Exhauust Elbow

[Jack]

Having problems with reaching 3400 rpm on my Yanmar 2gm. Can only get to 2800 under load and 3000 not under. My knot meter incated only 5.5 knots flat out so I don't think it is the Tach. I know that a blocked elbow can cause a decrease in power but how quickly? I am wondering if it something else that would rob the power within 2 weeks. Don't want to call a mechanic since there are none around here so it is a hike to get one out here. By the way, no change in propeller and I have checked the throttle cable.Any thoughts greatly appreciated.

 

[Steve Dion]

Not a big deal to R

Jack:It is really not a big deal to Remove and Replace the elbow. The elbow and gasket is about $100. The only real problem with getting the manifold and the elbow apart is the fact that they are welded with rust. It is best to do it with a torch, vise and a large pipe wrench and breaker bar. You may be able to remove the raw water intake elbow and prob around to see if there is any carbon build-up. Take a look at my Photo Forum picture essay on the subject. Before you mess with the elbow, be sure to check your prop too. I know you said that you are only getting 3000 RPM's in neutral but I would check this out anyway. Also pull off your air cleaner. Soak it in liquid dish soap and rinse it out well. You can just as well have an air intake problem. Where are you located? The elbow coking problem is much more prevelant in salt water than in fresh.

 

[Jack]

Fresh Water

I'm in feshwater and the engine really doesn't have that mnay hours so that is why I am thinking it may be another issue besides the elbow. I had looked at your post on the photo forum and the elbow fix really doesn't look that difficult except on the 28.5 access is more difficult. I will check the prop as suggested.I also think it might be something else since since the problem cropped up so quickly.Thanks.

 

[Les Andersen]

Throttle Cable

Jack,The elbbow generally cokes up over a fairly prolonged period of time and could cause your problem. But, since it happened quickly, I would first check the throttle cable to see if it has slipped and you are not getting full throttle. That should be a fairly simple check. If the screw holding the cable has slipped it is a simple fix. It can vibrate loose and the symptom you describe will occur immediately.Good LuckLess/v Mutual Fun