remove siezed motor mount bolt

[Hayden Watson]

I am replacing the motor mounts on my Universal M25XP and the port rear post is stuck in the hole. I had no problem removing any of the lag screws into the engine bed. All of the nuts on the 5/8" studs came loose top and bottom without problems. I used a hoist to raise the engine and 3 of the mounts fell out of their mounting holes but that forth one!!!!
The nuts top and bottom are backed off over 1/2" but the stud will not budge. Any suggestions? I have ...

• been soaking it with PB Blaster,
• heated the flange with with my heat gun.
• Rattled it in both directions with my impact driver
• beat on it with a hammer
• alternately tightened the upper and then the lower nuts to try to pull it out.

 

[Ralph Johnstone]

the port rear post is stuck in the hole.

Can you describe what this "post" is or better still, attach a picture of the offending little bugger.

 

[LeslieTroyer]

nut cracker!! split that sucker
Amazon.com: Elitexion 2pcs Nut Splitter Tool for Damaged Nut Remover: Home Improvement (or equivalent)

 

[twalker H260]

Assuming the motor is out of the boat and it’s the motor mount stud that’s stuck I’d have a couple of suggestions.

Loosen top nut, tighten lower nut , apply heat to motor ear the. Try hitting sides of ear simultaneously with two hammers.

Tighten nuts as above and try using an automotive ball joint remover or pitman arm remover.

 

[RitSim]

Is the motor mount bracket bolted to the engine block? If it is then take the bracket out and deal with it on the bench. Maybe use and arbor ress to push the stud out. If the bracket is not bolted on, then be careful using the hammer so as to not snap the cast bracket.

 

[Hayden Watson]

The post is the 5/8"ø threaded rod that comes out of the motor mount and goes through the hole in the engine mounting flange which is a part of the engine block casting. It has nuts above and below the engine mounting flange which allow the engine to be raised and lowered for alignment. Note that the stud is siezed in the tight fitting hole so this is not a threaded part. A nut cracker or any form of "breaking" will cost the purchase of a new engine because the hole is a part of the engine block.
It is strange because both the nut above and below came out without any problem and it is the unthreaded hole that is stuck. The other three mounts just fell out when I lifted the engine.
The engine is still in the boat with no plans to remove given it runs perfectly and starts with 10 seconds of glow plug.

 

[Sailor Sue]

Get a better penetrating oil - something like Aero Kroil and keep soaking the stud. Use one of the nuts from one of the other mounts and put it on top of the first nut on the stuck stud. Tighten the two nuts together and then try to wrench the stud in the mount - clockwise on the top nut, counter-clockwise on the bottom nut.

 

[jssailem]

You indicate that you have begun the lift.

It looks (in the image) that the engine flange might be at an angle to the bolt. It does not look like there is much clearance between the stainless bolt and what look like an aluminum painted flange on the engine.

Try altering the angle of the engine and the bolt. Perhaps dissolving the paint on the flange, it is possible that some paint seeped down the thread. I would suspect corrosion if the metals are dissimilar as they appear. I have found some success with Corrosion Block spray.

Short of dissolving the corrosion, and wiggling the engine, you may have to remove the motor with the mount attached. Then buy a new mount.

 

[Charles Erwin]

Since you are replacing the mount - I assume the new mount has its own new threaded stud - here is what you could do. Cut off the threaded stud flush with the top surface of the motor mount. Use a reciprocating saw with a new hack saw blade (non sparking), a dremmel with a cut off wheel, or what ever. Cut the underside too. Center punch the fresh cut and commence to drill it out. Start with a 1/8 bit then a larger bit as necessary. You don't have to drill out the remnant totally but get as much of it as possible. Then you can collapse what is left of the remnant with a hammer and punch but most likely it will fall out real easy.

Charles

 

[Hayden Watson]

You indicate that you have begun the lift.

It looks (in the image) that the engine flange might be at an angle to the bolt. It does not look like there is much clearance between the stainless bolt and what look like an aluminum painted flange on the engine.

Try altering the angle of the engine and the bolt. Perhaps dissolving the paint on the flange, it is possible that some paint seeped down the thread. I would suspect corrosion if the metals are dissimilar as they appear. I have found some success with Corrosion Block spray.

Short of dissolving the corrosion, and wiggling the engine, you may have to remove the motor with the mount attached. Then buy a new mount.

The photo is not my boat but same setup. The motor mount is not attached to the engine bed so when I raise the engine the mount is hanging free. The paint on mine is factory and the mount is not painted. I plan to use TEF 45 on the stud when I install the new.

 

[Hayden Watson]

Since you are replacing the mount - I assume the new mount has its own new threaded stud - here is what you could do. Cut off the threaded stud flush with the top surface of the motor mount. Use a reciprocating saw with a new hack saw blade (non sparking), a dremmel with a cut off wheel, or what ever. Cut the underside too. Center punch the fresh cut and commence to drill it out. Start with a 1/8 bit then a larger bit as necessary. You don't have to drill out the remnant totally but get as much of it as possible. Then you can collapse what is left of the remnant with a hammer and punch but most likely it will fall out real easy.

Charles

This will be my last ditch method if all others fail. there is not a lot of room and the drill would need to be long and i am concerned about getting a straight hole.

