Looking to buy a 1984 H31 and I'm a little concerned about its 2GM13. The owner (who seems credible and has been very candid about other issues) states the engine has recently been rebuilt but after re-installing in the boat, never could get it to run right. This is the symptoms: Starts up fine and sounds good, but when giving throttle, it loses power and bellows black smoke(and I mean black as smut). Questions: 1) I understand that black smoke in a diesel is always a fuel issue. Correct? 2) Owner states that he didn't replace the fuel injector pump, due to the high cost (~$900) and this is probably the problem. 3) I've been told that if the injector pump is the problem, it might not need replacing, only the timing adjusted??? 4) I've also been told that since the boat hasn't had the bottom cleaned in ~3years, the prop could be fouled with oyster shells and barnicles, which could cause the black smoke??? I know that some regard this engine as barely adequate horsepower for the 31, but I think it'll be fine for my needs. My main concern is to feel relatively certain that the engine is repairable, prior to making a offer. Any help appreciated
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Trouble Shooting 2GM
You've touched on some of the probable causes yourself. You didn't say if you've tried increasing RPMs with the tranny in neutral and gotten the same result. Also try to clean the prop and bottom to eliminate that option, and before rebuilding the high pressure pump, remove and check the exhaust injection elbow. Check out trouble shooting on Yanmarhelp.com as well.
You've touched on some of the probable causes yourself. You didn't say if you've tried increasing RPMs with the tranny in neutral and gotten the same result. Also try to clean the prop and bottom to eliminate that option, and before rebuilding the high pressure pump, remove and check the exhaust injection elbow. Check out trouble shooting on Yanmarhelp.com as well.
Gary,
I'll give you the short answer first. It's not dead. Now to answer you questions. 1) Heavy black smoke is usualy a fuel issue, BUT it can also come from engine oil being combusted. This can come from weak valve guide seals, or an overfull crank case. 2) It's not necessary to replace the injection pump at a rebuild. At the very least it should be serviced buy a reputable shop and calibrated. I'll expound upon this later. 3) Injector pump timing on a GM series is controled by the thickness of the shims between the pump and front cover of the engine. If these were not replaced, or the incorect thickness was replaced at the rebuild. You might see some change in performance. I don't think to the degree you describing. 4) Bottom fouling is a concern. More than likely you'll see a decrease in full throtle RPM and a decrease in boat speed along with increased smoke. Now I have a few questions, 1) What RPM can you get in neutral? and does the smoke decrease with increased engine speed? 2) What RPM can you get in foreward? and does the smoke decrease with increased engine speed? 3) Does the engine run smooth? or do the RPM's wander with a set throtle position? 4) How much oil is on the dipstick? 5) What's the total time on the engine? 6) Did the engine sit without running for any extended period of time? How long? From your post I'm leaning to a recalibration of the injector pump. This should run $200-300 depending on what they find. Injector pumps have an orfice that adjusts to engine load and fuel need. If the orfice sticks open it'll allow more fuel than necessary to the injector. Resulting in black smoke. Pat McCartin Inland Marine Diesel Buford, GA imd_ga@hotmail.com
I'll give you the short answer first. It's not dead. Now to answer you questions. 1) Heavy black smoke is usualy a fuel issue, BUT it can also come from engine oil being combusted. This can come from weak valve guide seals, or an overfull crank case. 2) It's not necessary to replace the injection pump at a rebuild. At the very least it should be serviced buy a reputable shop and calibrated. I'll expound upon this later. 3) Injector pump timing on a GM series is controled by the thickness of the shims between the pump and front cover of the engine. If these were not replaced, or the incorect thickness was replaced at the rebuild. You might see some change in performance. I don't think to the degree you describing. 4) Bottom fouling is a concern. More than likely you'll see a decrease in full throtle RPM and a decrease in boat speed along with increased smoke. Now I have a few questions, 1) What RPM can you get in neutral? and does the smoke decrease with increased engine speed? 2) What RPM can you get in foreward? and does the smoke decrease with increased engine speed? 3) Does the engine run smooth? or do the RPM's wander with a set throtle position? 4) How much oil is on the dipstick? 5) What's the total time on the engine? 6) Did the engine sit without running for any extended period of time? How long? From your post I'm leaning to a recalibration of the injector pump. This should run $200-300 depending on what they find. Injector pumps have an orfice that adjusts to engine load and fuel need. If the orfice sticks open it'll allow more fuel than necessary to the injector. Resulting in black smoke. Pat McCartin Inland Marine Diesel Buford, GA imd_ga@hotmail.com
P
Patrick
My two cents
1. No 2. No 3. Probably 4. Question is unclear. Barnacles indicate lack of use which might lead to several problems. The engine was probably never run hard enough at the dock to properly warm up. One result is that the engine is loaded too much by junk on the prop. That might contribute to the problem. More likely, I would suggest looking at the exhaust system starting at the elbow. Most mechanics I have used do not seem to think of this. If there is growth blocking the exhaust, that might be part of it too. Was everything reconnected properly? Check the hoses for kinking or internal failure. Does the smoking happen only under load (in gear) or does it occur in neutral too?
1. No 2. No 3. Probably 4. Question is unclear. Barnacles indicate lack of use which might lead to several problems. The engine was probably never run hard enough at the dock to properly warm up. One result is that the engine is loaded too much by junk on the prop. That might contribute to the problem. More likely, I would suggest looking at the exhaust system starting at the elbow. Most mechanics I have used do not seem to think of this. If there is growth blocking the exhaust, that might be part of it too. Was everything reconnected properly? Check the hoses for kinking or internal failure. Does the smoking happen only under load (in gear) or does it occur in neutral too?
G
Gary
I got it!
I shut my eyes and said yes. Now the drum roll to see what it'll take to get the Yanmar running right. The boat is a couple hours away, but as soon as I can get over there, I will make note of everyones suggestions post results. Thanks to all.....Gary
I shut my eyes and said yes. Now the drum roll to see what it'll take to get the Yanmar running right. The boat is a couple hours away, but as soon as I can get over there, I will make note of everyones suggestions post results. Thanks to all.....Gary
Leave it be
Why would you want to buy something that is broke. Let the owner fix it and you pay for it if you like or walk away. Either way you are going to pay for it. The difference is, you will know what the cost will be and can make a smart decision as to a price. Don't buy someone elses junk. If it was so simple they would have taken care of it.
Why would you want to buy something that is broke. Let the owner fix it and you pay for it if you like or walk away. Either way you are going to pay for it. The difference is, you will know what the cost will be and can make a smart decision as to a price. Don't buy someone elses junk. If it was so simple they would have taken care of it.
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