Harold might have been on to something after all. Although I've been on the river recently, there was precious little flow, and the smoking issue made me reluctant to really push it, although it still felt like I was pushing it compared to the canal. I think there could be a bit of a negative feedback loop there, with the smoke making me image the worst about my engine, and me therefore taking it easy everywhere, and allowing yet more gunk to build up in my exhaust.

 

I'm also wondering whether @john.k might be on to something with a cold engine. Perhaps mine would be happier with an 82 degree stat? (Don't know if it was just psychosomatic, or whether I was just deaf from the revs, but I could swear the sound improved when the engine got some heat into it too.)

 

I'm not calling it case closed yet, but thought it would be interesting to hear your thoughts on fitting a higher temperature stat, and doing more regular drag races!

[Tony Brooks]

The only reason for a lower temperature thermostat on a tank, keel or heat exchanger boat is to reduce the maximum domestic hot water temperature. No reason not to fit an 88C one and if it proves dangerous (scalding) fit a thermostatic mixing valve if you don't already have one.

 

If the noise is diesel knock you would expect it to reduce with a higher engine temperature because the delay period would be shorter so less unburned fuel igniting at once, so a lower pressure pulse.

[TNLI]

An Italian tune up to max continuous RPM for a few minutes is a good idea if you are using your engine at low power too much. If you do that a short while before shut down each trip it should help keep the cylinders and injector tips clean. Alas it does not solve any main block issues, and could even make some more serious faults like a leaking head gasket worse, although it seems to be a rare for a BMC 1500 HG to fail.

 

Universal type RPM gauges are cheap and easy to wire up to the alternator, although some older donkeys like the totally kaput one I discovered in my boat when first salvaged, have a mechanical RPM gauge. The cable was badly corroded, so I binned it, and a new one is probably not worth thinking about, although I could not find one on fleabay anyway. Typical example of a cheap electronic alternative:

85mm Car Boat Marine Tachometer Diesel Engine Tacho Gauge 0-4000RPM Hourmeter UK | eBay

The waterproof claim is probably rather Iffy, as lots of folks selling instruments say that without any real evidence. It's probably just water resistant to 1m.

 

Edited January 19, 2022 by TNLI

[David Mutch]

4 hours ago, Tony Brooks said:

The only reason for a lower temperature thermostat on a tank, keel or heat exchanger boat is to reduce the maximum domestic hot water temperature. No reason not to fit an 88C one and if it proves dangerous (scalding) fit a thermostatic mixing valve if you don't already have one.

 

If the noise is diesel knock you would expect it to reduce with a higher engine temperature because the delay period would be shorter so less unburned fuel igniting at once, so a lower pressure pulse.

I have a skin tank for cooling, and no calorifier (instant gas hot water), so I think I'll go ahead and change the stat. Thanks.

3 hours ago, TNLI said:

An Italian tune up to max continuous RPM for a few minutes is a good idea if you are using your engine at low power too much. If you do that a short while before shut down each trip it should help keep the cylinders and injector tips clean. Alas it does not solve any main block issues, and could even make some more serious faults like a leaking head gasket worse, although it seems to be a rare for a BMC 1500 HG to fail.

 

Universal type RPM gauges are cheap and easy to wire up to the alternator, although some older donkeys like the totally kaput one I discovered in my boat when first salvaged, have a mechanical RPM gauge. The cable was badly corroded, so I binned it, and a new one is probably not worth thinking about, although I could not find one on fleabay anyway. Typical example of a cheap electronic alternative:

85mm Car Boat Marine Tachometer Diesel Engine Tacho Gauge 0-4000RPM Hourmeter UK | eBay

The waterproof claim is probably rather Iffy, as lots of folks selling instruments say that without any real evidence. It's probably just water resistant to 1m.

 

I've always wondered with one that runs off the alternator whether they have to be calibrated somehow, as I'd have thought it depends on the pulley ratios to a great extent?