Yanmar 4BY2 Motor Mount Replacement

I am probably getting close to replacing my motor mounts and was wondering if anyone has had it done or did it themselves and was wondering how that experience went.

Hi Mike, I had the Yanmar dealer do it. Basically pulled the engine, changed all the hoses and all new motor mounts. Hoses generally replaced every five years. If you have access to a forklift you could probably DIY. And some are not access able unless the engine is out. Ask to paint the mounts before installation helps to reduce rust. Removing the engine allows servicing of the whole compartment then full cleaning. When engine was replaced the dealer used new slightly larger bolts for the mounts into the stringers. I was not able to get in time an oil drain kit that would have saved some aggravation before the engine was reinstalled.

ALICE J":2zcxqrg7 said:

Hi Mike, I had the Yanmar dealer do it. Basically pulled the engine, changed all the hoses and all new motor mounts. Hoses generally replaced every five years. If you have access to a forklift you could probably DIY. And some are not access able unless the engine is out. Ask to paint the mounts before installation helps to reduce rust. Removing the engine allows servicing of the whole compartment then full cleaning. When engine was replaced the dealer used new slightly larger bolts for the mounts into the stringers. I was not able to get in time an oil drain kit that would have saved some aggravation before the engine was reinstalled.

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I’m planning to have this done this Summer. What was the oil drain kit you were thinking of installing?
Could you let me know by PM what your cost was?
Thanks

Mike, I have not replaced motor mounts in a Ranger or Cut but I have replaced many in other applications. I did look at a R27 at the rendezvous last month. The owner asked me to look at his and advise. It is tight but not that bad of a job.

The less back breaking approach would be pull the engine. Mark all mounts for reference points for a close alignment. It will not be the same but you will be close. Remove the mounts. This is a good time to clean the bilge, replace bilge pumps, replace packing and if cutlass is do replace cutlass. I also would recommend inspecting the wood in the engine stringer the the mount lag bolts anchor to. I would suspect some will not anchor correctly. Normal construction is either aluminum plates drilled and tapped 3/8 SAE thread and glassed to the stringer or plywood glassed to the stringer and lag bolts used. Fluid Motion uses wood. In this case I would drill out the mounting holes to 1/2" dry out the wood then use a penetrating epoxy to soak into existing wood to seal and bond the fibers. Then epoxy 1/2 oak dowel rods into the holes. Pre drill the holes using one of the mounts as a template. When you set the engine back in place you will have good solid anchoring for the mounting lags.

If replacing the mounts without engine removal is desired. I would recommend replacing one at a time. Unbolt the engine coupler first. Measure as found mount hight and record for future rough alignment. Remove all top hold down nuts from the mounts. Remove the lag bolts to the mount being removed. Place a 4x4 cut small enough to fit in location next to the
mount. use a small pry bar to lift the engine using the mount bracket, slide the engine mount out. you may have to repair the engine stringer as described in the previous paragraph. It is a bit harder to do with the engine in place but it can be done . I looked at the R27 and felt there was enough room to do it. you may have to remove a few engine components if necessary.

After mounts are replaced a rough engine alignment should be done if on the trailer. When the boat sits in the water and the engine has been run for a few hours. Recheck alignment for final adjustment.

Really? I need to pull the engine every 5 years? I that what this is saying? Pardon me if this a dumb question.

tlkenyon":zoubrfja said:

Really? I need to pull the engine every 5 years? I that what this is saying? Pardon me if this a dumb question.

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I'm not sure that every 5 years is necessary. 5 years would be a good time to start accessing the mount condition. If the mounts have not been contaminated with oil, antifreeze and other petroleum base solvents or have been maintained by cleaning and rinsing with fresh water to prevent rust and corrosion. The mount should last longer than 5 years. With the exception of extended hours of run time. If in 5 years your engine has 1000+ hours its time to start looking a bit closer 1500 hrs change the mounts regardless of condition. One other note is mount location. Some engine manufactures designate mount locations. the mounts may look the same but they are designed to be front mounts, rear mounts, some are made for right side and left side of the engine based on the rotational torque of the engine. If you are DIY make sure you are installing in the right location for your specific engine. I don't know if Yanmar does this.

You can replace the mounts with out removing the engine. I have done both engine removal and replacement in the boat. It depends on how easy it is to pull the engine and what equipment is available at the time to pull the engine. The Rangers and Cutwaters have the engine installed below the cockpit sole. This is an easy engine pull providing a hoist is available. An engine located in a pilot house or salon would be much harder to pull, most of the time this requires disassembly of engine components to make clearance for engine removal. In this case mount replacement would be done in the boat.

