Help on descaling a Bukh engine.

I had a Bukh DV20 on my S&S34, I used to find the engine anodes only lasted about 6-9 months. If you can't knock it out of the way, maybe the jacket is really badly crusted up with deposits.

It took me a while to work out the best way of keeping the DV20 running cool. In the end, this is what I used to do every 2 years:

Loosen alternator belt, remove flywheel
Remove Y-tube, clean out deposits in distribution tube
Scrape out deposits from water jacket – use “special tool” made from bent coathanger wire
Take the opportunity to clean up the engine drip pan – impossible to get to with the flywheel in place
Replace Y-tube, flywheel, alternator belt, retension belt
Remove thermostat, clean deposits from water passages in thermostat housing and cap. Temporarily replace housing without thermostat.
Fit temporary hoses on Y-tube and thermostat off-take, pinch bypass tubing to occlude it (eg, squeeze with small clamp)
Pressure flush in both directions with fresh water
Remove engine anode, fit a blank cap
Make up 8L of 5% Hydrochloric acid. Brick Cleaner from Bunnings is concentrated, I think it's about 35% from memory, so you need to dilute it a fair bit. Be very careful: use protective clothing, gloves, eye protection and pour the acid into the water and not the other way around. When you've got your bucket of dilute acid, slowly run it through the engine – take about 1.5 hours.
Repeat pressure flush
Replace thermostat, anode; remove bypass occlusion; put it all back together – good for another couple of years!

HTH,
Chris.

I suggest you do a little test: scrape off a piece of crud that's hardened onto the thermostat or inside the water jacket wall. Place it in a glass jar, and check whether diluted Hydrochloric acid (or vinegar) dissolves it, and how long it takes to do it.

Depending on your findings, you increase the acid concentration.

Would be great if you could report your findings here. I tried this test a few years ago with Nulon radiator flush and also with diluted acid, with little success.
Can't remember the concentrations I used.

Fairly much a not too strong acid that will react with the salt in the system will do the job.

I used white vinegar in my raw water cooled Yanmar and let it bubble a half hour or so then fresh flushed it and repeated the process. Vinegar will certainly not harm your engine but HCl or H2SO4 might.

My Yanmar has plates on the front and rear of the cylinder head that I removed and I dug out an old anode remains and some scale from the water jacket.

Your engine is a man made thing as opposed to a God made thing and therefore imperfect and subject to failure. Treat it as such by giving it manufacturer recommended maintenance and it should serve you well.

Thanks for the response guys. That's excellent. The quandry I'm in now is do I start with something mild (vinegar) or hit it with the acid. I have plenty of time so I'm thinking of taking it in steps and starting mild. If I go the acid way would this system I'm pondering work?. I have a bucket and a submersible bilge pump and the plumbing needed to connect up a loop. The thermostat is already out so if I remove the impeller then I can pump the solution around with the bilge pump rather than start the engine. If I do this for a couple of hours how do I know if the solution is still active, does it froth or something so when it stops frothing you know its saturated and needs replacing?. I think my engine is really badly gunked up. Now what about the anode. I have an eazi-out that might tackle getting it out, if I can, should I poke around the water jacket with a suitable implement to dislodge as much gunk as I can. This of course will drop to the bottom of the water jacket but this shouldn't do any harm should it?. The alternative is to leave the anode in and see if whatever process I choose will loosen it thereby indicating that the process worked.

Never do the aggressive thing first, always learn to walk before attempting to run. If you start with the strong acid you risk damaging it and leave your self nowhere to go and maybe with a more expensive problem.

I would use the vinegar, diluted to maybe 25% strength and fill the entire cooling system and then run the engine till hot then let it sit till cold and repeat. If and when you think you have made some headway drain and flush the system and analyze the results. You may need to do it again and maybe even increase the vinegar ratio, let your observations guide you.

Thanks you two. Yes you're right L.C. I will use the vinegar treatment first. My engine is relatively easy to get to so using the advice from the forum I've got a plan that should work OK, or at the very least not cause damage, I will keep you updated on progress. Although that of course may lead to more questions. Thank you all for your input, it's much appreciated.

I researched the same issue some months ago for my raw water cooled Yanmar 3GM30 and, with the help from this forum, concluded that a product called Rydlyme was the answer. See www.rydlymemarine.com.
I haven't used it yet but will do in the coming weeks.

