mickywillis
Well-known member
Update to the update!
Last weekend we were able to get out and test whether the fouling removal on the prop had cured my problems. The well respected and known Mr Bav34 came along as observer along with Mrs Bav34 and all seemed well. Engine started without a hitch (as per usual) we motored off the mooring and were greeted with the sound of a singing prop, something I haven't heard since early this season. The engine felt better stronger and smoother, so I was grinning!
We were able to reach a max RPM in gear of 3000 RPM, but for some reason, this tailed off to about 2800 RPM, but I was happy as previously I'd only managed 2600.
For the next 40 mins, all was well. We pushed through the flooding tide towards the entrance to Langstone Harbour, the intention being for a sail and then a return back to the mooring. Checks were made at regular intervals using the GPS and Mr Bav calculated we were making a healthy 5.25 Kts (showing as appx 4 Kts on my Fishfinder/Log) so all seemed to point in the direction of a conclusion to my saga.
Upon reaching the entrance to Langstone, we hoisted sail and put Yanmar out of gear. I demonstrated to Mr Bav that out of gear, the little 9HP motor would rev to its max of 3600, which it happily did, but seemed to be missing at such high revs.
Then the problems started again. We put the motor into gear (sails up) and were troubled to reach 2500RPM at max throttle opening. Within minutes, the engine went back to its old routine of dropping about 500 RPM and then racing up to 2800 and then dropping back to about 2200 and then rising, etc, etc This seems to have been instigated by revving the engine out of gear to max RPM (for about a minute) and then letting the engine idle and then put under load.
For the first 40-50 minutes of the trip (before revving out of gear) the water/smoke from the engine was almost clear in colour and of a satisfactory temperature. Once revved out of gear, the water was black with evidence of soot/carbon particles. This continued until we reached the mooring (after running the engine at appx 2000RPM in gear)
BUT at no time at all, did the engine emit ANY black smoke?? Also, the water temperature was completely satisfactory, no signs of overheating.
Now what do I do??
Boat is out of the water this weekend for the winter. I can't test the engine under load until next spring lift in.
Do I have the injector rebuilt, remove the head and decarbonise the head, change the head gasket, get the prop repitched (or change the gerbox for my spare one) and go over the fuel system again? Or can I check the injector timing and governor assemby easily without too much hassle?
HELP!! I'm at wits end with this.
BTW didn't have time to run with alternator belt off, but I did switch battery switch into BOTH and No 1 and 2 batteries independantly, didn't seem to affect the load on the engine.
Also was unable to run on a seperate fuel feed, but I tried that a while back, which didn't appear to improve things.
I'm baffled ( and this from the man who rebuilt his own Triumph Stag 3 ltr V8 engine from scratch!!)
Its only a bloomin single cylinder engine thats causing me so much grief!!!
Last weekend we were able to get out and test whether the fouling removal on the prop had cured my problems. The well respected and known Mr Bav34 came along as observer along with Mrs Bav34 and all seemed well. Engine started without a hitch (as per usual) we motored off the mooring and were greeted with the sound of a singing prop, something I haven't heard since early this season. The engine felt better stronger and smoother, so I was grinning!
We were able to reach a max RPM in gear of 3000 RPM, but for some reason, this tailed off to about 2800 RPM, but I was happy as previously I'd only managed 2600.
For the next 40 mins, all was well. We pushed through the flooding tide towards the entrance to Langstone Harbour, the intention being for a sail and then a return back to the mooring. Checks were made at regular intervals using the GPS and Mr Bav calculated we were making a healthy 5.25 Kts (showing as appx 4 Kts on my Fishfinder/Log) so all seemed to point in the direction of a conclusion to my saga.
Upon reaching the entrance to Langstone, we hoisted sail and put Yanmar out of gear. I demonstrated to Mr Bav that out of gear, the little 9HP motor would rev to its max of 3600, which it happily did, but seemed to be missing at such high revs.
Then the problems started again. We put the motor into gear (sails up) and were troubled to reach 2500RPM at max throttle opening. Within minutes, the engine went back to its old routine of dropping about 500 RPM and then racing up to 2800 and then dropping back to about 2200 and then rising, etc, etc This seems to have been instigated by revving the engine out of gear to max RPM (for about a minute) and then letting the engine idle and then put under load.
For the first 40-50 minutes of the trip (before revving out of gear) the water/smoke from the engine was almost clear in colour and of a satisfactory temperature. Once revved out of gear, the water was black with evidence of soot/carbon particles. This continued until we reached the mooring (after running the engine at appx 2000RPM in gear)
BUT at no time at all, did the engine emit ANY black smoke?? Also, the water temperature was completely satisfactory, no signs of overheating.
Now what do I do??
Boat is out of the water this weekend for the winter. I can't test the engine under load until next spring lift in.
Do I have the injector rebuilt, remove the head and decarbonise the head, change the head gasket, get the prop repitched (or change the gerbox for my spare one) and go over the fuel system again? Or can I check the injector timing and governor assemby easily without too much hassle?
HELP!! I'm at wits end with this.
BTW didn't have time to run with alternator belt off, but I did switch battery switch into BOTH and No 1 and 2 batteries independantly, didn't seem to affect the load on the engine.
Also was unable to run on a seperate fuel feed, but I tried that a while back, which didn't appear to improve things.
I'm baffled ( and this from the man who rebuilt his own Triumph Stag 3 ltr V8 engine from scratch!!)
Its only a bloomin single cylinder engine thats causing me so much grief!!!
