and have tried everything I could find suggested in them to fix this problem. Here's the deal: My 2GM20F will no longer attain more than around 2000 RPM's in forward gear moving through the water. Used to run 3400-3600. It will attain 3600+ in nuetral and in reverse. It will also attain around 2450 in forward TIED TO THE PEIR! but not moving through the water. At 2000 RPM stops powering up, as I add throttle it blows black smoke and crud into the water. After a careful search of the archives and copious note taking, I went to the boat yesterday hoping to fix this. Here's what I've tried: 1)Hull is freshly cleaned/painted 2)Changed all fuel filters/tightened hoses/bled and re-bled 3)Ran brand new fuel from seperate can directly into manual bleed pump, eliminating current tank/hoses/Racor 4)Checked air filter/intake - sucks in plenty of air - will try to suck in a paper towel 5)Replaced mixing elbow 6)Checked entire exhaust system including muffler for blockage 7)Checked saltwater pump and strainer - pumps lots of water I'm at a loss. What do I do next and why on earth will she run higher RPM under load tied to pier than in transit? Fuel pump? Injectors? Help!
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Ken Osborne
Low RPM
Sure sounds like a problem with your tranny. Since it attains 34-3600 rpms in reverse but not forward I would look there. Not much you can do on your own though. When was the last time you changed transmission oil and did you use 30 or 10-30 weight motor oil? 2GM20 uses nothing else that I know of. With black crud coming out the exhaust, I'd have the injectors and pump checked, cleaned. Good luck. Tough problem. Let us know what the outcome is. Ken
Sure sounds like a problem with your tranny. Since it attains 34-3600 rpms in reverse but not forward I would look there. Not much you can do on your own though. When was the last time you changed transmission oil and did you use 30 or 10-30 weight motor oil? 2GM20 uses nothing else that I know of. With black crud coming out the exhaust, I'd have the injectors and pump checked, cleaned. Good luck. Tough problem. Let us know what the outcome is. Ken
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Miles
Prop fouled?
Have you checked the prop/strut? It sounds like the engine runs ok in neutral but is overloaded when trying to spin the prop. I'd start at the transmission and work back to the prop through the stuffing box and cutlass bearing if you haven't already. Let us know what you find, good luck!
Have you checked the prop/strut? It sounds like the engine runs ok in neutral but is overloaded when trying to spin the prop. I'd start at the transmission and work back to the prop through the stuffing box and cutlass bearing if you haven't already. Let us know what you find, good luck!
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Claude L.-Auger
Prop loaded with barnacles?
A few years ago even though the bottom was almost squeaky clean thanks to the antifouling, my prop got fouled severally by barnacles over a few weeks of not using the boat. When I took it out, I had exactly the same feeling you do and thought something was wrong. Cleaning the prop/shaft from barnacles solved my problem. Hope it's that simple for you. Good luck and do keep us posted.
A few years ago even though the bottom was almost squeaky clean thanks to the antifouling, my prop got fouled severally by barnacles over a few weeks of not using the boat. When I took it out, I had exactly the same feeling you do and thought something was wrong. Cleaning the prop/shaft from barnacles solved my problem. Hope it's that simple for you. Good luck and do keep us posted.
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Jim Maroldo
Yanmar not powering...
I can't solve your problem, Glenn, but I believe it's normal to turn more RPM's tied to the pier, because the prop will tend to cavitate because it's unable to move forward into undisturbed water. (kinda like plugging up the hose on your vacuum cleaner). Anyway, judging by what you are saying, I'd hazard to guess that the engine itself is OK. It would appear that something is loading the system up in forward gear only. Do these engines have a governor on them (could be as simple as those on your lawnmower)? The reason I ask is because if it does, and the drivetrain is loaded very heavily, then the governor will dump extra fuel in to try to come up to the requested RPM. Excess fuel + heavy load + low RPM = black smoke. Does this make any sense? Jim Maroldo s/v: Lil' Wass Ett
I can't solve your problem, Glenn, but I believe it's normal to turn more RPM's tied to the pier, because the prop will tend to cavitate because it's unable to move forward into undisturbed water. (kinda like plugging up the hose on your vacuum cleaner). Anyway, judging by what you are saying, I'd hazard to guess that the engine itself is OK. It would appear that something is loading the system up in forward gear only. Do these engines have a governor on them (could be as simple as those on your lawnmower)? The reason I ask is because if it does, and the drivetrain is loaded very heavily, then the governor will dump extra fuel in to try to come up to the requested RPM. Excess fuel + heavy load + low RPM = black smoke. Does this make any sense? Jim Maroldo s/v: Lil' Wass Ett
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Glenn Newcomb
Don't know about governor, bu cavitation
sounds like a logical reason for more RPM's tied to the dock...thanks! Anyone know about the governor question?
sounds like a logical reason for more RPM's tied to the dock...thanks! Anyone know about the governor question?
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David
Yanmar
You could try this to see if the drive train is free: with the engine off and the transmission in neutral grab the coupler and see if the shaft turns easily. If not there may be a problem with the stuffing box, stern tube, strut or cutlass.
You could try this to see if the drive train is free: with the engine off and the transmission in neutral grab the coupler and see if the shaft turns easily. If not there may be a problem with the stuffing box, stern tube, strut or cutlass.
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andy
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Glenn Newcomb
Dove on prop last weekend, no excessive
growth. Also, shaft turns freely by hand in either direction. Still perplexed.
growth. Also, shaft turns freely by hand in either direction. Still perplexed.
