Oil for BUKH DV10 Diesel Engine.

Hi Richard
Thank you for your reply and welcome - re the compression test what sort of equipment do I need to make the test?

Let's say the compression is lower than it should be is there any way to work out if it is a warped head/ blown head gasket (repair with the engine in the boat) or broken ring/scored cylinder/hole in piston ( remove engine to repair)
Merry Christmas
David
 
Hoxans said:
Hi Richard
Thank you for your reply and welcome - re the compression test what sort of equipment do I need to make the test?

Let's say the compression is lower than it should be is there any way to work out if it is a warped head/ blown head gasket (repair with the engine in the boat) or broken ring/scored cylinder/hole in piston ( remove engine to repair)
Merry Christmas
David
Click to expand...

No problem David

You need a compression tester and a suitable adaptor to fit your engines injector or glow plug fittings. Personally I've only ever tested petrol engines which have a reasonably standard sized spark plug hole and are very cheap to buy.

A basic diesel one would be something like http://www.amazon.co.uk/20-Piece-Co..._cp_263_3?ie=UTF8&refRID=1BC4GMZJB5J4XNMZAD6W for £27 but whether this has the fittings for your engine is not clear. Probably best to email the seller and see if they can get the info from the manufacturer or perhaps do a search online and see if you can track down some more info on your chosen model of tester.

Alternatively ask your local marine engineer if you remove the injectors or glowplugs (ask them which to remove for your engine) how much they will charge to test it for you. It would be a 10 minute job and they might do it for nothing if they believe they might get the work. If not, they might still charge less that the price of the tester.

The tester will soon show you if the cylinder is loosing compression. If you then put a teaspoon of oil into the cylinder and test again and the pressure increases you know it's not a rings/bore problem and you can probably fix the burnt valve / head gasket by just removing the head. Obviously if the oil addition does not change the compression then it could be a holed piston and the block needs to come off so you might as well take off the head first and see what's what. However, if the piston were holed the engine would be very unlikely to run at all so I don't think you need to worry.

I'm certain it will be the head gasket which is not a major job but do check the head for distortion before refitting as it might well need re-surfacing.

Good luck

Richard
 
b
vyv_cox said:
'Service CC' almost certainly means API CC. This is a very old grade but still widely used in canal boats, taxis, farm equipment, etc. Explanations on my website under Engine>what oil. Morris Lubricants still make it but I doubt you can buy it in any normal outlet, except agricultural. The nearest you will find is API CF-4 as even API CD is virtually unobtainable in UK now.
Click to expand...
The Nisis shop at the petrol station in Llangollen has 20/50 old fashioned motor oil for sale at about £12 for a jug, think its 5ltrs, will check tomoz for the spec
Stu
 
There should be a vacuum in the BUKH crankcase. That is why the engine has a 'vacuum valve' fitted. If there was positive pressure, oil would tend to be expelled past the crankshaft seals, and others.

If I were you, I'd want to have a look at the piston/rings and liner as well. The piston with the conrod is easily removed without lifting the engine provided you have two or three inches clearance under the engine so you can drop the sump.

I'd also want to check the water pump seals. If they were damaged, water can enter the engine via the chain case.

If you don't already have the BUKH workshop manual, you can download it for free.
 
parsifal said:
There should be a vacuum in the BUKH crankcase. That is why the engine has a 'vacuum valve' fitted. If there was positive pressure, oil would tend to be expelled past the crankshaft seals, and others.
Click to expand...

Well I've learned something there. Every engine I have ever worked on has had a positive crankcase pressure caused by piston blow-by. Most have them have a vacuum check valve of some kind but the purpose of that is to vent the positive pressure, usually to the intake manifold. When you remove the oil filler whilst the engine is running the pressure takes advantage of the new escape route.

I would still go for the compression test first rather than drop the sump, even if that were possible in situ.

Richard
 
Hi again Richard,

Thanks for the advice - all makes great sense - will arrange for these tests to be done

A question re the cylinder head - the engine was reconditioned about 5 years ago (400 running hours) and at that time the head was shaved/milled - this was done before I became involved with the boat - I am told that you can only mill/shave this head once because of the valve tolerances - if this is true is there a way of milling/shaving it again and making it work - I don't know a thicker head gasket?

