Topic: Yanmar 1GM10 rebuild (Starting problem resolved)

Last year (2007) my 1GM10 was stripped down and new main bearing shells, a new conrod, gudgeon pin, piston, and rings installed.  The cylinder was deglazed. The valves were reground in (everso slightly) and the whole thing rebuilt. Timing was verified. Etc.   And then after all that the engine would only start after a long haul on the batteries. Once it started and got warmed up then it would happily chug away at 2,700 rpm and use just 3/4 litre/hour (5.1 knots with a 2 blade Euro pattern 13 x 12 prop) (Compression before: 260 psi.  Immediately after rebuild: 320 psi)  Next day it would start easily. Give it a week then I was back to the long haul of wearing out the stater motor .....  Forget the rest of a long saga of finding that there was never any return fuel from the injector. Let's get to the smile smile smile bit .....

The Yanmar 1GM10 workshop manual tells you that you can't rebuild the high pressure fuel pump.  You can. It's only a question of finding a land based tractor diesel repair shop with no connection to the word 'Marine'  that repairs Yanmar or Kuboko generators.  He will have access to the secret world of how to acquire spares for the innards of the 'unrepairable/servicible' injector pump ie element without having to add the extra zeros that the swindleries demand.  The land based tractor man found that there there was some slight scoring in the element that reduced the pressure by ~18%  (hence, as he said, once you got the engine going it was very economical.)

I was told by a boatyard (who happened to be Yanmar Agents) that my 1GM10 with 1,564 hours clocked from new was "beyond repair" and that for the equivalent of USA dollars ~$9,400 (exchange rate at Feb 2008) they would take out the old defunct lump and replace it with a new one which would start ...........

The element and pump repair cost me $120 net of tax. The pump was fitted. The engine bled and primed.  The key was turned and the starter button pressed .... It started without hesitation smile smile smile smile smile

After 100 hours under 2/3rds running load the compression is now ~385 psi*  ..... The Tractor Diesel man said that given the lack of wear on the injector pump he reckoned it should last another 5,000 hours .... The Yard says that if you get 2,000 hours out of a 1GM10 then 'you are doing good' !!!!!

*Russian Xado snake oil was used. It seems to work. The compression will be monitored.  Fuel consumption is now 1 litre/hour at 3200 rpm and 5.4 knots.

Re: Yanmar 1GM10 rebuild (Starting problem resolved)

yessir - its amazing how often marine "mechanics" would rather just sell you something new instead of performing some troubleshooting and fixing.
this if course meaning that they can rebuild your "unserviceable" engine and re-sell it to someone else as rebuilt.

the 1gm10 is a little beaut of an engine, just a marinized version of its land based yanmar counterpart.  the onlt thing that could render this engine unrebuildabe would be having a bored out cylinder that wears oversize.  this engine doesn't have a sleeved block.  i'm pretty sure though, that you could sleeve it after it's been bored out and put a stock sized piston back in.  5000 hours of service out of a maintained motor should be a peice of cake

Re: Yanmar 1GM10 rebuild (Starting problem resolved)

I am having a similar problems with my 1GM10.  I removed the fuel injector pump and took it to a Yanmar dealer for repair/rebuild, I ended up having to buy a new one since they told me it couldn't be fixed.  I fitted the new pump but the rack will not move easily and is currently jammed back so that I am now unable to remove it.

Any suggestions on how to get this defective part out?

Re: Yanmar 1GM10 rebuild (Starting problem resolved)

I hope you removed the oil filler cap for access to the linkage to get it engaged correctly when refitting?

If you cant unjam the linkage from the pump via the oil filler, you'll need to get inside the timing case.

You *DO* have the workshop manual?
(if not, I recommend googling for: motoren ath yanmar menu)
See chapter 5 for removal of timing gear cover.

You will need to remove the hand start cover over the camshaft end, the pin in the shaft end and the pulley and its key from the crankshaft end.

Its fairly simple once you are in there, and will just be a matter of seeing what part of the linkage you've managed to bend or jam. I doubt the pump is actually defective.

Re: Yanmar 1GM10 rebuild (Starting problem resolved)

Thanks Ian,  I did get the rack to final move via the oil filler cap and a wire hooked around the fuel rack pin.  This is the same route I used to hook it to the linkage.  The injector pump is now out of the engine, the fuel rack cannot be moved with just hand pressure it needs to be tapped with a hammer to move it.

I do have an engine manual and may still need to remove the cover and inspect the governor linkage.  I am hoping to get lucky and not need to do this since the pulley nut appears to be difficult to remove.  If I do have to remove the cover does the water pump need to be removed?

Re: Yanmar 1GM10 rebuild (Starting problem resolved)

To remove it I'm fairly sure you don't have to remove the water pump, BUT you *MUST* get the pump shaft to engage properly with the drive gear when you refit it if you don't want to do damage so you'll almost certainly need to take it off anyway.  I suppose you *could* try and engage it with the impeller out and pump cover off, but as its seal to the timing case is an O ring, you'd do better to take it off rather than trash the pump cover gasket.   Refitting is supposed to be done with the pump cover off, but if you make sure the gear is visually aligned with the pump shaft, gently twisting the whole pump will get it to engage and then you can align the holes.

I hope you still have the old pump to refit and check the linkages haven't been distorted.  You can bet you'll need a timing case gasket if you have to go in there. If you do open it,  replace any shaft seals that show any signs of weeping oil.  My camshaft seal was bad and it always had oil on the hand start spindle.

Re: Yanmar 1GM10 rebuild (Starting problem resolved)

To remove it I'm fairly sure you don't have to remove the water pump, BUT you *MUST* get the pump shaft to engage properly with the drive gear when you refit it if you don't want to do damage so you'll almost certainly need to take it off anyway.  I suppose you *could* try and engage it with the impeller out and pump cover off, but as its seal to the timing case is an O ring, you'd do better to take it off rather than trash the pump cover gasket.   Refitting is supposed to be done with the pump cover off, but if you make sure the gear is visually aligned with the pump shaft, gently twisting the whole pump will get it to engage and then you can align the holes.

I hope you still have the old pump to refit and check the linkages haven't been distorted.  You can bet you'll need a timing case gasket if you have to go in there. If you do open it,  replace any shaft seals that show any signs of weeping oil.  My camshaft seal was bad and it always had oil on the hand start spindle.