white smoke no coolant loss

[Polly Graff]

Hello - I hope someone will be able offer an explanation for this because I'm deeply puzzled. Towards the end of last year I replaced the cylinder head gasket on my BMC 1.5 due to a blue smoke problem. I had the head skimmed by a highly reputable engineering firm then put it all back together. I then started the engine and was shocked to see that the exhaust immediately started producing a massive amount of white smoke. I mean truly massive - so thick that you couldn't see through it. It was the kind of amount that you would expect if there had been a catastrophic head gasket failure and the engine was about to blow up. I can't emphasise this enough - I have never seen so much white smoke. In fact, a small crowd gathered. Probably stupidly, I left it ticking over and the smoking continued unabated for about half an hour. Then, gradually it started to diminish and over the course of about another half an hour it stopped altogether. Again, probably stupidly, I took the boat out and cruised for a couple of hours during which the alternator belt snapped. I have no temperature gauge so I didn't notice at first. Fortunately, I was running with the engine cover open and in the end I noticed a tiny bit of steam coming from near the thermostat housing, so I then realised what had happened, again replaced the belt, and carried on. The next day, forgetting to check the coolant level (I know, I know ...) I started it and it again produced masses of white smoke so I switched it off after a few minutes. Now feeling too despondent to check anything, I decided to walk away and think about it. I've now come back to it today, 2 1/2 months later, checked the coolant level and I find that it has barely moved. So I'm struggling to understand how my engine can be producing that much white smoke with no (or virtually no) loss of coolant (baring in mind any loss associated with the slight overheating due to the belt snapping). Does anyone have any ideas/suggestions, please? My head is getting sore from scratching!

[Tracy D'arth]

If the white smoke is steam and not unburnt fuel from a duff injector or a fuel soaked silencer, then I suspect that the water is being displaced by gas from an imperfect head gasket or crack and that you are creating a gas pocket somewhere in the cooling system, probably the skin tank ( if it has one ).

Try venting the high spots and see if the water level falls.

Are you getting bubbles if you run with the cap off?

You have no charge warning light or temperature warning either?  Sounds like a recipe for disaster.

[MtB]

12 minutes ago, Polly Graff said:

I have never seen so much white smoke. In fact, a small crowd gathered.

 

Smoke seems unlikely. As does steam. Steam tends to vanish quickly rather than hang round to accumulate to the degree members of the public come to observe. 

 

My guess is atomised fuel, which in turn suggests low or no compression on one or more cylinders. Was the engine running "lumpy" when producing this amount of white haze? 

 

 

P.S. What did this 'smoke' smell like?

 

 

[Polly Graff]

Thanks so much for your replies. The white stuff smells like steam and feels kind of damp - and it completely obliterated the buildings behind the boat. The engine seemed to be running normally. It does have a charging indicator light but it was a very sunny day and I didn't notice it was on until I saw the small amount of steam coming from the thermostat area. Fitting a gauge is on my to do list. It didn't boil up - I stopped before it got that bad.

It does have a skin tank. In the process of refitting the head, I removed the stud from the top of the skin tank then filled up with coolant via the heat exchanger until it started pouring out of the top of the skin tank where I'd removed the stud. It took 30 odd litres. I should stress that I'm no mechanic really and I had to learn how to do the work as I was going along which is why it took me about six months to complete the job. (I don't live aboard and I live about 30 miles from where the boat is moored so I can only get to it when time permits.) I've not tried running it with the cap off - I'm assuming that if I try that and I get bubbles, that would be a bad thing? Also - sorry for my ignorance - this is very much a learning process for me and I'm in my seventies - what do you mean by venting the high spots and how do I do it? The only other thing that I can add is that I've had real problems getting a good seal on the rocker box cover, even with a rubber gasket. I think the cover may have a slight distortion. I was planning to sort that out later - so I was running it with a slight oil leak. I don't know if that could be causing a problem.

