Motor mounts, M-35 & M35 Cooling w/ Sherwood vs. Oberdorfer Pumps

[Breakin Away]

It looks like Bushings has a very wide variety of engine mounts:

https://www.bushingsinc.com/119-2/

Many of them are 5" hole spacing, but they are all for larger, heavier motors. The ones for motors like the M35B are typically 4" hole spacing. I don't know whether they have any customization capabilities, but it would be nice if they could mix&match some parts to come up with a 5" hole spacing with the right hardness of rubber and stud spec. to work with the 352 lb. M35B.  I think I'll give them a call and see what capabilities they have to come up with something like a DF-2205-2 with a larger base plate with 5" hole spacing. With their "competition" pricing their parts at $280 each, it would seem that they have a lot of potential profit margin with this design.

But then on the other hand...

https://forums.sailboatowners.com/threads/anyone-tried-these-motor-mounts.140689/#post-916087

Still researching what to do.

[KWKloeber]

There's NO comparison btwn Vetus and DF, hands down they are in different leagues.  I'd never replace my DF's on my 25 with the same. No reason to when the cost is essentially the same.

Verus has 5" also, but just for monster HP engines.

Are you aware that a proper weld is stronger than the metal welded? The metal next to it will fail before a weld does. 
One benefit is that the slot could be custom-sized for necessary lateral adjustment. Another is that the thickness of the plate could be set tsp the engine mount sits at the lower third of the isolator stud.

[KWKloeber]

Here's, unfortunately, the reply

"Believe that these were Westerbeke' s own design & you can only get them from Westerbeke. Thx, JD"

[Ron Hill]

Breaking : How many hours do you have on that engine? that you now need to change out mounts because they are "Too Soft" ??   

A question

[Breakin Away]

808 hours

[KWKloeber]

808 hours

Wait a minute -- Bad after 800 hrs and you want to replace them with the same?

[Breakin Away]

I think I am going to do some additional inspection and measurements before buying anything. When placed into gear, the torque of the motor pushes the shaft up (slightly) and to port (mostly), causing shaft-to-nut contact
at about 2 o'clock when looking aft toward the nut. I want to measure how far up the adjustment nuts currently are on the studs, since lateral movement would be reduced by 75% if I can raise the mounts enough to for the mounting flange to rest halfway lower on the studs. It may be that I can solve this problem by raising up the current mounts with spacers. But first I need to measure, and I will not be able to get to the boat until at least next weekend.

A few additional facts:

I originally discovered this issue when I put a white tissue under the stuffing box to help detect dripping water, and found fine bronze particles. At that time I did not know how long the problem had been happening. I've been putting down the tissues periodically for awhile, but this time I happened to have some sunlight hit the tissue at just the right angle to see some shiny specs, which led me to get out a magnifying glass and take a closer look.

Alignment appears to be fine when the motor is in neutral or not running. The packing nut is well centered on the shaft in this state, with an even 0.01" gap. The issue only appears when in forward, and gets worse at higher RPM (due to higher torque on the mounts).

The stuffing box was replaced in early 2019, along with original bronze shaft (Aquamet G22 upgrade), strut, prop, and coupler. I just inspected the old stuffing box and shaft that were removed at the time, and can clearly see wear patterns that suggest that this issue had been present (and undetected) for quite awhile before 2019. I purchased the boat in 2016, and not sure the surveyor would have detected this.

There are no vibrations in the system, except for idling below 900 RPM (according to the console tach). I have it on my list to recheck the idle RPMs using a strobe on the motor - it might actually be below the M35B spec of 800-1000 (Service Bulletin #236). Getting up to 950-1000 immediately eliminates the vibration. The <900 RPM vibration happens in neutral, so it appears to be unrelated to running gear or alignment.

I appreciate all your suggestions. However, the boat is 20 years old, and synthetic rubber can dry out and/or lose resiliency over time, even with low engine hours (oxidation in air and evaporation of plasticizers). Based on what I've read, it's not uncommon to replace mounts after less than 20 years. However, I understand that it is not a sure thing that my mounts are bad, or that new ones would be any better, which is why I am going to do some stud measurements and, if the motor is mounted too high on the studs, consider spacers under the current mounts as a first attempt before shelling out money for new mounts and/or custom welding.

[KWKloeber]

[edited]

Well that's a ton more info. 
Good info.  It does sound like more "study" is a wise path to follow.

Could you first observe the isolators/engine mount interaction and whatnot else while under different torques, maybe video it?  To nail down precisely what's happening?

Then IIWMB I think before I did more (depending on what I saw and where all the mounts sit on their isolator studs) my next step might be to remove one (or more) and determine their condition.