If you are a DIY and want to do the mount replacement without pulling the engine in a R-27 or 25-RC from what I saw when looking at the R-27 it can be done without pulling the engine. It will be tight but doable. The R-25 classic may be more difficult similar to the C26 because part of the engine is in the pilothouse. The difficult mount in my C26 would be the fwd/port mount.

Sorry Brian can’t recall the oil pump, but it would connect to the oil pan plug, so as to remove most of the oil. I believe the pump was mounted on the bulkhead. I thought the Reverso was overkill.

Thank you Brian for the detailed description on how to replace the motor mounts, ours are looking a bit rough on Gratitude so the time to replace is getting close. I plan on doing this myself IF the overhead beams in my storage unit can support a come-along and the weight of the engine. I guess I need to see what the 4BY2 weighs before I start. Looks like a fun (pun intended) project and a way for me to lean more about our boat. Another reason to buy more tools too!

Tim
Gratitude

This is a bit of an old thread, but probably growing in relevance as these boats age.

Short version - it was very possible to replace the mounts in a Yanmar equipped R-27 classic without removing the engine.

Long version - As mentioned earlier in this thread, take height measurements of all four mounts for rough alignment later. Also, part the shaft flanges and check for alignment before starting disassembly. Who's to say that it was aligned when you started?

The rear mounts were a piece of cake. Easy to access and this end of the engine was pretty light. I used a 4x4 across the engine compartment and a 2000lb rated ratchet strap to do the lifting. There was a lifting eye in the middle of the transmission housing, I used this and was able to do both mounts with a single lift. Made sure to wedge the engine up with some wood pieces and kept clear of the lift strap, just in case of failure.

The forward port mount was pretty easy too. Again, the 4x4 was placed across the engine compartment up on the steps to ensure sufficient lift space. I looped the strap through the upper alternator mount bracket for the lift. Lowered the adjuster nut on the rear starboard mount so that the engine could rock over on the forward starboard and rear port mounts. The front of the engine was pretty heavy, but well within the capability of the lift strap.

The forward starboard would have been pretty easy if it weren't buried under the heat exchanger and intercooler. I suggest removing these as it is probably time for an internal cleaning anyway. The heat exchanger was easy to get off. The intercooler had some bolts on the bottom that were tough to access. If you're in that far, might was well get the transmission oil cooler out too. All of these were coupled with single hoseclamps so all of those got replaced on the way back together.

With all that out of the way, the strap was looped around the forward starboard mount bracket, the rear port adjuster nut lowered and the engine rocked over to get the mount out and back in.

Findings - All lag holes were intact and did not require any rework. All mounts showed considerable rust on the lower flanges. All of the adjusters were at the uppermost extreme of their travel. There was some evidence of leakage from the forward cover of the intercooler, this was near invisible without removal. Both the intercooler and heat exchanger were dismantled for cleaning and resealing (another story), there was considerable blockage with hard mineral deposits.

Improvements made - There are several threads on here discussing rusting of the engine mounts. The mounts sit right on the stringers where water can/did pool. Considering that the old mount adjusters were maxed out (not great), I made up 1/2" fiberglass spacers and got longer lag bolts. The mounts now sit up off of the stringers so water will not pool around them. Of course, they are also cold galvanized and topcoated with matching Yanmar paint for good measure. The adjusters are now in the middle of their range as well, per the installation instructions. The cooling parts were cleaned with Barnacle Buster and a 3/16" aluminum rod and reassembled with new o-rings and grease. Some good tips here - https://www.sbmar.com/articles/cummins- ... intenance/

Anyway, it was a good couple of days of work but nothing overly challenging. Looking forward to many more years of quiet and cool running after this work.

have fun,
Brendan

irwinengineering":10gmf30q said:

This is a bit of an old thread, but probably growing in relevance as these boats age.

Short v
ersion - it was very possible to replace the mounts in a Yanmar equipped R-27 classic without removing the engine.
... snip
have fun,
Brendan

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Thanks Brendan, this is great info!

What replacement engine mounts did you use?

The replacement mounts were 'Metalastik' brand which matched what I took out.

Front mounts 17/1609/1-55, rear 17/1609/1-45. The front of the engine is heavier than the rear, hence the stiffer mounts. I also replaced the adjuster studs, part # HAD16-20.

The boat is noticeably quieter when running now.

Brendan