Engine Adfvice Please - BMC 1800

[alan_fincher]

O.K.

 

A new problem on Chalice for you people to mull over, please.

 

Our BMC 1800 runs fine, but has recently had its head gasket renewed, which involved also a second-hand replacement head, after the previous one was found to have several cracks, in one case resulting in a core plug not being held in place.

 

Although it never let us down before, there was evidence of the head gasket having had multiple failures, and it now runs a lot smoother than previously.

 

However,

 

Some time after this was done, it started spitting a black oily fluid from the exhaust. Some gets blown out, and forms light spotting on the canal, whereas some runs down the outside of the hull, creating a very thin small slick around that area of the counter, (not severe, but a little of course looks worse than it is).

 

However, it was neither doing this initially, and in fact has only done it rarely so far, and seems to fairly quickly correct itself, so that you would not then know it had happened, other than a bit of deposit below the outlet.

 

It has proved difficult to catch enough to establish what it is, but it is "black and oily"! My guess is it's black because of the carbon from the exhaust, and this doesn't necessarily mean it was black before passing through the exhaust.

 

My original thought was engine oil, but if it is, it's not enough to cause it to go down on the dipstick. I'm now increasingly thinking it's unburned diesel.

 

It seems to me if it were oil, (perhaps because the second-hand head or valve stems are not up to standard), it should be doing it all the time, but it is not. There seems to be no rhyme or reason, and you can do the same kind of manoeuvres a few minutes later, and it will have stopped.

 

I should add that prior to this the injectors were taken to a specialist recommended by forum members, and in fact what we got back were exchange, not the originals. However these were fitted before the head was off, and this intermittent problem has only started since.

 

My issue, because it only happens rarely, is that if I "get a man in", it's highly unlikely to do it when he visits.

 

Ideas, anybody, please ?

 

What is my mystery black fluid, and how do I stop putting any in the cut ?

[Nightwatch]

Hi Alan

 

Could it be the gunk that has collected in the exhaust over the months/years of running, (becoming loosened by condensation/cleaner air from the correctly running engine) being blown out?

 

An extended sentence/question I believe

 

As I have said before, I know a little about a lot so if you think this is nonsense then please ignore and I will possibly go away.

 

 

Martyn

Edited May 4, 2010 by Nightwatch1

[Albion]

O.K.

 

A new problem on Chalice for you people to mull over, please.

 

Our BMC 1800 runs fine, but has recently had its head gasket renewed, which involved also a second-hand replacement head, after the previous one was found to have several cracks, in one case resulting in a core plug not being held in place.

 

Although it never let us down before, there was evidence of the head gasket having had multiple failures, and it now runs a lot smoother than previously.

 

However,

 

Some time after this was done, it started spitting a black oily fluid from the exhaust. Some gets blown out, and forms light spotting on the canal, whereas some runs down the outside of the hull, creating a very thin small slick around that area of the counter, (not severe, but a little of course looks worse than it is).

 

However, it was neither doing this initially, and in fact has only done it rarely so far, and seems to fairly quickly correct itself, so that you would not then know it had happened, other than a bit of deposit below the outlet.

 

It has proved difficult to catch enough to establish what it is, but it is "black and oily"! My guess is it's black because of the carbon from the exhaust, and this doesn't necessarily mean it was black before passing through the exhaust.

 

My original thought was engine oil, but if it is, it's not enough to cause it to go down on the dipstick. I'm now increasingly thinking it's unburned diesel.

 

It seems to me if it were oil, (perhaps because the second-hand head or valve stems are not up to standard), it should be doing it all the time, but it is not. There seems to be no rhyme or reason, and you can do the same kind of manoeuvres a few minutes later, and it will have stopped.

 

I should add that prior to this the injectors were taken to a specialist recommended by forum members, and in fact what we got back were exchange, not the originals. However these were fitted before the head was off, and this intermittent problem has only started since.

