White vapour only at high revs under load

[Guy J]

43 minutes ago, Tony Brooks said:

 

Thanks, as I suspected. A very nice bit of DIY kit.

 

Now, with the latest photo, here is another very odd thing. The crankcase breather on the rocker cover seem to be connected to the manifold, and that part of the manifold I would expect t have coolant in it, so, unless I have misread the photo the "pipe" in the manifold mus pass through the water jacket into the exhaust tract. That pipe looks like copper or steel to me, so how is it sealed into the cast ally manifold, I ask myself. It is possible cast in or glued, and with the differential in thermal expansion I would be trying to see where that pipe enters the exhaust tact. Seems a potential leak point.

 

Also, I can't recall seeing that rocker cover breather on a marine 1.5D so suspect it may be a petrol rocker cover.

Thanks!  The crankcase breather is not connected to the manifold - it is misleading in the photo - it connects to the air intake via the air filter.

 

[Guy J]

We have attempted a number of tests suggested and have encountered various practical difficulties with uncertainties as outlined below.  

 

Pressure testing of the whole cooling water system proved inconclusive as access problems to all pipe connections made it impossible to rule out slight external leaks causing small pressure drops.

 

Next we drained the Bowman exhaust manifold/heat exchanger, removed the cooling water hoses from this and connected them together via a T section to an improvised header tank as suggested. Running the engine under load above 1500 rpm still produced white vapour from the exhaust as before. However, it seemed impossible to know if there was any remaining water in the Bowman tank as its construction prevents visibility of or probing the tank bottom around the lower section of the exhaust pipe passing through the tank. Wondering if any remaining water in the tank could, as has been theorised, be getting sucked into the exhaust via a crack opening up here, this test seemed possibly inconclusive.

 

Next the head was removed and its cooling water pathways pressure tested by a company specialising in this, with air and boiling water to 30 psi. No leakage was detected. They also tested the head for warping and proclaimed it OK. Now with the Bowman manifold system removed, its tank was filled with boiling water and pumped up to 10 psi. This dropped to about 5 psi after a few hours but was still at 5 psi 12 hours later. No water could be detected exiting from the exhaust pipe connection or from the exhaust manifold ports no mater at what angles the system was held at. We suspect that the initial pressure drop was caused by water and air contraction on cooling and imperfect sealing of the pressure cap when near its blow limit. When tested cold with air and increased tension on the spring in the pressure cap there was an initial drop from from 10 to 7psi which it remained at for many hours.

 

 

If cooling water is not leaking into the exhaust or intake via faults in the head or the Bowman heat exchanger/manifold as indicated by the above testing, can anyone suggest how it could enter via fault/s in the engine block or a faulty seal between block and head to explain continuous clouds of water vapour from the exhaust only under load above 1500 rpm. Also suggestions for any signs of causes of this to look for while the head is off. Reassembling with a new head gasket and trying the suggestion of restricting the water flow to increase the temperature when not under load could be done to prove that this exhaust water vapour emission is caused only by high temperature. This unfortunately was not done before engine disassembly.

Any other suggestions for observation or testing before or after re-assembly would be very welcome.

[Peugeot 106]

Another off the wall idea. If water was trapped in the exhaust pipe /silencer would it be possible that it would only be blown out of the exhaust at high revs. Has rainwater or water from some other  source been finding its way into the exhaust? 

[Tony Brooks]

3 minutes ago, Peugeot 106 said:

Another off the wall idea. If water was trapped in the exhaust pipe /silencer would it be possible that it would only be blown out of the exhaust at high revs. Has rainwater or water from some other  source been finding its way into the exhaust? 

 

I think we need some photos of the total exhaust run, it is possible any water getting into the exhaust could pool in the bottom of the silencer, but that should evaporate away after a time at high power.

[Guy J]

40 minutes ago, Tony Brooks said:

 

I think we need some photos of the total exhaust run, it is possible any water getting into the exhaust could pool in the bottom of the silencer, but that should evaporate away after a time at high power.

Thank you for your replies.  Yesterday we examined the exhaust closely; The end points downwards slightly,as it should, and it has been moored next to another canal boat since the problems started. We tried to see if we could get water up the exhaust pipe by using kettles etc., but it was not possible.  I then used my wet vac, which is very powerful , and it didn't suck anything out at all.  Sadly I therefore think this idea can be discouted.

