Is this a blown head gasket or what else could it be?

Conachair

Conachair

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Doesn't really look like it to me. Bukh DV20...

Symptons were (apart from not starting) :
Grey oil, rusty rocker arm and obvious water under the rocker cover
blow back through air intake (from the timing of it seemed to be just from one cylinder) & film of oil round the intake and inside the air filter housing.

So if it isn't the head gasket what could it be?

Or must it be the gasket?

Sponsered walk coming up for a new engine :mad::mad:
 
From the symptoms, clearly something is wrong.
Now that you have the head off, you will need a new gasket anyway. Carefully check the head for cracks and the valves and valve seatings for pitting.
If all this is ok, I would have the head skimmed. Put back together and you don't need new walking shoes :)
 
possibly on picture 3 left cylinder bottom left corner there is a blow, but there is so much mess and corrosion around that its difficult to tell.

If that was my engine, i would get the head sent to a machine shop for a check skim (minimum thickness) and then remove the studs from the block and scrape it back to shiney metal, then check the block for warping with a feeler gauge and straight edge
 
The block face looks pretty crapulous as well so it could do with a skim at the same time. The problem could also be caused by a crack or porosity in either casting which would require a good clean and pressure testing to find.
 
TNT said:
was there any smoke before it stopped?
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I was running it every couple of weeks for half an hour or so, then one day it wouldn't start, one cylinder of the injector pump was siezed so got that fixed, now this :mad:

New engine as soon as I can get some money together anyway, just need to get it running so I can at least move. Feels like good money after bad at the moment but not much choice in the matter.
 
First of all clean up the head and block surfaces. A scraper and then wet and dry used with paraffin as a lubricant.

Inspect for cracks or corrosion.

Do not have the head skimmed unless it needs it. Any decent engineering shop with a surface table will tell you if it is bowed but if it has not been overheated then bowing is unlikely, not impossible but unlikely.

If the head is not bowed and there is no evidence of surface damage I would fit a new head gasket and see if it runs.

The blow by is bad news if there is no evidence of head gasket failure as it means ring failure of some sort almost certainly.
 
I'd fit new head studs. That area around the stud hole between the cylinders looks like it's had some gas leakage at the least. Perhaps it wasn't torqued down sufficiently or maybe the stud has gone elastic.
 
[QUOTE
Grey oil, rusty rocker arm and obvious water under the rocker cover
blow back through air intake (from the timing of it seemed to be just from one cylinder) & film of oil round the intake and inside the air filter housing.
So if it isn't the head gasket what could it be?
Or must it be the gasket?
Sponsered walk coming up for a new engine :mad::mad:[/QUOTE]

Tried to enlarge your photos but poor results... difficult to see with any certainty.
I'm no expert at all, just an interested party...... 'thinking out loud'.........
If you say it quickly....and "stick a new gasket on and try it", it will at least eliminate that.

Grey oil, water under the rocker cover, blow back through air intake... if all that was happening and it was the gasket I'm surprised it isn't obvious to the eye... however, I'm wondering if it's a combination of gasket and poor valve seating??
If you do stick a new gasket on there and problems still exist then try and eliminate the good cylinder and work on areas involving the sick one.

I'd be taking more advice from diesel mechanics generally as well as those that have had Bukh experience.
I've also scoured the Bukh postings but couldn't spot anything similar, although I reckon it would be more of a general engine problem this and not peculiar to Bukh.
http://www.ybw.com/forums/showthread.php?t=278912
Good luck
S.
 
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Conachair said:
So if it isn't the head gasket what could it be?

Or must it be the gasket?

Sponsered walk coming up for a new engine :mad::mad:
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Unfortunately the pictures are not very good so you will have to look at what you have there and decide yourself.

The area on the block which forms the compression seal IE the 10 mm immediatly around the bore should have a uniform surface in appearance and colour. It should be smooth without any signs of grooving across it. The pictures suggest this is not the case.

The same area on the head seal surface should be the same with no areas of dark shadow or grooving.

The head gasket will also show if there has been blowby as it will have black shadowing or grooving where this has occured.

Some pictures suggest there has been more than a little blow by so I wonder if you have been using easy start...An easy way to overload the engine and stretch the head studs!!!!!

The blow back could be a sticking inlet valve and the stuck fuel pump plunger could have been a broken spring caused by salt contamination.

The water in the oil could have been either sea water leakage or excessive short term running the engine while cold and so not able to get rid of condensation.

You can not just machine diesel heads and blocks willy nilly as this can affect the compression characteristics. Check with Mr Bukh. If you have been using easy start of have started the engine when water has been on the pistons then I would suggezt a new set of head studs as some of yours could have been stretched. The gasket , head and block do actually suggest there has been major blow by but this could just be poor lighting for the camera. Maybe you could describe what the surface immediately around the bore appears to be like then we can comment further.

It is possible to check your studs if you have a good mechanic handy with a good torque wrench as stretched studs display obvious characteristics when an attempt is made to take them up to full torque.
 
Conachair said:
View attachment 12755
View attachment 12756
View attachment 12757

Doesn't really look like it to me. Bukh DV20...

Symptons were (apart from not starting) :
Grey oil, rusty rocker arm and obvious water under the rocker cover
blow back through air intake (from the timing of it seemed to be just from one cylinder) & film of oil round the intake and inside the air filter housing.