 

My issue, because it only happens rarely, is that if I "get a man in", it's highly unlikely to do it when he visits.

 

Ideas, anybody, please ?

 

What is my mystery black fluid, and how do I stop putting any in the cut ?

 

One question Alan. When does it do this spitting? Is it on first start up, when it has got warm or is it completely random?

Roger

[NB Esk]

Alan, I'd go for oil before fuel. If it had been a road vehicle, there wouldn't be much in the way of evidence at this stage.

 

Once it has cleared, does it do it again before it's shut down? How *second hand* was the head? Was it overhauled with new stem seals? Is there any difference in the colour of the exhaust fumes?

 

If it just does it the one time, it could be a dislodged or hardened stem seal, letting oil thro' to accumulate in the exhaust...

[alan_fincher]

One question Alan. When does it do this spitting? Is it on first start up, when it has got warm or is it completely random?

Roger

Sorry,

 

Not really specific on that, was I ? Sorry!

 

On our most recent trip, we noted it doing it within a few miles of leaving our mooring, but I can't say for certain when it started - I don't think it was immediately.

 

Whilst we were analysing "is it bad enough to force us to go back", it stopped doing it, so we carried on, and it was not seen again that day.

 

The next day it definitely was not doing it from cold, but after an hour or so as we pulled up for a lock, it was really not that good.

 

So we tried to bend down and actually catch what was coming out, but, apart from not really expecting to get hit quite so firmly by the deflected heat, I really only collected mostly soot, and not much liquid - it could have been anything oily, really.

 

It cleared quite quickly after that, and was not spotted again for the next two days.

 

I'm guessing that of the 50 miles we did at the weekend, for no more than about two of them was this a problem. However I'm obviously worried about it becoming a pollution creator away from home.

 

The randomness of the event to me squares more to me with "intermittent injector" problem, than an "oil getting past something" problem, but I have very little relevant knowledge. It doesn't cause rough running, but at one point when I revved it out of gear, the engine actually stalled as I dropped it quickly back to idle. It's never done that before, (or since).

 

It does seem to be idling a bit slower than it was, (all the time). Closer to 600rpm than the book figure of 650 rpm that it was hitting consistently before.

 

Once it has cleared, does it do it again before it's shut down?

Didn't seem to, at least on this weekend's trip

 

How *second hand* was the head? Was it overhauled with new stem seals? Is there any difference in the colour of the exhaust fumes?

 

The engineer, (well regarded on BMCs), did not seem to know the history of the head, (or at least was not telling me!).

 

I know it was "pressure tested", (whatever that means!), and skimmed as part of the deal.

 

There is no significant difference in exhaust fumes before and after the head swap.

 

I'm no exprt, but it throws "white smoke" sometimes if opened up too fast, (which I assume to be unburnt diesel), and some blueish smoke if revved to hard for it's elderly years, (which I assume to be burnt oil, although I very rarely need to top up between oil changes, so it can't be a lot).

 

If it were valve guides/seals, would it be so intermittent ?

[RLWP]

It sounds like condensation in the exhaust collecting "crap" and carrying it out as droplets. I wonder if your engine is running cooler now it's been sorted out?

 

Richard

[MoominPapa]

It sounds like condensation in the exhaust collecting "crap" and carrying it out as droplets. I wonder if your engine is running cooler now it's been sorted out?

 

Richard

Ours does that from cold, and it's quite easy to tell that the liquid is water: you can mop it off the roof and not see any oil "sheen" (chimney exhaust, not side-pointing one.) That doesn't tally with Alan's description of an oil sheen on the water where the stuff lands.

 

MP.

[Nightwatch]

It sounds like condensation in the exhaust collecting "crap" and carrying it out as droplets. I wonder if your engine is running cooler now it's been sorted out?

 

Richard

Does that sounds like something another member has suggested?

 

Martyn

[alan_fincher]

Ours does that from cold, and it's quite easy to tell that the liquid is water: you can mop it off the roof and not see any oil "sheen" (chimney exhaust, not side-pointing one.) That doesn't tally with Alan's description of an oil sheen on the water where the stuff lands.

