Ok, I am sure there will be many opinions here, but I would love to hear from those with previous experience... - Hunter 27 Cherubini w/ Yanmar small SB8 Diesel -At the end of last summer, I began to experience tough starting and some loss of power. -My yard / hauler suggested that before I do a total rebuild, I try a top end rebuild - I had Mack Boring totally rebuild the top end (new injector, new valves - redo valve seats, new springs and rockers, new exhaust elbow, shave head, new head gasket, bench test high press. pump, new lift pump, new thermostat). -With all this done, I reassembled the engine with all the spec. clearances and torques. I found that the engine has plenty of power and runs very nice. However, it is really tough to start! I am having the compression checked, I am fairly confident this is the culprit. I have done everything else..even checked the muffler for back pressure. Here is my problem. New England has a very short boating season. My guess is that the yard will want to pull the engine for the lower end rebuild. I may lose the summer as a result of this. This time of year is nuts with Hauling...not rebuilding. So here is my dilema... -Believe it or not, a Yanmar service agent told me that I could use a small amount of starting ether on a rag near the Air intake to help me get the sb8 going. It will eventually start without the ether, but after lots of battery cranking. I have tried the ether on rag trick once and it seemed to help consideralbly. I have heard that if you use too much ether, you run the risk of breaking a piston. - My other thought is to carry a third starting battery ...for the just in case. -Has anyone ever added Restore oil to the engine oil? It claims to increase compression. In any event, I will be rebuilding the engine in the fall...for sure. I am trying to come up with the best solution to salvage my 10 week boating season. Thoughts appreciated here. Thanks!
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Safer Add battery
So as not to hurt the engine so you can rebuild in off season I would add extra batteries to get it started or try one of those battery jump starters. nick
So as not to hurt the engine so you can rebuild in off season I would add extra batteries to get it started or try one of those battery jump starters. nick
Long cranking...
Continuous cranking will take a toll on the starter motor too. That's a lesser evil than the damage caused by ether predetonation though.
Continuous cranking will take a toll on the starter motor too. That's a lesser evil than the damage caused by ether predetonation though.
Replaced Fuel Lines?
Another thing to check is the fuel lines to the engine. If they're old it's possible to get a small air leak in a pinhole. First though, make sure all the hose clamps are good and tight and the fittings don't have an air leak. Consider puting a very small dab of Permatex on a thread as that will really help with a thread seal. The typical hose clamps can actualy cause an air leak especially on old thin hose. I'd try tightening the clamps first (that's really easy), then second doing the permatex on all the fittings leading to the fuel pump and maybe also on the ones leading to the high pressure pump, including the Yanmar fuel filter inlet/outlet and bleed screw. Lastly buy new hoses. Also check the fuel filter gasket seals. Doing this one step at a time will help locate the problem easier. If the above doesn't work then try the other more expensive rebuild steps.
Another thing to check is the fuel lines to the engine. If they're old it's possible to get a small air leak in a pinhole. First though, make sure all the hose clamps are good and tight and the fittings don't have an air leak. Consider puting a very small dab of Permatex on a thread as that will really help with a thread seal. The typical hose clamps can actualy cause an air leak especially on old thin hose. I'd try tightening the clamps first (that's really easy), then second doing the permatex on all the fittings leading to the fuel pump and maybe also on the ones leading to the high pressure pump, including the Yanmar fuel filter inlet/outlet and bleed screw. Lastly buy new hoses. Also check the fuel filter gasket seals. Doing this one step at a time will help locate the problem easier. If the above doesn't work then try the other more expensive rebuild steps.
i dont think your barking up the right tree
Im not sure a complete rebuild is what you need. the fuel hose ideas are great. and you should also look at the age of the fuel. If you have old fuel it may be the problem. Thats a great litle motor and it should start more easily. I would check out these ideas before i popped for a rebuild. I would think they would have checked the compression before they did all the work on it last time.
