Lifting a 1GM

[TDudley]

I own a 1981 27' Cherubini Hunter. I have to change the motor mounts and re-align the engine. I hate to have to do this since I just put is back in the water, but I am not interested in tearing up the new transmission or throwing a new prop or ripping apart a new PSS. Better to take it in the gut now than experience more pain later. Unfortunately, it was the motor mounts that I did not replace. And now when the motor is in gear, it shimmies like a hobby horse. And that can not be good for any of the new parts I have. I also know that I did not spend enought time in ensuring a perfect alignement.

The question is can I use the boom to lift the motor just long enough to remove the old mounts and install the new mounts. Another question is can I attempt this while the boat is in the water.

Any advice anyone can give would be great

Tony

 

[Benny]

No problem, you can do it while the boat is in the water. The 1GM being a one cylinder engine can rock quite a bit, especially after they have a couple of thousand hours in them. Are the mounts broken or excediningly soft? Pick up the engine from side to side and front to back and see if any side lifts off one of the pads signaling a broken mount or excessive travel. Check the alignment with the prop shaft, use a feeler gauge and measure the gap at the transmission connector, measure the gap at the top, bottom, and both sides; the gap should be even all around with a tolerance of no more than 0.2mm. Engine should be checked for alingment every 500 hrs and aligned if need be. If you replace mounts and align then check after the first 50 hours. Usually a broken mount will make a clacking sound as the top and bottom metal plates collide with each other. If the problem is just engine vibration adjust the valves, change the filters and let it warm up before you put it in gear. Good luck.

 

[Benny]

I'm sorry, regarding the lifting, I would stack a few 2X4s across the top of the companionway and attach a chain puller. Be carefull with the engine as it may rock especially if you conduct the operation in the water. A couple of guys should be able to manhandle it into a temporary wooden base in the cabin. We used to replace motor mounts one at a time with the engine in place to avoid major dissambly but I don't think you have the space in the h27 to do the work.

 

[Manny]

Tony - not sure about the 1 GM (my '80 has the Renault) but you may be able to wedge the engine up slightly from underneath with some wood once you disconnect the coupling and undue the motor mount bolts. I've got to assume they are roughly the same size and shape. I have been able to do this by myself fairly easily with the Renault weighing in @ roughly 220 pounds. You only need to go up a couple of inches and there is just enough space to work.

Manny

 

[garyc]

If think the engine weighs less than 100 lbs. Check the manual.

 

[Johnb]

For what it is worth I had the mounts on my 3QM30 replaced a couple months ago. The mechanic told me they do it by replacing diagonally opposite pairs on at a time. First slacken 2 off completely, then use the other two to raise the engine as far as it can. Rock it one way and replace one corner, rock it the other and replace the other corner. Repeat for the other diagonally oppposite pair. Seems simple, but I did not do it.......

They also told me they routinely add another coat of paint to Yanmar mounts.

John Brecher

 

[Ed Schenck]

The problem needs to be identified before you select a lifting method. Someone mentioned softness and/or broken metal. Another thing that happens is the lag bolts loosen. They are just screwed into the wooden rails under the thin f/g. It could be a combination of all three. And all are easily fixed but I would want the engine up high in order to really check it out. So I would opt for the lumber across the companionway.

On my boat with a much heavier 2QM20 I had the yard lift it out of the way with the forklift from the rack shed. They just let it hang there while I installed the new mounts. I would not use the boom. You are trusting too many unknowns like the topping lift and all the connectors. I guess you could use a 4x4 to support the end of the boom. A flexible shaft saver at the shaft coupling goes a long way toward saving the cutless bearing from vibrations and small alignment problems.

 

[sandpiper10471]

I have lifted a six cylinder Pathfinder and a Yanmar 4JH3 using the boom with no problems. I wouldn't use a topping lift - use a haliard. The six part mainsheet moved above the companionway does a nice job of lifting, especially if there is a winch available. And it never hurts to have some free beer on board. Then you can play Tom Sawyer!

 

[TDudley]

Thanks for the responses. I think using the boom with the addition of a 4x4 under it as insurance will work. But I have another question. Is the shaft considered in its "natural alligned position" as it sits. Its only 4 feet long with a 1 inch diameter. I tried to center it within the stern tube as I mated to two ends of the coupler, but this may be introducing some problems. And besides, it pretty difficult to keep the shaft "centered". What kind of trouble am I asking for if I let the shaft rub on the stern tube and allign the engine with the shaft as is.

As a somewhat side note:

I will check the all the bolts, but I know that the engine is not alligned correctly. First of all, I beat the leaving you-know-what out of the shaft side of the coupling to get it on the shaft. And, I am ashamed to admit, I have a gap between to two couplers. It is an equal size gap of about 1/4 inch, but a gap still the same. That is way more than the .04 inch tolerance most call for The couplers will not mate up because I dinged the shaft side up so much. This is something I have to fix. The way I will do it will be by cutting off the old coupler ( there is no way ot will come off by any other method) and replacing it with a new one. On the new coupler, I will spend some time filing the inside of the coupler down so that it sldes onto the shaft by hand with just a bit of resistance. Certainly not so much resistance that I have to use a hammer.

 

[Karl13265]

I removed the 1GM10 from my 1980 27 last year with no problem. Simply remove your throttle and transmission linkage, the exhaust and fuel lines and any other hard connections. Then place a double loop of 1/2" line under the motor in a fore & aft position and then leave yourself a single line long enough to place over your shoulders to lift with. The place the line over your head and across your shoulders and lift the motor is not heavy. Have an old piece of carpet and plastic on the sole to lay the motor on and have a second person steady the motor as you move forward and lower the motor to the floor.
To remove the shaft, first remove the prop and then draw the shaft forward into the cabin through the stuffing box. Take the shaft and coupler to a machine shop and have them press the coupler off the shaft. If your replacing the coupler great, if not have the shop clean up the coupler and key way and balance the shaft. Reassemble in the reverse order. Worked for me and as Manny and Ed can attest I've had problems that I couldn't see my way past. When you remove the old mounts do a rough measurement of the height of the old adjustments and start from that poin to align with the new. On completion of the job we stayed tied to the dock, started the engine and ran it up to varying speeds finally placing it in gear and doing the same run up. No vibrations, no worries.