 

MP.

What is running down from the exhaust outlet is definitely oily if you put your fingers in it.

 

It has to be engine oil or diesel, because there are no other fluids it could possibly be present in the engine.

 

Although the droplets spat onto the water are small, they produce the obvious rainbow pattern of something oil based.

 

I can believe there may be a load of historic soot in the exhaust, but the other things just should not be there.

 

If it was "residual crap" being ejected, I'd expect it to happen more at high revs, but little at idle. That's not what's happening.

 

Nobody has picked up on a possible injector malfunction. Is that unlikely, then ?

[Albion]

Sorry,

 

Not really specific on that, was I ? Sorry!

 

On our most recent trip, we noted it doing it within a few miles of leaving our mooring, but I can't say for certain when it started - I don't think it was immediately.

 

Whilst we were analysing "is it bad enough to force us to go back", it stopped doing it, so we carried on, and it was not seen again that day.

 

The next day it definitely was not doing it from cold, but after an hour or so as we pulled up for a lock, it was really not that good.

 

So we tried to bend down and actually catch what was coming out, but, apart from not really expecting to get hit quite so firmly by the deflected heat, I really only collected mostly soot, and not much liquid - it could have been anything oily, really.

 

It cleared quite quickly after that, and was not spotted again for the next two days.

 

I'm guessing that of the 50 miles we did at the weekend, for no more than about two of them was this a problem. However I'm obviously worried about it becoming a pollution creator away from home.

 

The randomness of the event to me squares more to me with "intermittent injector" problem, than an "oil getting past something" problem, but I have very little relevant knowledge. It doesn't cause rough running, but at one point when I revved it out of gear, the engine actually stalled as I dropped it quickly back to idle. It's never done that before, (or since).

 

It does seem to be idling a bit slower than it was, (all the time). Closer to 600rpm than the book figure of 650 rpm that it was hitting consistently before.

If it were an injector problem then I would expect to see white smoke (incomplete combustion) rather than spitting out of droplets. If you get one of these droplets on your hand and it is diesel then it will reek of diesel, not just a slight whiff, but if you haven't had white smoking and possibly some misfire at the same time then I doubt that it's fuel.

It has slight symptoms of coolant leakage from the description. You have to ask yourself what has changed compared to when it wasn't doing it and, I'm afraid to say that it's another (second-hand) head, and the work to fit it. Something in those few words holds the clue to the problem. I agree that it is not likely to be valve stem oil seals as it is so intermittent and yet it is difficult to be sure. If it were a petrol engine with the manifold vacuum that they run then it could be valve stem seals after a period idling but, in the case of a diesel they don't run with significant manifold depression (assuming a clear inlet tract, clean air filter and no brake booster vacuum developing throttle there as if it were in the Sherpa van).

I'm assuming that the second-hand head wasn't reconditioned before it was supplied to you? Any signs of coolant loss or bubbles in the coolant? Is the engine running at the same temperature as previously?

Roger

[RLWP]

Does that sounds like something another member has suggested?

 

Martyn

 

Maybe. If it's wrong, you can take the credit

 

Richard

[steamraiser2]

I've come across this before. Firstly check all the valve clearances to ensure that one is not a tiny bit too tight. That can cause the valve not to seat correctly and reduce the compression on that particular cylinder. Consequently unburnt fuel will blow out of the exhaust as the affected cylinder is'nt firing properly.. If you start an engine with a load of diesel hanging around in the exhaust you could well see white or grey smoke for quite a while. An important thing to bear in mind is that if the muck in the exhaust is residual it will clear pretty quickly.. if it keeps on doing it the fuel (or oil) is still getting in to the exhaust system.