Im not sure a complete rebuild is what you need. the fuel hose ideas are great. and you should also look at the age of the fuel. If you have old fuel it may be the problem. Thats a great litle motor and it should start more easily. I would check out these ideas before i popped for a rebuild. I would think they would have checked the compression before they did all the work on it last time.
I have replaced all the fuel hoses and the lift
pump. I am awaiting a compression test which should tell the story. In any event, I am wondering if the addition of the commercial product Restore may help
pump. I am awaiting a compression test which should tell the story. In any event, I am wondering if the addition of the commercial product Restore may help
HARD STARTING
I WENT TO A MACK BORING SEMINAR ON YANMAR ENGINES. HARD STARTING COULD BE CAUSED BY AIR IN THE FUEL LINES. YOU HAVE TO BLEED THEM FROM THE TANK TO THE MOTOR. ALSO CHECK THE MIXING ELBOW. A STARTING TRICK IS TO RELEASE THE COMPRESSION RELEASE, GET THE MOTOR CRANKING REAL FAST, THEN CLOSE THE COMPRESSION RELEASE.
I WENT TO A MACK BORING SEMINAR ON YANMAR ENGINES. HARD STARTING COULD BE CAUSED BY AIR IN THE FUEL LINES. YOU HAVE TO BLEED THEM FROM THE TANK TO THE MOTOR. ALSO CHECK THE MIXING ELBOW. A STARTING TRICK IS TO RELEASE THE COMPRESSION RELEASE, GET THE MOTOR CRANKING REAL FAST, THEN CLOSE THE COMPRESSION RELEASE.
Don't use starting fluid
Do not use ether as you may lierally blow the head off or at least the gasket. Gasoline will also work in a pinch but I wouldn't suggest that either though it is less likely to blow a gasket with the gas. I suggest you have a fuel delivery problem. You may try a fuel bulb like used on outboards to get the fuel pressure up and see if that is it. With the warmer temps of summer there is something wrong with fuel delivery or compression for it to take a long time to start. Diesels work without an ignition system and rely on compression so as long as the timing is the same it should work as before if the fuel is getting in the cylinder. If the cylinder walls are glazed or the rings are stuck you would have a compression problem. If it smokes more than before it may be one of those two. As a potential cure if you haven't gone for to long in that condition you may want to remove the injector and get some bio-diesel in the cylinder and see if it goes to the crank case very quickly. It would mean bad compression but bio is a better solvent than dino diesel and may remove carbon on the rings causing them to stick. When you use the engine after changing the oil because of fuel dilution you want to run the engine hard. Not just at the dock but under a load at 80-90% power for an hour or so to see if the rings loosen and you reduce glazing. You should not let a diesel idle for long periods or just use to get to sea from the dock without getting the engine up to FULL operating temp regularly. This will also make sure you get rid of condensation in the oil. georgelakesiii@yahoo.com
Do not use ether as you may lierally blow the head off or at least the gasket. Gasoline will also work in a pinch but I wouldn't suggest that either though it is less likely to blow a gasket with the gas. I suggest you have a fuel delivery problem. You may try a fuel bulb like used on outboards to get the fuel pressure up and see if that is it. With the warmer temps of summer there is something wrong with fuel delivery or compression for it to take a long time to start. Diesels work without an ignition system and rely on compression so as long as the timing is the same it should work as before if the fuel is getting in the cylinder. If the cylinder walls are glazed or the rings are stuck you would have a compression problem. If it smokes more than before it may be one of those two. As a potential cure if you haven't gone for to long in that condition you may want to remove the injector and get some bio-diesel in the cylinder and see if it goes to the crank case very quickly. It would mean bad compression but bio is a better solvent than dino diesel and may remove carbon on the rings causing them to stick. When you use the engine after changing the oil because of fuel dilution you want to run the engine hard. Not just at the dock but under a load at 80-90% power for an hour or so to see if the rings loosen and you reduce glazing. You should not let a diesel idle for long periods or just use to get to sea from the dock without getting the engine up to FULL operating temp regularly. This will also make sure you get rid of condensation in the oil. georgelakesiii@yahoo.com
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