Diesel (Bukh) starting oddity

[jerryat]

Hi Vic,

Many thanks for your thoughts. Whilst it's true that the joints have been re-made several times over the years, I always use new copper washers, gaskets etc on re-assembly.

I have run the engine for up to an hour at a time (as well as a much longer period motoring around) while checking each and every joint with tissue paper, which is the best thing I know of for showing up the slightest weep. Nothing at all.

Taking off the cylinder head is incredibly simple, takes no more than half an hour. and would at least eliminate another possiblilty.

Cliff is absolutely right about the fantastic knowledge and back-up Bukh owners get from Al Pearson and Norman Griffiths, with whom I've discussed my engines since 1985. Happily, SWMBO is keen now to replace the engine for the sake of her 'peace of mind' and, given that we're shoving off within 3-4 weeks and could be away for three years or more, I'll think we'll go down that route.

It does mean that someone will get a great bargain when I sell the existing engine!

I'll certainly let you all know what the problem is as soon as I know. Chatting to Al again today, we are both edging towards a faulty head gasket as the next logical thing to check - hence me whipping the head off next week.

Thanks again to all who've taken the trouble to reply. /forums/images/graemlins/smile.gif

 

[misterg]

At the risk of entering a granny/egg situation:

Have you tried bleeding the injector pipes while the engine is running? (i.e. just slacken off each union in turn, just a smidgen until you get a diesel weep, then tighten up again.)

Used to work on tractor engines running a bit rough - perhaps eliminates miniscule air bubbles trapped in the union?

Andy

 

[jerryat]

Hi misterg,

Definitely not a granny/egg thought! It's easy to forget the obvious when really puzzled about a problem.

Yes, we bleed the fuel through to the injectors by (usually) decompressing and turning the engine over until clear fuel arrives. The unions are then nipped up lightly and the engine started. Each union is then backed off a half turn until fuel appears (engine obviously briefly runs on one cylinder) then finally tightened.

The more I think about this one, the more I'm moving towards oldharrys thought of a cylinder head gasket problem. The reason we did so much on the fuel side of things was that Bukh and Lucas were 'pretty sure' that was the problem, though they were basing their views on the fact that compression was fine in both cylinders.

However, as the (comparatively) slow initial starting has got a tiny bit worse each of the last three times, it could well be that the gasket is breaking down at some point.

Clutching at straws maybe, but I'll have a look next week.

Good news is that whatever the cause, we have ordered a new Bukh 24 that will be delivered on Tuesday and that I'll fit in place on Thursday. I'll take the existing engine home, whip the head off, and let you know if the head gasket is the culprit.

I certainly wouldn't have bought a new engine if we hadn't been (aiming!) at a long cruise to the Med/Caribbean so soon, but with all the other things to organise, this was the simplest solution. It also relaxes SWMBO who was a bit concerned as the engine had been faultless since we've owned the boat - some 17 years.

Many, many thanks to everyone for your thoughts and ideas. This is the real strength of this forum and overwhelms the odd bit of 'barracking'.

I'll post a new thread with the 'results', as this page will be long gone by the end of next week.

Cheers Jerry

 

[cliff]

[ QUOTE ]
However, as the (comparatively) slow initial starting has got a tiny bit worse each of the last three times, it could well be that the gasket is breaking down at some point.

[/ QUOTE ]Now that snippet of information throws a different light on the situation and as you seem to have checked the "normal" causes then perhaps it is time to lift the head and renew the gasket after checking the block and head for damage etc of course!

So what are you thinking of replacing it with? Bukh do a turbo charged 24 giving IIRC ~ 32hp same foot print as the 24 though.
--------------------

"Artificial intelligence is no match for natural stupidity"

 

[jerryat]

Hi Cliff,

As I say in my last post, we've ordered a standard BUkh 24ME which, as you know, is the direct replacement for the 20hp.

I could whip the head off in the boat, but it's much easier to do on my bench, so assuming it's the head gasket, I'll check the head/block for any damage, and if not put on a new head gasket.

If I get round to it before we leave I'll put it on the market. It'll make an excellent buy for someone, as it had new pistons, rings, liners, ends, pump, etc etc etc just last season (when the engine was perfect!!) and is barely run in. In just the last two weeks it's had the HP fuel pump completely refurbished (new pistons and barrels) and new injector nozzles. There's no corrosion at all (inside or out) and it was re-painted last year, so looks like new as well.

I sort of understand SWMBO's concern, as we could well be covering up to 15K miles over the next three years, some of them in pretty backward places (west Africa/Cape Verdes etc) where the chance of getting spares is zero.

I think the Bukh's are fabulous engines, so although I did consider the Beta 20 and had a long chat with their very helpful and knowledgeable sales people, the quality of the Bukh swung us firmly in favour of replacing with the same.

Beta even do a 'kit' fitting that allows the existing engine beds to be used (Bukh/Fulmar) and were over four figures cheaper, but we'd miss the sound of the Bukh and especially, the hand-start facility. We've only needed the latter perhaps half a dozen times over the years, but it's THERE!!

As promised earlier, I'll let you know the outcome of the head investigation.

Regards Jerry