 

As you have had the head off its adviseable to get the head torqued down and the tappets set after a few days running anyway. Also..just to further depress you..if you have a cylinder that is not firing correctly you will be washing the lubricating oil off the top of the bore which will quickly wear out your piston rings on that cylinder. So my advice is to check out the valve clearances etc asap and to try and determine if the emissipn is fuel or oil. Fuel should be easy to fix as described. If oil is coming out I would suspect that the rings are worn or broken. Or..that the head gasket is leaking across an oil way. Either way get your spanners out sooner rather than later.

[alan_fincher]

If it were an injector problem then I would expect to see white smoke (incomplete combustion) rather than spitting out of droplets. If you get one of these droplets on your hand and it is diesel then it will reek of diesel, not just a slight whiff, but if you haven't had white smoking and possibly some misfire at the same time then I doubt that it's fuel.

It has slight symptoms of coolant leakage from the description. You have to ask yourself what has changed compared to when it wasn't doing it and, I'm afraid to say that it's another (second-hand) head, and the work to fit it. Something in those few words holds the clue to the problem. I agree that it is not likely to be valve stem oil seals as it is so intermittent and yet it is difficult to be sure. If it were a petrol engine with the manifold vacuum that they run then it could be valve stem seals after a period idling but, in the case of a diesel they don't run with significant manifold depression (assuming a clear inlet tract, clean air filter and no brake booster vacuum developing throttle there as if it were in the Sherpa van).

I'm assuming that the second-hand head wasn't reconditioned before it was supplied to you? Any signs of coolant loss or bubbles in the coolant? Is the engine running at the same temperature as previously?

Roger

Thanks - helpful, albeit rather depressing, if your fears are correct.

 

No, the head was not fully reconditioned - it was taken to a firm for skimming, (the engineer reckoned this greatly increases the chances of a gasket replacement being problem free), and was also "pressure tested", (whatever that means!). The valves were not removed at all, I believe.

 

The engine has an 82 degree thermostat, and runs rock steady at about this on the temperature gauge. But then it always did, even though the old head was found to be cracked, and the gasket having at some time been blowing in multiple places, so the cooling system seems able to deal with the engine potentially generating more haet than it should.

 

I've not noticed coolant loss, but this is masked by the use of a hose from the overflow into an unpressurised expansion bottle, so it would not be that obvious - I will check.

 

What's being ejected doesn't seem to smell of diesel, so reluctantly I guess it has to be oil. (It certainly looks more like oil. )

 

Excuse my ignorance, but if a defective head is allowing engine oil into the exhaust, what kind of potential failure(s) are we looking at, please ?

 

Clearly I need to raise again with the engineer, but if I can't demonstrate it doing it when I call him, I can imagine problems in convincing him.

 

Reliable people on BMCs seem hard to come by, but this man has been recommended by reliable forum members.

[Nightwatch]

Maybe. If it's wrong, you can take the credit

 

Richard

Thanks for that!

[alan_fincher]

As you have had the head off its adviseable to get the head torqued down and the tappets set after a few days running anyway.

Hmm it has had more than a few days running.

 

The engineer advised the need to re-torque it but only at anywhere between 50 and 100 engine hours. I tried to book this recently, but he was heavily committed to other work, (he has a wooden narrow boat!), and said it was not critical. As I'm now getting towards the higher of those numbers I'd like to get it done, but am not equipped to do so myself, and don't really want to try involving someone else.

 

That said, checking tappets is within my scope, so perhaps I can try that.

 

I can't really see why a wrongly set tappet would be that intermittent though, I'll admit.

 

Anyway thanks for all advice, even if I'm not liking what I'm hearing.

[jenlyn]

Thanks - helpful, albeit rather depressing, if your fears are correct.

 

No, the head was not fully reconditioned - it was taken to a firm for skimming, (the engineer reckoned this greatly increases the chances of a gasket replacement being problem free), and was also "pressure tested", (whatever that means!). The valves were not removed at all, I believe.