I managed to remove a lot of scale from my dv20 using SaltX (www.saltx.com). Soaked the block for 24h then flushed with water. Caution do not forget to detach hose to water injector as you can fill the exhaust up with water that can lead to water entering engine through the exhaust manifold.

OK time for me to chime in HG. I did the job on my Bukh a little while ago. I tried the mild stuff first (vinegar)
but it wouldn't budge it, I said at the time that my engine was badly gunked. A neighbour gave me some really
heavy duty stuff he uses to clear his toilet pipes of gunk. I think it was Rydlime. This stuff is more than 30%
Hydrochloric acid. I used it mixed 1 to 1 with fresh water, so it was still very strong but I was desperate.
I disconnected the flexible hose from the water pump and with a 1/2"to 1/2" plastic joiner added about an
extra 30cm of clear hose. Two reasons- one to isolate the pump, two to bring the water level well above
top of engine level. The clear hose was so could I see water level. Next I took off the thermostat housing
Two reasons- one to isolate the thermostat, two this is where I poured the fluid in. I had already drained
the salt water out of course. The reaction was quite violent with very smelly bubbles spouting out of the
block. It was towards the end of the day and by knock off time showed no sign of abating, so I packed up
and went home. I left it for three days, when I got back it was completely spent and inert. When I drained
it I expected to see it black, instead it was a greeny/orangey colour. Of course dissolved SALT. I put it all
back together started the engine and flushed with seawater. Perfect. NO damage no problems no worries.
You remember that my engine block anode was cemented in---not anymore. One advantage was that I
didn't have to run the engine to do it. Good luck HG, it's very do-able.

What are the symptoms of a damaged 0 ring HG.??? Once the fluid had got saturated with salt it went inert and it wouldn't
work any more, so time is not a problem (I think), and there's no outward sign of any difference in the sound of it,
but it doesn't get hot anymore. If you remember I took the thermostat out to keep it cool. That's all reinstated now
and running normally. Perhaps the 0 ring is a bit tougher than you think HG.??.

If your'e there HG, another thought. Could it be that the heat from the cylinders is heating up the salt deposits
within the block and not the cast iron and if these lose heat quickly through the cooling water,
your engine wouldn't get hot. What do you think??.

That's good HG. I'm interested in how the saltx will work. If it's good then I'll use it in the future
However I hopefully will not have to do it for a long time yet. Let us know how you
get on. Do you need to run the engine or leave it static as I did ?????.

Hi TKNick. I used that bucket and bilge pump method when I attacked the engine with CLR but I'm afraid the
result was not at all good. After 4hours of pumping I still couldn't free the stuck anode, that's why I
used the much stronger solution. That worked well. However I chose not to pump it but just to
pour it in and leave it. It worked really well for me.

Select to expand quote

TKNick said..
Hi Samsturdy,
Rydlime is a great product! Great for cleaning the raw water side of heat exchangers too. Apparently if you drop a sae shell into the diluted solution it will dissolve in about 30 minutes. It won't damage gaskets or other engine parts but the company states that anodes should be removed prior or replaced if left in place. Will use the stuff again in a few years just to keep the cooling galleries completely clean.

I have been very naughty Sam I bought some hydrochloric acid and diluted it let her bubble for 10 minuets after disconnecting the pump to block hose going into the Y tube and also removed the thermostat housing and the pencil anode buttoned evert thing up and poured it into the block with the help of a funnel and a hose.
Probally a wimps dilution rate but it moved some crusty creatures out of the cooling system
After that I connected every thing and ran the motor in forward for an hour at full throttle also helping to remove any carbon build up in the combustion chamber
and exhaust .
Next Ill give her a good service replacing all the filters, fuel lines and adjust the tappets.
I have not measured yet but might remove the exhaust manifold and cleaning properly . Not sure if I have enough room to remove the manifold in position yet Ill check tomorrow

By the way HG your'e engine is looking just great. Missus painted ours not long ago and made it looked loved just like yours.
If you think you Haven't cleaned it out well enough don't be afraid to have another bash at it 'cause
I was fairly savage with mine and yet it all worked out well, they're tough little fellers.