BUKH DV20- Salty Deposits in cooling & cracked exhaust Manifold

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aidancoughlan

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I was down at the boat today doing some stuff & gave a quick visual over the engine. I noticed quite a bit of salty deposit where the cooling water inlet pipe (coming from the impeller pump) enters into the engine block.
There is another hose pipe coming from the same point of access, and taking water to the manifold. I notice the manifold is cracked.

Anybody know what all this salt means ? The plate where the salty deposits are looks like it can be removed with an allen key, and I'll try that next weekend to investigate -but access is very restricted - the flywheel may have to come off to get access - is this a big job ?

What about the exhaust manifold - does this have to be replaced immediately?

thanks for any info...

Edit: I'll try see if I can add some pictures... here goes...
Salty deposits...
P1290017.jpg

Cracked Manifold
P1290025.jpg
 
Salty deposits are where the joint gasket is leaking, yes I would suggest that you remove the thing and renew the gasket. Apply lots of WD40 type stuff and allow to soak before you start anything.

The xhaust elbow might be repairable it depends on how thick the remaining metal is and whether you know of a good welder who can fix it.
 
Hi Aidan

You can get that plate off without removing the fly wheel but it is abit fiddly. The exhaust manifold probably needs replacing others will advise.

Howard
 
Thanks guys, I'll definitely have to clean out the salt from the waterways.... had a look at http://www.inadee.btinternet.co.uk/engineoverheating.htm last night - seems this can lead to enough deposit to block it up & overheat the engine.

If I cant get the plate off with the Flywheel in situ, I'll be carefull removing/replacing the flywheel !!! - see "Flying Flywheel" post at http://www.ybw.com/forums/showflat.php/Cat/0/Board/pbo/Number/539736/an/0/view/collapsed/

BTW, I've seen a second hand Bukh manifold for sale on the web somewhere for £60. Is it worth considering? Havnt checked the price of a new one yet, so supose thats the first question. Will check it today & ask BUKH about the salty stuff.
 
I have a DV10 which had the same salt deposit build-up but not evident from external inspection.

Remove the feeder pipes/hoses, and the plate in your picture with a 6mm allen key(see below) and you will find that there is a substantial build up behind this plate of more salt deposit blocking the entrance to the engine block water gallery. It is soft and easy to remove( if mine had not been I would have considered flushing with a mildly caustic solution or domestic Calgon- BUT this is my idea and I would have first sought advice- hopefully you won't need to bother either).

You will need to rod the part of the pipe which feeds into this plate to clear it- also soft and therefore easy. Once reassembled you should find improved water flow through block once water temperature sufficiently high to activate thermostat at top of engine and fed by the second branch of this pipe work.

However getting the allen key out of the lower hole, behind the flywheel is a devil of a job and took me about an hour with a standard 'L' shaped Allen key. Bukh recommend using one with a hex-ball end which I obtained for re-assembly but this too was a struggle although easier on re-assembly.

For next time I now have a long shaft flexible drive Stanley tool which takes a 1/4" socket, which in turn takes a 6mm hex stub, which I hope will give me enough clearance, and leverage to do the job more efficiently.

The salt deposit build-up, by the way, is down to the engine running at low revs, so in the future give it a blast every now and then for a while to clear it out.

If you want to talk it over, then PM me and I'll give you my mobile number
 
By the way, re the above.

Bukh exhaust elbows are well know for failing- it is false economy to repair or buy secondhand and some owners buy two new ones at a time, to reduce future inconvenience!!
 
Re: BUKH DV20- Salty Deposits in cooling & cracked exhaust Manifold

The simple solution to greatly extending the life of the exhaust elbow is to thoroughly degrease the inside with acetone or similar and apply four or five coats of epoxy paint, making certain that the paint is worked up into the water injection point.

I used some old International Interprotect last time and the elbow lasted over seven years with a wipe inside (yes, wipe off!) off every couple of years. Not bad, considering the Volvo and other equivalents don't last much longer than the Bukh ones otherwise.

As others have pointed out, removal, cleaning and replacement of the cooling spigot on the block is easy. I suggest however, that you make your own reinforced rubber gasket when you replace it. It will last indefinitely and never leak.
Do not over-tighten it.
 
Seal 28 and Super Seal 26 owners with Bukh engines have suggested replacing the Bukh exhaust with a Galv malleable 45 deg M/F Elbow 156G 1.5" screwed into a Galv Mall Sq Tee 161G 1.5"x.5" and finally Galv 3"long 1.5"pipe joining piece threaded both ends. The water connection are also made up from assorted Galv Mall .5" fittings. This I understand works fine and lasts for ever.

Geoff (TechnicalLibrarian SealSailing Assoc)
 
Re: BUKH DV20- Salty Deposits in cooling & cracked exhaust Manifold

Tried setting this system up in the local pipework store - it doesn't work uless you want the biggest heap of piepwork you've ever seen! And even then the risk is that water will run backwards into the engine.

