Exhaust elbow de-coke?

wragges

wragges

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Joined
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Nottingham, UK
www.minstercomputers.com
Hi All,

I suspect I need to do an Exhault Elbow removal and decoke this winter (water coming from the anti-syphon pipe and also lacks top-end revs)

So, what is the best solution (liquid) to drop the thing into to get rid of the coke? I can leave it to stand for up to 2 weeks if it helps.

At nearly £200 for a replacement, I would rather rework that re-buy!

Thanks,
 
I had buildup of soot in the thermostat housing and it was recommended to me by the engine manufacturer to let it soak for a day in a weak citric acid solution (citric acid powder available from the chemist for a couple of quid.) Use one or two teaspoons per litre of warm water). This made the black stuff a lot easier to shift.
 
Did the port engine a couple of month ago, you might need a wire brush if real bad. Water stopped altogether so a bit overdue. works fine now, suspect we need to do this about every 6 to 8 months, she gets used most weekends and often during the week all year round.
 
coat hanger wire to poke down water outlet, a piece of hardwood to knock lumps of crud off or, better still, brass drift but watch you don't puncture the water passageway which could have corroded quite badly although if that happens, its on its last legs anyway and don't forget to buy the gasket as you might split it when taking the elbow off ..

the amount of crud which came off mine (3gm yanmar) seemed to cover most of the pontoon ...
 
..and if you see any crack in the elbow, you can assume it's at the end of it's life. I saw a small crack in mine, about an inch long. Thought it might last a bit longer, but as I was removing it from the engine it crumbled apart in my hands.
 
Err... I carried out a de-coke on the exhaust manifold last winter and had to chisel the coke off! It never occurred to me at the time to use a liquid (I think I read a brick cleaner would help) cleaner - just lots of chipping and scraping.

P1010174.jpg


The picture doesn't show it as bad as it really was but the flange (lower part) had no appreciable hole for the air to pass and the water way was almost completely blocked. The black gunge in the flange was a build up of solids exactly on the joint between the flange and the heat exchanger. I wish I remembered to take an "after" picture!
The engine runs like a dream now it's clean.
Another side effect from the blocked exhaust was the soot from the unburnt diesel. It took most of last season to wash it through the flexible exhaust pipe.

Cheers
 
additional question

may I ask and additional question: any methods to ease the disassembling of the black rubber exhaust hose from the elbow ?

mine seems glued, I tried with ont of those Cobra rubber webs (similar to oil filter wrenches, only made of rubber) and I almost broke it while the pipe refused to move...

/forums/images/graemlins/mad.gif
 
Re: additional question

Probably baked on. Easier to cut off the exhaust hose and replace.

I bought one of those rubber strap tools. Worse than useless, first decent test and the handle broke; a complete waste of money.
 
[ QUOTE ]
but watch you don't puncture the water passageway which could have corroded quite badly

[/ QUOTE ] Very good advice as the 'walls' are very thin!. I know!. (1GM)
 
for what its worth, and i'm surprised to the antipodean response, the deposits will be a hard mix of rust, salt and carbon, degreaser wont shift it!. my volvo penta 2030 was suffering so i took the elbow off, it was down to about a half inch hole. i used an old wood chisel, then an oxy acetylene welding torch (gently) as the crud reluctantly gave up its grip the hole got bigger and bigger, the cast iron was rotten and after i left the thing for a couple of days in the damp garage it started to sweat and bits of rotten cast started to peel off. it was rotten thru and thru. i ended up buying a new one, about £150 ish. moral of the story, buy a new one!
i seem to remember that bukh go thru them pretty quickly?
Stu
 
Re: additional question

poke and lever with a thin screwdriver or do as i did and cut diagonally with a sharp knife and replace
Stu
 
Re: additional question

We used to put cast iron motorbike bits in a strong solution of caustic soda, brought them up lovely. I'll be doing mine next month. By the way , that powerful sink drain cleaner is caustic soda......
 
[ QUOTE ]
i seem to remember that bukh go thru them pretty quickly?
Stu

[/ QUOTE ]

Very True! ... but last time mine went, I bought a heavilly fabricated stainless-steel elbow, and still going strong at 10yrs. Previous elbows had struggled to make 5yrs. Best thing was it was slightly cheaper than the 'genuine' article.

Vic
 
Re: additional question

Forgot to add - I'll be putting the injectors in for checking/repair as well, then maybe the exhaust will stay clear for a while. 73s
 
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