I'm in the process of trouble shooting a cruising RPM issue with the 4JH2TE on our 1991 P42. I've replaced the Racor and engine filters, the fuel pickup tube does not have a screen and it is not plugged. The turbo blades spin freely and the mixing elbow is clear. In neutral the engine will reach its max RPM of around 4100 RPM and around 3800 in reverse, but in forward it will only reach 2500. We have an 18x14 RH fixed three blade, which I believe came with the boat. The prop and shaft are clean and aligned with the engine. On two occasions last year it did go to about 3100 RPM, but not since. The fuel rack runs its full course. While under way two thirds throttle will reach the 2500 RPM mark but the remaining third makes no difference in RPM. No black smoke comes out either. I'm about to have a Yanmar tech (who is stumped about my situation) take a look at it, but I would rather figure it out on my own. Any ideas? Terry
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Assume you checked the throttle linkage?
That's the only thing that quickly comes to mind, given that the prop size and pitch appear to check with the specifications on this site. I think the next step would be the tech. It looks as if you checked the obvious things. The things I would consider next would be injectors, the pump and compression. But, that's over my head. Good luck. Rick D.
That's the only thing that quickly comes to mind, given that the prop size and pitch appear to check with the specifications on this site. I think the next step would be the tech. It looks as if you checked the obvious things. The things I would consider next would be injectors, the pump and compression. But, that's over my head. Good luck. Rick D.
Yup
Terry, I think Rick is right (at least THIS time
)the key for me is that you mention no change in response for the last third of your throttle. My 4JH2E (fifty hp no turbo) is quite responsive in that part of the throttle. Skip the tech and have someone operate the throttle while you look at it ini the engine bay. I have a hunch you will find your problem right there.......where Rick said it would be. All Good Wishes Ron Hughes s/v "Best Revenge" P.S. very intelligent post
Terry, I think Rick is right (at least THIS time
)the key for me is that you mention no change in response for the last third of your throttle. My 4JH2E (fifty hp no turbo) is quite responsive in that part of the throttle. Skip the tech and have someone operate the throttle while you look at it ini the engine bay. I have a hunch you will find your problem right there.......where Rick said it would be. All Good Wishes Ron Hughes s/v "Best Revenge" P.S. very intelligent postLet me know what they find....
I have gone through the same thing with my 3JH3E. It lost RPM's and they have never come back. Linkages, injectors, and all sorts of things have been tried with no luck. The speculation now is that it might be the injector pump and nobody really wants to go there right now.... Brian
I have gone through the same thing with my 3JH3E. It lost RPM's and they have never come back. Linkages, injectors, and all sorts of things have been tried with no luck. The speculation now is that it might be the injector pump and nobody really wants to go there right now.... Brian
I'm sorry, that's what I meant by the fuel rack...
the throttle linkage on the fuel rack runs its full course. It could be a bad injector(s) or injector pump, but the engine has only 800 total hours. It almost seems like the engine is being starved of fuel. Some others told me it might be over prop'd, but the engine would be blowing black smoke. Has anyone ever cleaned their turbo with turbo cleaning fluid? I asked the local diesel repair shop and they told me they had never heard of such a thing. Thanks for your input. Terry
the throttle linkage on the fuel rack runs its full course. It could be a bad injector(s) or injector pump, but the engine has only 800 total hours. It almost seems like the engine is being starved of fuel. Some others told me it might be over prop'd, but the engine would be blowing black smoke. Has anyone ever cleaned their turbo with turbo cleaning fluid? I asked the local diesel repair shop and they told me they had never heard of such a thing. Thanks for your input. Terry
Re: Injectors
See the link for the Yanmar service schedule. It does suggest checking the injector timing and spray pattern at 600 hours. Note that it also calls for cleaning the exhaust mixing elbow every 300 hours. Possible it is a constricted exhaust elbow? If you can check that yourself, I'd be inclined to do so before having someone come out on the injectors. Good luck. Rick D.
See the link for the Yanmar service schedule. It does suggest checking the injector timing and spray pattern at 600 hours. Note that it also calls for cleaning the exhaust mixing elbow every 300 hours. Possible it is a constricted exhaust elbow? If you can check that yourself, I'd be inclined to do so before having someone come out on the injectors. Good luck. Rick D.
