Frozen transom mount bolts :-(

I have an old 7.5hp gamefisher that runs fine, but it's been in storage for years. The transom mount bolts are frozen bad! Heavily rusted. I tried soaking them in solvent and it didn't work. I even tried vice grips to grab the bolt in a spot that I didn't care about the threads and it wouldn't budge. Any ideas how I can fix this motor so I can mount and use it?

Try using a solvent called PB Blaster keep applying it for a few days, it just might work, blaster is good stuff. If not try and heat them up. That should work.

Any evidence of 3M 5200 or equivalent on the threads? If you're not concerned about reusing the bolts maybe try cutting them off with a rotary tool of some sort, drill out the bolt or pounding the remaining piece out with a BFH, but be careful.

All the through hull bolts on my tin had 5200 on them so the rotary tool got a good workout!

Good luck.

PB Blaster is good stuff for rusty bolts, but I really think Kroil is superior. I have used Kroil (Orange/Black can) to ease rusted lug nuts, u-joint nuts, and even exhaust manifold bolts loose. I think Kroil not only help lubricate things, it actually dissolves rust too.

I'll give them a try thanks

You can't beat heat.Maybe have to heat a couple of times but it will always come through.

crazymanme2 said:

You can't beat heat.Maybe have to heat a couple of times but it will always come through.

Click to expand...

I'm gonna try heat now, but I never did that. Can I use a regular pipe sweating torch? how hot should I get it? flame on the bolt? Do I cool quickly with water or let it cool on its own?

Jay415 said:

crazymanme2 said:

You can't beat heat.Maybe have to heat a couple of times but it will always come through.

Click to expand...

I'm gonna try heat now, but I never did that. Can I use a regular pipe sweating torch? how hot should I get it? flame on the bolt? Do I cool quickly with water or let it cool on its own?

Click to expand...

i would hit it with some blaster when its still warm and it should pull some into the threads but be careful it dont flare up on you, also try wire brushing the threads that are exposed so you dont have to run all the rust through the threads and dont try to ram it through one way work them back and forth with plenty of lube, i always slap a lil grease on mine before i put it away, and when i put it on the boat in the spring to avoid any problems like this good luck

Thanks a lot. Gonna try that this weekend. Someone gave me the motor and it's been sitting like this for prob 20 years. I was surprised it even ran. I sprayed the bolts with blaster, wire brushed it and I've been spraying blaster on it, then a few taps with a hammer everyday.

Use Mapp gas if you can get your hands on some. Usually available through any hardware store. Heat the aluminum until the paint goes away then start working the clamp assy. slowly in both directions. As the clamp tightens back down stop and reheat the aluminum casting around the clamp screw. When you can, grease up the threads and run the clamp screw back and forth until you are able to introduce grease into it.

Jay415 said:

crazymanme2 said:

You can't beat heat.Maybe have to heat a couple of times but it will always come through.

Click to expand...

I'm gonna try heat now, but I never did that. Can I use a regular pipe sweating torch? how hot should I get it? flame on the bolt? Do I cool quickly with water or let it cool on its own?

Click to expand...

Pappy said:

Use Mapp gas if you can get your hands on some. Usually available through any hardware store. Heat the aluminum until the paint goes away then start working the clamp assy. slowly in both directions. As the clamp tightens back down stop and reheat the aluminum casting around the clamp screw. When you can, grease up the threads and run the clamp screw back and forth until you are able to introduce grease into it.

Click to expand...

Like Pappy said heat the aluminum around the bolt. Not the bolt itself.
If you heat the bolt itself it may expand too much and brake the aluminum.
Let it cool on its own.

can't add too much to what's already been posted. PB blaster-very good, kroil-better, heat -almost a must. if you can get something on the threads so you can tap them right and left,(loosen tighten),and just get it to move a hair,and keep spraying and heating ,it should come loose. it may take awhile.

Haven't had a chance to try yet. But the person that gave me the motor snapped the end of one of the bolts (the flat part that you hold and turn) when and if I get these bolts loose, can they be replaced?

Need year and model but you should be able to get replacement parts.

Well I am giving up on this. Since I don't technically own the motor. I'm giving it back to the person who does. Instead I scored a 1999 Johnson 9.9hp that looks like new! Has prob less than 10 hrs on it. For $300. A little sun damage to the exterior but under the cover looks mint! It sat on the back of a 24' center console as a kicker and barely used. thanks anyway everyone!

Gave it back to my neighbor and heat did the trick! He heated up the aluminum and they loosen right up! Prob cause of all the PB Blaster I put on it everyday! lol: