Lower Unit Stuck - 2005 MFS15B2

[THudson]

Re: Lower Unit Stuck - 2005 MFS15B2

If you got the factory manual the torque specs are in the front section by bolt size...Probably on page 15 or 16.

Correct on pages 15 & 16.

At "Engine"
Cylinder Block-Crank Case = M8 x 1.25 Bolt 17-18 lb-ft
Engine Assembly = M8 x 1.25 Bolt 21-22 lb-ft

At "Other standards"
M8 Bolt, Nut = M8 x 1.25 8-11 lb-ft.

I believe these 6 bolts are M8...takes a 12mm socket. Thinking Engine Assembly is the right torque but trying to be sure....hate to screw it up at the finish line (no pun intended). Thanks!

 

[pvanv]

Re: Lower Unit Stuck - 2005 MFS15B2

Yep, 8mm bolts typically have 12mm heads. 18 ft-lbs should be fine.

It can be tough to get accurate readings at those torque values, and there aren't a lot of torque wrenches on the market that have those values in the middle of their range.

Don't exceed about 22. Be sure you use a good torque wrench, follow the pattern, and bring up the bolts evenly. That way you will get even gasket compression, and won't risk pulling aluminum threads out of the block. Incidentally, we clean the threads of both the bolts and block, and use a little lock-tite (blue, removable) on those bolts.

 

[THudson]

Re: Lower Unit Stuck - 2005 MFS15B2

Yep, 8mm bolts typically have 12mm heads. 18 ft-lbs should be fine.

It can be tough to get accurate readings at those torque values, and there aren't a lot of torque wrenches on the market that have those values in the middle of their range.

Don't exceed about 22. Be sure you use a good torque wrench, follow the pattern, and bring up the bolts evenly. That way you will get even gasket compression, and won't risk pulling aluminum threads out of the block. Incidentally, we clean the threads of both the bolts and block, and use a little lock-tite (blue, removable) on those bolts.

Clean bolts set now at 17 ft-lb using $22 3/8" torque wrench from Autozone. Added a dash of blue lock-tite to each bolt. I'll tweak to 19 ft-lbs, call it good and pull the rope. Fingers crossed.

 

[THudson]

Re: Lower Unit Stuck - 2005 MFS15B2

pvanv...the original problem that started this all was broken upper shift rod. You mentioned might be able to change without removing power head although others suggested necessary. Now that it is back together, I'm thinking it could be done and certainly would have gone that route had I known how it all fitted together. However, the learning experience of LU removal, power head removal, etc. has been frustrating but very rewarding at this point.....presuming it works of course. No doubt the knowledge gained will be useful going forward. Thanks!

 

[THudson]

Re: Lower Unit Stuck - 2005 MFS15B2

Yep, 8mm bolts typically have 12mm heads. 18 ft-lbs should be fine.

It can be tough to get accurate readings at those torque values, and there aren't a lot of torque wrenches on the market that have those values in the middle of their range.

Don't exceed about 22. Be sure you use a good torque wrench, follow the pattern, and bring up the bolts evenly. That way you will get even gasket compression, and won't risk pulling aluminum threads out of the block. Incidentally, we clean the threads of both the bolts and block, and use a little lock-tite (blue, removable) on those bolts.

Got it all back together and took it out for a test run for about 10 minutes on small lake nearby. Runs good although I notice the engine is pretty hot to touch...I honestly never paid attention in the past if tell tale was working. Seen your other post on this...tell tale is working fine but realize not related to thermostat, tell tale stream is not hot to hold hand in. How hot is too hot generally...I've seen 3 seconds to touch on cylinder head which is about all I can stand. Will the motor shut off or buzzer before overheating does damage? I've come this far and want to be thorough. Thanks!

 

[pvanv]

Re: Lower Unit Stuck - 2005 MFS15B2

Verify your temps with an IR thermometer. If severely overheating, the pee stream would be pretty hot.

 

[TOHATSU GURU]

Re: Lower Unit Stuck - 2005 MFS15B2

Water coming out of the upper exhaust port should be hot enough to keep you from keeping your hand under it for more than three seconds.

 

[THudson]

Re: Lower Unit Stuck - 2005 MFS15B2

Verify your temps with an IR thermometer. If severely overheating, the pee stream would be pretty hot.

Thanks, I gather there is no internal safeguard (shut down) or alarm that would identify this issue before doing damage? Seems logical there would be but maybe not on the smaller outboards.

 

[pvanv]

Re: Lower Unit Stuck - 2005 MFS15B2

Thanks, I gather there is no internal safeguard (shut down) or alarm that would identify this issue before doing damage? Seems logical there would be but maybe not on the smaller outboards.

Correct. The 15B has a CD, not an ECU, per se. You do have over RPM ESG, though.