I tried to attach the Bukh DV 8 manual to this email (shows the tolerances) but couldn't work out how to do that - if you have time the DV 8 manual can be easily downloaded from a Google search on the web - it is only a 3 mb file

Once again thanks for all the help
David
 
Hoxans said:
A question re the cylinder head - the engine was reconditioned about 5 years ago (400 running hours) and at that time the head was shaved/milled - this was done before I became involved with the boat - I am told that you can only mill/shave this head once because of the valve tolerances - if this is true is there a way of milling/shaving it again and making it work - I don't know a thicker head gasket?
Click to expand...

That's interesting. I'm not an expert in head reconditioning but whether it can be done more than once must depend upon how much had to be skimmed off the first time. If it was only slightly out of true, as it might be this time if it is at all, then I would hope that only a fine skimming would have been carried out. I can't see any reason why a similar shallow skim would be precluded, if it is necessary ..... which, of course, it may not be.

The only way to be sure would be to have the head checked or do it yourself http://www.superstreetonline.com/how-to/engine/impp-1007-cylinder-head-distortion-check/ is a good guide but there are plenty of others. If the head is distorted, a machine shop will be able to measure the distortion and from the clearances in your manual, be able to calculate whether there is enough metal in the head to enable a further skim. I would be surprised if the valve clearance is so small that a second skim is not feasible but it all depends upon the history and current distortion of course.

Thicker head gaskets are the simplest way of restoring valve clearances in skimmed heads and most car manufacturers will have a range available. However, I don't know whether smaller volume people like Bukh provide such options. You could call them and see what they recommend.

If they can't supply any thicker gaskets then you could certainly have one made, possibly using your old one as a pattern so try the remove it as carefully as possible. If you search online you should find a suitable workshop. It might even be a cheaper option than the proper Bukh part but, either way, it will be far far cheaper than a new cylinder head.

If you persevere there should be no technical reason why the head / gasket combination will not be fixable without spending too much, assuming that's all that needs doing. :)

Richard
 
RichardS said:
Well I've learned something there. Every engine I have ever worked on has had a positive crankcase pressure caused by piston blow-by. Most have them have a vacuum check valve of some kind but the purpose of that is to vent the positive pressure, usually to the intake manifold. When you remove the oil filler whilst the engine is running the pressure takes advantage of the new escape route.

I would still go for the compression test first rather than drop the sump, even if that were possible in situ.

Richard
Click to expand...
New one on me too! Wonder where the vacuum comes from?
S
 
RichardS said:
Well I've learned something there. Every engine I have ever worked on has had a positive crankcase pressure caused by piston blow-by. Most have them have a vacuum check valve of some kind but the purpose of that is to vent the positive pressure, usually to the intake manifold. When you remove the oil filler whilst the engine is running the pressure takes advantage of the new escape route.

I would still go for the compression test first rather than drop the sump, even if that were possible in situ.

Richard
Click to expand...

If you remove the oil filler cap on a BUKH in good condition while it is running and slide a piece of paper over the hole, the suction will hold it in place.

Don't believe me? Try it or ask Al at BUKH Ltd
.
 
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parsifal said:
skipper_stu said:
New one on me too! Wonder where the vacuum comes from?
QUOTE]

A plastic tube connects air intake to a flap valve next to the pushrods. It's illustrated in the workshop manual
Click to expand...

Presumably that's the common non-return (one-way) check valve between the crankcase/cam box/pushrod tube (they're all connected through the oilways) and the intake manifold / air filter that I referred to? I'm very familiar with those but the amount of suction is not usually sufficient to create a vacuum in the crankcase but is more a case of preventing the positive crankcase pressure from getting too high. However I've only ever worked in depth on one single cylinder engine and that had a crankcase breather direct to atmosphere so I'm not disputing your observation. :)

Richard
Click to expand...
 
I think 'vacuum' may be a little overstated, there is a small depression of crankcase pressure. I don't know on the DV10 but on the DV20 there is a small drilling between the inlet ports in the cylinder head. This connects to the diaphragm valve. The drilling becomes blocked with carbon over time and needs to be kept clean but no mention of it in the manual (well, not my version of the paper one that cost me a fortune years ago).
 
My BSA had a timed breather that opened as the pistons were going down, in a an attempt to keep a partial vacuum in the crankcase.
It still sprayed oil around the place, but did attempt to direct the worst of it onto the drive chain.
 
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