Cracked exhaust elbow and water pump not working

bigmig0

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I have bukh dv10 which has been faultless. however just gone to the boat today and the exhaust elbow has a large crack in it about 6 inches long. Also water is not pumping through the engine ( nothing coming out of the exhaust ). I have checked the impellor and it is dry. I have turned the engine over with the starting handle and the impellor turns but when i briefly ran the engine it wasnt pumping water through.Is it possible the 2 are linked. any help greatly appreciated.
 

rhumlady

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The exhaust elbow has a habit of cracking after about 5 years. any longer than that and you are on borrowed time. It is probably not related to the lack of water. If you are not getting any water through to the exhaust then it could be a few things like a worn pump not priming or a build up of salts in the engine / thermostat area. You should try running the engine with the hose from the pump disconnected and see if any water is coming through then you know which way the problem lye's.
 

bigmig0

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Today is the first time i've been to the boat since winter. It was working fine till Nov although i did notice a fine crack in the elbow at that time. i have followed bukh wintering advice by releasing drain plugs etc and removing the impellor over winter. It is kept on Lake Windermere.
 

Bilgediver

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Probably not linked if the impeller is dry. Did you reassemble the water pump with a liberal coating of vaseline on the impeller and case? Maybe your sea inlet is blocked with lake crud. Can you poke something down the inlet strainer and out through the hull to confirm clear.

I suspect it is a case of the pump not priming and you could also help by filling the water pump with water by disconnecting the hose from skin fitting and drawing water in then quickly putting back on the fitting and starting up.

Cracked elbows are a routine item on old engines .
 

Bilgediver

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Please will you be able to simplify how i prime the pump. Sorry for the inconvenience
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Fill it with water and have the sea cock closed. Either remove the inlet hose at the boatside and holing the end high fill the hose and pump then when all full put thumb over hose end and quickly reconnect without losing water. OR remove discharge hose at furthest end from pump also with sea cock closed and fill pump and hose and reconnect.

Start the engine and open sea cock. Hopefully you should not need to do this again.
 

Gin

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[ QUOTE ]
The exhaust elbow has a habit of cracking after about 5 years

[/ QUOTE ]

My last one lasted less than 3 seasons and was replaced last summer. I've just noticed that there are external signs of something going on in exactly the same place by virtue of a line of 'blueing' from heat presumably, so it will need watching very closely
 

jax

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Had the problem of "no water" a while ago checked every thing - impeller, blockage, loose hose etc Then found O ring on inlet water strainer lid had failed - replaced with new and all OK - might be worth checking
 

vyv_cox

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As others have said, it sounds like a pump priming problem. I had the same trouble for some time, seems to have been due to wear of the front cover due to operating in shallow, silty water (Holland) for a number of years. In my case cooling water would run out of the pump when sailing in choppy conditions and fail to re-prime when needed. Replacing the cover has fixed it. As others say, greasing the impeller will work, but probably only once, it can't be expected to solve a worn cover problem more often.

On some pumps the cover can be reversed, saving the trouble and cost of a new one. Don't try it if there are stamped letters and numbers on the front face.
 

Bilgediver

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by virtue of a line of 'blueing' from heat presumably, so it will need watching very closely
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I wonder if the flow rate is low and there is scaling in there???

Might be worth taking off and giving a dose of Fernox or brick cleaner .
 

Gin

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I don't honestly know. I can only say that prior to the new elbow being fitted I had had an overheating problem which turned out to be calcium deposits collecting at the point where the inlet 'Y' diverter entered the block; once cleared all was well and there has always been a reasonable amount of water exhausting since and no more overheating alarms.

In view of your comment perhaps I should speak to Bukh this coming week to hear what they think- thanks for the thought
 

colvic

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Start at the entry point of the cooling water into the boat. Is water comming in? If so is it passing through the filter OK? If no water on view then is it possible to pass a stiff wire down the intake tube and through the skin fitting to make sure it is clear.

My inlet tubing was of sufficient diameter that I could use a plumbers 15mm bending spring dropped into the intake hose via the first filter. Did this every few months and the system worked just great.
 

neil_s

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Have you tried a new impeller? I found that after about two years use the impeller seemed to get a bit floppy and gave problems with not priming. You can make up an exhaust elbow for a Bukh using standard cast iron pipe fittings. You need a 45degree M&F elbow, 1.5 inch, a 1.5 inch barrel nipple, a square Tee, 1.5 X 0.5 inch, a 0.5 inch hose tail and a 0.5 inch 45 degree elbow. Pipe Center will supply!



Cheers! Neil
 

Gin

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Just to tidy up a loose end.

I spoke to Bukh this morning and they tell me that the 'blueing' is not indicative of anything I should be concerned about, but to 'keep an eye on it'.

They also say that elbows should last more than 3 seasons and in my case what I had factored out was 2 seasons of lay-up.

Seemingly corrosion continues even in such circumstances so, on that basis, the last elbow did indeed last 5 seasons.
 
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