1gm10 high rise elbow

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nemodreams

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Alternate 1gm10 exhaust elbows - high rise ?

I have seen various units - usually cast stainless ? - that claim to fit a 1gm10.
I do not see how these can connect to the exhaust flange studs ?
They just seem to have a thread connecton. I see no sign of a flange.


PS - I am very familiar with the 1gm10 elbow - I know about the US 304 remakes that can be imported.
My elbow is not leaking. I'm just sussing out possible future alternatives for when my 'new' elbow of four years ago
pickles through, which will probably not be that long !
 
Don't think anybody produces a ready made high rise manifold for a 1GM, although it is possible to make one either welding it up or using threaded components to make the bend. However, not sure it is necessary and the chances of corrosion of the standard elbow can be reduced considerably by fitting an anti syphon valve in the hose between the outlet on the head and the water injection point, and regularly removing and cleaning the inside of the elbow. The corrosion occurs when the engine is not being used. The elbow on mine was the original 1992 and was still fine when I sold the engine in 2009.
 
Thanks - sort of what I thought. I couldn't find anything.
I'm not sure of the history on my first elbow - but the new one has been off twice in 4 years - cleaned and checked , done little milage - I have an anti syphon and good vetus waterlock etc - yet its showing surface pitting already inside the inner tube.
I don't see what can cause pinhole corrosion like this while not being used ? They are stainless after all - even if poor grade.
 
Don't think a Yanmar one is stainless. The corrosion is caused by moisture in the carbon that stays there after the engine is switched off. Worse if the engine is run at light loads. Needs to be run hard and thoroughly warmed up each time. Also has a habit of kicking back when shut down which can suck spray back in before the anti syphon does its job.
 
Tranona said:
Don't think a Yanmar one is stainless.
Click to expand...

My Yanmar original wasn't. I now have one of the american stainless ones, at which I will be giving a good hard stare this spring, as it has done two seasons. At around 1/3 the cost of a Yanmar MS one these days, it doesn't have to last long to be worthwhile.
 
John Skewes at Cellar Marine (01326 280214) in West Cornwall makes replacement 'high rise' exhaust elbows for 1GM's. He told be they look like 'scaffolding' but do the job, and are cheaper than the Yanmars (but dearer than the American ones!!)

When I checked my elbow a couple of years ago it looked fine, both on the outside and the inner pipe. However, when I filled the space between the two tubes with water I noticed water seeping from within the inner tube. The corrosion was on the top of the inner tube and couldn't be seen with the eye. I sent mine off to a company in Northern Ireland who, for £50, cut out the old tube and replaced it with a stainless one. I still check it each winter, and so far it seems OK.
 
Well the one I took off seemed to be stainless of some grade
( I presume the original 1993 ) - and the new one I put on was the same ( 2009 ) Yanmar ordered part.

If you take a look at the report that appears on this site -
http://www.shrimperowners.org/

see under technical/ engines / exhaust elbow - pdf - Some analysis was done on several elbows,
including cutaway pics - interesting !

...so there is at least another opinion as to their being stainless. Even the best grade of stainless is not
well suited for the purpose.
 
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Standard stuff for 1GM elbows - but they are not stainless, although they look nice and shiny because of the protective coating on the outside. They are mild steel - and rust. Stainless is not necessarily the answer as they can corrode at the welds rather than the pipe itself. However, if they are made of 316 grade and the weld of the inner to the outer is well clear of the injection point should last longer if the welding is good.
 
If it were mild steel it would be magnetic - it is not magnetic. Try it sometime ?
Very slightly magnetic around the flange area - probably due to formation of martensite or ferrite locally-
around welds or cold forming. The tubes are not megnetic.
 
nemodreams said:
If it were mild steel it would be magnetic - it is not magnetic. Try it sometime ?
Very slightly magnetic around the flange area - probably due to formation of martensite or ferrite locally-
around welds or cold forming. The tubes are not megnetic.
Click to expand...

Totally agree
All 4 original 1GM10 exhaust bends I have dealt with have been stainless steel inside and out, they are dull grey and not polished and they are not or only very slightly magnetic.

Pete
 
Thanks Pete - :-)

With regard my original post - what I was was wondering was - if you fabricate an alternate elbow where the water
joins the exhaust at a distance from the port flange - does this compromise the temperature of the exhaust port ?

It is after all - being cooled very close to the head ? Would a 1gm10 be ok with a dry pipe for the first 8" -
as maybe a high loop - then introduce the water, before it meets the hose ?

This is very standard on many installation diagrams I see.

Maybe the standard elbow is that way just to make it as short as possible.

It is much easier to make up a system - ie from 1" 1/4 bsp bronze fittings - if the water enters
after a high rise at the manifold.
The main problem is the flange fitting which would have to be fabricated ?
 
Hi Nemodreams

I know it is not Hi rise but I have recently bought a DC TIG welder and have knocked up an exhaust bend for my 2GM20F out of 304 stainless as a project. The thinking behind it is that it is usually the inner pipe that goes so hopefully with this design I will just have to replace the simple to make inner pipe and flange and keep the rest, there are obviously gaskets between the 3 flanges and with the water being introduced a little lower down hopefully there is less chance of it getting back up into the engine.
I am going to insulate the top section as it will not be water cooled and I will be carrying the old bend with me just in case :) If it works out I will make a couple of spare inner pipes.

View attachment 40412

Pete
 
Hope this isn't drifting the thread because I know nothing of the Yanmar exhaust elbow apart from what I have read here and elsewhere.
Is there a reason for the seemingly complicated, thus costly, design? Is there any reason why a simple elbow such as that used by Beta could not be used? It seems that such a design would be much easier to fabricate.
What I'm talking about... http://www.boatpartsandspares.co.uk/beta-marine-exhaust-elbow-1215-p.asp
 
Is the 1gm 10 freshwater/heatchanger cooled! I can't remember seeing one that is but the reason I ask is that on my 3G 30 which is freshwater etc. I have a 10 inch dry riser from the manifold and then a cast bronze elbow with threaded raw water insert to run the seawater into the rubber exhausts hose and water traps ...
 
Alahol2 the elbow in your pic looks similar to the 1GM10 one with the shorter exhaust pipe inside and the longer water jacket outside only it's aluminium instead of stainless steel (probably a bit thicker) and a lot cheaper.

Blueboatman a 1GM10 is a raw water cooled engine unless it has been converted to fresh by the owner.
 
pete said:
Alahol2 the elbow in your pic looks similar to the 1GM10 one with the shorter exhaust pipe inside and the longer water jacket outside only it's aluminium instead of stainless steel (probably a bit thicker) and a lot cheaper.

Blueboatman a 1GM10 is a raw water cooled engine unless it has been converted to fresh by the owner.
Click to expand...

Aha, ta. Then there would/could/might be concern at raising and quantifying the exhaust valve temperatures by adding an extended dry run..
Sou da like it might be worth the OP putting in a call to Cellar Marine?
 
My 'New' Yanmar elbow failed after 3 years, I fitted one of the high rise elbows fabricated by Cellar Marine and kept the boat for at least another three years without any problems. The high rise elbow does obviously raise the height of the engine profile and I have heard is not suitable for a Shrimper.
 
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