yanmar 1gm10 engine and shaft alignment

[John6275]

finally got my 1984 Cal 27 III in the water last weekend. started and ran fine but when I put it in forward there is a lot of thumpinging. there is a little in reverse but not as much. after watching a lot of YouTube I attempted a shaft alignment. not much difference and not even sure if its better. engine even seems run rougher. YouTube videos not as helpful as I had hope. it seems to be a heck of a puzzle to adjust the mounts.
is there a position to place mounts and adjust from there?
hope someone has some helpful info or videos or I'm going to have to find a mechanic and around here thats not easy for this type of boat and motor.

 

[Tally Ho]

Was the engine moved ? Or any work done on the drive train? Cutlass bearing inspected / replaced?

What kind of prop do you have? I assume it is clean since you just put the boat in the water.

Hard To help trouble shoot without more info, maybe a video of the engine running, and in gear with a load on it.

Greg

 

[John6275]

I just bought the boat. PO took prop shift out, had it checked and tried, new cutlass and put it all back together before I took position. prop is a 3 blade.
engine was not removed but I did adjust things around in my efforts to align and stop the thumping.

 

[John6275]

shaft trued

 

[Benny17441]

Did you replaced the mounts? They might look good (you cannot go by sight) but they could be soft and shot. The single cylinder engine is inherently unstable from a vibration stand point and requires the restraint of good working engine mounts.

 

[John6275]

No, I did not replace the mounts but they look to be in good condition. I will inspect them closer but not sure that's going to correct the alignment issue.

 

[RoyS]

In neutral, turn prop shaft by hand. Does it spin freely? Usual alignment procedure is to unbolt coupling, motor to shaft. If motor mounts are difficult to access it is nice to have two cut short open end wrenches just for alignment adjustments. Loosen all motor mounts then adjust, up, down, forward, back, side to side until the faces of the coupling are exactly flat together and aligned center to center. However, this is sort of an art form and other factors come into play. Try to adjust motor mounts evenly so that if you are, for example, raising engine rear, adjust both rear mounts up equally. At the same time, and this is easier out of water, you want the shaft to be approximately centered in the stern tube and centered also in the shaft cutlass bearing. You may want to dive down and look. Assuming all rough adjustments are close and shaft is centered in stern tube and not binding in cutlass bearing, and centered with motor hub, final fine adjustments are made with feeler gauges inserted between coupling halves to achieve equal spacing all around coupling faces within a few thousands of an inch. Engine should be equally supported on all four mounts.Tighten all motor mounts, recheck alignment with feeler gauges and bolt coupling halves together. Lastly, in neutral, rotate shaft by hand. It should spin freely without any binding or rubbing on the stern tube. Job requires patience. Take your time. I would not trust this job to some strange hourly yard employee.

 

[John6275]

Ok, I understand the process and appreciate the detail. Since its in the water and I have tried this process , and it is defiantly an art form, to to noticeable success, is there a place to start from to get closer. say for example taking motor mounts all the way down or all the way? Some place I will have reference to be even and equal? A way to make sure engine is centered or similar to start from?
Shaft does spin by hand when I rotate it. I'm not sure how freely it should spin in place but I can turn it with one hand.
I guess I'm the yard guy, lol.
Really appreciate all the help.

 

[RoyS]

No starting place as you describe. Free hand rotation is good starting place.

 

[John6275]

OK, thanks again. spent several hours trying yesterday. I will try some more next time I can get to marina.
Really would like to go sailing, lol.

 

[Ralph Johnstone]

Really would like to go sailing, lol.

So whadya need an engine for ?

Everything that has been discussed so far. If I missed it sorry for that but if it wasn't mentioned, when you have the couplings disconnected, run the engine in gear to ensure it's not something within the engine itself.

And yes, alignment is mostly an art ................ up on one corner, down by an equal amount on the opposite corner, back and forth, side to side up and down, round and round until you're ready to lose it .

As @RoyS mentioned, an unlisenced mechanic is the last person you want doing this job.

 

[John6275]

didn't think about running it when shift was disconnected. thanks
As far as needing the engine, I am a new sailor and trying to sail in and out of the marina...... I might need a little more practice on that.

 

[Ralph Johnstone]

As far as needing the engine, I am a new sailor and trying to sail in and out of the marina

Wow .

I can't do that, and I'm an old sailor ................. sort of, just sort of.

 

[Benny17441]

No, I did not replace the mounts but they look to be in good condition. I will inspect them closer but not sure that's going to correct the alignment issue.

You can look at them and they can look new, Stick a lever under the engine and pry it in different directions, the deflection should be minimal. Adjust the valves. Observe the shaft while turning for any oscillation. Have the prop balanced. Then align.

 

[John6275]

You can look at them and they can look new, Stick a lever under the engine and pry it in different directions, the deflection should be minimal. Adjust the valves. Observe the shaft while turning for any oscillation. Have the prop balanced. Then align.

I will try that regarding mounts. As far as value adjustment, recommendations? The prop will probably be one of last options since in the water.

 

[Ralph Johnstone]

As far as value adjustment, recommendations?

You may be able to find a copy of the maintenance manual for your engine in the archives. HOWEVER, valves being either too tight or too loose do not cause rough running. Burnt valves and a few other problems, but not rough running.

 

[RoyS]

Regarding a starting place for this project: Check if motor mounts appear tight. Side to side vertical adjustments should be near equal. Front to rear vertical adjustments may be unequal. Unplug shore power cord. Dive down with flashlight and mask and determine if everything under water appears sound. Is the propeller bent or damaged? Is the strut straight? Does the cutlass bearing appear distorted or worn? Are the zincs tight? Is the propeller shaft centered entering the stern tube? If all good below, loosen coupling nuts and bolts and check alignment with feeler gauges. If within a couple thousands then alignment is probably OK. If alignment needs adjustment proceed with those instructions above.

 

[John6275]

No, I did not replace the mounts but they look to be in good condition. I will inspect them closer but not sure that's going to correct the alignment issue.

Is there a place in this forum that shows the best place to get motor mounts and part numbers?

 

[Ralph Johnstone]

Is there a place in this forum that shows the best place to get motor mounts and part numbers?

I'd suggest leaving the engine mounts as a last resort. Not the cost but because they are the ultimate PITA to replace unless removing the engine which is another whole story. I replaced one several years ago because of a fuel leak onto the rubber and it was all the way.



Try sitting in front of the engine (with the cover off) while it's running and see if anything leaps out at you (USE EXTREME CAUTION). Finding the source may not be as difficult as you think.

Try carefully prying the engine a small amount one way or the other while running to see if the problem increases, decreases or ? ? ? ? This may indicate alignment as the cause. Loose bolts ? ? ? ? Grab the engine (when stopped ) and heave it every which way and see if it bottoms out audibly on anything. The answer will not come quickly or easily. Hell, I've spent >20 years trying to locate an extremely intermitant leak in the V berth which will disappear for a year and then reappear.

 

[Alan Gomes]

Is there a place in this forum that shows the best place to get motor mounts and part numbers?

The front and the rear mounts are not the same.

Front mounts: Yanmar Part # 128170-08350
Rear mounts: Yanmar Part # 128170-08340

The firmness of the rubber is slightly different from front to back, so when you install them be sure you don't mix them up.
You can of course buy them from your local Yanmar dealer. I got mine sometime back off of eBay.