Engine Adfvice Please - BMC 1800

[Radio-Ga-Ga]

As far as valve clearance goes set them to the makers gap, a bit too wide just causes an extra bit of noise, but never set them too tight, it can cause valve and seat burning (valve opens to early closes too late)

 

If the clearances continualy get tight it usualy indicates a valve or seat problem. so worth checking again after some more hours. no suggestion thats the case here, they often change shortly after rebuilding.

 

Best of luck with it.

[RobinJ]

A bigger gap means the valves clear the pistons by more not less

Well spotted, I was trying to explain why the 1500 has them set to 0.015" and the 1800 0.014", so I really meant smaller!

[Albion]

Update on this, if any of those who have given advice is prepared to ponder it a bit more......

snipped

 

He has no immediate suggestion for other engineers in the area, so I can really only start phoning around to see who might help, (or start buying the required tools myself!).

Unfortunately to torque a 1.8 head properlyyou need a special crow's foot ring spanner (was a Churchill special tool some years ago) to get under the rocker shaft. I happen to possess one from when I rebuilt and marinised my own 1.8

 

He confirms that pressure testing the head involves sealing all holes, then pressurising with air, to look for cracks or other leaks.

Exactly

 

He says failures of oil-ways in BMC head gaskets are rare, as there are much bigger margins there, and they are not the bit that ever usually fails. Anyway failure of a brand new gasket would be very rare, if the head has been skimmed.

I tend to agree if it has been installed correctly and with care

 

He believes problems with valves valve seats, or valve guides could not be this intermittent.

Again, I tend to agree

 

He can only still suggest a possible misbehaving injector, and says part combusted diesel may look like oil, and not smell of diesel.

Hhmm, not so sure. When diesel part combusts you are left with some burnt fuel and some unburnt fuel.........and what does unburnt diesel fuel smell like.........a bit like diesel fuel in my opinion. It is possible that the partially burnt fuel droplet is coloured black by carbon but should still smell of diesel fuel IMO. However, partial/incomplete combustion usually results in white smoke during the occurrence and I don't remember you mentioning that this droplet problem was always accompanied by or preceded by white smoking. I'm not entirely convinced by an intermittently erratic spray pattern on a mechanical injector. Might be worth removing them and having them crack pressure tested and spray pattern examined as that is relatively easy and cheap to do (beware of getting the tip seals left down the injector hole and they are a once-off use anyway). It might eliminate the injectors from the equation but be prepared for a 'no-problem-found'

Roger

[alan_fincher]

Hhmm, not so sure. When diesel part combusts you are left with some burnt fuel and some unburnt fuel.........and what does unburnt diesel fuel smell like.........a bit like diesel fuel in my opinion. It is possible that the partially burnt fuel droplet is coloured black by carbon but should still smell of diesel fuel IMO. However, partial/incomplete combustion usually results in white smoke during the occurrence and I don't remember you mentioning that this droplet problem was always accompanied by or preceded by white smoking. I'm not entirely convinced by an intermittently erratic spray pattern on a mechanical injector. Might be worth removing them and having them crack pressure tested and spray pattern examined as that is relatively easy and cheap to do (beware of getting the tip seals left down the injector hole and they are a once-off use anyway). It might eliminate the injectors from the equation but be prepared for a 'no-problem-found'

Roger

 

Thanks for all the continuing advice.

 

I understand what you are saying about the diesel, and am, I'll admit, struggling to believe that the black oily stuff that neither looks nor smells like it actually started life as that.

 

That said, I can't see if it's oil, how it can be getting there in such an intermittent way.

 

I'm not using any significant oil, that I can see.

 

I'm still trying to get my brain around what the gap on the tappets being set slightly too small could have meant....

 

I guess it must mean, as said, that if anything the valves open too soon, and close too late, (and by a bit too much at their maximum).

 

At it's most extreme, if completely overdone, I assume they might not close fully at all, but see no evidence that they are (or were) that far out.

 

I don't know where to go from here, really......

[MoominPapa]

I don't know where to go from here, really......

I can't remember if any conclusion was reached about the crankcase blow-by system?

 

It might be worth completely disconnecting any crankcase connection from the air filter and making temporary alternative arrangements for it, just to be sure that it's not dumping the occasional slug of oil down the inlet.

