Using something like Loctite 680

[John Timmins]

I have a vintage outboard motor that started making a squealing noise. The engine had maybe 50 houurs of running time since it got "broken in" following an overhaul of new 6205 SKF ball bearings for the crankshaft, new crank seals, rings etc.

The lower crank 6205 ball bearing outer race is spinning where is rests between the block and other half of the crankcase. The block halves are a metal to metal surface sealed with Loctite 518.

I do not want to use a center punch to raise the seating surfaces of the crankcase to make better contact between the outer race and the block. While this would help, assembly and final hardening up of the crankcase with proper seal of the block halves might becone a NEW problem.

Question: I have been told by instructor of the Orlando Mercury Marine service school that using something like the loctite can "build up" the casing "missing metal" up to .015. I might try this before rebuilding a replacement power head. How does this work ? Do I use Loctite 7649 for a cleaning agent then put a bead of the 680 around the outer race of bearing, install quickly then tighten up the crankcase bolts to the correct torque?

I suppose a SMALL bead around bearing since I don't want a lot of excess squishing out into the crankcase. I can post a picture or two if needed for this discussion.

Thanks, Daytonajohn

 

[Jeff Ivers]

I don't remember the locktite numbers, but when restoring a Lotus Elan, I used locktite green to seat a very loose bearing in the rear MacPherson strut assembly with no problems. Clean, apply, and assemble are the correct steps. Do not attempt to rotate the item until the prescribed set-up period has lapsed per the package instructions.

 

[Slippery]

I use Loctite 680 on a daily basis assembling bushings onto electric motor shafts. I also used Loctite 638 and 648.

My method is as follows:

1. Clean everything really well with alcohol
2. Put a bead on the id of the bushing
3. Place a bead on the motor shaft
4. Insert bushing on motor shaft
5. Clean residue with alcohol

I would not use their primer if you want the best adherence. From my testing, the primer helps it cure quicker but it never achieves as much final strength as if it was being used without primer.

Also heat is your enemy. If the part will get hot, Loctite might not work.


Sent from my iPhone using Tapatalk

 

[greatlaker]

I use Loctite 638 for slip fit assemblies all the time. Clean with solvent first.
Loctite primer helps both final strength and speeds up final cure time.
635 for tighter fitting parts also.

 

[cyamaha2007]

I use it all the time also. Green bearing race and retainer. Good stuff.

 

[zkling]

What motor are you working on? How much radial clearance do you have?

 

[alberto]

There are a LOT of fake/counterfeit SKF bearings (and other manufacturers) out there. I wonder if maybe you got one of the counterfeit ones?

 

[Kwikasfaki]

Get a Loctite wall chart and go by the recommended product, 680 is for permanent fixing, something like 641 is for bearing fitting.

 

[John Timmins]

Thanks for all your posts. I will add some pictures and explain the problem.

About fake bearings....the industrial outfit where I buy bearings has some personnel that are idiots, give bad answers, and have NO competition. they are a statewide operation; while I could use another of their offices like Orlando instead of the local idiots, they pass on courier fee of $15 to ship a bearing from a different store.... They do have a Loctite chart - I just need to go in there and not talk to anybody. OK rant over !

As a result I have gone to NAPA for bearings and SKF crankshaft seals. A local hydraulics place handles all my o-ring needs.

the 6205 bearing that is spinning in the casing shows WEAR MARKS on the outer race where is was spinning against aluminum. Tell me that is a quality bearing....NOT.

 

[Firebrick43]

I would suggest NOT using 7649. It’s an accelerator and for DIY work that you can let set for 25-48 hours you don’t need it and you surely don’t need to have less time at assembly if you use it.

Use 7070 to clean.

the 6205 bearing that is spinning in the casing shows WEAR MARKS on the outer race where is was spinning against aluminum. Tell me that is a quality bearing....NOT.

The outer race spinning on an aluminum bore is rarely a bearing quality issue but a bore wear issue from previous damage/bearing failure.

Just checking but you didn’t use a sealed bearing?

 

[RaisedByWolves]

I use Loctite 680 on a daily basis assembling bushings onto electric motor shafts. I also used Loctite 638 and 648.

My method is as follows:

1. Clean everything really well with alcohol
2. Put a bead on the id of the bushing
3. Place a bead on the motor shaft
4. Insert bushing on motor shaft
5. Clean residue with alcohol

I would not use their primer if you want the best adherence. From my testing, the primer helps it cure quicker but it never achieves as much final strength as if it was being used without primer.

Also heat is your enemy. If the part will get hot, Loctite might not work.


Sent from my iPhone using Tapatalk

The primer is brain cancer in a can.

For OPs application heat should not be an issue unless he burns the engine down, and then, we’ll…