Injectors??
If it were the injectors he would not be getting the 3800 RPM in reverse (which should be near normal and more than adequate). Is the throttle and trans shift on the same handle or is it a two handle set up? Look at the shift /throttle alignment and stops at the helm station. Measure the throttle rod movement at the pump linkage in full speed reverse and full speed forward. I would be willing to bet there is a difference. Look at the logic---3800 rpm in reverse ---sounds like the engine is fine---sounds like the injector pump is fine, putting it in forward does not make this pump cease to function. Got to be somewhere between the end of the throttle cable---trans linkage---and the shift -throttle lever. Just my thoughts --please let me know what you find.
If it were the injectors he would not be getting the 3800 RPM in reverse (which should be near normal and more than adequate). Is the throttle and trans shift on the same handle or is it a two handle set up? Look at the shift /throttle alignment and stops at the helm station. Measure the throttle rod movement at the pump linkage in full speed reverse and full speed forward. I would be willing to bet there is a difference. Look at the logic---3800 rpm in reverse ---sounds like the engine is fine---sounds like the injector pump is fine, putting it in forward does not make this pump cease to function. Got to be somewhere between the end of the throttle cable---trans linkage---and the shift -throttle lever. Just my thoughts --please let me know what you find.
Reverse
Just curious... I have heard that the engine will always turn more rpm in reverse.. I am not sure why, but my guess would be because the prop isn't loading up like it is in foward, so it is easier for the prop to turn just as if you had changed the pitch? That is a guess and only a guess Brian
Just curious... I have heard that the engine will always turn more rpm in reverse.. I am not sure why, but my guess would be because the prop isn't loading up like it is in foward, so it is easier for the prop to turn just as if you had changed the pitch? That is a guess and only a guess
BrianBlocked Filter Inlet?
Terry, I had the dreaded fuel bug and cleaned everything - or so I thought, even taking the fuel line home and blowing it out with an air hose. No improvement on the power situation. Eventually I took the Racor filter off the boat and discovered a plug of black diesel bug lodged in a narrow right angled bore on the inlet side. Blew it out by mouth and a great dollop of crud shot out. The only problem was that the outlet pipe was right by my ear and I got an earful. Ugh!!
Terry, I had the dreaded fuel bug and cleaned everything - or so I thought, even taking the fuel line home and blowing it out with an air hose. No improvement on the power situation. Eventually I took the Racor filter off the boat and discovered a plug of black diesel bug lodged in a narrow right angled bore on the inlet side. Blew it out by mouth and a great dollop of crud shot out. The only problem was that the outlet pipe was right by my ear and I got an earful. Ugh!!
Don, good idea, I'll check the inlet side of the..
Racor. When I cleaned and replaced both Racors there was a small amount of that black sludge. Yanmar service told me that reverse gear has a lower ratio than forward gear, which partly explains the difference. I've checked the throttle linkage (dedicated and separate from the shifter linkage) and at the helm with what shows on the engine and it looks normal to me and to another skipper. I'm going to double check the mixing elbow, too. I want to rule out everything I can before I consider changing the prop pitch. BTW there were a few times this past season when I would shift into forward gear, increase throttle and the engine would hesitate for a few seconds before increasing speed to match the throttle position. Terry
Racor. When I cleaned and replaced both Racors there was a small amount of that black sludge. Yanmar service told me that reverse gear has a lower ratio than forward gear, which partly explains the difference. I've checked the throttle linkage (dedicated and separate from the shifter linkage) and at the helm with what shows on the engine and it looks normal to me and to another skipper. I'm going to double check the mixing elbow, too. I want to rule out everything I can before I consider changing the prop pitch. BTW there were a few times this past season when I would shift into forward gear, increase throttle and the engine would hesitate for a few seconds before increasing speed to match the throttle position. Terry
Fuel starvation problems; a long story