 

 

MP.

[Albion]

I'm still trying to get my brain around what the gap on the tappets being set slightly too small could have meant....

 

I guess it must mean, as said, that if anything the valves open too soon, and close too late, (and by a bit too much at their maximum).

That is correct if too tight by a reasonable margin. In that case you would not get correct compression and then this would encourage incomplete combustion and white smoking. In your case though I seem to recall you said that it was only the difference between an easy sliding fit and one where the feeler would start but not cleanly slide through the gap. If that is the case then you wouldn't affect the compressions significantly

 

At it's most extreme, if completely overdone, I assume they might not close fully at all, but see no evidence that they are (or were) that far out.

If they had been this bad you certainly would have noticed a misfire and white smoking and you would have, eventually, burnt out the valves. There is no way that your engine was that bad.

 

I know it's not of huge help but I think you need to take it for another extended run and carefully note what seems to happen before and during teh spitting event (if it recurs of course).

 

The only other mystery event that I've had once on the engine that I marinised was a faulty non-return valve on the outlet of the injection pump (just where the injector pipes are attached to the pump). That little adaptor looking device is a non-return valve and caused some start up misfire/uneven running for me once. I'm not suggesting that it is the answer to your particular problem but it illustrates how many, not immediately apparent, sources of problems there are.

 

Roger

[Radio-Ga-Ga]

If they had been this bad you certainly would have noticed a misfire and white smoking and you would have, eventually, burnt out the valves. There is no way that your engine was that bad.

 

I know it's not of huge help but I think you need to take it for another extended run and carefully note what seems to happen before and during teh spitting event (if it recurs of course).

 

Hi Albion couldn't quote from your response.

 

I agree with both of these points. I never did think valve clearances were an issue, but got drawn into it when somebody who did gave some avice that wasn't quite right.

[RLWP]

I can't remember if any conclusion was reached about the crankcase blow-by system?

 

It might be worth completely disconnecting any crankcase connection from the air filter and making temporary alternative arrangements for it, just to be sure that it's not dumping the occasional slug of oil down the inlet.

 

 

MP.

 

What he said. It's good advice

 

Richard

[alan_fincher]

I know it's not of huge help but I think you need to take it for another extended run and carefully note what seems to happen before and during teh spitting event (if it recurs of course).

Still struggling to find an explanation to this.

 

To recap, tappets have been checked, and initial running on the mooring failed to produce anything spat from the exhaust.

 

So this weekend it has been to Aylesbury and back over two very hot days, (circa 8 miles and 18 locks each way).

 

In synopsis:

 

1) Starts well - no excess smoke.

2) A couple of hours before anything noted from exhaust.

3) Not being run particularly hard at this point - although possibly one of the slightly shallower bits.

4) Not massively "spitting" this time, even if opened well up - more a residue running down from exhaust, that then forms a small slick on the surface.

5) No excess smoke of any type at this stage.

6) Didn't last too long - most of the trip there's nothing serious, although hard to prove how much delay there is between anything being produced in exhaust and the time it appears at the outlet, either spat out, or running down.

7) On day 2 there was similar evidence of a bit of residue after an hour or twos running, but possibly less severe.

8) If it's oil, it can't be much of it - I'm still not having to top it up.

9) There is no evidence that I'm loosing coolant.

10) We really cannot smell diesel at all in the residue if we wipe some up with a clean rag.

 

This is not a mega-problem, (yet!), but it never did this before.

 

I've not experimented with the breather arrangements yet, though.

 

Any further thoughts, please ?

 

To the cynics who said "has your engineer really broken his leg ?", all I can say is that if it's a hoax, it's an elaborately maintained one! He was at the fracture clinic, leg fully plastered, as I was in having my broken pelvis reviewed. A third boater was there too - we seem keen on fracturing things!

[paulcatchpole]

It's not 'slobber' is it, Alan?

 

Brief description from the first google hit I could find:

 

Oil, fuel, or coolant leaks

 

Most often, oil leaks are not in fact leaks but the result of “wet stacking” (or “engine slobber”) caused by excessive no-load run time. Diesel engine generators are designed to operate with a load — most effectively in the 70% to 80% range of rated output. When generators operate considerably below the rated output level, the engine can start to over-fuel or “wet stack” and damage the engine.