 

[Tony Brooks]

35 minutes ago, Guy J said:

Thank you for your replies.  Yesterday we examined the exhaust closely; The end points downwards slightly,as it should, and it has been moored next to another canal boat since the problems started. We tried to see if we could get water up the exhaust pipe by using kettles etc., but it was not possible.  I then used my wet vac, which is very powerful , and it didn't suck anything out at all.  Sadly I therefore think this idea can be discouted.

 

 

In that case, I fear we are back to fuel or oil fumes, despite your tests. As burning diesel produces twice as much water vapour than the fuel burned, the white vapour would condense into water droplets, but it is the absence of diesel smell that baffles me. Please let us know if/when you eventually solve it.

 

I once had something similar on a 1.5D and eventually we found a crack in a cylinder wall. It was very difficult to find being down the bore and only saw it when w dropped an illuminated lamp bulb into the bore. Solved by sleeving.

 

 

[Peugeot 106]

Are there any dye penetrant or other tests you could do on the engine to find cracks or porous castings? If the engine is out how about a bench test. Could you run it briefly without coolant?

[agg221]

I think at this stage I would be taking the head back off, removing the pistons and injectors, and checking for cracks in the bores with dye penetrant.

 

Alec

[Peugeot 106]

Probably not relevant but years ago I had a Seagull outboard that misbehaved. It turned out that the casting was faulty (porous) and was leaking coolant. It was  found it with a dye penetrant test

[jim mitchell]

Since (if i read all the posts correctly )  the head is currently off , if you have access to Dye penetrant it would be worth trying the cylinder bores.

 

The pressure tests etc that were done may well not show anything as even boiling water is well below any temperatures generated when running - unjacketed exhausts can easily be seen glowing red at night - one of the main reasons for the jackets is to keep the engine room cool.

 

I don't know how long you ran for at 1500 rpm but any water trapped around the manifold could have given the white vapour until all had completely dried out.

 

Also when reassembled did you do any tests at different loaded speeds for time intervals  to see if the 'vapour appears'

eg  would it appear if you ran at 1450 rpm for X minutes. 

I am just checking that on loading the engine it is not "automatiically" increased in speed and seeking to see if gradually increasing load or speed the vapour can be detected as a wisp that builds as they increase.

 

Providing the manifold is steel/ iron cast and not aluminium  running without exhaust cooling water would do no harm to the engine itself though the engine space will get hot quite quickly.

 

[hider]

I have read this thread and am confounded.

If it is water that is getting into the engine it must be from somewhere at a lower pressure than the cylinders or the exhaust.

The only place with a low pressure in an engine is in the inlet ports.

I bet when they leak tested the head that they tested with the valves in and closed. So they would not know if it was cracked in an inlet port.

[Guy J]

Thanks, again, just to clarify, the engine is in position but the head is off. Will consider your replies now.

[Peugeot 106]

Another daft idea that could do with clarifying by Tony or someone with more knowledge than me. On my engine the crankcase vacuum starts to build at around 1500 rpm where your problem seems to arise. A quick read of google seems to indicate that condensation can build in the oil if the breather isn’t working. Could that cause the white smoke. Tony does earlier say there is something odd about your breather as he thinks it is a petrol cover

On 17/06/2024 at 12:03, Guy J said:

Thanks!  The crankcase breather is not connected to the manifold - it is misleading in the photo - it connects to the air intake via the air filter.

 

On my engine a restrictor is fitted to the air inlet if the engine runs continuously below 1500 rpm I think to increase the vacuum. Would it be worth doing a vacuum test (home made manometer from see through hose stuffed and sealed down dip stick tube)

[Tony Brooks]

9 hours ago, Peugeot 106 said:

Another daft idea that could do with clarifying by Tony or someone with more knowledge than me. On my engine the crankcase vacuum starts to build at around 1500 rpm where your problem seems to arise. A quick read of google seems to indicate that condensation can build in the oil if the breather isn’t working. Could that cause the white smoke. Tony does earlier say there is something odd about your breather as he thinks it is a petrol cover