 

The engine has an 82 degree thermostat, and runs rock steady at about this on the temperature gauge. But then it always did, even though the old head was found to be cracked, and the gasket having at some time been blowing in multiple places, so the cooling system seems able to deal with the engine potentially generating more haet than it should.

 

I've not noticed coolant loss, but this is masked by the use of a hose from the overflow into an unpressurised expansion bottle, so it would not be that obvious - I will check.

 

What's being ejected doesn't seem to smell of diesel, so reluctantly I guess it has to be oil. (It certainly looks more like oil. )

 

Excuse my ignorance, but if a defective head is allowing engine oil into the exhaust, what kind of potential failure(s) are we looking at, please ?

 

Clearly I need to raise again with the engineer, but if I can't demonstrate it doing it when I call him, I can imagine problems in convincing him.

 

Reliable people on BMCs seem hard to come by, but this man has been recommended by reliable forum members.

 

its unburnt fuel mixed with crap from your exhaust, put a screw driver on the rocker cover and listen to the rockers/tappets, a distinct tappit noise may emit from the cover, then needs adjustment

[RLWP]

Thanks for that!

 

Sorry Martyn, I have a task I'm avoiding which is making me a bit spiky. Yes, you did point it out first and I missed it when I skipped through the thread first time.

 

Looks like it's not a popular theory though. Major engineering problems seem to suit Alan better

 

Richard

[Albion]

Thanks - helpful, albeit rather depressing, if your fears are correct.

 

No, the head was not fully reconditioned - it was taken to a firm for skimming, (the engineer reckoned this greatly increases the chances of a gasket replacement being problem free), and was also "pressure tested", (whatever that means!). The valves were not removed at all, I believe.

Skimming ensures a clean flat face against which the gasket mates. It's a common practice but, with diesels you do have to be a bit careful because a small skim can increase the compression significantly. From memory most diesels are allowed only one skim and some very modern ones none at all. However, we are talking a 1.8 so they are a bit more tolerant. The pressure testing is to check for cracks in the casting etc that cannot be seen by the naked eye because they are too small or somewhere not visible. Again, fairly standard practice. I'm not overjoyed that the valves weren't removed, checked and lapped. You would check for stem/guide wear at the same time and, of course, when you're in that far would do new stem seals providing the valve guides weren't worn as that would knock out the new stem seals quickly

 

The engine has an 82 degree thermostat, and runs rock steady at about this on the temperature gauge. But then it always did, even though the old head was found to be cracked, and the gasket having at some time been blowing in multiple places, so the cooling system seems able to deal with the engine potentially generating more heat than it should.

You would tend to get increased pressure in the cooling system with those faults

 

I've not noticed coolant loss, but this is masked by the use of a hose from the overflow into an unpressurised expansion bottle, so it would not be that obvious - I will check.

 

What's being ejected doesn't seem to smell of diesel, so reluctantly I guess it has to be oil. (It certainly looks more like oil. )

 

Excuse my ignorance, but if a defective head is allowing engine oil into the exhaust, what kind of potential failure(s) are we looking at, please ?

Valve guides and/or stem seals into the cylinders and then into the exhaust but I would expect to see some bluish smoke. Having said that the diagnosis of engine smoke isn't easy for anyone as differing colours can mix and create an apparently different colour. For example, you can get a mix of white (incomplete combustion) mixed with blue (oil burning) and it can look greyish

 

Clearly I need to raise again with the engineer, but if I can't demonstrate it doing it when I call him, I can imagine problems in convincing him.

 

Reliable people on BMCs seem hard to come by, but this man has been recommended by reliable forum members.

 

 

its unburnt fuel mixed with crap from your exhaust, put a screw driver on the rocker cover and listen to the rockers/tappets, a distinct tappit noise may emit from the cover, then needs adjustment

 

There is just one slight flaw with this idea though in that the proposal was that the compression was reduced and misfire occuring due to a tight tappet. If it is tight then you won't hear it tapping. That's why you should check valve clearances irrespective of whether they are rattling or not.

