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TOPIC: What caused my cylinder head to crack?

What caused my cylinder head to crack? 20 Jan 2022 21:42 #127649

  • Peter Smith
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It’s a strange event Martin has experienced. The Kaboda engines are pretty robust as an industrial engine.
He doesn’t seem to have have had a flooding event where the engine could ingest bulk water.
If there is water in the fuel the filters should remove / trap the water droplets. If the water is emulsified in the fuel it would change from Chardonnay or Rose colour to milky. Injecting fog from the air should not be an issue.
If these checks are negative I would suggest looking at the cooling and if there can be an air lock in the system from time to time ,particularly when coolant is replaced.
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What caused my cylinder head to crack? 20 Jan 2022 14:25 #127637

  • Richard Cooper
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In my experience water in fuel injected will make the engine rattle - then it stops because ithere's not enough diesel to make it run. The rattle is presumably metal to metal contact on big ends and main bearings. It can't be good for the compression rings either - brittle little things they are. I guess eventually real damage would happen. Water coming in via the air intake is. as Paul says catastrophic. Shropshire libraries had a mobile library with the air filter / intake beneath the vehicle, one of the drivers wrote off two separate engines going through big puddles. Ouch.
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What caused my cylinder head to crack? 20 Jan 2022 07:59 #127633

  • Paul Hayes
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Does significant water addition in a diesel crack heads or bend shafts and rods?
Or can do both?

In liquid form, as in my example of a fire appliance in deep flood water, yes, very much so, very quickly, and easily, with catastrophic failure of the engine.

Paul Hayes
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What caused my cylinder head to crack? 20 Jan 2022 02:25 #127632

  • Chris Rowling
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Hi all

Does significant water addition in a diesel crack heads or bend shafts and rods?
Or can do both?

I note the online causes of diesel engines overheating listed include blocked/dirty diesel injectors so bug/dirt could possibly cause it that way.

Cheers
Chris

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What caused my cylinder head to crack? 19 Jan 2022 18:45 #127627

  • Chris Hanley
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If the engine is running, say 1000 rpm and it picks up water in the fuel that water will not compress and the piston will knock against solid incompressible water. You will hear this as a knock. It could be that this was enough to crack something.

Diesel is also uncompressible. Any water in the fuel will be go through the injector pump and get delivered into the combustion chamber as if it was pure fuel. There are two significant differences. 1. There will be a partial burn, which will cause white smoke and may well cause a knock which at higher revs gets smoothed out because they happen at a higher frequency. 2. The other significant problem is that the injector pump relies on the fuel for lubrication. Fuel which has been contaminated with water will cause excessive wear in high pressure fuel pumps. This is most noticeable in pressure jet type central heater boilers (Kabola and similar).
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What caused my cylinder head to crack? 19 Jan 2022 18:23 #127624

  • Richard Cooper
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No Idea why it knocked at 800 rpm but ran ok a bit faster, Just random mysteries I guess, hopefully it will be ok now.
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What caused my cylinder head to crack? 18 Jan 2022 21:47 #127604

  • Martin Jones-Gerrard
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Richard Cooper wrote: If the engine is running, say 1000 rpm and it picks up water in the fuel that water will not compress and the piston will knock against solid incompressible water. You will hear this as a knock. It could be that this was enough to crack something.


So if some water in the fuel tank got sucked into the fuel supply pipe and the fuel/water seperator filter couldn't cope with the volume of water present then some of that water would make its way into the cylinder via the fuel injectors and so if the 'knock' that Richard refers to was the violent misfire that I recorded I can certainly imagine that could have initiated a crack in the cylinder head which could then have propogated over time until coolant entered the cylinder and thus clouds of white smoke became visible from the exhaust.

The only thing I don't really understand is why the knocking occurred at 800rpm but disapeared when the engine speed was raised above 1000rpm. Any thoughts on that would be appreciated.

Cheers,

Martin

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What caused my cylinder head to crack? 18 Jan 2022 17:19 #127592

  • Paul Hayes
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Richard Cooper wrote: If the engine is running, say 1000 rpm and it picks up water in the fuel that water will not compress and the piston will knock against solid incompressible water. You will hear this as a knock. It could be that this was enough to crack something.


We went through flood water in a fire appliance once, sucked water into the air intake and totally wrecked the engine, that made more than a knock, and we certainly heard it🤣.

Paul Hayes
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What caused my cylinder head to crack? 18 Jan 2022 16:38 #127591

  • Richard Cooper
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If the engine is running, say 1000 rpm and it picks up water in the fuel that water will not compress and the piston will knock against solid incompressible water. You will hear this as a knock. It could be that this was enough to crack something.
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What caused my cylinder head to crack? 18 Jan 2022 10:56 #127587

  • Paul Hayes
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Hello Martin

This may be totally bonkers, but it could be a theory that might fit the facts.