 

Wet stacking — an accumulation of carbon particles, unburned fuel, lube oil, condensed water, and acids in the exhaust system — is caused by low-combustion chamber temperature. When a diesel engine wet stacks, the engine will need to be cleaned up by loading the unit for a few hours and burning off the excess fuel. If a diesel engine generator steadily runs loads considerably below the rated output level, you should pair the generator with an automatic load bank, which will place a false load on the generator system, keeping the engine properly loaded and preventing a “wet stack” condition.

 

This sort of thing is mentioned on the stationary engine forums quite a bit...

 

PC

[RLWP]

<snip>

Any further thoughts, please ?

<snip>

 

Yes! You have an old BMC that starts clean, runs fine, doesn't use oil and doesn't use water. What on earth are you worrying about?

 

We will all be better off when your pelvis improves and you can take the helm again and start doing some proper boating!

 

Richard

 

[alan_fincher]

Yes! You have an old BMC that starts clean, runs fine, doesn't use oil and doesn't use water. What on earth are you worrying about?

 

We will all be better off when your pelvis improves and you can take the helm again and start doing some proper boating!

 

Richard

 

Despite having a BMC 1800, I do aspire to "mildly green" credentials. (OK, I know the two hardly go hand in hand, but scrapping an elderly slightly unclean engine, and manufacturing a replacement one is probably less environmentally "friendly" than trying to keep it going!...)

 

I don't like leaving any oily fluids on the cut, even in small quantities, and even if I don't know what they are.

 

In the bilge, in small amounts, for safe disposal I can live with, but I don't want to be "doing a mini BP" to the waterways!

 

I consider a round trip of the Aylesbury Arm is "proper boating" BTW. All the thrills of the GU, but without the slightest chance of the irritation of the wide beams!

[RLWP]

Despite having a BMC 1800, I do aspire to "mildly green" credentials. (OK, I know the two hardly go hand in hand, but scrapping an elderly slightly unclean engine, and manufacturing a replacement one is probably less environmentally "friendly" than trying to keep it going!...)

 

I don't like leaving any oily fluids on the cut, even in small quantities, and even if I don't know what they are.

 

In the bilge, in small amounts, for safe disposal I can live with, but I don't want to be "doing a mini BP" to the waterways!

 

I consider a round trip of the Aylesbury Arm is "proper boating" BTW. All the thrills of the GU, but without the slightest chance of the irritation of the wide beams!

 

Then, to salve your concious, take a sample and get it analysed properly, not just asking some blokes on the internet

 

Richard

[alan_fincher]

Then, to salve your concious, take a sample and get it analysed properly, not just asking some blokes on the internet

Oh but you are all just so much more than "some blokes!".

 

I agree it would be helpful to know that "it's engine oil", "it's diesel" or even that "it's whale blubber", and it would help narrow the hunt.

 

I would probably still be looking for help as to why its coming from my exhaust pipe, though, (particularly if it's the whale blubber.

[paulcatchpole]

Look, I don't mind my shlobbber suggestion being ignored, but I'm having a hard time getting CreamCheese to stop tittering about the phrase 'wet stacking'...

 

I value my contribution, worthless though it might be...

 

 

PC

[sociable_hermit]

Oh but you are all just so much more than "some blokes!".

 

I agree it would be helpful to know that "it's engine oil", "it's diesel" or even that "it's whale blubber", and it would help narrow the hunt.

 

I would probably still be looking for help as to why its coming from my exhaust pipe, though, (particularly if it's the whale blubber.

).

[alan_fincher]

Look, I don't mind my shlobbber suggestion being ignored, but I'm having a hard time getting CreamCheese to stop tittering about the phrase 'wet stacking'...

 

I value my contribution, worthless though it might be...

 

 

PC

Not ignored, Paul, but I can't get my brain around why it might "slobber" now, when it didn't before.

 

Or indeed to "slobber" at sometimes, but not others.

[paulcatchpole]

Not ignored, Paul, but I can't get my brain around why it might "slobber" now, when it didn't before.

 

Or indeed to "slobber" at sometimes, but not others.

 

Sorry Alan, I really wasn't having a go!

