I have a problem with my 1GM. It starts not as well as it used to. Also after its run for a while it seems to lose a bit of power and has lots of soot in the cooling water. I have searched on the internet - could be a crack in the cylinder head. This has been confirmed as possible by Cutler Marine.

We shall see when they look at it. Has anyone had any similar experiences?

Tim Reeder

Tim,

have you taken off the cooling water inlet hose from the cylinder head?

It is I believe a particular problem with the 1GM, that the head corrodes. You can check the deterioration by looking at the size remaining on the inlet & seeing how rusty it is!

275/30 "Cascada"

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Hi Tim, i can confirm what John says - check the exhaust water injection bend where the water injection point is. Remove the whole thing (just undo the exhaust and water injection rubber hoses and the bolts from the head flange)
Check that the inner pipe is not perforated as this lets injected cooling water go back to the exhaust port at the head. Also check the head exhaust port from the manifold flange back to the valve is at least as big as your index finger all the way through . This is where a build up of crud (salt and rust?) can build up and choke the engine. If this crud is excessive and old, it can also lead to perforation between the exhaust port and the coolant chambers which surround the port.
I had to replace the head this year when I had the same problem.
Despite the cost of new exhaust injection bends, seems they may be cheaper than new heads!
Best of luck
chrisN

Chris John

Thanks for your help. Very useful - will do, but it seems a bit better at the moment. Fingers crossed!

Tim

Just looking around at other sources of info on 1GM10's and saw this:-
http://exhaustelbow.com/ 

Anyone with any experience of this solution?

Regards

Dick

quote:

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Originally posted by chris nichols

Hi Tim, i can confirm what John says - check the exhaust water injection bend where the water injection point is. Remove the whole thing (just undo the exhaust and water injection rubber hoses and the bolts from the head flange)
Check that the inner pipe is not perforated as this lets injected cooling water go back to the exhaust port at the head. Also check the head exhaust port from the manifold flange back to the valve is at least as big as your index finger all the way through . This is where a build up of crud (salt and rust?) can build up and choke the engine. If this crud is excessive and old, it can also lead to perforation between the exhaust port and the coolant chambers which surround the port.
I had to replace the head this year when I had the same problem.
Despite the cost of new exhaust injection bends, seems they may be cheaper than new heads!
Best of luck
chrisN

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Dick
Dark Star P275 No 36

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Hi,
Having spent a small fortune replacing my GM1 on Cleo last winter and still being afloat and using her regularly so far i have not yet done and routine checks or servicing on the engine, i decided to bit the bullet and go ahead and order this on line-- i was buying a new mixer elbow every 2 or 3 seasons.

I received an e-mail confirming my order and about 6 days later the mixer elbow arrived in the post. cost about £60.00
The cost from the main dealers is now nearly £150.00--- so well worth it

This is much heavier than a yanmar original and therefore should last a lot longer too

time will tell !
Peter Lowry

I took the elbow off last winter and checked it but it was fine after 19 years.

My problem is that my Yanmar has managed to start up backwards twice. What I mean is that it fires normally and runs but with air sucked in through the exhaust and grey smoke blown out through the air filter into the engine box. First time I thought the boat was on fire!

I have serviced the engine and had the injector serviced too, but has anyone else experienced this? I am told it is a feature of single cylinder engines. If it happens again I am not sure what to do next.

Kate

Yay for the hundredth post!

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Hi I have had this only happen to me once and like you i thought the boat was also on fire--

not sure why --- I am going into marine power in the week and will ask the question
Peter Lowry
Cleo

http://exhaustelbow.com/  :

"My elbow does fit the 2GM with the side mounted exhaust manifold. Later 2gm's have a rear mounted manifold above the driveshaft."

Geoff Sheddick
Parker 27/146 "Stroller'

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I'm glad to say that servicing the injector solved all my starting problems and this year the engine has only run forwards.

The only issue to report has been erratic running at high revs which I think may be due to some dirty fuel bought in Dunstaffnage, or maybe just the tank getting shaken up crossing the Bristol Channel. Either way leaving the boat for a fortnight and letting the fuel settle again seems to have sorted it.

I think this winter will be when I clean out the bottom of the fuel tank for the first time.

Kate

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