Silly questions on engine mount

Ken13559

Ken13559

.
Oct 29, 2005
2,362
Hunter Marine 326 303 Singapore
Qn.1 Both starboard engine mount has rust on the base plates and the rubber at plate is lifted. The supporting rubber are still ok as far as I can tell. Port side are good and no rust.
Question is can I just change 1 or both of starboard sides (condition depending) instead of all 4 pieces?
Engine is 18 yo Yanmar 2GM20F.

Qn.2 One of the mount Lag Bolt hole is stripped. Any advise on how to repair the hole? I'm thinking of filling it with match sticks or similar thin strip of wood and with wood glue. Not sure which make/type of wood glue or wood putty or .....?

Thank you.

Ken Y
 
Davidasailor26

Davidasailor26

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May 17, 2004
5,695
Beneteau Oceanis 37 Havre de Grace
If one side is rusty and the other isn’t I’d check on whether there may have been a water leak of some sort from a pump, heat exchanger, etc first.

For question 2 - I probably wouldn’t rely on wood glue there. Thickened epoxy would be where I’d start thinking. Does it go into solid glass or something with wood?
 
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Ken13559

Ken13559

.
Oct 29, 2005
2,362
Hunter Marine 326 303 Singapore
Davidasailor26 said:
If one side is rusty and the other isn’t I’d check on whether there may have been a water leak of some sort from a pump, heat exchanger, etc first.

For question 2 - I probably wouldn’t rely on wood glue there. Thickened epoxy would be where I’d start thinking. Does it go into solid glass or something with wood?
Click to expand
1. Yes there was leak of seawater over at starboard side where the SCW Pump is. Rectified leak.
2. I think its wood inside the stringer. What epoxy should I use? Devcon? JB Weld?

Ken Y
 
mermike

mermike

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Nov 21, 2012
740
Yamaha 33 Port Ludlow, WA
In answer to question #2, use West Systems or similar. You will need to be aware of ambient temperature. There are specific hardeners for cool (and hot) temperatures. The epoxy will not kick if the substrate and ambient temperature are too low. It will kick too fast if it's hot out. Do NOT mix a large batch in high ambient temperatures. Read the directions for the specifics.

Assuming this is a vertical hole you're filling, you want it to be a fluid. Mix it up and pour it in. Get all the air bubbles out. Let it set up, then drill to size appropriate to your attachment hardware. Make a few holes in a test substrate and try it so you can determine cure time and the correct drill size before you commit.
 
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Ken13559

Ken13559

.
Oct 29, 2005
2,362
Hunter Marine 326 303 Singapore
mermike said:
In answer to question #2, use West Systems or similar. You will need to be aware of ambient temperature. There are specific hardeners for cool (and hot) temperatures. The epoxy will not kick if the substrate and ambient temperature are too low. It will kick too fast if it's hot out. Do NOT mix a large batch in high ambient temperatures. Read the directions for the specifics.

Assuming this is a vertical hole you're filling, you want it to be a fluid. Mix it up and pour it in. Get all the air bubbles out. Let it set up, then drill to size appropriate to your attachment hardware. Make a few holes in a test substrate and try it so you can determine cure time and the correct drill size before you commit.
Click to expand
Thank you :) I'll look up West System.
 
jibes138

jibes138

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Jan 27, 2008
3,086
ODay 35 Beaufort, NC
Epoxy doesn't have a lot of strength for threads. If the material around the hole is solid I recommend you get a screw thread insert, drill the hole oversize and thread it for the insert then install the insert. You will end up with a stronger thread system than the original installation since the thread insert is a larger diameter than the original and made of a stronger material. screw thread inserts | McMaster-Carr
 
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mermike

mermike

.
Nov 21, 2012
740
Yamaha 33 Port Ludlow, WA
jibes138 said:
Epoxy doesn't have a lot of strength for threads. If the material around the hole is solid I recommend you get a screw thread insert, drill the hole oversize and thread it for the insert then install the insert. You will end up with a stronger thread system than the original installation since the thread insert is a larger diameter than the original and made of a stronger material. screw thread inserts | McMaster-Carr
Click to expand
Also a good approach.
 
Ralph Johnstone

Ralph Johnstone

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Jan 4, 2006
7,272
Hunter 310 West Vancouver, B.C.
jibes138 said:
Epoxy doesn't have a lot of strength for threads.
Click to expand
I'll second that. In fact, it has no strength as it crushes to powder under the extreme pressure of the lag bolt threads.

If luck is on your side, you might try a one size larger diameter lag bolt and the larger diameter thread MIGHT, MAYBE, IF YOU GO TO CHURCH REGULARLY, AND ALWAYS TITHE, be large enough to overcome the thickness of the rotted wood. Doubtful at best. Only tightening it with the new mount in place will tell the tale. Make sure the interior of the hole is dry before trying this. The only reason I even suggest this is that drilling a new hole in the stringer, under the engine, can only be described as a slow, painful death. Replaced the rear support on mine about 10 years ago and I swore never again.

jibes138 said:
If the material around the hole is solid I recommend you get a screw thread insert
Click to expand
What will produce a 100% cure is either the screw thread insert or a hard wood dowel glued into the drilled out stripped hole. And this requires some experimentation to get the right size pilot hole for the dowel. Remember, the grain of the dowel is 90 degrees to what a normal screw would see so the pilot hole is critical to either avoid stripping or splitting of the dowel and possibly the stringer.

Whatever you do, don't use toothpicks or epoxy, both of which will strip. Use something that will hold for years to come or you'll have alignment problems for the rest of your life.
 
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Ken13559

Ken13559

.
Oct 29, 2005
2,362
Hunter Marine 326 303 Singapore
Thank you guys. Looks like a challenging job to me. I'll take baby steps on this repair. Don't want to make things worst than it is.

Ken Y
 
TimFromLI

TimFromLI

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Jan 7, 2014
451
Beneteau 45F5 51551 Port Jefferson
I used West systems g-flex with filler to fill the hole then redrilled it with a forstner bit, It held fine for the two seasons I used the boat till I sold it. The new owner hasn't mentioned any problems with it for the 3 seasons he's had the boat. Temperature must be right though, it won't cure in cold weather. Contact West sytems and see what they recommend; their technical support line is superb.

Stripped Engine mount lag bolt

The wood holding one of the lag bolts on the front motor mount of my 32-3 is stripped. The wood is otherwise solid and dry. I planned on drilling it out with a 5/8 bit and filling it with west sytems two part epoxy. Then drill a pilot hole and tighten the lag into the hardened epoxy. Any...
ericsonyachts.org ericsonyachts.org
 
Last edited:
S

Sovt

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Jul 2, 2014
23
Fuji 36 New Baltimore NY
How about drilling it a bit oversized and epoxying a dowel in the hole.
 
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