[Tracy D'arth]

Bubbles in the filler means gas in the cooling system, from either the gasket or a cracked head.

Gas will collect in any high spot in the system, calorifier feeds, skin tank, pipes. It displaces the water, making it look full when it isn't. Vent by letting the gas out from vent point on the skin tank and high parts on pipes and calorifier flow and return pipes.

Did you grease the head gasket?  I always do, or smear with Hylomar on both sides.  Was the top of the block clean and flat?

How did the original head gasket fail and what were the symptoms?

[dmr]

I only have very limited experience of this (on the BMC B series petrol which is the same family).

Mine was filling up with water overnight from a failed head gasket then making a good cloud of steam on startup, but only for a short time till the water had gone. Im surprised that yours goes on for so long as the combustion should push the water out rather than letting it in.

Once you are 100% sure its water and not fuel then its 99.9% certain that the head needs to come off again for more investigation. There are loads of people about who are familiar with that engine.

Its often said "never take an engine apart till you know what is wrong with it" but in your case I think just get the head off.

As you are getting a lot of water in then hydraulic lock is a real possibility and this can cause extensive damage so get the head off now, it gets quicker and easier the more you do it 😀.  I think I had mine off three, maybe four times before I realised that there were a whole batch of dodgy head gaskets at the local shop.

 

As yours goes on for a while before stopping a cracked head might be the explanation.

[magnetman]

Isn't there something with the BMC 1.5D where the head gasket can be put on the wrong way round ? 

 

I've got two 1.5D engines but fortunately never had any of these problems but I'm sure I have read somewhere about this issue. 

 

 

[Tony Brooks]

FWIW, I have also known a 1.5 with cracks in the bore - it was a pig to find and we only did it by dropping a lit light bulb down each bore. Maaybe worth checking if everything else has been done.

 

Is this a wet exhaust boat by any chance, and exactly what type of cooling system do you have (direct raw water, heat exchanger raw water, or skin tank/keel cooling.

 

If you sent the head away to be skimmed, then what happened to the injectors? Who took them out and could one or more pintals have been knocked off the nozzles.

1 minute ago, magnetman said:

Isn't there something with the BMC 1.5D where the head gasket can be put on the wrong way round ? 

 

I've got two 1.5D engines but fortunately never had any of these problems but I'm sure I have read somewhere about this issue. 

 

 

 

I think so, but I think it blocks the rocker oil feed. It may also restrict the coolant path between head and block, but I can't see the producing steam in the exhaust. I might result in overheating, though.

[ditchcrawler]

1 hour ago, Tony Brooks said:

FWIW, I have also known a 1.5 with cracks in the bore - it was a pig to find and we only did it by dropping a lit light bulb down each bore. Maaybe worth checking if everything else has been done.

 

Is this a wet exhaust boat by any chance, and exactly what type of cooling system do you have (direct raw water, heat exchanger raw water, or skin tank/keel cooling.

 

If you sent the head away to be skimmed, then what happened to the injectors? Who took them out and could one or more pintals have been knocked off the nozzles.

 

I think so, but I think it blocks the rocker oil feed. It may also restrict the coolant path between head and block, but I can't see the producing steam in the exhaust. I might result in overheating, though.

Isn't there a problem torqueing the head without a special tool ?

[Tony Brooks]

Just now, ditchcrawler said:

Isn't there a problem torqueing the head without a special tool ?

Yes, unless the rocker shaft is taken out of the pedestals and put back once the head had been torqued down. That is a lot of work and fiddley fitting the rockers, springs and spaces onto the shaft as you slide it into pedestals in situ.

 

Probably easier to buy a suitable crows foot - if you can find one, as the nuts are AF, imperial, not metric.

 

 

[Tracy D'arth]

6 minutes ago, ditchcrawler said:

Isn't there a problem torqueing the head without a special tool ?

You need either the special tool or a 11/16" AF crowfoot wrench.

