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Diagnose my 2QM15?
Hi all,
Recently I asked for advice here on my 79 Yanmar 2QM15. Based on advice here I had the head gasket replaced. A shop inspected the head, but didn't Xray it, or whatever it is they do. The guy who replaced the head gasket is apparently at the limit of his abilities, so my next plan is to have it looked at by a shop. I was hoping I could get some good clues from the diesel experts here first. I'm not sure how long the problem I am about to describe has existed but there may have been versions of the problem present since I bought the boat a year ago. It has been somewhat intermittent, but seems worse since the head gasket replacement. The motor starts hard, but instantly with a squirt of starter fluid. It runs with a knock at almost all RPMs, but no knock at full throttle with a little black smoke. After about 5-10 minutes, the power drastically decreases. It will keep running in neutral, purring like a kitten at all RPMs, however a fair amount of black fluid pours out of the exhaust, to float on the water, not much smoke. Any ideas? Stephen |
In article ,
Stephen Trapani wrote: The motor starts hard, but instantly with a squirt of starter fluid. It runs with a knock at almost all RPMs, but no knock at full throttle with a little black smoke. After about 5-10 minutes, the power drastically decreases. It will keep running in neutral, purring like a kitten at all RPMs, however a fair amount of black fluid pours out of the exhaust, to float on the water, not much smoke. Sounds like low compression (hard starting) and injector mis-timing. The black fluid is simply dissolved soot, which could indicate the need for at least resetting valve clearances when you're not pulling significant power. Could also mean a burnt valve. Either could cause hard starting. Looking again, the new head gasket would require readjusting the valves, so make sure that's been done. Using starter fluid is dangerous. The hard starts could also be from undersized battery or cables, or slightly corroded connections. We have 1/0 and 2/0 cable runs of less than 6' and can start with 11 volts. When we had smaller and longer cables, it took at least 12v when everything was clean and tight. Years ago, my car wouldn't start due to an extra ohm or two resistance in a cable connector. Simply squeezing the connector in a vise fixed it for almost 15 years (Mom's car). The drastic power decrease after a few minutes could be a mostly-blocked fuel filter, fuel tank pickup or vent. Change filters, clean the bowls and see if it still happens. Then open the fuel fill. If still no joy, pull the pickup out of the tank and see if there's a screen at the bottom. Remove if there is. Once, I had so many dead critters in the tank that a straight tube clogged. Siphoned the fuel out of the tank through a Baja filter (West Marine has a good variant) to give the filters a break. Luckily, we had less than 5 gallons onboard at the time. I'd also suspect overheating at full power, except that the alarms aren't going off. Any change in the reservoir level, day to day? If those steps don't solve it, I'm afraid you're looking at a rebuild, but don't start worrying until you've exhausted alternatives, as that's a remarkable engine from what I've heard. -- Jere Lull Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD) Xan's Pages: http://members.dca.net/jerelull/X-Main.html Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/ |
Stephen Trapani wrote in
: Any ideas? Stephen I assume it has a heat exchanger, not raw water cooling. Fill the fresh water side with coolant. Leave the cap off the fresh water heat exchanger. Start the engine and idle it until it warms up a little, but not hot. A little coolant will naturally escape as it expands. Watch the level with the cap off. See any massive bubbling, indicating there are hot gasses escaping from the cylinders into the cooling passages in the head and cylinder walls? This'll tell you if the head is cracked or is warped enough to let gasses bypass the head gasket into the cooling system. Not rocket science, but reliable. No computer is necessary...(c; Also, note if the engine runs smoother with the pressure cap off it. Sometimes small quantities of pressurized coolant squeeze their way into the cylinder as it sucks in fresh air, compress and EXPLODE INTO STEAM inside the cylinder head as the piston comes up over TDC, making a bad knocking sound, too! Are you losing coolant for no apparent reason? This may be why if you are. Flush out the bilge with fresh water after midnight when the greenies aren't watching to get the little coolant out of the bilge...(c; No fun.... -- Larry |
It's risky and often counterproductive to look for unseen second
guesses, expert or otherwise, when you are not doing the work yourself & a shop is about to assess it firsthand. Unless they are grossly incompetent, the best you may do with other input is to prejudice their thinking & delay them in locating the real problem, or maybe **** them off. If you don't trust them you shouldn't call them aboard. BTW a disassembled & cleaned head is easily & inexpensively inspected for cracks or similar flaws by penetrant dye-checking, requiring no x-ray. |
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Larry wrote:
wrote in oups.com: maybe **** them off You must admit, though, it _IS_ fun to point out the separated wires leading to the run solenoid....seconds after you look in the hole he's been pouring over for the last 3 hours...(c; I suppose if one's idea of fun is a 3 x $80.hr = $240 additional cost for a small joke, I should be looking for work with these generous, rich people too. Please send email & plane tickets, I will handle the rest. ;-) I have found both as a ship fleet manager/Owner's rep and now a part-time lowly yacht bilge contortionist, that the very best thing the Owner or his rep can do in his own interests, is go away after initial instructions and stay away or shut up until either asked for something or until the work is completed. Then, if there are 3 hours of excess charges on the draft account or preliminary bill slip for finding a fooken wireG, it is dealt with THEN and refused. He who has the gold makes the rules, not the process. This also avoids all problems or claims of split responsibility. (i.e., "You are the yard or expert and I don't think you will prevail in an arbitration over taking 3 hours to find a solenoid wire with no interference by the Owner and no requests for further information; I could trace out & draw a whole vessel's wiring in 3 hours and you owe me dinner for telling you this along with the reduction, too, plus another $100 for insulting me with your piece of **** account.") :-) This works all over the world, and builds good relationships - even though you will not get the $100, dinner may be a hamburger, and you know it. |
Dave wrote:
On 19 Jul 2005 16:46:14 -0700, said: Owner or his rep can do in his own interests, is go away after initial instructions and stay away or shut up until either asked for something or until the work is completed. Yes, but it isn't it a very good idea to instruct the mechanics to ask you what to do you when they know what's wrong and tell you what they think should be done and what it's going to cost? And at that point when they ask you that, isn't it a good idea to have some idea of the likely problems and options? I know I've been in these kinds of situations before with exactly this boat, I've regretted not having enough information, and I've loved every time I'd previously had advice from experts like some of the guys here, and been able to either trust the mechanic to go ahead with what he thinks, or stop him! Stephen |
Jere Lull wrote:
In article , Stephen Trapani wrote: The motor starts hard, but instantly with a squirt of starter fluid. It runs with a knock at almost all RPMs, but no knock at full throttle with a little black smoke. After about 5-10 minutes, the power drastically decreases. It will keep running in neutral, purring like a kitten at all RPMs, however a fair amount of black fluid pours out of the exhaust, to float on the water, not much smoke. Sounds like low compression (hard starting) and injector mis-timing. The black fluid is simply dissolved soot, which could indicate the need for at least resetting valve clearances when you're not pulling significant power. Could also mean a burnt valve. Either could cause hard starting. Looking again, the new head gasket would require readjusting the valves, so make sure that's been done. Using starter fluid is dangerous. The hard starts could also be from undersized battery or cables, Yes, I have a low battery bank. Old batteries and it turns over fairly slowly. Once the engine is warm, it starts in a second or two every time. or slightly corroded connections. We have 1/0 and 2/0 cable runs of less than 6' and can start with 11 volts. When we had smaller and longer cables, it took at least 12v when everything was clean and tight. Years ago, my car wouldn't start due to an extra ohm or two resistance in a cable connector. Simply squeezing the connector in a vise fixed it for almost 15 years (Mom's car). The drastic power decrease after a few minutes could be a mostly-blocked fuel filter, fuel tank pickup or vent. Change filters, clean the bowls and see if it still happens. I did this all once. Maybe the Racor needs changing? I had the tank all the way out and cleaned by two mechanic friends. Then open the fuel fill. If still no joy, pull the pickup out of the tank and see if there's a screen at the bottom. I'm going to call him and ask about the screen at the bottom.... He says no screen at the bottom. Remove if there is. Once, I had so many dead critters in the tank that a straight tube clogged. Siphoned the fuel out of the tank through a Baja filter (West Marine has a good variant) to give the filters a break. Luckily, we had less than 5 gallons onboard at the time. I'd also suspect overheating at full power, except that the alarms aren't going off. Any change in the reservoir level, day to day? Reservoir? If those steps don't solve it, I'm afraid you're looking at a rebuild, but don't start worrying until you've exhausted alternatives, as that's a remarkable engine from what I've heard. Would a diesel needing a rebuild run hard for ten minutes, then lose RPM and pushing power? Stephen |
Larry wrote:
Stephen Trapani wrote in : Any ideas? Stephen I assume it has a heat exchanger, not raw water cooling. It's raw water. Fill the fresh water side with coolant. Leave the cap off the fresh water heat exchanger. Start the engine and idle it until it warms up a little, but not hot. A little coolant will naturally escape as it expands. Watch the level with the cap off. See any massive bubbling, indicating there are hot gasses escaping from the cylinders into the cooling passages in the head and cylinder walls? This'll tell you if the head is cracked or is warped enough to let gasses bypass the head gasket into the cooling system. Not rocket science, but reliable. No computer is necessary...(c; Also, note if the engine runs smoother with the pressure cap off it. Sometimes small quantities of pressurized coolant squeeze their way into the cylinder as it sucks in fresh air, compress and EXPLODE INTO STEAM inside the cylinder head as the piston comes up over TDC, making a bad knocking sound, too! Are you losing coolant for no apparent reason? This may be why if you are. Flush out the bilge with fresh water after midnight when the greenies aren't watching to get the little coolant out of the bilge...(c; No fun.... -- Stephen ------- For any proposition there is always some sufficiently narrow interpretation of its terms, such that it turns out true, and some sufficiently wide interpretation such that it turns out false...concept stretching will refute *any* statement, and will leave no true statement whatsoever. -- Imre Lakatos |
Stephen Trapani wrote in
: It's raw water. Sorry............................Yecch. -- Larry |
Larry wrote:
Stephen Trapani wrote in : It's raw water. Sorry............................Yecch. Any water passage I've seen in the engine still looks completely uncorroded. Stephen |
Try this:
Get a plastic milk jug, cut it open so you can wipe it clean with a rag. Put fuel in it. Get some clear tubing from Lowes or Home Depot. Run the tubing to the fuel fitting on the inlet to your fuel pump. Fill the tubing with fuel and allow it to siphon the fuel from the milk jug. Start your engine. If it does not lose power as it did before, then suspect your fuel filtration. The Yanmar mechanical fuel pumps seem to go bad all the time. I got an electrical pump from JC Whitney that I put in series with the mechanical one. It is wired to the starter so it always provides low pressure to the engine. It keeps the engine primed. It sounds like you have both engine timing and fuel problems. Valve timing is easy to set on this engine. Injection timing is a little harder but a COMPETENT mechanic can do it. You can do it yourself if you can follow the directions in the service manual. For cold starting, use the decompression levers. Relieve compression on one or both cylinders, get it turning then put in compression, this will get things lubed well and moving before you are trying to work against the compression. You might also check your fuel return line. If it is blocked, you can have problems. When you are priming the engine, remove it from the fitting on the injectors, blow into it (a little diesel fuel in your moth will not hurt you) to see if it is clear. Take the exhaust hose off the exhaust manifold and run the exhaust into a 5 gal bucket This will fill your cabin with smoke so be careful but the idea is to see if your muffler is clogged.. |
You really need to get a service manual. Try Mastry Marine in St.
Petersburg, FL for it. |
Stephen Trapani wrote:
Yes, but it isn't it a very good idea to instruct the mechanics to ask you what to do you when they know what's wrong and tell you what they think should be done and what it's going to cost? Huh? It should be normal without instructing. And at that point when they ask you that, isn't it a good idea to have some idea of the likely problems and options? They should have more of these than you do if they have repaired hundreds of boats to your one or three. It's certainly a good idea to challenge & contribute to their ideas in accord with what you do know, and certainly to approve/disapprove the course of action, because ultimately you are directing the work. This is not the same thing as dictating what the whole problem may entail & the specific details of how to go at it. If you are capable of the latter (and a few are), you should give them a spec up front. But what you do know is also not the same thing as what others may try to deduce unseen from your best attempts at description & tell you. This is the nexus of the matter. I know I've been in these kinds of situations before with exactly this boat, I've regretted not having enough information, and I've loved every time I'd previously had advice from experts like some of the guys here, and been able to either trust the mechanic to go ahead with what he thinks, or stop him! Indeed there are times to stop or even discharge him/her/them. But we have come full circle to the problem of their competence & your selection of them, in a case of less-than-complete knowledge of the problem & all applicable repair methods. I'm simply trying to make the point that a good one has seen & solved such problems hundreds of times more than the best owner, and that with the right parties it is a dance of wielding & balancing authority over (what is supposed to be) superior experience & abilities. The yard's primary job is to relieve you of as much money as possible at the least burdened cost, and yours is as a conservator of funds & dictator of the end results. Yards are very expert at diminishing the bank accounts of those who micromanage with various interruptions & ideas and get them to pursue or change course in more than one direction. Just mentioning another idea to an onboard mechanic in a boatyard can increase your bill by 2 manhours & tap productivity by twice that, by getting him to "go find & talk to his manager about it." The time for all "how-to" ideas to be hashed through & resolved is before anything (including the ticking of the money clock) starts, leaving only any emergent "off course" situations for interfacing & dealing with