So if it isn't the head gasket what could it be?

:
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Cracked cylinder head. Pal had exactly the same symptoms and thats what it turned out to be. Get the head pressure tested by a decent engine outfit and then you will know.

And proper repair will be far cheaper than a new engine
 
wotayottie said:
Cracked cylinder head. Pal had exactly the same symptoms and thats what it turned out to be. Get the head pressure tested by a decent engine outfit and then you will know.

And proper repair will be far cheaper than a new engine
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Hi, is this typical of Bukh twins or Bukh generally or did said friend have a different engine?

Bukh seem fantastic engines but of course some are a bit long in the tooth I guess??
 
The head mating surface looks pretty bad to me.I can't tell from the photos if the head has the concentric rings machined on.If not that means it has been skimmed already which means that most certainly it cannot be done again.I had a Bukh engine fill with water through a hole at the bottom of one of the liners.Corrosion was the cause.The simptoms were similar to what you have.A cracked head is also likely.These heads massive as they are are very easy to warp or crack if overheated.
 
Scotty_Tradewind said:
Hi, is this typical of Bukh twins or Bukh generally or did said friend have a different engine?

Bukh seem fantastic engines but of course some are a bit long in the tooth I guess??
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Nope. He had a Bukh twin in a Sadler. We struggled for ages to find the problem because there clearly was water in the oil but no sing of a breach in the head gasket. To make things worse the first engine shop said they had pressure tested the head when they hadnt so we tried a lot of other things and re-fitted the head twice at the cost of head gaskets. To be fair they subsequently paid our extra costs but it was still a PITA.

Yes it is a fairly common Bukh problem but the engines are so designed that they are well worth re-building rather than replacing. Apart from anything else, the cost of the auxiliaries for a replace is silly,
 
from the boat, with fixed head...

Hi
sympathy..!
Have you heard of crack detector? Two aerosols. clean up and spray on red oily one, wipe off, spray on white powdery stuff. Red soaks out of cracks and shows them. You can test the bores as well as the head.
My Yanmar single cyl showed some white smoke but after it refused to run, it would start if the water was turned of. Stopping when water was allowed to circulate.

Not a solution obviously but a clue.

My head cost 20 pounds to skim and 40(!) for the Yan gasket...

I'll rephrase that, the boat's head skim cost....:D

Good luck

Nick



Nick
 
Perhaps if before taking the head off you had done a Compression Test the problem would have been evident. Anyway without reading all the other posts before you replace the cyinder head take the head to an engineering works and have it checked to see if it has warped. thus causing the gasket to blow.
I once bought a horsebox off a lady who had a garage replace a blown cylinder head and the garage said that the head was ok . 500 miles later the head went again and the garage refused to do anything saying it was the engine. The lady could not afford to have the garage take the engine out so I bought it. Had the head off and an engineers shop said that in engineering terms the head was "Shaped like a banana" but to the human eye, it was perfect. Anyway on a two cylinder head a check should only cost peanuts. And on Ebay the other day there was a Diesel Compression Tester for sale.
The only other time I have had "Blowback" on a diesel is when I had a "Richard Head" working for me and we were towing a dumper to start and he had it in reverse so consequently the engine started going backwards with the exhause as the inlet and the inlet as the exhaust.
 
Head:- cheaply and easily checked.

Get a piece of 6 or 8mm float glass from a Glazier.

Stick some 800 grit wet & dry to it with spray mount.

Move the head around the paper in a figure of eight for about five minutes.

Examine Head. You ought to have a nice uniform matt surface.

If not, how big are the bad bits?

I've flattened a couple of diesel engine heads like this (you just need to do it enough to get a uniform finish over most of it)

Mounting the sheet of glass on a bit of 3/4 exterior ply, take the studs out and you can flatten the block as well.

You don't usually remove more than a couple of thou' this way, skimming will always take a bit more, 10 or 20 and this can seriously effect the comp ratio.

The Dye Penetrant idea was good if you suspect a crack. Diesel engines ought to be a bit stronger than that though.

You might be getting blowback if the guides are knackered, too.

I brought a deep sea seal back to life this way (not for beginners this). I used progressively finer grit and started with 6000. I finished it with barkeeper's friend straight on the glass.
 
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Thanks for all the help guys.

All I can do really is clean it up and stick the head back on, got a new gasket already. And see what happens.

The engine is history already, too many problems with it and way underpowered for the boat so all i need is short term propulsion. Throwing money at this one ain't the way to go.

I'll post the next installment. :)
 
wotayottie said:
Cracked cylinder head. Pal had exactly the same symptoms and thats what it turned out to be. Get the head pressure tested by a decent engine outfit and then you will know.

And proper repair will be far cheaper than a new engine
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Photos attached ( possibly taken by phone (?) are not very clear and details are lost, however I would agree with above sensible comments and start with a pressure test on the cylinder head and crack detection before doing any machine work on it. As for the condition of the lube oil, and presence of oil in the air intake (where the crancase breather pipe is possibly connected) it strongly suggests worn out compression or possibly broken piston rings or damaged cylinder leading to poor compression- assuming valves are tight- and consequently to poor or not at all starting.
 
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