Stihl clambshell reassembly question 025

[Chipper461]

I am reassembly an older Stihl 025 and I noticed when installing the engine pan back onto the cylinder/crank assembly that there is some slight rocking on the crank bearings that does not let the pan sit flush with the cylinder. It almost seems as if the bearings are not fully seated in the journals of the two halves. I did not move anything or remove the bearings so this has to be the way it was before. The crank bearings obviously would have the be the tightest factor when joining the 2 halves or they would risk spinning in the journals instead of being held in place. Is this little bit of play normal and gets taken up as the engine is torqued to spec in the saw frame? I went ahead and applied sealant and assembled the engine and torqued up to spec in saw and it seems to have pulled the halves together. I was just wondering while waiting for it to set up and vac/press test if anyone else has seen this in a clambshell engine? thanks!

 

[cus_deluxe]

Ive not done an 025 but have experienced the same thing on the handful of other clamshells ive done. Just give it a pressure/vac check and away u go. At least on the ms290s ive done you have to becareful to get the seals lined up nicely when mating the two halves

 

[Chipper461]

Yeah, the seals seemed to fit in their grooves nicely, will check press/vac tonight and see what happens! I think the torque spec I went with was roughly 11 N-m (8.1 ft-lb) for the 4 engine mount fasteners

 

[cus_deluxe]

I never torque bolts on saws. A little loctite on those clamshell threads and just get em nice and tight.

 

[a. palmer jr.]

I usually put the pan on and torque it down using shorter bolts then let the engine sit overnight. Remove the pan bolts the next day and put engine in the saw. It takes a few hours for the sealer to dry.

 

[Chipper461]

Well I VAC and pressure tested last night and all was well so I suppose the only thing to do now is throw it back together and see what I got. Thanks everyone for the tips/advice. I will report back after reassembly!

 

[MnSam]

I like to test statically and while turning the crank under vacuum.

 

[blsnelling]

I would not pre-assemble the engine and then remove the bolts. Assemble it in the chassis as it should be. Otherwise, you're asking for air leaks, IMHO.

 

[Chipper461]

Yea I was skeptical of assembling out of the saw and I never have tried that ever so it may work, but I figured I wanted to see how it would seal while mounted in the saw.

 

[a. palmer jr.]

I've done several out of the saw with no bad results but you do have to let it set overnight with the bolts in it. It works okay that way if you have other things to do. You can't assemble some of the newer clamshells that way since the bottom of the engine is the plastic engine cradle. I may be wrong but I think the 291 is that way. I know some of the plastic Poulan and Craftsman saws are that way also..

 

[heyduke]

i haven't tried it yet... but next time i do an 029 i'm going to try leaving the bottom in the plastic case, there would be two advantages. first, you wouldn't have to remove the bar stud, and second, you wouldn't have to screw around figuring out just the right angle to get the entire "short block" back into the plastic case.

 

[Chris-PA]

I know some of the plastic Poulan and Craftsman saws are that way also..

The Poulan/Craftsman clamshells all have removable metal bottom pans, but most of the Husqvarna ones have the cap molded as an insert into the plastic chassis.

 

[a. palmer jr.]

I've not done many Poulans or Husqvarna clamshells, just parted them out..