Steaming Old Bukh!!

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OrwellTiggerToo

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The Bukh 20; fitted with new impellor, pump face-plate, thermostat and exhaust elbow; having all the associated pipes and filters cleaned; produces steam by the shed-load.
As Tigger Too heads up the Orwell, crowds gather on the banks to await the arrival of the ancient Mississippi steamship heading for Ipswich; it's getting a mite embarrassing; people are tutting disconsolately when all that appears is a 1983 Westerly.

So what haven't I considered that may cure the problem?
 
When you find the answer...

...do drop me a line, as the 1968 Volvo MD2 in Mirelle does likewise.

Of course, having, so to speak, an even more adverse "boat to engine ratio", our progress is even more stately!
 
I think that if you search the forums you will find that this topic has been discussed many times. Most Bukh 20s seem to be afflicted with the same emissions problem: mine always was before I changed to a Yanmar. I believe that the cause may be something to do with the coolant design. The flow of water through the engine is relatively small, the thermostat and bypass design discharges hot water to the exhaust and when it hits the exhaust elbow some of it flashes to steam. The only consolation I can offer is that I have never heard of an engine failing as a result of this phenomenon.
 
> Most Bukh 20s seem to be afflicted with the same emissions problem: <

This one does come up regularly, and really puzzles me. /forums/images/graemlins/confused.gif I've had Bukh's (in the last two boats) since 1979 and never had this problem. Maybe I'm just lucky, or maybe it's to do with doing regular maintenance, including such things as flushing through at least twice a year with fresh water and emulsifying oil.

I do see 'steam' occasionally if the (early) morning or (late) evening is very cold, but then this is common to most boats/engines I've seen in similar conditions.

Still, happy to remain puzzled ........... and 'steam' free!!! /forums/images/graemlins/smile.gif /forums/images/graemlins/smile.gif
 
Seems that there must be too little water passing into the exhaust to drop the temerature enough to stop it flashing in to steam. Suggest re checking the pipework for obstructions, sometimes a rubber hose looks perfectly good outside and has collapsed internally. Also make sure the strainer is clear. A more serious problem occurs where the water passages in the engine block are becoming choked with calcium and/or salt deposits, restricting the flow, and increasing the temparature, possibly boiling some of the water within the block or cylinder head, which will rapidly deposit minerals.
 
Mine has always given off steam. It had a recent rebuild, with the bores/liners etc done professionally and still steams gently under way. Exorst etc all new, so no collapsed hoses, and it does not overheat.

The pumps are quite small bore on these engines, and mine did tend to overheat to start with until I fitted a slightly wider bore inlet valve and pipe after which it was fine.
 
This was why I asked if it was raw water cooled. (I have seen some converted to fresh water indirect) Any engine reliant on salt water cooling will be especially susceptable to this. I have only ever stripped down 2 Bukhs (which is actually a tribute to their reliability) but the old big twin Volvos were particularly bad in this respect having quite narrow water galleries and 2 tiny holes to transfer water to the manifold from the block. These become clogged with salt and the flow restricted. There may be enough water flowing to maintain a tolerable engine temperature with the thermostat wide open all the time but when the restricted flow gets to the overheated manifold it creates lots of steam. The good old Bukhs are now getting a bit long in the tooth and probably increasingly suffering the same way. That's why the Guy who regularly flushes his will have less of a problem.
 
Re: When you find the answer...

Check that the cooling water passages between the exhaust manifold and the cylinder head are not furred up. My Bukh doesn't steam.

Cheers! Neil
 
measure exhaust flow?

It might be useful to measure the flow of water out of the exhaust and compare it with the volumetric flow rate expected from the pump.
This idea occurs in the Betamarine manual; its not original to me.
The idea is you put a short wide pump onto the exhaust and hang a bucket on the end, then find volume collected in a suitable time.
Do be careful not to poison yourself with the fumes.
If you have a jabsco type pump the expected volume would be the (pump volume minus the impeller volume ) times the impeller rev rate.
 
Not withstanding all the comments above, you do seem to have missed at least two very important items.

One - check the pipe between the pump and the block is not furred up. This will severly reduce the flow of coolant reaching either the block or the bypass.

Two - check the thermostat housing by removing the hoses and checking both inlet and outlet are free from crud. - I had to take a drill to the housing on my Bukh to open the passage way up to "normal"

In addition check the intake hose and filter if fitted.