Note that Wbeke uses the same isolators on the XPB and on the 35B [ and 40B.]   Food for thought.

[Ron Hill]

Breaking : The first thing that I'd try is to replace the fwd port mount (incase oil from changing the filter may have gotten on the "rubber") and see if that helped.  Do you know if any of the "Prestone" internal coolant might have dripped on any of the mounts (while changing to new hoses?).

A few thoughts

[Breakin Away]

You guys suggested that 808 hours was a short lifetime for engine mounts. I talked to a mechanic today who said that Westerbeke says to replace them every 500 hours. I've been unable to find this in my manual. He also said that lateral motion should be impossible unless the studs are broken. Comments?

Breaking : The first thing that I'd try is to replace the fwd port mount (incase oil from changing the filter may have gotten on the "rubber") and see if that helped.  Do you know if any of the "Prestone" internal coolant might have dripped on any of the mounts (while changing to new hoses?).

A few thoughts

In the time I've owned the boat, there has never been a drip of oil or Zerex on any of the mounts. It is not difficult to ensure this never happens. I'm not sure that replacing only one mount would be a good use of time, since you need to redo the whole alignment with each change.

[KWKloeber]

PS  If you are looking at sizing other than Wb isolators the rule of thumb is 60-70% of the weight sizes the rear ones, 30-40% the front.

I remember some forum post where a westerbeke owner made an adapter plate for 4" CushyFloats - not welded but bolted to the plate and plate drilled at 5".  Interesting approach, but not how I would go.

The Wb isolators "encapsulate" the rubber -- so long as the rubber is "totally intact" (theoretically) one can't move sideways.  But if the rubber is compromised, not competent, then (theoretically) they can move sideways. 
You only know you can show.  Why not ask him where he got that info about the hours - page and line number.

This is what I am saying -- you need to get your head down in there and nail down precisely what's going on.
I never automatically trust someone else who has a vested interest in separating me from my cash when that person knows I am ignorant about what s/he's telling me.

[Breakin Away]

PS  If you are looking at sizing other than Wb isolators the rule of thumb is 60-70% of the weight sizes the rear ones, 30-40% the front.

Are these percentages for each isolator (65%+65%+35%+35%=200% total) or for the sum of front/rear (65%+35%=100% total)?

As you might know, Westerbeke specs the same for all 4 corners. P/N 040510 is 75-125 lb. With a 352 lb engine, that's 21-35% of the engine weight for each mount (or 84-140% total), so that's a lot less support than your first suggestion.

I'm calling people about potential haulout facilities for this fall (might change from my current yard), and I'm working in a discussion about motor mounts as part of that discussion. The guy I spoke to today took over ownership of the marina from his parents and has been doing engine repairs for his whole life. He seemed very knowledgeable, rattling off all sorts of facts from memory (including key differences between C34MkI and C34MkII, and differences between Wb B-series and prior motors). His statement of 500 hour replacement interval was from his memory. As you can probably tell, this guy also seemed a little arrogant and snarky (in other words, too much like me  ), so I did become a little suspicious of him. Among his "hot button" issues is user forums, which he insists I am wasting my time with. However, he also rattled off some of my neighbors as regular customers of his service department, and I'll check with them about whether this guy is as good as he seems to think he is. While I am considering DIY for this job, I'm also considering hiring it out since I may get in over my head and need to buy an awful lot of tools (and spend dozens of hours making trips back and forth to my boat in accumulating the needed tools).

[KWKloeber]

The 35B engine is probably 370 - 375 wet weight.

375 *(40%) / 2 =   75 static lbs. ea. front
375 *(60%) / 2 = 113 static lbs. ea. rear

Understand this is rule of - you would need to know the center of gravity of the M35B/tranny but it's close (give or take.)


I know there's a way to make an adapter plate, even w/o welding.

[Jim Hardesty]

I talked to a mechanic today who said that Westerbeke says to replace them every 500 hours.

Using that Shamrock would be on it's 3ed set.  Something to consider.  Estimating cars, 500 hours @ 50mph would be 25,000 miles.  Don't know of any cars that call for motor mount replacement intervals.  Not saying that your motor mounts don't need changing, just think that would be very short life unless some harm was done to them or they were defective.
Jim

[Breakin Away]

The 35B engine is probably 370 - 375 wet weight.

375 *(40%) / 2 =   75 static lbs. ea. front
375 *(60%) / 2 = 113 static lbs. ea. rear

Understand this is rule of - you would need to know the center of gravity of the M35B/tranny but it's close (give or take.)


I know there's a way to make an adapter plate, even w/o welding.

If I go with Westerbeke, should I do the rear ones with #040511 (125-220 lb)? The mechanic seemed to want to go stiffer.