stiff threads lower unit

[nicknight]

I have a 2007 Merc 40HP.
Previously I put a dab of 271 loctite (red stuff, and never again) on the 4 bolts that hold the lower end onto the engine. They came out a little stiff.

3 of the 4 go in pretty easy but ht 4th is noticeably stiffer going in. I don't think it i cross threaded at all...the threads are just a bit out of whack or some gunk is in there. I tried different bolts.

I have figured out the difference between the restorer, rethreader, chaser and cutting tap. I don't have a rethreader (bolt) but plan on getting one.

The thing I am not sure about is using a rethreader on the type of metal the outboard casing is made of.

The lower end will have to come off again in a year or two at the latest and I am terrified that I am going to screw up that bolt hole.
Any experienced advice on this that I can get???

nickNight.

 

[lilmomo225]

Re: stiff threads lower unit

u should use a thread chaser on it being careful u have it started straight and use tap magic or wd-40 to lube it while chasing the threads it isnt going to hurt the ALUM just turn a little and back off

 

[lilmomo225]

Re: stiff threads lower unit

USE A THREAD CHASER and lube it with tap magic or wd-40. just make sure u are started straight and turn a lil then back off, turn a lil more then back off...... the chaser will not hurt the alum. just dont crossthread it. i used the same stuff on mine and never again...it what the manual calls for though

 

[nicknight]

Re: stiff threads lower unit

thanks.....so these chasers....did they have straight slots on them or were the slots on them a different cut on each end???

thanks,

NN

 

[Sunfish12]

Re: stiff threads lower unit

Wire wheel the bolt and I use never seize on mine and have never had a problem.

 

[RZR2007]

Re: stiff threads lower unit

I would run a blind hole tap through them and use Accu-lube #10

 

[nicknight]

Re: stiff threads lower unit

Fixed it:
Previously I did start to run a tap through it but quickly realized that I was taking away thread.....that is what a tap will do. The first few threads for that particular blind hole are very loose.

I sprayed some wd 40 in and tool a not too sharp dental pick and ran it through the theads then cleared out as much wd40 as I could....done. Dental picks rock....no loctite this time....not eve the blue stuff.

I cannot figure out why the service manual says to use the red loctite on 1/2 the thread when the stuff requires heating to remove it.

Anyone care to chime up on that one?

nickNight.

 

[RZR2007]

Re: stiff threads lower unit

Fixed it:
Previously I did start to run a tap through it but quickly realized that I was taking away thread.....that is what a tap will do. The first few threads for that particular blind hole are very loose.

I sprayed some wd 40 in and tool a not too sharp dental pick and ran it through the theads then cleared out as much wd40 as I could....done. Dental picks rock....no loctite this time....not eve the blue stuff.

I cannot figure out why the service manual says to use the red loctite on 1/2 the thread when the stuff requires heating to remove it.

Anyone care to chime up on that one?

nickNight.

Yes a tap will tear the threads IF it is not started straight. The loc tite is to prevent the bolts from vibrating out, only need a small dab half way down the bolt, no need to coat the threads. You probably had some rust,etc. in there as well, or used way to much of the loc tite. I've never had to heat it to remove bolts when properly used. Think the red stuff is bad, try some 680!

 

[nicknight]

Re: stiff threads lower unit

Yes a tap will tear the threads IF it is not started straight. The loc tite is to prevent the bolts from vibrating out, only need a small dab half way down the bolt, no need to coat the threads. You probably had some rust,etc. in there as well, or used way to much of the loc tite. I've never had to heat it to remove bolts when properly used. Think the red stuff is bad, try some 680!

I may use the blue stuff but will just keep an eye out for now. there was no rust

Tapping the threads will damage them even if it is started straight. Once a bolt is screwed in there and torqued the threads move a little......use a tap = bad.

 

[RZR2007]

Re: stiff threads lower unit

I may use the blue stuff but will just keep an eye out for now. there was no rust

Tapping the threads will damage them even if it is started straight. Once a bolt is screwed in there and torqued the threads move a little......use a tap = bad.

Tap won't hurt a good thread, over torque/over yield = stretched threads = bad

 

[Bigabe82]

Re: stiff threads lower unit

AAAAAAAAAy, panama city! it's me, fort walton!

 

[RZR2007]

Re: stiff threads lower unit

AAAAAAAAAy, panama city! it's me, fort walton!

Sent you a PM!

 

[Bigabe82]

Re: stiff threads lower unit

I don't think that we know each other. I was just saying that because I saw your profile info there. Oh, and my browser didn't let me receive that pm. I tried to open it and my browser said "unable to open due to pop up blocker".

 

[nicknight]

Re: stiff threads lower unit

Tap won't hurt a good thread, over torque/over yield = stretched threads = bad

Just going by what the mechanics say AND my experience:

I did not over torque my bolts (maybe a dealer did?).....I tapped one about 1/2 an inch, got some flakes and now the thread for that spot is nowhere near as good as the rest of the thread.

but if it works for you and you KNOW the bolt has never been over torqued by anyone.

 

[RZR2007]

Re: stiff threads lower unit

Just going by what the mechanics say AND my experience:

I did not over torque my bolts (maybe a dealer did?).....I tapped one about 1/2 an inch, got some flakes and now the thread for that spot is nowhere near as good as the rest of the thread.

but if it works for you and you KNOW the bolt has never been over torqued by anyone.

Your sure you had the tap started straight and it was the same pitch,size and thread count of the bolt? Blind hole taps are tough to get started straight. I'm just going by my experience (20 years as a tool and die maker)

 

[nicknight]

Re: stiff threads lower unit

Your sure you had the tap started straight and it was the same pitch,size and thread count of the bolt? Blind hole taps are tough to get started straight. I'm just going by my experience (20 years as a tool and die maker)

I did not force it and took care, but I am not skilled like a tool and die guy.....is it possible someone else overtightened them? sure. How is one to know?

Does average Joe have the same experience as a 20 year Tool and Die guy? no...so maybe they shouldn't take their chances.

My neighbor is a super careful guy when it comes to working on his car....even he screwed up his threads...$800 later he was back to normal.

 

[RZR2007]

Re: stiff threads lower unit

My neighbor is a super careful guy when it comes to working on his car....even he screwed up his threads...$800 later he was back to normal.[/QUOTE]

Maybe he should have used the dental pick....

 

[Fishing Dude too]

Re: stiff threads lower unit

Thread locker takes only a drop to lock a bolt, or a nut. Another thing you can do is use a small peice of tuflon pipe tape to lock them in. Thread locker is easy enough to use put drop on somthing the dip edge of bolt on it for correct amount. Use it at work all the time from 2mm bolts to 45mm bolts main thing is don't use to much. The nicest to use is a 2 part mix marked food grade comes in a sringe type aplicator.