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Allen
Air/Fuel Starved
This is just a guess, but I would put $$ on it that your engine is fuel starved. This could be caused by a fouled injector, a clogged fuel filter, clogged fuel line or return line, or a weak fuel pump. Given all of the checking you've done, I'd guess you have a weak pump. Here's why I think this is it: 1. It works ok in reverse: In reverse, the prop isnt' pitched as aggressively, and the transmission is geared differently. This means that there is less load on the engine in reverse, and less fuel required to bring it up to speed, so reverse operates normally. 2. It works tied to the dock: Again, with cavitation there is less fuel required to bring it up to speed under these conditions, and while tied to the dock, all seems fine. 3. Thick, black smoke: This is indicative of either 2 things. A. The engine is under heavy load (like when you give it full throttle from a stand-still, as you might do while docking) B. There is inefficient combustion. Combustion requires only 2 things in a diesel: a proper fuel/air mixture & healthy compression. It's one or the other, and since the engine seems to run well in all manners except in forward under load, I'd be willing to bet you have a fuel issue. Have a mechanic check the fuel delivery rate & I bet you'll find that it's lacking. I've got a 2GM20F on my Catalina 30 & I love it. Let me know what the final results are & good luck! Allen Schweitzer s/v Drambuie C-30, Hull #632
This is just a guess, but I would put $$ on it that your engine is fuel starved. This could be caused by a fouled injector, a clogged fuel filter, clogged fuel line or return line, or a weak fuel pump. Given all of the checking you've done, I'd guess you have a weak pump. Here's why I think this is it: 1. It works ok in reverse: In reverse, the prop isnt' pitched as aggressively, and the transmission is geared differently. This means that there is less load on the engine in reverse, and less fuel required to bring it up to speed, so reverse operates normally. 2. It works tied to the dock: Again, with cavitation there is less fuel required to bring it up to speed under these conditions, and while tied to the dock, all seems fine. 3. Thick, black smoke: This is indicative of either 2 things. A. The engine is under heavy load (like when you give it full throttle from a stand-still, as you might do while docking) B. There is inefficient combustion. Combustion requires only 2 things in a diesel: a proper fuel/air mixture & healthy compression. It's one or the other, and since the engine seems to run well in all manners except in forward under load, I'd be willing to bet you have a fuel issue. Have a mechanic check the fuel delivery rate & I bet you'll find that it's lacking. I've got a 2GM20F on my Catalina 30 & I love it. Let me know what the final results are & good luck! Allen Schweitzer s/v Drambuie C-30, Hull #632
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james rohr
More than likely dirty injectors
I have a 2Qm15 in my O'day 30. In the days when the rings were starting to get weak I would have the same problem. With less compression you get less effecient combustion of fuel. this starts the problem of carbon build up on the injector nozzel that in turn starts the problem of not having the right spray pattern to combust properly. It will only continue to get worse. A TRUCKERS TRICK THAT WAS GIVEN TO ME AND WORKS FOR A WHILE IS. GET A QUART OF ATF, YES AUTOMATIC TRANSMISSION FLUID. ADD 1 QT TO FUEL TANK AND THE PROBLEM WILL PROBABLY CLEAR UP IN ABOUT 1HRS RUN TIME. the atf has a lot of detergents and it usually clears it up. this is a cheap attempt and if it works a lot easier than removing injectors and having to bleed entire sys. I always put a qt in mine with each fill up. the orig engine lasted 23years before finally rusting away from the inside out. it was one of those ****** raw water cooled models. if its not the injectors do a compression test. more than likely its getting low. if so then its time for a ring job,valve job or both. By the way the ATF works better than the crap they sell you for $8.00 and call it diesel injector cleaner. so invest $1.29 and see what happens, before spending a bunch of dough on a mechanic in the yard.
I have a 2Qm15 in my O'day 30. In the days when the rings were starting to get weak I would have the same problem. With less compression you get less effecient combustion of fuel. this starts the problem of carbon build up on the injector nozzel that in turn starts the problem of not having the right spray pattern to combust properly. It will only continue to get worse. A TRUCKERS TRICK THAT WAS GIVEN TO ME AND WORKS FOR A WHILE IS. GET A QUART OF ATF, YES AUTOMATIC TRANSMISSION FLUID. ADD 1 QT TO FUEL TANK AND THE PROBLEM WILL PROBABLY CLEAR UP IN ABOUT 1HRS RUN TIME. the atf has a lot of detergents and it usually clears it up. this is a cheap attempt and if it works a lot easier than removing injectors and having to bleed entire sys. I always put a qt in mine with each fill up. the orig engine lasted 23years before finally rusting away from the inside out. it was one of those ****** raw water cooled models. if its not the injectors do a compression test. more than likely its getting low. if so then its time for a ring job,valve job or both. By the way the ATF works better than the crap they sell you for $8.00 and call it diesel injector cleaner. so invest $1.29 and see what happens, before spending a bunch of dough on a mechanic in the yard.
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neal duett
2gm20f
I have owend the same engine. I would hire a desiel machanic and do a pressure check of both cyclinders. Kind of sounds like one of the cyclinders does not have enough compression. You should have minumin of 385 lbs per cyclinder to run correctly. This engine has a compression ratio of 44 to 1. It is very high. I had a simalure problem with my motor, it was a bent rod on the number two cyclinder. Hope this helps and good luck.
I have owend the same engine. I would hire a desiel machanic and do a pressure check of both cyclinders. Kind of sounds like one of the cyclinders does not have enough compression. You should have minumin of 385 lbs per cyclinder to run correctly. This engine has a compression ratio of 44 to 1. It is very high. I had a simalure problem with my motor, it was a bent rod on the number two cyclinder. Hope this helps and good luck.
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