Terry, our 1991 Legend 43 also has a 4JH2 series Yanmar with a long history of fuel starvation, making it difficult to run at higher RPMs, particularly if the fuel tank was less than full and/or the fuel filters were starting to get a little dirty. In the first few years we struggled mightily with that problem but got some relief by upgrading to a higher flow (20 gph) 220 series Racor pre-filter. However, the problem would still rear its ugly head from time to time. Finally, last year we decided to go to the 500 GFS turbine series, not only because of the higher flow rating (60 gph) and, thus, lower resistance but also because of the much lower replacement element cost (the price of the Racor 500 elements is only 1/3 of that of the 200 spin-on elements). While installing the new 500 GFS turbine filter housings (we installed two of these in parallel, using 3-way valves to enable rapid switching underway) the local engine mechanic noticed that the long feeder tube running from the stern-mounted tank to the engine with relatively little drop only had a 1/4" ID and thus made a poor match with the 500 series filters. He replaced it with a 1/2 " ID tube (hope I got all the dimensions right as I am only working from memory) and -- PRONTO -- our 12-year old fuel starvation problem was solved. In fact, we sailed and motored the whole season on a single 500 filter without any signs of fuel starvation. Note that we always use a special fuel pressure gauge to monitor the pressure drop across the filter. In the past, however, we already would get fuel starvation problems beofre the pressure drop across the filter went into the yellow warning zone on the gauge. An alternative, which I have often considered, but never quite found the time and space to install, is a so-called "day tank" mounted directly above the engine, thereby providing a much better gravity feed configuration with a very short feeder tube connection. Hope this may give you some more things to try. Success! Flying Dutchman
Terry, our 1991 Legend 43 also has a 4JH2 series Yanmar with a long history of fuel starvation, making it difficult to run at higher RPMs, particularly if the fuel tank was less than full and/or the fuel filters were starting to get a little dirty. In the first few years we struggled mightily with that problem but got some relief by upgrading to a higher flow (20 gph) 220 series Racor pre-filter. However, the problem would still rear its ugly head from time to time. Finally, last year we decided to go to the 500 GFS turbine series, not only because of the higher flow rating (60 gph) and, thus, lower resistance but also because of the much lower replacement element cost (the price of the Racor 500 elements is only 1/3 of that of the 200 spin-on elements). While installing the new 500 GFS turbine filter housings (we installed two of these in parallel, using 3-way valves to enable rapid switching underway) the local engine mechanic noticed that the long feeder tube running from the stern-mounted tank to the engine with relatively little drop only had a 1/4" ID and thus made a poor match with the 500 series filters. He replaced it with a 1/2 " ID tube (hope I got all the dimensions right as I am only working from memory) and -- PRONTO -- our 12-year old fuel starvation problem was solved. In fact, we sailed and motored the whole season on a single 500 filter without any signs of fuel starvation. Note that we always use a special fuel pressure gauge to monitor the pressure drop across the filter. In the past, however, we already would get fuel starvation problems beofre the pressure drop across the filter went into the yellow warning zone on the gauge. An alternative, which I have often considered, but never quite found the time and space to install, is a so-called "day tank" mounted directly above the engine, thereby providing a much better gravity feed configuration with a very short feeder tube connection. Hope this may give you some more things to try. Success! Flying Dutchman
Henk, sounds like that might be the problem...
If I mounted a pressure guage onto the inlet side of the Racor that should show me whether I have a flow problem. You're right! I thought it was 3/8 inch ID hose until I pulled it off yesterday, 1/4 inch. Maybe 3/8 or 7/16 inch was the size your mechanic used to replace your old hose. One half inch seems awfully big. I need to have the Yanmar mechanic do the 1,000 hour service, e.g., torque head bolts, injector spray pattern, pump timing, etc. I'll have him check the inlet pressure and replace the hose myself. Henk, thanks for sharing the solution to your problem. I'll let you know the outcome. Have a very Merry Christmas and a Happy New Year to you and your family. TerryS/V Belle-Vie P.S. What RPM difference did you experience with your 4JH? Our max right now is 2500, but it should be around 3500 in forward gear. Did you have a three blade fixed?
If I mounted a pressure guage onto the inlet side of the Racor that should show me whether I have a flow problem. You're right! I thought it was 3/8 inch ID hose until I pulled it off yesterday, 1/4 inch. Maybe 3/8 or 7/16 inch was the size your mechanic used to replace your old hose. One half inch seems awfully big. I need to have the Yanmar mechanic do the 1,000 hour service, e.g., torque head bolts, injector spray pattern, pump timing, etc. I'll have him check the inlet pressure and replace the hose myself. Henk, thanks for sharing the solution to your problem. I'll let you know the outcome. Have a very Merry Christmas and a Happy New Year to you and your family. TerryS/V Belle-Vie P.S. What RPM difference did you experience with your 4JH? Our max right now is 2500, but it should be around 3500 in forward gear. Did you have a three blade fixed?