On my engine a restrictor is fitted to the air inlet if the engine runs continuously below 1500 rpm I think to increase the vacuum. Would it be worth doing a vacuum test (home made manometer from see through hose stuffed and sealed down dip stick tube)

 

On a standard 1.5D (or any other similar engine) three is no connection between the breather and inlet manifold as such. The breather vents into the fresh air side of the air filter and as there is no throttle butterfly it is doubtful if you ever get a depression (vacuum) in the breather. You would get a build up of pressure as speed and hence piston blow by increases. It is known that the oil mist separator inside the side cover that the breather pipe attaches to can block, as can the hose to the air cleaner, so it would be worth taking the side cover off and checking it is clear. We don't know where that breather pipe from the rocker cover goes, but probably into the air cleaner. As far as I know those engines with valves or restrictors in the breather system all vent into inlet manifold where the air cleaner will cause a degree of restriction and thus cause a depression in the breather, especially at higher revs when more air is passing through the air cleaner - however I have difficulty seeing how a wire mash type air filter could create much depression when the breather is on the outside of them.

 

With the rocker cover breather, there may not be one on the engine side plate.

[Bee]

If the head is off I think I would have a really good look at the bores and see if there just might be a crack but it sounds as if the cause is something in the whole engine and not just 1 cylinder. Might be worth detaching as much gubbins from the engine as possible, pipes, hoses, even the air filter just to see what happens if you run it  for a very brief period (Don't wreck it though!)

[Peugeot 106]

2 hours ago, Tony Brooks said:

 

On a standard 1.5D (or any other similar engine) three is no connection between the breather and inlet manifold as such. The breather vents into the fresh air side of the air filter and as there is no throttle butterfly it is doubtful if you ever get a depression (vacuum) in the breather. You would get a build up of pressure as speed and hence piston blow by increases. It is known that the oil mist separator inside the side cover that the breather pipe attaches to can block, as can the hose to the air cleaner, so it would be worth taking the side cover off and checking it is clear. We don't know where that breather pipe from the rocker cover goes, but probably into the air cleaner. As far as I know those engines with valves or restrictors in the breather system all vent into inlet manifold where the air cleaner will cause a degree of restriction and thus cause a depression in the breather, especially at higher revs when more air is passing through the air cleaner - however I have difficulty seeing how a wire mash type air filter could create much depression when the breather is on the outside of them.

 

With the rocker cover breather, there may not be one on the engine side plate.

The breathers on my engine terminate in the inlet manifold as you say. I have done vacuum tests and the change from slight pressure to vacuum occurs at around 1500rpm with or without the filter and rises quickly. You do get more vacuum by restricting the inlet eg hand over it or more restrictive paper filter.

if the breather was blocked you would expect any condensation from the oil discharging into the air inlet to be less. If the air inlet was blocked (knackered air filter or blocked intake) you’d expect more condensation to be pulled into the inlet manifold which could come out of the exhaust. 

 

i’m not convinced by my own theory but am just wondering if something odd is happening at 1500 rpm and whether it could be related to crankcase vacuum in which case it could be worth examining the breather pipes are clear along with the air filter and inlet manifold etc since no other evidence has been found

 

presumably if the pistons are still in a dye penetrant test will not be able to reach the bores underneath the pistons where any cracks could be leaking coolant into the oil. Again as a rooky I’m assuming the water jacket extends under the pistons. Obvious question is there any sign of water in the oil? If not then the cracks in the bores should not leak water into the crankcase but could leak into the cylinders will likely be accessible to the dye penetrant.
 

it’s just odd that this seems to start at 1500rpm. What else other than crankcase  pressure changes at this rpm?

[Guy J]

Thanks very much to everyone for their help and interest.  I will try to reply logically, clearly and comprehensively.

 

As we know, increasing the engine speed to above 1500 rpm under load produces large amounts of water vapour.  As I mentioned, I have run the engine with almost no water in the header tank, and the white vapour is unchanged (Bowman unit almost impossible to empty completely – see previous post again). 

 

It’s been mentioned a few times that water would not be able to ingress the cylinder due to the much higher pressure in the cylinder than the water system. If there had been, for example ,a leak in the seal between the engine and head, why could water not be sucked in on the inlet stroke, when the pressure is much lower and diesel / air are entering the combustion chamber.  The issue would then be, why is it only happening after 1500 rpm?

