Yanmar 3JH3CE water pump replacement advice

[Captain Bill]

I just splashed after 3 weeks on the hard and no water coming out of the port engine. So ok, after drying out for three weeks in 90 degree weather, the impeller has given up the ghost. Wrong! I get down below to do a quick impeller change and what do I find? The heads on two of the cover plate bolts have snapped off. The new water pump will be here Tuesday, so this morning I start to see about getting the old pump off. Two of the bolts holding it on appear to be completely blocked by the forward motor mount bracket. The only option I see to get the pump off is to jack up the motor and remove the bracket. If anyone has changed one of these pumps and knows of a better way I'm open to any ideas they might be willing to share.

[boden36]

I don't understand why you need to replace the whole pump due to a couple of snapped screws. Have you tried to remove them?

[Captain Bill]

The pump is 16 years old and has 4500 hours on it. I don't have a spare at the moment. There is no access to get the old bolts out without removing the pump so it has to come out anyway. If I can get the old bolts out without damaging the case, I'll rebuild it and make it my spare. If I get a new one I can be on my way immediately and repair the old pump when I have time. I've already spent too much of the summer on repairs.

[Nineteen]

Hi Bill

I have a 3JH3BE and unfortunately I think you are correct. If I want to replace the pump then I will have to remove the port forward mount.

As for drilling the broken screws out in situ - you have buckleys and none. The pump will still have to come out to achieve that. It is bad enough having to change the impeller with 4 good screws.

Cheers
Tom

[aliddell]

I had a Yanmar 3JH2E, in my Pacific Seacraft 34. Same issue. In addition, to remove the impeller, was next to impossible as it was behind the alternator and just in front of the starter....very poor design for a boat.

[shorebird]

I have a Yanmar JH in my Hunter 376, with best access to all of the engine I could imagine...except the water pump">raw water pump, which is so inaccessible, I had a mechanic replace the impeller this time around. Next time, I will have to use a video camera to see what I'm doing, or just get used to doing it by "feel" alone.

[GALAWA]

I have 2 YANMAR 3JH3 engines on my catamaran.
These engines have been badly designed regarding access to the raw water pumps.
Merely to change the seal on the pump's shaft on the engine side, you have to take the pump out , which requires supporting the engine upward and removing one engine's leg.
It is (relatively) easier to remove the whole (leg + silent block) together, without changing the height adjustment of the leg. This is done by unscrewing the silent block from the engine's bed (and undoing the bolts on the engine's casing of course).
The next difficulty comes from the attachment of the pump to the engine. My steel bolts, married to the bronze pump and the engine's steel since 1999, were definitely seized. After grinding the bolt heads flush, I could remove the pump, pour WD40 on the thread of the still protruding bolts and unscrew them with pliers.
I later replaced the beheaded bolts with stainless steel bolts in the hope they will be more amenable in the future.
Next , in order to change the pump's seal, you need to extract a roller bearing, change the seal and insert the roller bearing again. This is best done by a mechanic with special tools. This is were there there is a case for having a complete spare pump aboard.
Good luck (+ some determination !)

[Captain Bill]

Originally Posted by GALAWA

I have 2 YANMAR 3JH3 engines on my catamaran.
These engines have been badly designed regarding access to the raw water pumps.
Merely to change the seal on the pump's shaft on the engine side, you have to take the pump out , which requires supporting the engine upward and removing one engine's leg.
It is (relatively) easier to remove the whole (leg + silent block) together, without changing the height adjustment of the leg. This is done by unscrewing the silent block from the engine's bed (and undoing the bolts on the engine's casing of course).
The next difficulty comes from the attachment of the pump to the engine. My steel bolts, married to the bronze pump and the engine's steel since 1999, were definitely seized. After grinding the bolt heads flush, I could remove the pump, pour WD40 on the thread of the still protruding bolts and unscrew them with pliers.
I later replaced the beheaded bolts with stainless steel bolts in the hope they will be more amenable in the future.
Next , in order to change the pump's seal, you need to extract a roller bearing, change the seal and insert the roller bearing again. This is best done by a mechanic with special tools. This is were there there is a case for having a complete spare pump aboard.
Good luck (+ some determination !)

This is exactly what I ended up doing yesterday. Fortunately for me the bolts were in good shape. My engine space allows me to place a 2x4 above the engine. I unbolted the engine mount from the bed and used a ratcheting strap over the 2x4 to barely lift the engine mount off of the bed. I then unbolted the bracket from the engine and removed the entire assembly. From there it was pretty straight forward to remove the 4 bolts holding the pump in place.

If I would have just removed the height adjustment nut I would have bad to raise the engine about 2 inches to clear the bolt and that would have put a lot of torque on the water seal of my sail drive, which is, needless to say, not a good idea with the boat sitting in the water.

[Jeanneau 45.2]

Bill, one other advantage to how you managed the motor mount removal (i.e. disconnecting from the engine bed and block and not futzing around with the motor mount alignment stud) is that you avoided the risk of changing the drive shaft coupling alignment. Having recently done this repair and for the benefit of any others contemplating the procedure, let me share the additional value of tracing the motor mount shoe and its bolt holes onto the engine bed with a sharpie after unbolting and prior to lifting the engine as way to ensure the mounting shoe/motor mount and the machined casting which bolts to the block are correctly located while reassembling. Also, if you can't lift the engine (as I could not given inadequate headroom) using cribbing and a final tapered shim to lift the port fore corner of the engine a few thousands of an inch also works ... just be sure to insert the shim under the block and not use the oil pan (it can deform). Lastly, the pump is gear driven, so it is necessary to cant the pump to allow driving/driven gear faces to mate when removing and reinserting the pump drive shaft into the block. Alan

Sorry I didn't see the thread sooner, but you apparently didn't need my sage advice, lol.