Would appreciate any advice... MY @QM15 has always run great, had it for the last 5 years. Recently I have to crank it and crank it to get it to start up. I have bled the fuel system and dont feel like that is the problem but i could be wrong. Once it catches it runs great. If i turn it off right after starting, i.e. the engine has not warmed up, I can restart it easily right away. When i let is sit for a few hours I have the same problem and have to really crank it to get it started. It seems on the surface like an air leak but ive bled and changed all the crush washers and no fuel leaks from anywhere when its running. I have done research and it seems like it could be the fuel system or the tank vent or the exhaust blocked or who knows what else. Can anyone offer advice on where to start I would really appreciate it! Thanks all.
Yanmar 2QM15 Please help
- Thread starter GJensen
- Start date
- Status
Hard starting
Is probably related to the weather. Those things have no glow plugs, and cooler temps make them harder to crank. I had one in last boat, and if the temp. was below 50, it started slow. One thing I found out was more throttle. That did not cure it, but helped quite a bit.
Is probably related to the weather. Those things have no glow plugs, and cooler temps make them harder to crank. I had one in last boat, and if the temp. was below 50, it started slow. One thing I found out was more throttle. That did not cure it, but helped quite a bit.
I thought I started this post, but I must have been dreaming.
I have the same engine in a 1981 H30, with the exact same problem. Cranks for 5 minutes before starting. I read someones post saying how they kept a hair dryer onboard to warm the engine for 5 minutes before starting. I tried this with a heatgun for several minutes, aimed into the air cleaner and the injector side of the engine.
Then came the test. Cranked for 20 seconds and started.. Next years budget includes buying the admiral a new hair dryer and turning her old one into a {preheater}.
I have the same engine in a 1981 H30, with the exact same problem. Cranks for 5 minutes before starting. I read someones post saying how they kept a hair dryer onboard to warm the engine for 5 minutes before starting. I tried this with a heatgun for several minutes, aimed into the air cleaner and the injector side of the engine.
Then came the test. Cranked for 20 seconds and started.. Next years budget includes buying the admiral a new hair dryer and turning her old one into a {preheater}.
To Further Complicate the Issue ....................
.................... I'm going to throw in worn piston rings.
The fact that the engine will re-start immediately while still cold indicates that the initially dry piston rings are sealing poorly and allowing air to escape from the cylinder. Hence the compression combustion temperature is not being reached and the engine won't fire. Crank the engine long enough and the rings get oil and away you go. Once the rings have been wetted with oil from the first momentary run, they seal, no air leakage, compression combustion temperature is reached, and the engine fires immediately.
Are we looking at a ring job
? I doubt it, seeing as how the engine runs well after being started. Heaters seem to give it the added combustion temperature to get it going. If your engine has unloaders, use them to roll your engine over quickly for 5 seconds and you'll have oil in the rings. Close the unloaders and you're ready to start immediately.
If all else fails, use your wife's fancy new hair dryer in the engine air intake, it'll make her real happy.
.................... I'm going to throw in worn piston rings.
The fact that the engine will re-start immediately while still cold indicates that the initially dry piston rings are sealing poorly and allowing air to escape from the cylinder. Hence the compression combustion temperature is not being reached and the engine won't fire. Crank the engine long enough and the rings get oil and away you go. Once the rings have been wetted with oil from the first momentary run, they seal, no air leakage, compression combustion temperature is reached, and the engine fires immediately.
Are we looking at a ring job
? I doubt it, seeing as how the engine runs well after being started. Heaters seem to give it the added combustion temperature to get it going. If your engine has unloaders, use them to roll your engine over quickly for 5 seconds and you'll have oil in the rings. Close the unloaders and you're ready to start immediately.If all else fails, use your wife's fancy new hair dryer in the engine air intake, it'll make her real happy
.
Hi all, I have on e of these engines as well, circa 1978. I was discussing the general condition of my engine as it has a pre-heater so was was concerned about its hard starting as we as steam from the exhaust etc. According to my mechanic they were always hard-starters and he installed many preheaters even when they were relatively new engines.
His advice was to make sure the valve clearances were on spec as that can be a reason for starting that is harder than usual.
More than one person has told me in person and on this and other forums that these engines are very robust and will last a very long time.
His advice was to make sure the valve clearances were on spec as that can be a reason for starting that is harder than usual.
More than one person has told me in person and on this and other forums that these engines are very robust and will last a very long time.
These engines do have a decompression lever so using it is an option to get her cranking over smartly.Ralph Johnstone said:.................... I'm going to throw in worn piston rings.
The fact that the engine will re-start immediately while still cold indicates that the initially dry piston rings are sealing poorly and allowing air to escape from the cylinder. Hence the compression combustion temperature is not being reached and the engine won't fire. Crank the engine long enough and the rings get oil and away you go. Once the rings have been wetted with oil from the first momentary run, they seal, no air leakage, compression combustion temperature is reached, and the engine fires immediately.