Background.

For a while there have been experiments into adding water to the combustion process of diesel.

As I understand it it goes like this.
60% or so of the heat produced in combination is waste.

So if you boil water using some of this heat to make steam it expands, increasing pressure in the combustion chamber, which gives more force on the piston, therefore, more power is produced by the engine.

An internal combustion steam assist engine could be one way of putting it.

Water has been added in three ways, direct injection using a second injector, a mist injected to the air intake, or water emulsified with the diesel.

So expand from this (perhaps), Diesel Bug is biological growth. The biocide kills it.

Some biocide suppliers say something like "The treated biological waste is then injected into the engine and burnt"

So, next step, anything biological contains water, dead or alive.

Your dead Bug, after further treatments there may be quite a lot, are transported to the combustion chamber.

I think that most experiments have been with larger slow running Direct Injection machines, generator, ships, truck type engines.

Could it be that, emulsified Bug was injected into your fairly light weight indirect combustion chamber carrying water with it.

Because of this steam was generated,
which caused during this period of "a small amount of white smoke", However over a period, the increased stresses due to the increased pressure, caused metal fatigue and a micro crack opened to connect one of the water galleries to the cylinder, which allowed larger quantities water into the cylinder, producing large amounts of white smoke (water vapour) to be seen.

As I said this is only a theory, it could be a load of nonsense.

Paul Hayes
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What caused my cylinder head to crack? 17 Jan 2022 12:59 #127564

  • Chris Rowling
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Hi Martin

That is quite cool, I am jealous. Your skin tanks must be impressive.

Mine runs around 90-95 and alarms at 105 (oil pressure sender alarms first). And some poor engineer sat inside and measured the temperatures with another sensor and confirmed the overheating.

Are thermometer sensors ever faulty?

Cheers
Chris

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What caused my cylinder head to crack? 17 Jan 2022 11:30 #127563

  • Martin Jones-Gerrard
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Hi Chris,

Thanks for your reply.

I've not been aware of any overheating problems since I bought the boat. The engine seems to run at a steady 80degrees at my normal operating speed of 1500 to 2000rpm. My engine and generator are both connected to the same keel cooling tank but i've no idea what size the tank is, it runs most of the length of the keel and there is no raw water intake so just relies on heat dispersal through the hull steel I guess.

The boat was in the hire fleet in its early years but the previous owner had it since 2005 and appears to have been a very careful owner. So although the concensus is that overheating is the most likely cause of the problem (and I'll certainly be paying particular attention to the operating temperature in future) i just wanted to discover whether there are any other potential causes for a cracked cylinder head that I should be aware of.
Cheers,

Martin

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What caused my cylinder head to crack? 17 Jan 2022 07:27 #127560

  • Chris Rowling
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Oops sorry Martin

Re read your post.
Check your skin tank size against BM recommendation. Should be bigger than what they say for warmer waters of France. Ours main tank is recommended size but a lot is under with a relatively small vertical side tank. The BM gennie overheats too (12kW at 1500 rpm I would guess) and that has two tanks, second added to try and stop overheating I would wager (and an epic failure). The first tank measures up to BM recommendation.

Did your boat ever do time as a rental? Renters may be he cause of overheating rather than prior owner, there is a tendency to rush back the day prior to handover being due.

Have you one or two fuel tanks?

Cheers
Chris

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What caused my cylinder head to crack? 17 Jan 2022 07:17 #127559

  • Chris Rowling
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Hi Martin

We have a 2005 Beta 75 (Kubota 4 cylinder) in a 139 Euroclassic (a tiddler compared to your 149, ours is 10 tonnes lighter). Our engine is skin cooled and I have noticed that above 1750RPM the skin tank does not cope with the amount of heat produced and the engine overheats if run longer than it takes to heat the calorifiers.

Is yours raw water or skin tank cooling?


Cheers
Chris

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What caused my cylinder head to crack? 16 Jan 2022 21:53 #127558

  • Richard Fiedorowicz
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Hello Martin,
My experience is in diesels being used on generating sets - the smaller engines were all of a similar size to those used in barges - 4 /6 cylinder
Virtually all cracked heads were from over heating - perhaps the previous owner had failed to check the coolant level “as it never goes down”
(until it does 😳)
It could in theory have been the victim of frost damage - with the damage becoming worse with use.
The only other cracking I’ve seen is between valves and this could be fixed by stitching - this tended to be repaired even if superficial and a new seat fitted as they could drop out.