Terry, this has been a good read even though
I only have a 3gm30f. It sounds like Henk has solved your problem. Figures.
I only have a 3gm30f. It sounds like Henk has solved your problem. Figures.
Terry 4jh2te rpm problems
Terry I'm reading lots of good info here about what could be your problem but I have a question. Did you engine EVER run the higher rpm at cruise and what was the wide open throttle rpm's (in gear)?Has this been a problem since you bought the boat or has it just recently developed?The prop is correct (check spec here on HOW web site)so you are most likely not overproped,was there another change or did something else happen that may be related to the lack of higher rpm's? Still thinking about your problems and let us know what the final "cure" is.
Terry I'm reading lots of good info here about what could be your problem but I have a question. Did you engine EVER run the higher rpm at cruise and what was the wide open throttle rpm's (in gear)?Has this been a problem since you bought the boat or has it just recently developed?The prop is correct (check spec here on HOW web site)so you are most likely not overproped,was there another change or did something else happen that may be related to the lack of higher rpm's? Still thinking about your problems and let us know what the final "cure" is.
Terry-another possible help
Terry-check the link below and post your problem there for more ideas. the guys who run the site are former Yanmar dealer mechanics and are very very good. Worth a try! Good Luck !
Terry-check the link below and post your problem there for more ideas. the guys who run the site are former Yanmar dealer mechanics and are very very good. Worth a try! Good Luck !
Terry: return hose ID...
I don't think our mechanic replaced that as we were in a big hurry to cast off for the outer islands. In fact, he did not even replace the first few inches of the feeder hose since that would have required opening up the aft wall of our stateroom to gain access to the tank. So, when we start getting ready for the 2004 season in June I will need to review the entire kluged set-up one more time. Thinking somewhat longer about the return hose, though, perhaps it is not so bad after all to create a little bit of a stagnation zone in the return hose as that might perhaps act like a mini-buffer when needing to rev up the engine in an emergency. Wonder what other people's thoughts are in regard to this question. Terry, you also asked about my RPMs. Unfortunately, the answer is rather embarrassing for me. But, ok, in the kindred spirit of Xmas here goes: I rarely go over 2200 RPM......... Both the Maxprop pitch and the alternator pulley ratio have been adapted to these very low operating speeds. The reasons behind this unusual configuration are a mix of calculation (e.g. with regard to the ability to charge at over 100 Amps at only 1200-1400 rpm in anchorages while reducing interior noise and heat production) and opportunism (we used to have some engine vibration at higher RPMs that I was simply unwilling to deal with in a rigorous manner during the first few years). Of course, I was also aware that this goes against common wisdom and that dire consequences might threaten us in the long run (e.g. excessive carbon deposits). However, after 4000+ hrs on the engine (in 13 years) it still runs perfectly fine and starts by just pointing at it. OK, I am not trying to advocate this as the best way to run one's diesel even though I once met an old merchant marine engineer who strongly encouraged me to keep doing it because, as he said (while shifting the tobacco to the other side of his mouth) "the lower yur RPMs the less yur wear 'n tear" (followed by a healthy flow of diesel-colored tobacco juice). Nonetheless, let's please regard this as a family secret...) Season's Greetings Flying Dutchman
I don't think our mechanic replaced that as we were in a big hurry to cast off for the outer islands. In fact, he did not even replace the first few inches of the feeder hose since that would have required opening up the aft wall of our stateroom to gain access to the tank. So, when we start getting ready for the 2004 season in June I will need to review the entire kluged set-up one more time. Thinking somewhat longer about the return hose, though, perhaps it is not so bad after all to create a little bit of a stagnation zone in the return hose as that might perhaps act like a mini-buffer when needing to rev up the engine in an emergency. Wonder what other people's thoughts are in regard to this question. Terry, you also asked about my RPMs. Unfortunately, the answer is rather embarrassing for me. But, ok, in the kindred spirit of Xmas here goes: I rarely go over 2200 RPM......... Both the Maxprop pitch and the alternator pulley ratio have been adapted to these very low operating speeds. The reasons behind this unusual configuration are a mix of calculation (e.g. with regard to the ability to charge at over 100 Amps at only 1200-1400 rpm in anchorages while reducing interior noise and heat production) and opportunism (we used to have some engine vibration at higher RPMs that I was simply unwilling to deal with in a rigorous manner during the first few years). Of course, I was also aware that this goes against common wisdom and that dire consequences might threaten us in the long run (e.g. excessive carbon deposits). However, after 4000+ hrs on the engine (in 13 years) it still runs perfectly fine and starts by just pointing at it. OK, I am not trying to advocate this as the best way to run one's diesel even though I once met an old merchant marine engineer who strongly encouraged me to keep doing it because, as he said (while shifting the tobacco to the other side of his mouth) "the lower yur RPMs the less yur wear 'n tear" (followed by a healthy flow of diesel-colored tobacco juice). Nonetheless, let's please regard this as a family secret...