Are we looking at a ring job
If all else fails, use your wife's fancy new hair dryer in the engine air intake, it'll make her real happy
hard to crank over
sounds like air leaks in fuel lines and or injector pump to me ya have to crank and crank to bleed the air then on a quick restart it starts right up cause air still blead I'd start by replacing all banjo fittings and o-rings on filters and such then if that doesnt work pull line off injector and do volume test and if ya have help; watch for alot of air in fuel as it come out the line
sounds like air leaks in fuel lines and or injector pump to me ya have to crank and crank to bleed the air then on a quick restart it starts right up cause air still blead I'd start by replacing all banjo fittings and o-rings on filters and such then if that doesnt work pull line off injector and do volume test and if ya have help; watch for alot of air in fuel as it come out the line
Re: To Further Complicate the Issue ....................
thanks for all the great advice everyone... If i put decompression on and then hand crank it does that put oil in pistons? Also is unloaders same as decompression on? what a great site that everyone helps each other out. Also i appreciate the hair dryer and preheating options but that only works in a slip for me unless i figured out a way to heat something(hot water bottle etc) on alcohol stove and then put it on engine... if i were to do that would the injectors be the place to warm up?
thanks for all the great advice everyone... If i put decompression on and then hand crank it does that put oil in pistons? Also is unloaders same as decompression on? what a great site that everyone helps each other out. Also i appreciate the hair dryer and preheating options but that only works in a slip for me unless i figured out a way to heat something(hot water bottle etc) on alcohol stove and then put it on engine... if i were to do that would the injectors be the place to warm up?
also it might not be all that bad as even with the problem it will start in about 15 seconds... its just that it used to start in 2 seconds every time. Here on the chesapeake getting the lines ready for a 7-10ft surge in the next few days courtesy of Sandy : )
An engine that is cold and then started for even a few seconds is still cold to the touch but the combustion chamber is hot. Just because you can't feel that heat does not mean it is not there.
I have an air heater installed and if is below 50 F and I don't use it it will not start without lots of cranking. Using the air heater she starts right up.
for the record the oil rings do not do anything for compression they scrape the excess oil off the walls. The COMPRESSION rings do have a lot to do with maintaining the compression but they work even when dry. the do wear a lot when dry though.
I have an air heater installed and if is below 50 F and I don't use it it will not start without lots of cranking. Using the air heater she starts right up.
for the record the oil rings do not do anything for compression they scrape the excess oil off the walls. The COMPRESSION rings do have a lot to do with maintaining the compression but they work even when dry. the do wear a lot when dry though.
Not sure of yours, but most of these boat engines never see a wrench unless they quit. Valve clearance check/adjustment, Injection timing check/adjustment, injector cleaning and testing. You could have perfect compression, but the engine still wont start if everything is off/out of adjustment/out of whack. A 2 degree change in injection timing can cause hard starting, so could valve clearance, as could gunked up injectors. Imagine if all three were off a bit, it might not start at all. So start with those checks and adjustments and see where it leads.
Do NOT use starting aids such as Ether or starting fluid on diesels with prechambers. If your not sure read your manual or ask. With compression ratios often over 25:1, ether can crack the head, break the prechamber, bend the rod, bust a whole through the piston. Or you might get lucky and it will just pop the head gasket
Some have very good luck building some combustion chamber heat before trying to actually start, by cranking with the throttle closed and in idle shut off. Without injecting fuel you crank a few short bursts, 5 or 10 seconds each, with shorter rest periods. Without injecting fuel the cold fuel isnt cooling the chamber as much. Crank, rest, crank, rest, crank, rest, crank, and using your third hand, throttle up to the start position during a rest period, and crank again.
Do NOT use starting aids such as Ether or starting fluid on diesels with prechambers. If your not sure read your manual or ask. With compression ratios often over 25:1, ether can crack the head, break the prechamber, bend the rod, bust a whole through the piston. Or you might get lucky and it will just pop the head gasket
Some have very good luck building some combustion chamber heat before trying to actually start, by cranking with the throttle closed and in idle shut off. Without injecting fuel you crank a few short bursts, 5 or 10 seconds each, with shorter rest periods. Without injecting fuel the cold fuel isnt cooling the chamber as much. Crank, rest, crank, rest, crank, rest, crank, and using your third hand, throttle up to the start position during a rest period, and crank again.
Cuttos to the sailor that suggested the lift pump. This is a rubber diafram, and over time, short or long can go bad. Rebuild it or put in an electric fuel pump. I am going to suggest that the fuel injector pump is loosing it primp. When you keep turning the engine over you are forcing fuel into the pump and the cyclinders and it will eventually start. It acts just like an air leak in your fuel system. Can't tell the difference. If you check all of the places that air can get into the system and you don't find anything, this may be the problem. You may have to take the injector pump off and take it to a qualified injector pump shop. It doesn't have to be a marine engine shop either. Millions of over the road trucks have to be fixed. Right? Hope it is something simple like a leak. Good Luck.
The usual three reasons a diesel doesn't start is because: 1. Air in the system - as mentioned above, must bleed until all the air bubbles are removed. Do it in sequence and for each cylinder. If you are getting solid fuel coming out, then your kingston pump works fine. 2. Fuel contamination...water. Use clean fuel, fill up your tank before winter storage to eliminate condensation, make sure the rubber o-ring on your deck fill is good so rain water isn't getting in the fuel. 3. Fuel Contamination....dirt or other bad stuff like algae. Clean/replace fuel filters. If you are in a tropical area, then use additives like Bio-Bor. If the above ideas are not the culprit, then consider poor compression which is essential for starting a diesel. If you have rusty cylinder rings, or worn rings, then you are not getting a proper seal for good compression. Taking an ounce of oil and putting it in each cylinder sometimes gives a temporary seal to the rings so that the engine starts. If that works, then you might need some work in that area. If your problem is during cold weather days, then the heater solution is a good strategy. If you are in the middle of a hot summer, then that might not be the problem. Hope this helps someone.
- Status