Regarding the possibility of a cracked seat under the value – the valves were indeed left in situ, and I will call the company who carried out the tests (Gosnay’s Engineering in Romford) to see if / how they were able to check this.

I am currently using fuel from a plastic can,  and I emptied and check this yesterday for signs of water, and there are none.

I have run the engine several times, but once for about 30 mins at quite high revs (in neutral) in order to reach its normal operating temperature  and to boil off any water vapour that may have accumulated in the manifold.

Regarding the symptoms, I have run the engine in neutral up to about 3000 rpm with  no sign of water  vapour. Returned to neutral, went into gear (boat tied up) and slowly increased the revs. On approaching 1500, traces of white vapour appear, then a slight increase in engine speed produces clouds of white smoke; it is not possible to do this for long as people think the boat is on fire!

To answer some more points – I’ve been testing with no breather pipe attached from the rocker cover.  The configuration is as follows: one tube from the rocker breather, one tube from the engine breather (side of the crankcase) teed together to go into the air intake.  These have all been disconnected for testing so there is no extra gubbins around.  I have checked the breather pipe from the engine, and it is unobstructed.  There are no other engine symptoms at 1500 revs except the white vapour.

 

Regarding the potential problem with a vacuum in the crankcase breather – this pipe has not been connected for a while so a vacuum would not be possible.

I will now buy some engine dye to test the block head and, I hope, the cylinders too.  Is there any reason I can’t test the cylinders, two at a time, taking care with the dye itself.

 

[Peugeot 106]

It’s all very odd as it seems to be on/off. Water isn’t being chucked  into air inlet or onto/into exhaust is it at certain revs when in gear? Would be interested to see if anything happens in reverse though load won’t be as big

[StephenA]

37 minutes ago, Guy J said:

Thanks very much to everyone for their help and interest.  I will try to reply logically, clearly and comprehensively.

 

 

Regarding the symptoms, I have run the engine in neutral up to about 3000 rpm with  no sign of water  vapour. Returned to neutral, went into gear (boat tied up) and slowly increased the revs. On approaching 1500, traces of white vapour appear, then a slight increase in engine speed produces clouds of white smoke; it is not possible to do this for long as people think the boat is on fire!

 

 

 

 

Steam doesn't hang round like that - especially on a warm day. If it's hanging round enough for people to think the boat is on fire then it really sounds more like smoke (of some sort) rather than steam

 

Any chance of video footage?

[agg221]

56 minutes ago, Guy J said:

Thanks very much to everyone for their help and interest.  I will try to reply logically, clearly and comprehensively.

 

As we know, increasing the engine speed to above 1500 rpm under load produces large amounts of water vapour.  As I mentioned, I have run the engine with almost no water in the header tank, and the white vapour is unchanged (Bowman unit almost impossible to empty completely – see previous post again). 

 

 

I will now buy some engine dye to test the block head and, I hope, the cylinders too.  Is there any reason I can’t test the cylinders, two at a time, taking care with the dye itself.

 

There are two different types of dye penetrant testing. Either should work but the approach is slightly different for each.

 

With both types, you start by getting everything wiped absolutely clean and free from oil and grease. You need to use a solvent for this because you need to get the oil and grease out of any cracks or the dye can't get in. There are spray solvents sold for the purpose but I tend to wipe down with a very wet lint free paper or cloth saturated in white spirit, then wipe dry and repeat until it looks clean, then do the same again using acetone or gunwash thinner (it takes a lot less solvent this way and you are working with your head quite close to it so the vapour isn't great).

 

One type of dye is fluorescent, the other coloured intense purplish red. The dye is sprayed on and left for the specified time to soak in, then the surface wiped free of dye using a piece of lint free paper or cloth damped with solvent. The aim is to get it clear but not soak any dye out of cracks.

 

If you have used the fluorescent dye, you then inspect it with an ultraviolet light. If you have used the coloured dye, you spray on the developer which is basically powdered chalk. Timings before inspection are usually quoted on the can. Cracks will be obvious by the colour. If you use the fluorescent dye then no clean-up is really needed, but if you use the coloured dye the chalk needs wiping off.

