Paul, I don't know if I would call it a chronic problem but it is not uncommon, we had 1 lag bolt stripped and there's threads on here discussing it. I believe the stringers are solid wood not plywood. The one we had strip is the forward bolt on the front starboard mount, so it's pretty easy to get at.

Based on what I read here, I did the toothpick repair with epoxy. This involves cleaning out the bolt hole, then you line it with toothpicks coated in lots of epoxy and when it sets up put the bolt back in. You can do this without taking the mount or anything else off so it's pretty simple.

Last summer, the 3rd summer since I did this repair, I noticed some creep starting in that bolt, so I think it is not going to be a long term fix. If that's the case then I am going to ream the hole out, fill it with thickened epoxy and then re-drill it. That will probably require removal of the mount and some engine pieces so it will be a harder fix, but I think more durable long term.

The toothpick method works for us, but we NEVER use epoxy, just silicone sealant. They're called LAG bolts.

I don't think I'd use silicone, as it will pretty much preclude using any other kind of adhesive later, if needed. I'd use round, hardwood toothpicks, not the flat ones, which are softer and probably Titebond III mixed with sawdust. Coat the threads of the lag bolts with beeswax or parafin wax and they won't stick to the glue. Note that Titebond III takes longer to dry then type I or II and is water proof.

There's a hardware product, the name of which I cannot recall, which is a bolt that has machine threads on one end and wood threads on the other end.

My concept is to screw this bolt into the engine bed and use the protruding end which is a threaded stud to secure the motor mount with a nut and lock-washer.

The product is available in stainless steel in common thread sizes. I've found a source on the Web but have lost the bookmark.

This is my plan for stripped engine mount lag screws. I would embed the "wood screw" end with epoxy in the stripped mount hole. Once installed, there would be minimal risk of stripping the engine bed holes again as motor mount adjustment and replacement would only involve working with the nuts on the studs.

I hope I've painted a good enough word picture to describe what I have in mind. When I figure out the name of these bolts, I'll post it with a link. Maybe someone else knows?

Cheers,

Aha.....hanger bolts.

For example:

[URL]http://www.boltdepot.com/Hanger_bolts_Stainless_steel_18-8_3_8-16.aspx[/...

Just anoter suggestion!
[url]http://www.pbase.com/mainecruising/sealing_the_deck[/url]

The toothpick is in my mind a temporary solution. I would think that cleaning out the rot and repairing the hole would be a more permanent fix. There are several articles similar to the link above from Maine Compass. In this case I would think if the mount has one good hole that by removing the mount you could repair the bad hole by cleaning the rot out than reinstall the mount using the good hole to locate it and spot the hole with the mount with a drill the size of the mount hole than remove mount drill proper lagbolt size hole to depth. Reassemble and lag down.
This would give you a good anchor and when other hole fails you can repeat this process for that hole knowing you have a good hole to work with.

Of course the drawback is if there is sufficient room to accomplish this even with the mount out of the way.

Gary, the clearance for the drill was why I didn't just fill and re-drill the hole. It looked like I'd have to take a lot of stuff off the engine to get clearance to drill the hole out again. If you had a 90 degree drill head adapter it might be easy. I like Graham's idea, those hanger bolts set in thickened epoxy in the hole would be way stronger than the original lags into wood. If my one iffy lag does come loose this year I'm going to try the hanger bolt fix.

Bud,
It definitely may not be easy depending on what mount there is trouble with. The back two would be more than likely the hardest of the four. In lieu of removing the motor it would appear the alternator would have to come off on the port side and perhaps the oil filter? The aft port side may require removing starter. Front starboard looks like the water pump and I will need to get close and personal to see if the starboard aft is doable. Looks like hoses for the SAft for sure. Again not being right at the boat and under the engine cover there could be difficulty in the process. A right angle drill might be the problem solver. Attached are some pictures of my engine in it's space.

re. the hanger bolts. Wouldn't they make future removal of the engine mount more difficult? You'd now have a protruding 'stud' going through the lower hole(s) in the engine mount; you'd have to get the mount over that stud in order to remove it. With the stock configuration, you do have to jack the engine up far enough to get the stud of the upper mount clear, but with the hanger bolt, seems to me you'd have to jack it up even further. Probably possible, but something I'd want to consider.

Gary, on our engine the mounts ultimately bolt to the side of the engine block, if you supported the engine then undoing those bolts would solve that problem? Unless they were rusted solid and then you would get material for a new tech article about removing snapped off/mangled bolts from an engine block!

True. Not sure how much play there is to line the holes up with the bolts though. I believe the holes where the mounts bolt to the bed are ovals, so you have a bit of play fore and aft. I guess if you bolted the mounts to the block, then to the bed that would work. I'd have to try it with one hand while standing on my head ;)

Not saying the hanger bolts wouldn't work, I'm sure they will, just wanted to note the difference.