You might also consider flushing the block through with Fernox™ or the like. Before anyone jumps in and says Fernox™ will damage the engine, I have used it quite sucessfully as have a number of others on the forums to clean out the water passages in the engine.

You say it is a new elbow - is the hole in the casting big enough to allow a good flow of water through? I had to take a mini grinder to the elbow on my Bukh and open up the water injection port by removing excess metal from the casting process.

Finally I would not worry about a little "steam" provided the engine temperature is O.K.
--------------------
hammer.thumb.gif
"Artificial intelligence is no match for natural stupidity"
 
Re: measure exhaust flow?

A dumb question, but is your water trap functioning correctly, it should convert the steam to hot water before it exits the exhaust shouldn't it? These engines have phenomenal reputations for reliability so I am guessing something to do with the exhaust system.
 
I have a Bukh DV10ME which may have a different cooling system.

I think my boat has probably only used its engine for motoring on and off moorings for the last few years and when I throttled up to about 1/2 revs, I too got a lot of steam and a screaming overheating alarm. When I throttled back, steam reduced and alarm stopped.

Upon enquiry of Bukh, who were very helpful, they told me the raw water leaves the pump and heads straight out over the top of the engine into the exhaust until the thermostat opens when hot to divert water throught the engine block to cool it.

When an engine is used as I think mine has been then a build up of salt water crystals occur at the entrance from the T piece copper diverter pipe and the entry to the block which is normally much larger than the diverter pipe and thus allowing an unimpeded flow of cooling water when needed .

When I removed the T piece diverter/pipes/hoses I found a substantial white deposit exactly at the point of entry to the block which was easily cleared and the section of the diverter pipe feeding this entry point, which also was partially blocked ,needed to be rodded through with a wire and cleaned up with vinegar.

l Haven't tested it yet as the boat was coming ashore when the problem arose but I am confident it will improve/resolve my situation and if your engine is similar it may work for you too.

If the plate attaching the diverter pipe to the block is behind your flywheel it is a devil of a job without either a flexible socket driver with a 6mm Allen key insert or a short 1/4" drive socket handle for same. The normal Allen key and the ones with a hex. ball end just couldn't give me enough purchase unless I had cut them down to suit

Hope this helps
 
The watermota petrol engine in my freeman 22 always steams well when underway. The engine doesnt over heat, so, although its a little embarrassing to look like a steam ship, ive left it alone after much trying. I clened the passages in the engine and head as much as possible a couple of years ago, but i made no difference whatso ever, infact its probably worse as it must be cooling it better. My advise would be to leave alone unless its overheating. I like to keep things simple (well try at least!)
 
Sound advice from a man who knows his own engine. Every engine has its particular weakness. I would follow his suggestions!
 
This sounds sensible too if yours has the same arrangement. Check ALL external pipes and passageways before stripping down further.
 
I agree, always check the easy things first. However, I offer the following:
1: My boat was based in Holland for six years, where for the majority of its time it was in fresh water, and every time it returned from the sea it would always have at least 60 minutes of fresh water flushing before berthing. Nevertheless it always steamed.
2: About half way through its time in Holland I rebuilt most of the engine, particularly the injection tube from the pump into the block, the thermostat housing, exit to the exhaust manifold. The manifold was replaced. After this there was no detectable change in the levels of steam.
3. A friend had a Fulmar fitted with a Bukh. It steamed from the day he bought it. He pestered the Bukh ULK agent unmercifully and they suggested many possible solutions to him. He tried every one, costing him a great deal of money. None made the slightest difference.

In the end, all agree that this is not a problem. Spending lots of time and money is unlikely to make any difference. Enough said?
 
Reply to all...

Thanks for the info everyone.
Mine's a raw water cooled engine so I might find that the galleries are blocked slightly. Hydrochloric acid / water mix, should clean the galleries out.
Measuring the water flow on the 'out' side of the pump and comparing it to the exhaust elbow flow might give me an insight into whether I'll need to proceed as above.
As the temperature of the engine stays within acceptable (cool) parameters I'm wondering whether the pump might be working innefficiently; oversize main housing or undersize impellors!
All the pipes are clear and recent.
One of the only other things that strikes me is that it takes quite a while for water to emit from the exhaust after start up. Could there be something in that?
 
Re: Reply to all...

That's how I remember mine. Probably a consequence of the very small flow rate. The pump bore on my Bukh was a size smaller than on its Yanmar replacement. I think that when the thermostat opens it diverts a large proportion of the bypass water, so what hits the exhaust elbow is essentially at engine running temperature.
 
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