Active Active   Unanswered Unanswered

Engine mounting bolts are loose

Keeping your powerboat under power is a lot easier with good advice. Post your power systems questions here.

Moderators: Don Ayers, Don Vogt, Al Benton

solopar
Posts: 17
Joined: Mon Oct 29, 2012 2:05 pm
Contact:

Engine mounting bolts are loose

Post by solopar » Wed Dec 19, 2012 5:29 pm

I have an 1957 Capri (19') with a KFL 131 hp engine in it. I noticed that the mounting bolts that attach the engine to the frame are loose. I tried to tighten them up, but it appears that they are stripped. There doesn't appear to be any wood rot on the frames so I think that years of vibration just wore the wood out. Short of replacing the frame I was thinking of drilling out the bolt hole, epoxying in a substantial size dowel rod and then re-attaching the bolt. Think this will work? Any other ideas?

Thanks much!

User avatar
Jim Godlewski
Posts: 529
Joined: Sun Feb 14, 2010 12:32 pm
Location: Saint Clair Shores, Michigan
Contact:

Post by Jim Godlewski » Wed Dec 19, 2012 6:51 pm

It seems to me, and I could be wrong here but doesn't this bolt have a nut on it? This photo is my mid 50's K.

Image
1956 17 Sportsman CC-17-2310
1930 Model 100 7152
https://1956chriscraftsportsman.shutterfly.com/

User avatar
Doug P
Posts: 1036
Joined: Thu Jul 24, 2008 4:24 pm
Location: Pacific NorthWest
Contact:

Re: Engine mounting bolts are loose

Post by Doug P » Wed Dec 19, 2012 7:12 pm

solopar wrote:I have an 1957 Capri (19') with a KFL 131 hp engine in it. I noticed that the mounting bolts that attach the engine to the frame are loose. I tried to tighten them up, but it appears that they are stripped. There doesn't appear to be any wood rot on the frames so I think that years of vibration just wore the wood out. Short of replacing the frame I was thinking of drilling out the bolt hole, epoxying in a substantial size dowel rod and then re-attaching the bolt. Think this will work? Any other ideas?

Thanks much!
Works well....

User avatar
steve bunda
Posts: 416
Joined: Thu Dec 14, 2006 5:59 pm
Location: wisconsin
Contact:

Bolts

Post by steve bunda » Wed Dec 19, 2012 7:31 pm

Hi Solo, I think you are asking about the square head lag bolts that fasten the engine mounts to the stingers.The dowel method is good for badly worn out holes, engine replacement and wood rot, but sometimes a couple of mahogany wood splinters dropped down the hole with a little glue can firm up the lag.

charlesquimby
Posts: 203
Joined: Thu Jun 21, 2012 8:22 am
Location: St Leonard, Maryland
Contact:

Post by charlesquimby » Thu Dec 20, 2012 8:44 am

Are the lags bronze? Steel lags tend to rust and effect the surrounding wood when moisture is present. See if you can get bronze ones another inch longer, or better yet one diameter larger if they will go through the mount. Blow the hole out with air gun, ensure the hole is dry, then run the bolt in to ensure fit and ability to tighten (not overtighten). Remove the bolt, blow out hole again, then reinstall with a dab of 5200. Just a dab to act as a thread locker. If you have to go longer, drilling a healthy sringer will be neccessary. Just one man's idea. CQ

User avatar
rpccc43
Posts: 235
Joined: Mon Jul 02, 2007 2:18 pm
Location: Irondequoit, NY
Contact:

Post by rpccc43 » Thu Dec 20, 2012 3:39 pm

The Gougeon Brothers (West System)would tell you to drill out the hole slightly larger than your fasteners, fill it with epoxy then pre-drill for the fastener and drive it home. I have used this method for handrails and it works well.

solopar
Posts: 17
Joined: Mon Oct 29, 2012 2:05 pm
Contact:

Post by solopar » Fri Dec 28, 2012 5:18 pm

It is the square headed lag bolts that attach the engine to the stringers. I'm not sure if they are steel or bronze, but I'll replace with bronze. It sounds like using a lag bolt an inch longer and perhaps a size bigger might do the trick (adding a Mahogany splinter and either 5200 or West epoxy as a thread lock). I'll let you know how it turns out when I get it finished. Thanks for the advice!

