Yanmar 1gm 10 starting backwords!

No difference guys. Will go through bleed procedure again top to bottom. Can see it ending up on the bench.

For such a simple engine they do confuse sometimes! I'm at a lose to explain your issues now as you have addressed everything that should have been able to cause your problem. Hopefully a final bleed will do the job.

dukeofted said:

For such a simple engine they do confuse sometimes! I'm at a lose to explain your issues now as you have addressed everything that should have been able to cause your problem. Hopefully a final bleed will do the job.

Click to expand...

Yeah.......just like old Land Rovers lol. Bled this morning . I have the modern Cav separator so pumped straight to fine Yanmar filter and bled. To IP and this would not pressurise at bleed screw with my CAV housing pump or the Yanmar lift pump, despite turning the engine to get it on cam of lift pump. I spun it up with de comp lever and it bled. Cracked injector and spun up then closed when fuel spurted.. At 2 /3rd throttle it spun up and after 5 seconds it started properly.........not in reverse. Let it tick over nicely for ten minutes then killed it. Couple of minutes later. back to the same. Stuggled to fire and on releasing button it started backwards and I cut it off. Air could be getting back in somewhere after turn off, so will check that out further.

The CAV pumps are notorious for leaking air as the o ring is easy to leave out of accidently double up.

the lift pump (if it's the same as the 2GM that I have) is also a pig.
I'd recommend (as a test) bypassing the tank/lift pump and use another container above the engine straight to the filter, bleed start, turn off, let it cool and try again after a few hours or next day.
If it starts easily then I'd say liftpump is the culprit - I've dumped mine and replaced it with a 50euro elect. pump but it's on a generator and rarely runs for over an hour at a time.

Had trouble last year with old CAV thing. Fitting this one worked.https://www.ebay.co.uk/itm/274848579277

To conclude with this engine. Removed to bench. Stripped it all down. Valves slightly pitted Head perfect. new valves, stem seals, grind in. Piston rings worn, bore within spec. New Yanmar piston and wring pin, and bore honed. Big End replaced, new main bearings pressed in, Crank measured round and within spec. Oil pump measured spec. Cams within spec, including fuel cam. New Governor springs. New injector pump plunger and barrel, new delivery valve, new injector nozzle fitted and pop tested. New Exhaust Elbow. All gaskets , seals renewed and a real clean and paint. Goes good and no smoke now at any revs. It's got 3 hrs of mixed running mostly up the rev range, so fingers crossed. Thanks for all replies!

Glad you got it all sorted out. Did you manage to get all that doe at a reasonable price, or was it getting towards the cost of fitting a new engine?

I spent about £600 on bits and done everything here on bench. I got the the IP stuff, NOS in yanmar sealed packets 1/2 price.Got a good deal on gen Yanmar piston and rings, again NOS. The head gasket and crank bearings, I used Recmar, which is Italian pattern. The Recmar stuff is good, looks and feels similar to ridiculous prices of Yanmar, so used many other of their parts, like seals for w/pump and T/Stat. The Exhaust Elbow was a stainless pattern of double thickness 316 stainless from a company in England, very nicely made. So nowhere near new engine price. Those 1gm10 are 5grand with gear box.

Thank you.
Sounds like a plan if my 2gm20 ever starts misbehaving!