Jump to content

Yanmar Yse12 rebuilding


Recommended Posts

I acquired this motor for parts but have been thinking I might strip it and see whats required for rebuilding. My motor has to clag out sooner or later and to have one in the shed to plonk in would be cool. Has anyone worked on these and got any special tools they don't want or can lend. Need a 54mm socket for flywheel and slide hammer as injector is stuck in the head. The heads off the good motor in the boat. If anyone is taking parts to the scrappy let me know as may be interested.

IMGP3782 (800x532).jpg

IMGP3785 (800x532).jpg

Link to post
Share on other sites

a 2 1/8" socket works well on the flywheel, you'll also need about 600>800mm long piece of 25mmx25mm RHS to put under the socket and against one of the flywheel lugs, the other end of this rests on the floor and lets you jump on the breaker bar to get the nut off..........and that's only 1/2 the battle

and the flywheel nut you'll see 2 12mm holes so you'll need to make a puller of sorts put a heap of weight on the puller then belt the crap out of it with a bigger hammer than you've shown there (I used a splitting axe) and eventually it'll come off, puller I made was of 16mm flat bar with 3 holes in it, 2 were to pick up the 12mm holes and for the centre one to push against the crank I used a 5/8 " nut and bolt with the nut under the flat bar and screwing the bolt against the crank as I said load it up and give it a goodly clout . The injector, flip the head over and you'll see the pre combustion chamber between the valves get a socket as close to size of the chamber/nozzle and once again the hammer, if times on your side you can try soaking it in diesel for a while prior , mines a YSM12 so a bit different casting round the bore area and has a water divider/ thermostat oh and a starter motor but the rest matches ok

Link to post
Share on other sites

Thanks L4. Might invest in a socket and 3/4 extension. Have made pullers like that before, might have something lying around to do the job. Quite good to use big artillery now and again, sort of satisfying! The head is not so simple though, it has what looks like some kind of diffuser covering the pre chamber, I don't want to take that out or damage it as would be a bit of a disaster if it fell out later while underway. Maybe they all don't all have them or have been removed in the past. Not sure what its purpose is?

IMGP3796 (800x532).jpg

Link to post
Share on other sites

that bit with the holes in it is the end of the precombustion chamber and nothing but friction holding it in, pretty substantial in construction, have exactly the same prob with the injector on a donor motor I have so did a little hunting for penetrating stuff that'd work and came up with this

http://forums.sailinganarchy.com/index. ... pic=158883

interesting to see just how it works

Link to post
Share on other sites

First let me say I have no experience of this particular engine. However, I would suggest that if this is held in by friction, it will be an interference fit, and pressed into place. May be hard to get out, especially cold. Without the interference fit it would risk dropping in to the cylinder with temp change and vibration.

Why take it out at all?

IMO it will be there to assist in complete distribution to the cylinder for combustion.

Link to post
Share on other sites

Yes there are 4 different sized holes in it so it would have to be aligned properly. I don't want to take it out IT but L4s suggestion of drifting the stuck injector from the bottom cannot be done with it there. I think a slide hammer with correct thread to screw into injector base is the only way to extract it.

Link to post
Share on other sites

k cold day, lawns done so time to play , bit of 5mm plate with a hole in it so it sits as a washer tween those 2 injector parts wind a coupla 8mm bolts into the holes either side first, then reassemble the injector with the plate/ washer In between and you'll have enough room to get an open ender in there to unwind the 8mm bolts and pop the injector out, I did wave an oxy torch round the top to pop the rust off though and out it came, the nozzle fit in the head is a pushfit as in finger pressure and is prone to carbon buildup/ sealing so youll need to use the hammer and right size drift/ socket then clean both with scotchbrite there is a washer tween the injector and top part of the precombustion chamber as well as copper ones between the top and bottom part of the chamber as well as the head, keep em you'll need em

Link to post
Share on other sites

I installed the smaller version of this motor the YSE8 in a yacht nearly 40 years ago. The engine was reliable enough but being a horizontal engine it was a bit of a thumper at low revs. Later versions (1980 onwards) of engine became the YSM8 and YSM12 the only difference being the switch to Bocsh fuel pumps. The original YSE8 and YSE12 were prown to excessive smoking (to the point of leaving soot on the transom and surrounding water when the throttle was opened, the later YSM series didn't suffer so badly from this.

This problem was purely because the original Yanmar ram type fuel pump was supplying fuel faster than the engine could burn it. The main disadvantage with these engines compared to modern ones is weight and the amount of space they take up. The gear lever needs quite a bit of weight to shift FNR so morse type cable controls won't work, it pretty much needs to be linkages

Link to post
Share on other sites

For all these motors short comings I have sort of got attached to them. It has been surprisingly reliable and never let me down apart from battery once and big diesel bug problem once which is hardly the motors fault. They do have a reputation as having the loudest diesel knock of any diesel made! Being down below when motoring can only be described as unpleasant. The slow revs thump is probably its best feature! The fuel pump is impressive that it works at all, I understand there is a needle that wears and also the governor linkage is a bit delicate. As a 35 year old boat I have decided not to upgrade a lot of original equipment because whats the point, its never going to be a light or fast boat so am more in restoring mode. Had to redo the sterntube deadwood and after being tempted by a dripless system decided to stick with the old gland. Saving a $1000 had something to do with it! Original winches also staying. Also atempted to get the old Wasp propeller driven log going but to far gone unfortunately. Have gone electronic there.

IMGP3651.JPG

IMGP3637.JPG

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...