 

[dmax]

As Sailor Sue said, I would try to unscrew the mount from the hole - I had a similar situation and turning the bolt was key to breaking the bond, no amount of pounding/pressing worked. You should be able to get a wrench on the bottom bolt and once it is bottomed out, be able to spin the mount. If that doesn't work, drilling it out as Charles stated is probably your best bet.

 

[Hayden Watson]

Get a better penetrating oil - something like Aero Kroil and keep soaking the stud. Use one of the nuts from one of the other mounts and put it on top of the first nut on the stuck stud. Tighten the two nuts together and then try to wrench the stud in the mount - clockwise on the top nut, counter-clockwise on the bottom nut.

I have been using double nuts locked together on the top side. I have used both straight torque with wrenches in both directions and my 900in-lb impact nut driver in both directions. I got lucky and the double nuts are just a tiny bit out of alignment so that the bit of slop in the socket allows it to drop over both nuts and i can impact drive in both directions without the nuts coming apart.
I have never heard of Aero Kroil. Does it work better than PB Blaster (which has always been my go-to)?

 

[Hayden Watson]

As Sailor Sue said, I would try to unscrew the mount from the hole - I had a similar situation and turning the bolt was key to breaking the bond, no amount of pounding/pressing worked. You should be able to get a wrench on the bottom bolt and once it is bottomed out, be able to spin the mount. If that doesn't work, drilling it out as Charles stated is probably your best bet.

twisting the stud has been my primary force. The mount is free from the boat and elevated an inch above the bed so the only contact is the corrosion between the stud and mount. I have used the bottom nut both to try turning the stud and as a "puller" by tightening it up against the flange to pull the stud down. I have done the same with the top nuts to turn from the top and as a puller to pull the stud up. Each day I go out and work on it for 20-30 minutes. Tap, tap, tap. Pull, pull, pull, Twist, twist twist, spray, spray, spray... repeat until frustration is too much for the day.
Last night I degreased the flange and made a dam around the stud with butyl tape and filled it with PBB. Hopefully that will let it soak in better.

 

[dmax]

Man, that is a tough one, sorry for your pain. Would a right-angle drill help to drill it out?

 

[Hayden Watson]

Given that there are no threads involved, I hope that it is just a matter of patience in letting the PB do its thing on the corrosion. I don't have (or know of one to borrow) an angle drill but that would be a good way to get in there.

 

[Charles Erwin]

Can send one if it comes to it.

 

[Ranger_12]

Since you are replacing the mount - I assume the new mount has its own new threaded stud - here is what you could do. Cut off the threaded stud flush with the top surface of the motor mount. Use a reciprocating saw with a new hack saw blade (non sparking), a dremmel with a cut off wheel, or what ever. Cut the underside too. Center punch the fresh cut and commence to drill it out. Start with a 1/8 bit then a larger bit as necessary. You don't have to drill out the remnant totally but get as much of it as possible. Then you can collapse what is left of the remnant with a hammer and punch but most likely it will fall out real easy.

Charles

I had same problem last week with my M25XP. I had the motor out of the boat and it was still a pain. I tried everything and ended up drilling it out with increasing drill bit sizes. It's soft metal but it is seized tight to the bracket. I think it would be easier if you can unbolt the bracket from the block (3 bolts) and work on it on a bench.

 

[berner73]

I am replacing the motor mounts on my Universal M25XP and the port rear post is stuck in the hole. I had no problem removing any of the lag screws into the engine bed. All of the nuts on the 5/8" studs came loose top and bottom without problems. I used a hoist to raise the engine and 3 of the mounts fell out of their mounting holes but that forth one!!!!
The nuts top and bottom are backed off over 1/2" but the stud will not budge. Any suggestions? I have ...

• been soaking it with PB Blaster,
• heated the flange with with my heat gun.
• Rattled it in both directions with my impact driver
• beat on it with a hammer
• alternately tightened the upper and then the lower nuts to try to pull it out.

Condolences, truly no good deed goes unpunished. I despise when projects devolve into such chores.

To your point in a subsequent reply, above all else do no damage to the engine bracket (i.e. be careful w/ off axis forces). As Ranger suggests, if you can remove the bracket from the block, this is likely your best option as I imagine access is very limited as is. I believe heat and penetrating oil will eventually work, but I don't think a heat gun is enough - I would get a torch on it while protecting the surrounding area with a welding blanket and/or heat sinks.

To carry you through the journey, think about the sense of accomplishment when the stud finally does break free!

Best of luck

 

[Hayden Watson]

I am singing a song.
s, u, c, c, e, s, s. Seven little letters that spell SUCCESS!!!
To day I went out and on one of the times of running the lower nut up tight to the bottom of the flange, it turned turned all the way to the water-lift muffler which was just a bit farther than usual. I flipped the wrench and took another bite and with about max effort I could push, the wrench again went to the water-lift. Two more flips, still at max push and I had turned the nut 1/2 turn farther than it had gone before so I knew one of three things was happening, stripping the nut, stripping the threads in the stud or pulling the stud through the hole.
I backed off the nut to see if the threads were ok and it turned with finger pressure so back to tightening. after over one full turn of the nut pushing the wrench about as hard as I could manage there was a loud "pop" and the next turn was about half the torque. after a few more, it was down to a quarter. and then the motor mount started to turn and I was able to wiggle it out.
I looked to see what damage there was inside the hole and it was as smooth and shiny as the day it was made.