Bukh DV20 Exhaust elbow

joyfull said:
Unbelievable. Three nuts off. One still very very reluctant.

Should the flange just pull off (with a bit of help)?

When I get the new elbow do I need to add gasket or paste or clean the face etc
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Yes. Just rock it a bit to unstick it.

I think there might be a spring washer behind each nut which you need to catch.

You also have to remove the water injection hose, probably easier where it connects to the thermostat housing if it won't come out of the old elbow.

Just a new gasket would be good. Clean up any remains of the old one.

I know this duplicates advice but at least we are consistent.
 
Mistroma said:
Actually, I had a sudden flash of inspiration and am pretty certain it was a Hammerite product we used in industry (hence my unmarked container :D)/

Hammerite mention "Glassguard Protection"
As the HAMMERITE Rust Cap coating dries, millions of heat-hardened glass flakes interlock with special resins, forming a super-tough barrier that seals out moisture to prevent rusting.

HAMMERITE -MANUFACTURERS -Paint Colors

I didn't see a reference to temperature resistance. I might be tempted to buy some before it is banned for some reason (things which work well and contain VOCs do seem to be banned eventually these days :D).
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Thanks.
 
Fourth nut off. Three came out unmarked (no washers). The last one is now stuck in the socket, so must have rounded a bit. I think the diesel advice did the trick.

Once I get the old elbow off I have to decide whether to go for the Bukh oem elbow, keeping the existing flange (£151 excluding the flange but including a new water pipe) or try the fabricated steel option (£65) which includes a new flange and no water pipe.

Of course I have to separate the elbow from the flange as well if I go oem which from comments above can be quite absorbing!
 
I had a stainless exhaust elbow made in a hurry for my last boat, still fine when I sold it 20 odd years later, it was welded fittings. I have one ready to go on my 29 next time the thing blows. No hesitation.
 
forelle541 said:
I had a stainless exhaust elbow made in a hurry for my last boat, still fine when I sold it 20 odd years later, it was welded fittings. I have one ready to go on my 29 next time the thing blows. No hesitation.
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I am thinking of going the stainless way. The cast one I have finally managed to remove just shatters into small pieces when I try and grip it to unscrew the hose (still stuck in the casting.

Anyway I will see if i can separate the flange and threaded part. If not I will just buy the all in one stainless made up one.
 
Yes to a new gasket at the exhaust/flange joint but if reusing the flange and adding a new elbow then a cement on the thread is needed. Otherwise exhaust gases will leak.
Well done on loosening your nuts!
 
Never heard of a cement on the thread. Surely the locknut will settle the threads against each other sufficiently. Cement would just make it more difficult to remove next time wouldn't it?

But never mind, I've only replaced my Bukh elbow about 4 or 5 times in the last 30 odd years with no leakage. Maybe I was lucky!
 
James_Calvert said:
Never heard of a cement on the thread. Surely the locknut will settle the threads against each other sufficiently. Cement would just make it more difficult to remove next time wouldn't it?

But never mind, I've only replaced my Bukh elbow about 4 or 5 times in the last 30 odd years with no leakage. Maybe I was lucky!
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I can see that there is a square block on top of the water manifold which I think is for the thermostat. Is it safe to have a look inside to check the thermostat and maybe replace.

The DV20 has been in the Centaur since new. So 44 years and maintenance looks minimal with all the hoses looking blackened and tired and generally rusty. Yet it has worked without fail for the year I have had the boat although I do not stress it and sail as soon as there is wind.

So far I have changed the engine oil (not the gearbox oil yet because the dipstick is seized) and replaced the alternator that was not charging. I am thinking about the engine anode but figure out it is going to be hard to remove.
 
The thermostat is quite pricy. Ditto the housing. I wouldn't recommend taking them apart unless you really need to.

The anode can come off its mounting bolt as you unscrew it and either fall into the water jacket or get stuck in the bolt hole. Not to worry! It won't do any harm if it's fallen off. Check the new one once a year. I found after a few years it stopped wasting away. I don't know why but didn't worry about it thereafter.
 
James_Calvert said:
The thermostat is quite pricy. Ditto the housing. I wouldn't recommend taking them apart unless you really need to.

The anode can come off its mounting bolt as you unscrew it and either fall into the water jacket or get stuck in the bolt hole. Not to worry! It won't do any harm if it's fallen off. Check the new one once a year. I found after a few years it stopped wasting away. I don't know why but didn't worry about it thereafter.
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Ok. I will leave the thermostat and have a crack at the anode. Thanks
 
Mistroma said:
I still have the paper workshop manual and think I might even have a scanned copy somewhere. I can look for the PDF if it is of use to anyone.
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You can download the Operators Manual and Spare Parts Manual (and various other bits) for the DV20 and other models from the Bukh Denmark website starting here -
Download - Generelt materiale

The DV10 & 20 Workshop Manual is also on the same website, but now seemingly not publicly displayed. It can be downloaded via this link (note it will likely take a little while for this big document to slowly download):
https://bukh.dk/upload_dir/docs/FAQ/Bukh ME - Data/Bukh ME - 10-20 ME/Bukh 20 ME - Manuals/Works shop manual/Work Shop Manual - BUKH DV 20 ME.pdf
 
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You mentioned considering replacing the thermostat. The Bukh thermostat is currently about £96, it seems. You will also need a new gasket and O-ring, I think.

You can test whether your existing thermostat is working properly by putting it in a saucepan of water and heating it up, checking that it opens and closes properly, and (using a thermometer) at the correct temperature. It should begin to open about 60 degrees C if you have direct (seawater cooling), and about 75 degrees if you have indirect (freshwater) cooling. (There are two different thermostat part numbers for the different temperatures - see Spare Parts Manual). The temperature spec., and information about dismantling the housing, is in the Workshop Manual.
 
joyfull said:
Ok. I will leave the thermostat and have a crack at the anode. Thanks
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The anode is a peice of cake to remove, its just stuck inside the big brass cap nut on the end of the engine. Or should be, and as other have said should be replaced yearly to prevent your engine block waterways corroding theough. New anodes were some silly price for tiny bit of metal but cheaper than engine (I got mine from Cutlers but TS Norris do them also)
 
Still looking at the options (I have not separated the flange from the elbow yet - it is rusty and solid).

Saw this on ebay from Dublin. Looks sensible, anyone tried one?
 

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I see what they are trying to do, reduce the temperature at the elbow, but wasn’t there something earlier about the water has to inject further down the pipe so that it can’t go backwards?
Others may feel differently, of course.
 
Charlie Boy said:
I see what they are trying to do, reduce the temperature at the elbow, but wasn’t there something earlier about the water has to inject further down the pipe so that it can’t go backwards?
Others may feel differently, of course.
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Looking at their design the water seems to be injected into an internal doubler jacket that then flows down the pipe to avoid back flow.
 

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I
I'm not really arguing against the item you've found but 5 years trouble free use is unimpressive. Maybe they were only first produced 5 years ago? Anyway you should expect a year or two longer than that from the Bukh item.

Hopefully your exhaust hose can be suitably oriented as there's no rotational adjustment available.
 
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