during execution. Since the latter are always found by the yard, that is what is meant by having them come to you, not "instructing." And when they do, you both will already have pre-discussed options from your initial dealing, which will save even more time unless a major new problem is unearthed. This seems all the more relevant in a typical small boatyard or small marine mechanic situation where the worker may be punching in/out on 4 different boats in the same day, and in a very real sense you are also competing with other owners' interests to keep your productivity higher (and your bill lower) than theirs. In such a siutation there will be at least one boat where significant worker time was allocated that didn't do ****-all, you may be certain. :-) With good people, the healthy & ongoing distrust should be financial, not technical. If you get good at this, you will have the lowest bills and the highest respect, and they will remember you for years and befriend you as a prime customer. Excellent repair people care even more about their pride than the money, and it is well-earned with years of deckplate innovative solution thinking & living out the results. Minimize this subtle but powerful fact at your peril. :-) It is true that repair excellence is getting rarer by the day in the entire marine world & has been for 40 years. I'm trying to help you deal more productively with the superior goods, if you find them - which is always the hardest part of the task. Trying to educate the inferior goods yourself won't make them any better, and will only give them split responsiblity to point at as soon as convenient - even if you were "right." HTH |
Dave wrote:
Sure glad I didn't follow this advice this spring. Asked Minneford's to replace the muffler and adjust the stuffing box, as I wouldn't have time for the stuffing box before leaving on Sat. Fortunately, I didn't trust them and came an extra couple of hours early. Muffler replaced, nothing done to the stuffing box, and no mechanic in sight. Rather typical - multi-tasked yard timing is not owner timing & often such an item is done in the last hour. I adjusted the stuffing box myself. Relieving them of responsbility for any results. I'm curious what the bill will say. You didn't sight it before leaving? Delay is a bad idea - their memory gets "creative." I'd be more concerned with this business practice than the minor inconvenience of twisting a couple of nuts or installing another packing ring, unless you own preferred stock in Minneford's. :-) |
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In article ,
Stephen Trapani wrote: Jere Lull wrote: The hard starts could also be from undersized battery or cables, Yes, I have a low battery bank. Old batteries and it turns over fairly slowly. Once the engine is warm, it starts in a second or two every time. Work on that in any case. I would make sure the battery was well charged and the connections clean and tight before at least one cold start, to eliminate (or confirm) the starting circuit as a problem. A warm engine will usually start more easily than a cold one, and a low battery's charge will improve quickly. Thus, an easy warm start doesn't help diagnose the problem much. The drastic power decrease after a few minutes could be a mostly-blocked fuel filter, fuel tank pickup or vent. Change filters, clean the bowls and see if it still happens. I did this all once. Maybe the Racor needs changing? I had the tank all the way out and cleaned by two mechanic friends. The one time I had critter problems, it didn't clear up until I'd changed the filter twice and brushed off my last one once or twice. Even then, we couldn't pull full power until we'd motored a few hours at low power. Lots of critter corpses fell to the bottom of the bowl as we slowly bounced along. I'd also suspect overheating at full power, except that the alarms aren't going off. Any change in the reservoir level, day to day? Reservoir? Sorry, I forgot that the 2QM15 was raw-water. I was trying to figure out whether you might be overheating without the alarm going off. You have water coming out the exhaust from your other posts, so I tend to assume you aren't overheating in 10 minutes. Any sign/smell of overheating as you lose power? Any little things that might not seem important? If those steps don't solve it, I'm afraid you're looking at a rebuild, but don't start worrying until you've exhausted alternatives, as that's a remarkable engine from what I've heard. Would a diesel needing a rebuild run hard for ten minutes, then lose RPM and pushing power? I don't believe so. Most of the time, they seem to get cranky about everything. What you're describing sounds consistent and repeatable. What happens if you're not pulling high power? Do you have a drop-off if you motor at 200, 400, ... fewer RPMs? If you do, does it take longer? And about that drop-off: Does the engine die, or will it continue to run at the lower power for a long time? How high is that lower power? For that matter, what are the RPMs at high power? As I write, I also wonder: Is the stuffing box hot when you get the drop-off? I still primarily suspect fuel delivery. If it's not the filter, than possibly something that's binding when the engine gets up to operating temperature. -- Jere Lull Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD) Xan's Pages: http://members.dca.net/jerelull/X-Main.html Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/ |
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