Misfiring is likely to have been a symptom of the cracked head rather than the cause:-
- lower revs = low compression = poor combustion and rough running engine
- higher revs = higher compression = better combustion and problems are hidden for a few hours

The contaminated fuel would only cause the engine to run rough due to a blocked injector (someone else can advise if that’s possible with diesel bug as I have no idea), fail to rev under load due to blocked filter, start and then stop after a period of time due to a blocked filter.

I hope that this years cruising is better for you!

Richard
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What caused my cylinder head to crack? 16 Jan 2022 21:25 #127557

  • John Booker
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I don't have first hand experience of this Beta 75 , the base engine for which is a Kubota v3600, but white smoke in any diesel is either too much or too litt;e fuel to burn properly, too little compression to ignite the fuel or water entering the combustion chamber.. These engines are of the indirect injection type where cobustion takes place within the cylinder head and the hot combustion gasses are squirted out of an orifice on to the piston. Heavy duty direct injection engines are designed to have the combustion take place directly on top of the piston, and they are noisier though more robust for that reason. The cylinder head of an indirect injection engine is a much more intricate casting having to accommodate the combustion chamber entirely as opposed to partially with a direct injection design. This complexity of the casting makes it more susceptible to cracking due to the thin metal sections between the water jacket and combustion space., Uneven or rough running produces violent stresses within the cylinder head, which if not reduced quickly will cause damage. My guess would be that the initial white smoke inicated the start of water leaking from a small cylinder head crack, which then grew progressively to failure. In normal running the combustion process is a smooth ignition and burning rather than a detonation. Detonation causes much higher gas pressures than combustion with an audible knocking sound inside the head. Using ether spray to start an engine will cause similar damage because that causes detonation rather than burning if used to excess. . As indirect injection designs go Kubota are among the best, and are quite tolerant of a little bit of rough running at startup, but there is a limit and that must have been exceeded in this engine.
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What caused my cylinder head to crack? 16 Jan 2022 18:54 #127555

  • Martin Jones-Gerrard
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Its a long tale but there is a question at the end

We bought our boat in July 2018 after it had lain idle for 3 years due to the unfortunate illness of the previous owner. It is a 15m Euroclassic barge built in 2000 and fitted with a Beta 75 keel cooled engine with a PRN260 gearbox.

We enjoyed trouble free cruising during 2018 but in 2019 we experienced a couple of problems.
First I got a little too close to a lift bridge and gave the boat a good bump and shake. We carried on cruising for another hour or so until we reached port but the next day the engine would not start. Investigation revealed that the diesel/water separator filter was clogged with gunge. After a thorough clean and replacement of the filter element and replacement of the diesel filter the engine started again and seemed to be running OK but I had discovered the delights of diesel bug infection. I added a good dose of Marine16 diesel bug treatment to the tank and managed to suck some dirty fuel from the bottom of the tank.

To date I have removed about 30litres of dirty diesel from the bottom of the tank and have had to replace the filters on a couple of occasions as they become too clogged up after about 100 hours of engine running. I have also added a couple more doses of diesel bug treatment.
Then one day we were out cruising when we felt/heard a bump under the boat. I didn’t see anything in the water but assumed we had hit a log or other submerged object. Nothing appeared to be amiss, so we carried on for another hour or so before mooring up for the obligatory lunch break. After lunch the engine started as normal but about 10 minutes later as we manoeuvred into a lock, we experienced a violent misfiring in the engine as I cut the revs to idle speed (about 800rpm). Increasing revs to above 1000rpm overcame the misfiring so we immediately headed to the nearest port about 5 km away via another couple of locks where we again experienced the violent misfiring each time I reduced the revs to idle speed.

Once safely in port I removed the weed hatch cover and discovered that all 3 blades on the propeller were bent presumably as a result of the bump we had felt earlier in the day. Replacing the propeller and adjusting the engine idle speed to 1000rpm seemed to resolve our problems and we were able to return to our home port without further problems.
Then in 2020 during a lull in the pandemic we set off for a 1month cruise. All was going well for the first few days but then one cold morning we noticed white smoke from the exhaust. This appeared to clear after a period of time but over the next few days we saw the white smoke again from time to time until one afternoon we were trailing large plumes of white smoke behind us. The next morning the engine wouldn’t start. A suspected blown head gasket turned out to be a cracked cylinder head.

A new cylinder head was ordered and fitted and the engine now seems to be running smoothly but due to covid restrictions we have only managed to travel about 100km since the engine was repaired.

So the question is; what caused the cylinder head to crack? The violent misfiring experienced that day back in 2019 would seem to be the most likely cause but what caused the misfire? Is it possible that water or muck in the fuel got through to the cylinders and caused the engine to misfire violently at 800rpm but run normally at 1000rpm?

Thanks in advance for all help and advice.

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