User avatar
Pete DeVito
Posts: 483
Joined: Fri Jun 02, 2006 6:48 pm
Location: Florida

Post by Pete DeVito » Fri Dec 28, 2012 8:21 pm

Solo,
Always a good idea to plug the holes and redrill just as you decribed. I have pulled engines out of some of my boats and over time the lag bolts will not hold as they should. Get your dowel and then drill the hole to fit the dowel and glue it in and let it set. Set your engine correctly to the coupling and then redrill your holes. If engine stringer is in good condition no need for any major work..
I own a 1957 Capri and the photo below is the correct square headed lag bolts for your model you should have two sizes.
Pete
Image
Past Project 1948 17' Deluxe
Past Project 1957 19' Capri
Future Project 1955 17' Special Sportsman

User avatar
Doug P
Posts: 1036
Joined: Thu Jul 24, 2008 4:24 pm
Location: Pacific NorthWest
Contact:

Post by Doug P » Fri Dec 28, 2012 10:19 pm

I agree with Knotty, also a size bigger lag screw maybe too large to fit engine mounts

bing
Posts: 16
Joined: Thu Mar 03, 2011 10:56 am
Location: Port Angeles, Wa.
Contact:

Doweling Holes

Post by bing » Sat Dec 29, 2012 11:27 am

If you use a dowel, the lag bolts threads will be pulling with the grain of the dowel and does not hold as well. I took a 3/4" oak board and a 1" hole saw on a drill press and drilled out 4 plugs for each hole. You have a pilot hole in these so I ran a 1/4" all thread rod and glued each piece together and then removed rod after glue dried. Drill out your motor mount holes to 1" and glue these plugs in the hole. You now have a pilot hole for the correct bit sizing for the lag bolt. I used Gorellia Glue for gluing because it expands. You can make the plugs longer or shorter by adding/subtracting plugs. Now you are pulling against the grain.

User avatar
debiby
Posts: 168
Joined: Tue Aug 22, 2006 5:38 pm
Contact:

Post by debiby » Sat Dec 29, 2012 12:24 pm

What about using one of the lead expanders you run your bolt into like you use in concrete? As you run the lag bolt in it eexpands and holds tight.
Dan Biby
38' Challenger "DreamOn"

charlesquimby
Posts: 203
Joined: Thu Jun 21, 2012 8:22 am
Location: St Leonard, Maryland
Contact:

Post by charlesquimby » Sat Dec 29, 2012 3:18 pm

Expansion anchor seems like a good way to permanently ruin a stringer. CQ

User avatar
Doug P
Posts: 1036
Joined: Thu Jul 24, 2008 4:24 pm
Location: Pacific NorthWest
Contact:

Post by Doug P » Sat Dec 29, 2012 4:06 pm

I was going to suggest duct tape and C-clamps :lol:

solopar
Posts: 17
Joined: Mon Oct 29, 2012 2:05 pm
Contact:

Re: Engine mounting bolts are loose

Post by solopar » Thu Apr 25, 2013 6:40 am

I just noticed this post, funny as shit! We used to make fun of my dad for fixing everything with a hammer, can of wd40 and a roll of duct tape:) I guess I should have listened to his advice earlier in life!

Gravity
Posts: 1
Joined: Fri Dec 30, 2005 10:20 pm
Location: Dallas, TX
Contact:

Re: Engine mounting bolts are loose

Post by Gravity » Mon Apr 29, 2013 9:27 pm

Be sure your engine mounts to the stringers are strong, whatever method of fix you use. The full thrust of the propeller is transferred to your boat at these joints. At high speed the thrust can be over 2000 pounds. If your engine mounts are not of high integrity the engine can twist on the stringers causing vibration or worse.
Learning is a joy!

Post Reply

Who is online

Users browsing this forum: No registered users and 7 guests