Roger

[paulcatchpole]

Sorry Martyn, I have a task I'm avoiding which is making me a bit spiky.

Richard

 

Hope that's nothing to do with our stern tube and shaft setup...

 

PC

[RLWP]

Hope that's nothing to do with our stern tube and shaft setup...

 

PC

 

No, it's a task set by your employers

 

Richard

 

University of Warwick undergraduate

[Radio-Ga-Ga]

Personaly I would give more credance to the condensation point made earlier, as the engine appears to be running ok any oil or fuel in the combution chamber is going to be burned, if a cylinder was running so badly that fuel or oil was passing into the exhaust there would be a noticeable loss of performance. hopefully at some stage when you catch some of the liquid it will evaporate off your hand leaving carbon behind, and put your your mind at rest.

[DHutch]

Of cause otherwise, you could just run it, and forget about it until it dies, or being a bmc, probably never!

 

Not really want to want to hear after spending money on it to be fixed however, i quite understand.

 

 

Daniel

[LEO]

Hi Alan,

 

Interesting problem, but the chances of that particular engineer causing problems by overlooking something is remote.

 

Prior to the repair you had probably been running the engine with a chronic fault for years - this will have caused the exhaust to carbon up and the current problem may be cured by cleaning out said exhaust.

 

Diesels throw out lots of bits of carbon and it may be these settling on the water.

 

Bearing in mind the work you had done. I would have the cylinder head nuts re-torqued sooner rather than later.

 

Try the simple things first, these BMC's are getting a bit 'long in the tooth' and really are being used in an strange environment for a diesel (although in your boat it may be being 'opened up' more than most).

 

Bearing in mind the age of design and manufacture of these BMC's perhaps they should be considered as 'Vintage engines' and one has to make allowances for the age and unknown history of the engine/head (although to be fair the engineer appears to have checked it over, skimmed it and pressure tested it before fitting it).

 

You could always take your boat to the Engineer for checking over.

 

Adopt the 'Kiss' policy with a bit of Michael Winner mixed in.

 

Leo.

 

Editted - I first used the word 'Thrown' with regard to Michael Winner - whilst many would like to see him thrown in the canal, I quite like the guy.

Edited May 5, 2010 by LEO

[nb Innisfree]

If it were an injector problem then I would expect to see white smoke (incomplete combustion) rather than spitting out of droplets.

Roger

 

True but I used to own an Audi Turbodiesel which developed a diesel leak between the fuel pump and fuel tank which resulted in diesel leaking when parked overnight and leaving air in the fuel line. When I started next day it would misfire for a while and throw out lots of blue smoke, as soon as the air was purged from the fuel line it ran normally. Never been able to work that one out.

[David Schweizer]

Hello Alan, (you are honoured to get my first response since my last hopital visit - more about that when I summon sufficient energy)

 

Sorry to sound a pessimist, but what you describing is very similar to the early symptons with the BMC 1.5 on our boat before it finaly decided to become smoke generating machine. At that point it was spewing engine oil out of the exhaust and the bandaged flexible section of pipe was saturated with oil, and a little oil seems to go a long way, causing a minimal drop in the engine oil level shown on the dipstick. In other words, despite the fact that it was still perfoming well, the engine was thoroughly knackered (worn bores, worn valve stems, worn camshaft, worn big ends, etc) and had to undergo a full re-build.

 

You have not mentioned the history of your engine, however you did once tell me it's origins, and there are those in the Midlands who have very little good to say about the people who reconditioned your engine quite a few years ago. To quote one engineer, " They replace as little as possible,- only anything that is seriously worn, but leave in place anything that will last a few years after the warranty runs out.

 

I would suggest that you need to speak to a reliable engineer who is independant of all the big places making lots of money from the boating world, and secure an honest assesment. I think you know who I would recommend, but if you want details PM me.

 

P S thanks for the PM last week I will reply some time.

 

David

Edited May 5, 2010 by David Schweizer