[magnetman]

Would one of this type work or does it need to be an open ended crows foot ? 

 

 

Open type 

 

 

Britool seems to be the right brand for this although possibly not many in stock. 

Edited January 13 by magnetman
typo

[Tony Brooks]

Just now, magnetman said:

Would one of this type work or does it need to be an open ended crows foot ? 

 

 

 

 

That would work BUT the fact that the socket extension fits to one side of the jaws means you have to be careful to get the correct torque. I am not sure how much difference this makes practically. The BMC too had the square of the extension in a flat that was bent back over the rocker shaft to it was over the centre of the stud

[Tracy D'arth]

If the square is to the side of centre of the bolt, with reference to the torque wrench, not over or before, then the torque will be correct.  In fact it will make very little difference.  Hard to express what I meant!

 

Ah, if the foot is at right angles to the torque wrench, not in line, is what I was trying to describe.

 

Always a ring if it will fit.

Edited January 13 by Tracy D'arth

[Polly Graff]

Thanks again for all these replies and apologies for delay in responding. I ran out of 'boat time' and had to come home. A lot of questions/suggestions have been made so I'll work through them.

 

Thanks Tracey D'Arth - I'll try running it with no cap and if I get bubbles I'll try taking the skin tank stud out again and see if gas or water comes out. It doesn't have a calorifier. If I start disconnecting the top pipes (thermostat housing, pipe that leads to the skin tank, heat exchanger, etc.,) won't that just result in any coolant that is being displaced to the top of the system (i.e., in the heat exchanger and the thermostat housing) pouring out? How will I know if there is gas in there as well? (Sorry these are probably simple questions but I'm new to this.) I didn't grease the head gasket. I thoroughly cleaned the top of the engine block before refitting everything - I couldn't see anything obviously wrong with it. Re the original gasket - I was getting blue smoke and after ruling out obvious things, I took the head off and got the engineer to come and have a look. He checked the bores and concluded they were fine - no evidence of oil burning off that way but he observed that the gasket had blown between the second and third bores and suspected that oil may be getting through to the exhaust system through that. Weirdly, I was not losing oil and never had to top it up. Irritatingly, when the white smoke eventually died down after I renewed the head gasket, I still had the blue smoke problem!

 

Thanks DMR - the white smoke is pure white and, as I said, smells and feels like steam. I do get blue smoke once the white smoke stops. Not masses of blue smoke - just a bit more than I feel comfortable with. I'm not averse to taking the head off again once I've ruled out other possibilities. I got the gasket (and everything else) from Calcutt boats - which I believe are highly thought of - but I suppose a dodgy gasket is a possibility.

 

Thanks Magnetman - yes, I'd read about the possibility of putting the gasket on the wrong way round so kept the old one, stored the right way up, to make sure I didn't make that error. I also looked at various sites on line and You Tube as belt and braces.

 

Thanks Tony - I removed the injectors before sending the head in to be skimmed and stored them in order. I didn't touch them again until I refitted them. I replaced the little copper washers. I did look at the pintals and didn't see anything different to the pictures I had of them. Also, just thought I'd mention that, following on from a previous reply I had from you some months ago, I replaced the 10/40 oil with 20/50 oil for older engines.

 

Thanks Ditchcrawler and Tony - cooling is via a skin tank. There is a heat exchanger but thats just where I top up the coolant. Can't see that it serves any other purpose. I didn't know where to get the correct torquing tool so I took the removal of the rocker shaft, etc., route, so as to torque down in the correct order.

 

However, there may be a torquing problem. The workshop manual indicates 71lb psi for most of the nuts and less (somewhere in the the mid 30lbs psi) for some - I think these were the ones that go through the rocker assembly brackets - sorry the manual is on the boat and I'm not there at the moment. My torque wrench is in Newtons so I had to convert to those from Lb psi. I suppose there is a possibility that I got that wrong. However - if that is the problem, I can't understand why the coolant level has barely moved after running the engine for over three hours producing copious amounts of steam for the first half to three-quarters of an hour. Two of those hours were with the engine under load - cruising.

