Crankcase Assembly Discussion

[bobw]

Getting to reassemble the powerhead on my ’57 Fastwin. Although I’ve opened up, rebuilt and resealed a few motors without any trouble in the past, thought I would throw out a few questions I’ve always wondered on and see what others have to say.

1. I’m using Permatex anaerboric sealer to reseal the crankcase halves. I won’t be putting this motor into service for some time after I finish it and my understanding is the Permatex primer/activator is not really needed as long as the block mating surfaces are clean. If I don’t use the activator, should I apply the sealer to just one surface or both surfaces?

2. Is it OK to re-use the original con rod screws or should one try to find NOS screws?

3. I’ve read varying recommendations when installing the rod screws. Install dry? Coat with oil? Use loctite threadlocker?

Discussion welcome – not trying to start a debate LOL!

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."

[billw]

Okay, I’ll jump into the fire. I use the anaerobic sealant with no primer. I have done quite a few this way and haven’t seen any problems yet. I’ve done probably half a dozen FDs and Fastwins this way

I use the screws over.

I put two stroke oil on the screws.

Haven’t had one of my projects ever grenade; although my personal engines don’t get a lot of hours. Rebuilding power heads at work is pretty much over with, due to prohibitive cost.

Long live American manufacturing!

• This reply was modified 3 years, 10 months ago by billw.

[fleetwin]

Like Bill says, the primer is not necessary, unless you are planning to fire up the engine that same day…. But, I would only apply the sealer to one side of the block. I would apply the sealer to the crankcase cover half only because the crankshaft isn’t in the way. You must be very careful with the sealer, you don’t want to plug any passages or have it ooze into a bearing. A tiny dab of the needle bearing grease around the bearing cages and passages will keep the sealer out of these areas. Again, this is such an important operation that you want to take time doing. Too much sealer will plug up passages, get into bearings, and may actually shim the halves apart slightly. Improper prep, or not enough sealer will result in the dreaded external leaks once the powerhead is fired up…

Theoretically, the rod screws should be replaced, but that seems like an extreme safety precaution. Those screws are hardened, and breaking them is highly unlikely. But, if I had pulled a powerhead apart that had been exposed to some questionable work previously, I would probably replaced the screws. Make sure the fracture joints line up properly before assembly…If you can’t get the rods to line up satisfactorily, this usually indicates someone has been in there before, and tightened the rods when they weren’t properly oriented or aligned. Like Bill says, use only some two stroke oil on the rod screw threads on this style rod.

The only other thing I will add is to determine whether or not an oring is used on the upper bearing of this engine. This may be one of the engines with that crazy recirc system that draws the oil away from the bearing/seal where the oring is not used. Check all the passages to ensure this system will work properly, you sure don’t want oil all over the points.

[bobw]

OK, thanks for the confirmations. I’ve always applied the sealer to one side only but always have some concern about blocking the oil passages. On that same motor, I found some NOS rod screws because the motor had been locked up and the old screws looked a little sketchy. Otherwise, I’ve always re-used the original screws. And I’ve always used oil on the screw threads.

Fleetwin – good tip on the dab of grease around the bearings and passages. And you are right, this motor does not have or use an O-ring on the upper crank bearing. Not sure I totally buy into that recirc system but guess I’ll find out after I get it running. Waiting on delivery of a new gasket set before I start reassembly.

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."

[fleetwin]

bobw wrote:

OK, thanks for the confirmations. I’ve always applied the sealer to one side only but always have some concern about blocking the oil passages. On that same motor, I found some NOS rod screws because the motor had been locked up and the old screws looked a little sketchy. Otherwise, I’ve always re-used the original screws. And I’ve always used oil on the screw threads.

Fleetwin – good tip on the dab of grease around the bearings and passages. And you are right, this motor does not have or use an O-ring on the upper crank bearing. Not sure I totally buy into that recirc system but guess I’ll find out after I get it running. Waiting on delivery of a new gasket set before I start reassembly.

I’m with you on that crazy recirc deal…Not having an oring to seal between the bearing case and crankcase halves is nutso….Unfortunately, in this case, you can not add one or you end up plugging up the system and the oil gets into the points… It’s just too bad the engineers couldn’t have added an oring at a lower point on the bearing and used both systems…

[bobw]

You also brought up another good point about taking time to do this seal job correctly. Whenever I do one of these, I’ll tell the wife I’m out of touch for awhile, turn off the cell phone, turn off the radio in the shop and close the door to the shop. Not a good time to be interrupted!

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."

[fleetwin]

I’m with you, I used to reassemble powerheads at night when I was alone in the shop. I remember not being able to remember tightening one of the rods on a V6, needless to say, didn’t sleep a wink. Ripped the damn thing apart only to find I had torqued all of them….Boss was pissed at me of course…
What is the saying in carpentry, something like “measure several times so you will only have to cut once….”

[bobw]

I’ve done stuff like that before myself. In my case, I sometimes think it’s more like “measure with a micrometer, mark with chalk and cut with an ax”.

Bob

1937 Champion D2C Deluxe Lite Twin
1954 Johnson CD-11
1957 Evinrude Fastwin 18
1958 Johnson QD-19
1958 Johnson FD-12
1959 Johnson QD-20

“Every 20 minute job is only a broken bolt away from a 3-day project.”
"Every time you remove a broken or seized bolt an angel gets his wings."

[Author]

Posts