) Season's Greetings Flying Dutchman
Henk, for years my Max prop was set for low rpms
and when I pushed the engine above 2300, the over heat alarm would sound. During the rebuild of the engine, I found the inner tubes of the heat exchanger coated in what appeared to be calcium from coral. I removed it with a long 1/4" drill. I don't know if it acted as an insulator because I also re-pitched the prop too. In any case, problem solved.
and when I pushed the engine above 2300, the over heat alarm would sound. During the rebuild of the engine, I found the inner tubes of the heat exchanger coated in what appeared to be calcium from coral. I removed it with a long 1/4" drill. I don't know if it acted as an insulator because I also re-pitched the prop too. In any case, problem solved.
Fred, the alternator is the biggest stumbling
block, right now. In order to get some 120 Amps (out of a maximum output of 150 Amps cold) I need to run it at approx. 4000 rpm. With a special small alternator belt pulley (plus the highest grade alternator belt money can buy, namely Gates triple green stripe) I can do so at no more than 1200-1400 engine RPMs ! This means we can still hear each other below-decks and I am not heating the galley slave area up any further than our living at 17 degrees S already does..... Unfortunately, however, the maximum RPM that the alternator can sustain is in the 6000-6500 RPM range. Do the math and you will see why I cannot run my engine very far above 2000 RPM for any length of time without requiring a whole series of modifications. Moreover,everything works fine right now. Thanks for reminding me about the heat exchanger, though. The last time we cleaned the insides was in Hawaii in 1998. I don't have any overheating alarms going off, fortunately. Moreover, I always watch the cooling water temperature quite closely. Flying Dutchman
block, right now. In order to get some 120 Amps (out of a maximum output of 150 Amps cold) I need to run it at approx. 4000 rpm. With a special small alternator belt pulley (plus the highest grade alternator belt money can buy, namely Gates triple green stripe) I can do so at no more than 1200-1400 engine RPMs ! This means we can still hear each other below-decks and I am not heating the galley slave area up any further than our living at 17 degrees S already does..... Unfortunately, however, the maximum RPM that the alternator can sustain is in the 6000-6500 RPM range. Do the math and you will see why I cannot run my engine very far above 2000 RPM for any length of time without requiring a whole series of modifications. Moreover,everything works fine right now. Thanks for reminding me about the heat exchanger, though. The last time we cleaned the insides was in Hawaii in 1998. I don't have any overheating alarms going off, fortunately. Moreover, I always watch the cooling water temperature quite closely. Flying Dutchman
Henk, a clutch would fix that
Mounting an electric clutch on the altenator might be one solution to excessive RPMs. Just flip a switch and take the altenator off line when you want to run your engine at higher RPMs. This ofcourse is one more gadget to break, but might come in handy in a pinch. I have attached a website of a clutch manufacturer. Happy Holidays Ward
Mounting an electric clutch on the altenator might be one solution to excessive RPMs. Just flip a switch and take the altenator off line when you want to run your engine at higher RPMs. This ofcourse is one more gadget to break, but might come in handy in a pinch. I have attached a website of a clutch manufacturer. Happy Holidays Ward
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