 

I think I need to check whether I've got air in the system once I fully understand how to do that - I refer to my question above about checking the top pipes - still not absolutely clear how I do that. I think I also need to slacken off all the head nuts in order and tighten them down again this time using an old style, Lb psi torque wrench which I've now acquired (its one of those with a pointer and a scale attached to the business end). Or alternatively, if someone knows the correct conversion formula for Lbs psi to Newtons that would be gratefully received. I've found more than one formula online - hence my slight uncertainty.

 

If these things solve it - all well and good. If it improves it but does not solve it fully, I'll replace the head gasket again. I would still very much welcome any further ideas/suggestions.

 

I can't tell you how grateful I am for all your thoughts and observations.

 

 

[MtB]

4 minutes ago, Polly Graff said:

Thanks DMR - the white smoke is pure white and, as I said, smells and feels like steam.

 

In which case it probably IS steam or water droplets.

 

I wonder if the exhaust system/silencer is managing to fill up with water when the engine is not running. The exhaust gasses blowing through a few litres of water could account for the sheer volume of the stuff you describe.

 

Can you perhaps disconnect the exhaust at the manifold to see if the white smoke is actually originating in the engine itself? 

 

[Polly Graff]

Now that is a thought. To be honest, I can't see how water could be getting into the exhaust system but you never know. While I was doing the work I obviously had to disconnect the exhaust and I had it tied up on the level with a piece of rope for six months. I don't think water could have got into it, as such, but I suppose six months worth of condensation could create quite a build up. I do get a lot of condensation in the engine compartment. When I go down there its often dripping of the underside of the stern deck, above me. Thanks for this thought - I'll try it and see what happens once I've tried a few of the other suggestions I've received. Thanks again.

[Col_T]

A litre of boiling water will convert to 1600 litres of steam, though you would probably notice that much condensation in an exhaust pipe or that much loss of coolant.

[Tony Brooks]

 For clarity - torque is measured in foot pounds (ft lbs) Newton meters (Nm), not psi. I think the numbers are correct, but the units not. Yes, the smaller ocker pestle retaining nuts would be about 30 ft lbs, but they would have nothing to do with the present problem, they don't hold the head down. It would be wrong for the long head studs that also hold the head down. They need to be the same as the other head studs.

 

As long as you start tightening in the middle of the head and work outwards in a circular path, the actual order is not important.

[Tracy D'arth]

I doubt that the blue smoke was/is due to a head gasket leak. Normally it is due to piston ring and bore wear or valve oil seals and guides wear. How much oil does/did the engine use?

You say that this is skin tank cooled but is there any water injection into the exhaust elbow to cool the silencer?

Any chance of a photo of the top of the whole engine?

[Tony Brooks]

On 14/01/2024 at 11:57, Polly Graff said:

Thanks Ditchcrawler and Tony - cooling is via a skin tank. There is a heat exchanger but thats just where I top up the coolant. Can't see that it serves any other purpose

 

I was pondering your problem last night and this phrase seems a bit odd. I think that you probably mean that you have an exhaust manifold that can have a heat exchanger core fitted with two smaller hose connections, but only has the two large hose connections and no heat exchanger core inside. That is perfectly normal for tank cooled boats, but it is probably better not to call the exhaust manifold a heat exchanger because it can confuse. However, sometimes a heat exchanger cooled engine is fitted to a skin tank or keel cooled boat by using the skin tank to cool the water passing through the exchanger core, which in turn cools the engine coolant. This requires another header tank and another pump, usually a brass Jabsco type pump. I don't think you meant yours is like this, but it is a possibility. If so the Jabsco type pumps wear and also need regular rubber impeller changes, otherwise they stop working properly, and you get overheating. I can't see how this would initially cause the white exhaust fumes though.

[Tracy D'arth]

Need that photo.