I have had a small drip which appears to be coming from the area where the bellhousing connects to the engine for the 3 years I have had the boat but this week it got worse and is dripping about a teaspoon/day. I suspect the rear engine seal. The Yanmar manual is not very helpful as it doesn't have procedures for changing it. As I see it, the basic procedure is to disconnect the cooling water hose from the filter, disconnect the shifter cable, unplug the wiring harness, remove the antifreeze overflow tank then remove the nuts from the top of the engine mounts. After that I should be able to use a couple of come-alongs hung from the boom to lift it clear of the mount studs and move it forward into the cabin. After that I will need to split the bell-housing from the engine and then remove the flywheel. After that I haven't a clue. I would very much appreciate any advice from someone who has done the job before. Also, if there are any corrections/suggestions to my above noted plan of action, special tools required etc; I would appreciate comments. Thanks in advance. Reg
Suspected rear seal leak on Yanmar 2GMF
- Thread starter Reg M
- Start date
I just finished pulling the transmission and flywheel on my Yanmar. It was actually very simple and straightforward. Rather than move the engine forward, why not disconnect the propshaft and slide it back? On mine it gave me enough room to remove the transmission out of the way. My seal is okay so I can't help you there, but access was easy with the trans removed.
Coupla notes:
There is a small external oil line that runs from the bottom port side of the block, up and across the rear of the block to a connection just above the bell housing.. Not uncommon to have the line puncture from vibration or corrosion.. It has a banjo connection which also could be leaking.. If it is the rear seal, the seal is in a main bearing carrier which can be removed from the block after the flywheel and housing are removed..The carrier is sealed into the block with an o-ring, so if ya take the carrier out, ya might as well replace the ring and the seal.. The seal and ring should be available locally from a bearing supply place .. They are metric sizes.. or you can get them from Yanmar.. On the h-34, there is not enough room to pull the housing and transmission without lifting the engine slightly off the mounts.. I would not lift it from the boom The chunk weighs about 225 pounds with oil and water in it.(pretty good strain on the topping lift). Some folks have used a 4X4 wood post across the companionway to lift the engine with a come-along.. Better to block it up to get the parts loose then set it back on the mounts until new parts are ready to go in .. then you can block it again, install parts, re-install engine and align.. Folks have reported that the engine only had to come forward a foot or so and up about half that, and there was enough slack in the water, fuel and electrical connections to do the work without disconnecting.. Your engine may be more tightly connected..
I have not done the job, but a couple of folks on the site have..
There is a small external oil line that runs from the bottom port side of the block, up and across the rear of the block to a connection just above the bell housing.. Not uncommon to have the line puncture from vibration or corrosion.. It has a banjo connection which also could be leaking.. If it is the rear seal, the seal is in a main bearing carrier which can be removed from the block after the flywheel and housing are removed..The carrier is sealed into the block with an o-ring, so if ya take the carrier out, ya might as well replace the ring and the seal.. The seal and ring should be available locally from a bearing supply place .. They are metric sizes.. or you can get them from Yanmar.. On the h-34, there is not enough room to pull the housing and transmission without lifting the engine slightly off the mounts.. I would not lift it from the boom The chunk weighs about 225 pounds with oil and water in it.(pretty good strain on the topping lift). Some folks have used a 4X4 wood post across the companionway to lift the engine with a come-along.. Better to block it up to get the parts loose then set it back on the mounts until new parts are ready to go in .. then you can block it again, install parts, re-install engine and align.. Folks have reported that the engine only had to come forward a foot or so and up about half that, and there was enough slack in the water, fuel and electrical connections to do the work without disconnecting.. Your engine may be more tightly connected..
I have not done the job, but a couple of folks on the site have..
Last edited:
I did that on my 3YM30 on my 2007 H-36 and yes I did need to move my engine forward
to get the tranny to clear and pull the tranny and bell housing together because the bolts to tranny inside bell housing.
So need unbolt motor mount and cooling hoses and cables and anything that can’t stay with motor moving forward and my engine could move forward a foot or two but it was just right
to get the bell housing and tranny together.
Everything came off pretty easy and yes my boat was in the water but not problem and did not touch shaft and the seal comes out easy and new went in with round pvc.
Every thing went back on easy except fly wheel was very heavy and could not lift in to place on my stomach so had to lift into place hang over engine from front of engine and was easy that way.
I did religement the shaft with a feeler gauge because unbolting the motor mounts changes the alignment.
Just ask if need my help or info.
Nick
to get the tranny to clear and pull the tranny and bell housing together because the bolts to tranny inside bell housing.
So need unbolt motor mount and cooling hoses and cables and anything that can’t stay with motor moving forward and my engine could move forward a foot or two but it was just right
to get the bell housing and tranny together.
Everything came off pretty easy and yes my boat was in the water but not problem and did not touch shaft and the seal comes out easy and new went in with round pvc.
Every thing went back on easy except fly wheel was very heavy and could not lift in to place on my stomach so had to lift into place hang over engine from front of engine and was easy that way.
I did religement the shaft with a feeler gauge because unbolting the motor mounts changes the alignment.
Just ask if need my help or info.
Nick
I got the seal from Yanmar and shocked how cheap and also did replace the tranny inner seal on the shaft while out and check the shift seal and mine was leaking so changed that while tranny out and tranny very light and don’t take shift lever out just replace seal and all seals from Yanmarwas very cheap.
Put Honda scissor jack under motor and pulled motor forward and everything went well just
many hours of labor taking a part and back together.
Nick
Put Honda scissor jack under motor and pulled motor forward and everything went well just
many hours of labor taking a part and back together.
Nick
Looks like part 20 on the schematic. How it came loose I don't know. I had these packed at a Pack 'n Ship, but can't imagine how it simply came loose!?