routine inspection of our mixing elbow(legend 29.)

[Barry Wiles - ARANRHOD]

h all since allan's advices see details 7 july 2008 i bit the bullet and bought a mixing elbow to keep onboard  just in case. (don't know how i would have fitted it at sea) anyway this winter i decided to inspect ours  the engine has done 1500 hrs (2001) when i took it off it looks like we have been living on borrowed time.
         the exhaust chanel had reduced in diameter to aprox 3/8inch.
         its one of those jobs were if you can afford it, get someone else to do it . also i took allan's advice and bought the coupler however my old one matched the new swan neck and old base.
          tools you will need is a 2ft stilson and a lump hammer , i decided to take the 4 bolts out first and then twist the whole unit through the control cables into the toilet area.
          i spent about an hour trying to get the 2ins pipe off by inserting screw drivers around the pipe and eventually using the stilson to twist it clear. used wd40 also.
          brought the unit home put into my vice and brayed it with a hammer (lump) got it turning about a turn and called it a day.next day i coninued to thump it with the hammer and eventually after a further turn i screwed it of.and it was an easy job to screw the new swan neck to the old coupling.it is now ready for  returning to the boat+new gasget deap joy

       

[Don Alexander - Autumn Legend]

Hi Barry,
May I suggest you reassemble the various parts using 'anti-seize' grease.  This is a copper or nickel loaded grease which is claimed to have permanent anti-seize properties.  Look on E-Bay (see below. Cut & paste) for a small tube £5.40 + free postage; otherwise shops make this stuff very pricey!

Whilst on this topic I note the Americans are paranoid over mixing elbow blockages on SBO and this has caused me to have removed my mixing elbow twice since 1996.  On both occasions there was no sign of a build up.  So I asked at Marine Power, who are the local Yanmar guys, and was told they never see blocked elbows.  Curious?  Is it something in the water or is it my engine (Yanmar 3JH2E)?

May I raise a general question - who else has suffered a partial blockage of their water injection bend and on which engine?

http://cgi.ebay.co.uk/Molyslip-Copaslip-Hi-temp-anti-seize-grease-lead-free_W0QQitemZ120532800581QQcmdZViewItemQQptZUK_CarsParts_Vehicles_CarParts_SM?hash=item1c10509445

[Dylan Whittaker - Caitlin]

Hi Don,
if you can bear to wait Mike Kendall has done an article for Wavelines on the subject - should be with you in the next couple of weeks! On the strength of it and other posts I had mine replaced at last engine service as a precaution - L33 5 yrs old - but haven't seen the old one yet.
Cheers
Dylan
Caitlin

[Don Alexander - Autumn Legend]

Thanks Dylan.
Am looking forward eagerly to your next posting.
I am anxious about my bend as I have not had it off the engine for four or five years - boat was new in 1996.

FWIW;  Last time it was removed I noticed that, rather than a build up of crud, the little weir inside the bend had partly rusted away so that further degradation could result in water splashing back into the exhaust manifold.  Also my anti-siphon in the cooling circuit usually gets sealed within a month or so of being cleaned out and is then unable to let any air in.  This means the exhaust injection bend has water in its feed tube permanently and I wonder if this dissolves the crud before it has a chance to harden; so at the next startup it blows any detritus away?
Fortunately there seems no tendency for water to continue to siphon into the exhaust system and then to fill the engine!!!

[robinwren - Wombat]

Hi all,
My elbow has arthritus. The one on the boat, a L33, started leaking around the welded joint after only 2 years use. It is the Yanmar 29hp. A new elbow was going to cost £185.00, so I took the old one to my loacal welder who did the job for a pint of best. It was not blocked at all when I took it off. I see on the Australian website for the engine, that re-welding seems to be common practice down under.
Regards,
Robin Wren - Wombat

[ISADORA - Gaye and Conway]

The one on our L33 started showing signs of leaking a (slight rust stain from a pin prick around the flange to pipe weld) after slightly less than 2 yrs. But it was replaced under warranty by Marine Powerb Bursledon. Some parts of the engine have 2yr warranty period. Hope its not to late for you?

Conway

[Silver Surfer]

Have had a little experience of this. It has been put to me that engines that are used quite a lot for motor sailing (ie not particularly loaded and hence run cooler) are prone to crudding up and corrosion.
Also a slight word of caution on the use of extended stilsons etc. you will get it apart but the manifold casting is prone to burst open. Hence really good practice to use prevention as has been suggested with lubricants.

[Barry Wiles - ARANRHOD]

hi don thanks for that advice ,i bought some anti -seize grease.
      When I tried to fit the pipe back it would not have it .not only had the end of the pipe enlarged with some wastage it was as hard as hell and no joy with the clips. so no other option but to buy a new length of pipe .on 29s its a meter and about 4ins if that makes sense,  I re fitted the muffler end first and then immersed the swan neck end in a jar of hot water  and then fitted to  the neck. the jubilee clips pulled up as nice as pie.
      we launched last week and had a shake down cruise . all went well.

[Colin Worth - Skoolie Too]

Here's my pennies worth, a bit long winded but wil get there in the end.

Skoolie Too, new in 2005.
At first we never ran the engine much above 2800 revs, then struggling against an ebbing tide into Poole I upped the revs to give us a bit more. At 3200 the engine overheated (if this happens to you - run the hot taps (Don Alexander top tip)). After that we kept the revs down to 2800.

Advance two years and two failed Volvo props (see discussions on that elsewhere) we changed to a Kiwi prop. Don't all hiss & boo, it was the right decision at the time and still is. However I noticed we were loosing approx 1/2 a knot under power. We then started having trouble engaging reverse, lever would go back but no pick up of revs. I checked all the linkages etc but to no avail. This was a bit hit & miss & was certainly better after a lift out. I was greasing the prop at 12 month intervals at this point.

After a couple of near misses when manouvering in marinas in a gust, (when you need reverse, you really need reverse!) I resolved to sort the problem out.
Don had then posted a prop pitch calculator which he ran for me and albeit with some slightly duff information which I had given him, gave me a pitch angle of 17^o, my Kiwi had been set to 22^o. Time to have a go at the Kiwi boys.

They assured me that 22 was correct, and after explaing the problem, suggested I check the exhaust elbow (got here at the end). This was actually as clean as a whistle. I then remembered that one of the early services I had had done, the engineer left the old impeller on the chart table and it had a blade missing. Now I assumed that either the old blade would get flushed out by itself, or the engineer would have tracked it down and removed it. Wrong. I dismantled the cooling system and found two blades against the heat exchanger.

This was why I was overheating. Next I dried out and greased the prop very thoroughly, as we sail right the year round, the service interval should be a lot less than once a year.

The end result is tht we can now rev to 3400 or more, boat speed is up by about a knot and we get reverse every time.
I guess my engine has been running alot hotter than normal and may explain the clean elbow, so will be keping an eye on that in the future.

If you have got this far, well done, there just might be something in here that helps you.

Cheers
Colin
Skoolie Too

[Trevor Archer - Hullaballoo]

Yahoooo Colin
I had two impellor blades broke off and ending up in the heat exchange stack when Hullaballoo was brand spankers  >:(after only  4 hrs running. Actually not that unusual on a brand new engine. How long was your brand new engine been sitting around with two blades in the water pump sitting bent at the same angle……? Sooooo that’s summit else I am rigid on, I always put a new water pump impeller in at the STARTof EVERY season, about 20 squid, much cheepness for  piece of mind, a  bit like the 5 squid fuel filter element ....bargain.

H Balloo