The pipework people said a lot of owners come in for these parts every year for a variety of engines and it's good business. I asked why 'good business', and they said because this sort of set-up seldom lasted more than two seasons before it rusted out!! For me it's a definite no-no!!

There's some confusion on this thread. Aiden, your photo shows the cracked exhaust (injection) elbow, NOT the manifold. A new manifold was quoted at £800.00 to me a few years ago, so Lord knows what they cost now. I doubt if you do need a new one of those. A new elbow is much cheaper.

Incidentally, though I recommend epoxy painting the inside of a NEW elbow before fitting, I was so annoyed at the coat last time, that I had a very heavy duty stainless steel exhaust elbow made by a local chap. That's only been there a couple of seasons, so I can't claim huge longevity yet, but certainly there is no sign of carbon build-up so far.
 
Re: BUKH DV20- Salty Deposits in cooling & cracked exhaust Manifold

People on the Westerly Ownwers site recommend the S/S option. Figures of 14 years being talked of which would be a whole lot better then five years for the Bukh original.
 
Re: BUKH DV20- cracked exhaust Manifold

I have had 3 exhaust elbows made out of heavy stainless steel. You will have to wait untill on efails before I know the outcome. The total cost for 3 was £ 90. I have found the life of the cast ones about 4 to 5 years.
 
Re: the cooling water inlet branch. I always take the flywheel off, it is not on a taper and there is no key, after removing the six bolts, slide it forward. I put a block of wood underneath ready for it to rest on when removed. It is quite heavy so watch your fingers and toes!

After several attempts to make this joint watertight with different joint materials and sealants I realised that the problem is aggrevated by the plate not being flat. If you lay a steel ruler along it's face and hold it up to the light you shouldn't see daylight under it, if you can, it's bent. I think they get bent as a result of overtightening the bolts fixing it to the block. Make it flat, fit a new joint and that ought to cure the trouble.
When you refit the flywheel you should apply thread locking compound to the threads of the six bolts [after cleaning and degreasing] and tighten to the specified torque. If you apply a very light smear of grease to the spigot on the crankshaft, the flywheel will come off easily next time.
 
Many thanks everyone for your input..

I will remove the plate/branch where the water cooling hoses enter the engine - (I'll try the WD40 solution). I'll try getting it off first without removing the flywheel (I have a flexible thingy somewhere that might get me in at it) - if not I'll take the flywheel off.

I asked BUKH about the salt deposits, they didnt seem too concerned - suggested cleaning behind the plate with a pipe cleaner when it comes off, but **Not** to put any chemical solution inside the engine, but that the cooling water 'branch' (where the hoses enter the engine) can be cleaned with kettle descaler or citric acid after removal.

Interesting about Gin's comment on low-revs causing the salt deposits- the salt deposit wasnt there last year when I bought the boat, and I've been running it very easy all season after having an engine fire on board on my first day out after increasing revs (subject of a previous post, wont go into the reasons here).

I might try JerryAt's tip on making a rubber gasket - would a bit of inner tube from a bicycle tyre do ? I'll experiment & see if it's too thick or too light. Thanks for putting me right on the 'Manifold' description - it is of course the exhaust elbow that's cracked, the manifold is fine (didnt know what its called).

The Exhaust elbow... I'll probably go for the BUKH replacement at £59 this time round... I dont have the time to source someone locally to make one in stainless steel, although this seems the way to go (gordon, rhumlady, jerryat). I wonder why dont BUKH make them this way ?

I'll watch out for Twisterowner's & JerryAt's tip on re-assembly of the inlet branch (ensure it's flat, dont overtighten it), and I'll make sure to use some thread locking compound on the 6 bolts of the flywheel when putting it back.


BTW, I checked out a few prices at BUKH...FYI...
A new hose from the water pump to 'branch' plate is £25+vat
A new cooling 'branch', plate & hose to 'manifold' (I think to the thermostat)is £65+VAT.
A new exhaust elbow (including hose from manifold) from BUKH is £59+VAT.
A new gasket for the plate is £1.50+vat

I'll replace the exhaust manifold, clean the inlet branch and fit a new gasket (£1.50!) - or try making my own if it seems very flimsy. Seems like giving the whole thing a good flush with fresh water would be no harm too.

All in all, lots of good advice - many thanks to all.
 
Re: BUKH DV20- Salty Deposits in cooling & cracked exhaust Manifold

HI Aiden,

>>I might try JerryAt's tip on making a rubber gasket - would a bit of inner tube from a bicycle tyre do ? I'll experiment & see if it's too thick or too light.<<

NO!! A bit of inner tube will NOT do!! What you need is a bit fibre reinforced rubber sheet (about 2mm or so thick) and cut the gasket from that. Any type that is used where heat is a factor will do. The thickness happily takes up any uneveness in the fitting.

The material must be capable of dealing with quite high temperatures for many cycles without cracking or breaking up, inner tube will not do this. The gasket I have has been there for well over ten years now without a single sign of leaking.

I'd have a word with your local decent sized autofactors outfit and if they don't have it, they should be able to tell you where to get it.
 
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