 

I happened to spot it on some of the stationary engine forums whilst reading up on bearing designs and failure modes, and thought of your problem.

 

No idea really if it's that relevant, but something to add to the knowledge in the background perhaps.

 

Richard's right, I think - time to either ignore it or get it analysed to see what it is.

 

PC

[Mrs Tawny Owl]

Richard suggests (because it's my turn on the computer and I won't let him on!!) that you mop a bit of it up on a paper towel.

 

If you let it dry a bit you should then be able to see if it disappears or stays oily.

 

If it just leaves a dry deposit it's probably water with soot in it, if it stays oily it's probably engine oil. Give it a sniff and that should tell you if it's diesel.

 

He also offer the option of fitting sails to get rid of the problem. (Would be greener too).

 

Sue, (under instruction.)

 

When talking of being green I consider the 1L per hour I use for my holidays, starting only 5 miles from home to be much greener than jumping on a plane, even with a BMC 1.8

 

Richard is also with you on not replacing a perfectly good working engine to get a more efficient one, the car he drives daily is nearly 40 years old.

[MoominPapa]

When talking of being green I consider the 1L per hour I use for my holidays, starting only 5 miles from home to be much greener than jumping on a plane, even with a BMC 1.8

It would take an awful lot of persuasion to get me up in a plane powered by a BMC 1.8. A Lister, on the other hand would be fine, since I'd know it would be too heavy to get into the sky where the falling-down danger is.

 

 

MP.

[Grace and Favour]

It would take an awful lot of persuasion to get me up in a plane powered by a BMC 1.8. A Lister, on the other hand would be fine, since I'd know it would be too heavy to get into the sky where the falling-down danger is.

 

 

MP.

 

MP - - Falling down from the sky is a much overrated danger . . . .

 

By far and away the vast majority of the falls are perfectly safe - even exhilarating (!)

 

It's only the last millimetre of each fall that causes any problem

[Evo]

Just out of interest, anyone know where you can get piston rings for a BMC 1.8. All the engine reconditioners in Coventry seem to have disappeared, there used to be 4 or 5 now I cant find a single one.

[alan_fincher]

Just out of interest, anyone know where you can get piston rings for a BMC 1.8. All the engine reconditioners in Coventry seem to have disappeared, there used to be 4 or 5 now I cant find a single one.

ASAP Supplies lists availability in a +0.020 inches and + 0.030 inches sizing.

 

They only show standard size as "Unpriced Item", please mail for availabilty.

 

Are you sitting down.....

 

The priced ones list at £152.36 per set, after online discount applied!

[RLWP]

Just out of interest, anyone know where you can get piston rings for a BMC 1.8. All the engine reconditioners in Coventry seem to have disappeared, there used to be 4 or 5 now I cant find a single one.

 

Midland Cylinder Rebores still appear to have a 'phone number:

 

Midland Cylinder Rebores

Torrington Avenue, Coventry, Warwickshire CV4 9BL

p: 02476471124

 

Looks like they moved.

 

Richard

 

There's a place up by B&Q (the big one, not the Alvis one) that supplies rings and so on to most of the country. I'll try to remember their name for you

[alan_fincher]

Richard suggests (because it's my turn on the computer and I won't let him on!!) that you mop a bit of it up on a paper towel.

 

If you let it dry a bit you should then be able to see if it disappears or stays oily.

 

If it just leaves a dry deposit it's probably water with soot in it, if it stays oily it's probably engine oil. Give it a sniff and that should tell you if it's diesel.

 

It stays oily.

 

I really can't see if it were largely water based, why it should form a rainbow like slick on the canal surface, it it runs down the hull-side. Water mixed with water doesn't usually do that, even with a bit of soot in.

 

I have said repeatedly there is no discernible smell of diesel.

 

I think it's oil, even without getting it analysed, and am only trying to get people's best guess as to how it's ending up there.

 

Although Richard may seem to think I have time on my hands, I really, REALLY, do not like leaving even a small slick of oil on the canal surface. I don't even like leaving spotting on the surface.

 

This has (so far) only looked fairly bad once, but the last thing I want to do is end up miles from home with it having got appreciably worse.

 

Hence my persistence in trying to get it sorted now.