I have a 1983 yanmar 3gmf in my 34' hunter. I had it rebuild. I am having a problem starting. Once I get it started, she shakes and after a few minutes, it takes off. I had it running for the 1st time for about 45 minutes after the rebuild. Stoped the engine then try to restart. I have broken 2 starters from, what I think, is kick back. I feel the timing for the fuel injector is very much off. that is why the hard starting. Any help on how to adjust the timing??
fuel timing problem
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Timing of the injectors is done sort of like we used to do when we rebuilt a gas engine distributor. You had to reinsert the distributor exactly the way it came out and hope no one turned the engine over.
It sounds like the injector pump was reinstalled without regard to timing. You might do this yourself with the right Yanmar manual. Or you could pay your local Yanmar mechanic.
It sounds like the injector pump was reinstalled without regard to timing. You might do this yourself with the right Yanmar manual. Or you could pay your local Yanmar mechanic.
Wojo:
Why do you need to worry about this. The company that rebuilt your engine should be addressing this as well as the starter issues.
Can I ask you if this was a "certified" Yanmar company or someone that just knows diesel engines?
Why do you need to worry about this. The company that rebuilt your engine should be addressing this as well as the starter issues.
Can I ask you if this was a "certified" Yanmar company or someone that just knows diesel engines?
There are timing marks
on the flywheel. One is for the valves and one is for the injector pump and yet another for top dead center. They could also be on the camshaft end. You will have to set the camshaft/crankshaft to the timing mark and then line up the injector pump timing marks. I'm not a yanmar mechanic and use the put it back together EXACTLY like it came apart method Ed mentioned. Look at all the shafts where you can see them rotating against a fixed surface. There will be a mark somewhere.
I've also seen using the TDC mark to set the injector FWIW.
on the flywheel. One is for the valves and one is for the injector pump and yet another for top dead center. They could also be on the camshaft end. You will have to set the camshaft/crankshaft to the timing mark and then line up the injector pump timing marks. I'm not a yanmar mechanic and use the put it back together EXACTLY like it came apart method Ed mentioned. Look at all the shafts where you can see them rotating against a fixed surface. There will be a mark somewhere.
I've also seen using the TDC mark to set the injector FWIW.
Here is a link to some Yanmar manuals. The first one is for the GM series and it will have the timing stuff. Basic timing is 18 degrees before top dead center. There is a mark on the flywheel that you can see after removing the starter. The timing is set by shimming the injection pump piston unit.. so if the correct number of shims was not put back in, you could be seeing advanced timing. The fuel cam is on the forward end of the camshaft, so if the cam and flywheel marks aren't aligned, you could be seeing timing not set correctly.. http://www.motoren.ath.cx/menus/yanmar.html
cam timing
Definitely need to check those timing marks! If they look good make sure the valves are adjusted and operating properly then move on to the injection timing. The fact that you've chewed up a couple starters gives me the willies. Hopefully it is just and injection issue but if the timing marks are not right you may have some piston/valve interference issues at play.
...there are rebuilds and then there are rebuilds..I'll keep my fingers crossed that you got the good kind. Let us know how you make out.
Definitely need to check those timing marks! If they look good make sure the valves are adjusted and operating properly then move on to the injection timing. The fact that you've chewed up a couple starters gives me the willies. Hopefully it is just and injection issue but if the timing marks are not right you may have some piston/valve interference issues at play.
...there are rebuilds and then there are rebuilds..I'll keep my fingers crossed that you got the good kind. Let us know how you make out.
As Capt. Dare has said "there are rebuilds and then there are rebuilds". If you have valve & piston problems as well as injection pump problems you have not only not saved any money but have wasted a bunch. How much are the two starters worth, $395 each from Yanmar. To break a starter you have to have a real problem and when the starter breaks I'd bet you have a ring gear that at least needs to be replaced or is damaged enough to ruin another starter before you do replace it, or the complete flywheel. The ring gear is $365 and if you need the complete fly wheel it is closer to $925. So at best 2 starters, $800 and a possible ring gear you are at $1,200 and the problem isn't fixed, you are still at square one. That few k is slowly, no quickly going away.
I'm not trying to be mean here Wojo. I'm just pointing out there really are very few short cuts in boat maintenance. And the rebuilding of an engine or transmission in a boat has even fewer.
Stop fooling around and get a qualified Yanmar tech to have a look see before you spend 10k real quick.
stuff
One more thing to check. Assuming the timing marks on the cam gear and crank gear are aligned correctly, it is still (I believe) possible to install the fuel cam on the end of the camshaft wrong way around. One end should be marked and I think the marked end goes toward the cam gear and governor gear. If you can download or purchase a workshop manual the pics should be a big help.
One more thing to check. Assuming the timing marks on the cam gear and crank gear are aligned correctly, it is still (I believe) possible to install the fuel cam on the end of the camshaft wrong way around. One end should be marked and I think the marked end goes toward the cam gear and governor gear. If you can download or purchase a workshop manual the pics should be a big help.
Re: stuff
I would not think you can flip it if it is a heli-cut gear. Don't know if it is or not.
I just pulled up the manual and the cam gear looks like it is a heli -cut. The crank gear has one dot on one tooth and the cam has two dots, one on two different teeth. They align with the one on the crank between the two on the cam. Easy enough. Then the injection pump timing gear (which is a cam) is put on with the "O" facing out. So apparently it can go on backwards. The only problem here is the the complete timing cover must be off of the engine to check any of this.
The injection timing for number one cyl is complicated to say the least unless you are familiar with this diesel. It takes a complete set of shims, mic's and a learned skill to set this up properly.
But either way I think it is time for a Yanmar Tech to have a look see. Sounds like there are to many potential places for this to get serious if it hasn't already.
Good luck.
I would not think you can flip it if it is a heli-cut gear. Don't know if it is or not.
I just pulled up the manual and the cam gear looks like it is a heli -cut. The crank gear has one dot on one tooth and the cam has two dots, one on two different teeth. They align with the one on the crank between the two on the cam. Easy enough. Then the injection pump timing gear (which is a cam) is put on with the "O" facing out. So apparently it can go on backwards. The only problem here is the the complete timing cover must be off of the engine to check any of this.
The injection timing for number one cyl is complicated to say the least unless you are familiar with this diesel. It takes a complete set of shims, mic's and a learned skill to set this up properly.
But either way I think it is time for a Yanmar Tech to have a look see. Sounds like there are to many potential places for this to get serious if it hasn't already.
Good luck.
The timing is set, by myself, thanks to KLOUDIE1 and the manuals sent. Just waiting on the starter, by the way, I am getting these for free. I do have some connections...
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