 

Alec

[jim mitchell]

Probably a silly thought but since the fault arose suddenly and after working around the engine.

 

Is this a wet exhaust system ?   is a water lubricated  'cutless' bearing fitted to the prop shaft  ?

and supply to that bearing from the water injection supply line ? 

 

I.e.  could running the prop shaft at 1500 +   be creating hydrodynamic pressure and adding or starving the  water injection to the exhaust such that the resultant water vapour is created ?

 

In which event, have the bearing supply / return lines been inadvertantly swopped  over where they join the exhaust system ?

[Bee]

A timing issue (Too retarded?) will create quite a lot of white vapour - not steam - but this does not seem to fit your problem. (Just walk past a haulage yard on a cold morning and watch half a dozen old British lorries starting up - if you can find any!) Its the 1500 rpm bit that I can't understand. Is there any emulsified oil under the rocker box?

Edited July 14 by Bee

[Guy J]

On 14/07/2024 at 14:07, Peugeot 106 said:

It’s all very odd as it seems to be on/off. Water isn’t being chucked  into air inlet or onto/into exhaust is it at certain revs when in gear? Would be interested to see if anything happens in reverse though load won’t be as big

Thanks again.  Water is not being chucked into air inlet or onto exhaust when in gear - the engine is well inside the boat away from the weed hatch and any other water sources.  I have been testing the engine in reverse only, with the stern pushing against the bank.  

 

Regarding the white vapour emitted from the exhaust, it is definitely water of some sort (as explained in previous posts) but, as you say, it doesn't look or behave like steam.  I have attached a picture showing this, I don't think you can attach videos..

 

I have used Parweld dye on the block top surface, with no indication of cracks.  The head has already been pressure tested.. so i haven't dye tested this.

 

The boat has a traditional grease-lubricated stern gland, well away from the engine which is inside the cabin.

 

There is no emulsified oil under the rocker cover.

 

I am considering replacing the head, with a new head gasket, and performing a test previously suggested, by restricting the cooling water flow and revving not under load to increase the temperature to determine if the white emissions from the exhaust are caused only by a temprature increase and not by some other effect of putting the engine under load.

 

As I am clutching at straws rather, I thought I would ask if anyone can confirm that the test I did for water vapour or diesel is definitive?  I am aware that a small amount of water comes out of the exhaust of all diesel engines, and that it doesn't mix with diesel.  To clarify, I caught some vapour in a 10l plastic container, it condensed and I tasted a drop or two.  There was no hint of diesel, and the vapour doesn't smell of diesel, either.

 

Before I reassemble the engine, can anyone suggest any other tests I can do while the head is off?

 

 

[jim mitchell]

Can you dyepen the cylinder bores  two at a time with them at BDC, i recall Tony saying he once found a crack in the bores ( a very rare occorance)  and it was cured by sleeving that cylinder - might be worth the try while dismantled.

 

also if you can rig a tall plastic litre bottle half filled with cold clean water and bubble the exhaust through it - maybe at 1450 rpm?  ( so some vapour but without appearing to be on fire) ) and then leave it to cool etc  any diesel present (even if emulsified at first) should separate out overnight and be seen as a distinct top film layer.

 

May at least prove all the vapour is from a water source.

[Peugeot 106]

 

Is the condensed water you collected coloured with antifreeze? I’d be taking the exhaust manifold off and pressure testing it. Maybe the company that did your head could test it. I realise you have already tested it but it does sound like the culprit

I realise that you’re not keen to take it off as it’s awkward but they are susceptible to rot and frost damage and it would be worth eliminating it as a possible cause as it is full of water with the exhaust passing through it so to me is an obvious candidate

I bought a cast iron one that was rotten to the core when I tested it!

 

could you run the engine briefly

with it off? you will have no coolant so don’t run for too long

 

also some engines eg Luster Alpha engines that use direct cooling have the direct water injection straight out of the manifold into the exhaust. When they are used for indirect cooling eg skin tanks the hole coming out of the manifold is blanked off with a gasket. This can leak coolant into the exhaust.

Also if yo can easily run with the exhaust disconnected try that

 

also (I dob’t know why) try it in forward rather than reverse

 

best of luck I expect you are really fed up