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Stihl MS290 Nightmare Rebuild Questions…

Alaskan Stihl

Alaskan Stihl

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Hello Any Stihl Chainsaw Mechanics out there:

I think I have dove way off in the deep end in this project…and let me just say, I am frustrated beyond the point of recovery!

I have a Stihl MS290 that was given to me (junkyard special) as it had a scored piston and cylinder. I purchased an aftermarket one (LilRedBarn.net). Also purchased a pressure/vacuum gauge as well as a new 1/4” Proto Torque Wrench.

And this is where my problems began…

After successfully dismantling everything, I got the new piston in and started torquing it up to 40 in/lbs (first run) it seemed a little tight (but no torque click). Tightened just a little more….little more…CRAP! Turns out this brand new [email protected]“!!!?&! Proto Torque Wrench is GARBAGE! It failed to click on any setting! Of course, as my luck goes, it fricking partially strips out (1) of the base threads (there are a total of (4) Base Bolts). It seemed to get a partial bite…but once the Dirko Glue dried and I tested it….FAILED around the seam where that partial stripped bolt is.

Ok, so, I noticed that the Stihl Bolt sticks out just far enough (and has room) to install a locknut on the bolt…BUT OF COURSE…Stihl has their own proprietary bolt pattern. I did find one (Locking Nut….not Nylock) that halfassed might work. So, went ahead and glued & cinched everything down….waited 8 hours…Pressure tested.
So, for the FOURTH time fighting to get the thing to test…FAILS…I am about ready to call this thing a parts pile. What is the big secret here that I am missing? Is it really that difficult to get a pressure test to pass on these Stihl Saws?

Question #1. What is the proper way to install the Dirko Glue? Do you put a single bead in the groove of the base plate? Or, do you put a bead on both? Or do you put a bead on both and smooth everything out? Differnt videos show differnt ways…none of which gets me a passing pressure test.

Question #2. How long should I let the Dirko Dry? Hours? Days? Months?

Question #3: I am tempted to drill out the partial stripped hole of the cyclinder head and install a regular stainless bolt with locknut. Has anyone tried that before?

Any other tips on rebuilding a MS290? I read in here where someone had a nightmare trying to get a pressure/vac test as well and had to re-glue several times. I am going to give it one more try…and if it fails….then I’m done with that headache and I will have spare parts for my running MS290…
 
HarleyT

HarleyT

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I never have done one of the aftermarket kits, but have heard of a lot of problems using the aftermarket fasteners.
I never use a torque wrench either, so no help there either.
Can you put up some pics? Pics of the original fasteners, and one of the Stihl ones to compare with. Also some pics of what you have left to work with on the cylinder/
 
MontanaResident

MontanaResident

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I commend you on still trying to get the 290 going again. I was always going to rebuild mine, but sold it before it ever got to the point of needing a new piston and cylinder. I did rebuild a Husky 350, and bought the parts for the 290, so I can share that you'd probably be better off buying a new cylinder, as the after market ones are very inexpensive.

I can't remember the last time I used my torque wrench. Tight is tight is my new mantra.
 
cookies

cookies

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I put sealant on both surfaces then smear it in and around using my finger coating the surfaces evenly then bolt together outside of the saw and let it sit a couple of hours minimum if not 24hrs then remove bolts and install into the saw body and retighten the bolts. Those cylinders often come without threads requiring them cut using the bolt making it a huge PTA. I would hit the hardware store and find the next size up in bolt with a shank that will pass through the saw case and get its matching tap for the cylinder. In raw aluminum I would use COARSE threaded fasteners for the strongest thread hold. you can also shave down the cylinder corner making it flat to allow a nut to be added to the top of the bolt. Yes these saws are frustrating the first time you build one, yes these saws can be a huge pain in the arse and aftermarket parts can be trash right out of the package so look at everything carefully and use a small painbrush to apply 2 stroke oil to bearings/seals/piston etc during assembly. Like stated above use a T handle to assemble because it will limit the force able to be applied and reach into tight areas. If you want a torque wrench get a tool truck brand..IE mac , matco snapon...yup you will cry because its expensive but it will likely outlive you.
 
Vintage Engine Repairs

Vintage Engine Repairs

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My experience of torque wrenches is I get more over tightened and stripped bolts than doing it by hand using T wrenches (much better feedback) - I don’t use a torque wrench much now. Though I will on the cylinder bolts.

In answer to your question, take the bolt out and do it properly. Drill that hole and tap to one size bigger. Doesn’t have to be stihls propitiatory thread pitch, just go machine fine metric. Hopefully you have space.
 
cscltd

cscltd

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I think you may have to take apart and clean off old sealer and reapply.
when you tested it and leaked, replacing bolt will probably still cause a leak as sealer sets up in hour or so and cures about 12-24 hours.
Could also replace all bolts with machine threads instead of self tappers. May have to helicoil them though
 
Alaskan Stihl

Alaskan Stihl

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Thanks all for the tips everyone!
Here is something else I discovered:

While attempting to seal the (2) Halves together, each time I had problems with the Clutch Side Crank Seal popping out of its saddle. I would then have to loosen it up, reposition it back in place and tighten everything back. I am sure this is probably a instigator for all my problems trying to get a proper test?

Further inspection reveals that, on the Flywheel Side…there are both “Inner & Outer Ridges Molded into the Aluminum Cast” of the Seal Saddle. These ridges appears to keep the Seal in place while tightening.

Problem is…on the Flywheel Side, it does not have the “Outer Ridge” on either the Base Seal Saddle, nor the Cylinder Seal Saddle. It finally dawned on me that this is obviously why I keep having problems with it popping out each time.

Obviously, next time I make my attempt at sealing this catastrophe together, I will immediately install the Bar Oil Pump before tightening the (4) Base Bolts.

The question is: What am I missing here? Shouldn’t the Clutch Side also have that “Molded Outer Ridge” molded into the Base & Cylinder (to hold the Seal in Place)? I guess that is also the job of the Bar Oil Pump (to hold the Clutch Side Crank Seal in Place)? Kind of wish the books or numerous various YouTube videos would have mentioned that….or was I lucky enough to get a Stihl Base and Aftermarket Cylinder that had manufactured defects…???

Hopefully everything will work out this next time (hasn’t been an easy or fun project that’s for sure).
 
Alaskan Stihl

Alaskan Stihl

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Correct: I read where it states which seals to use (since I broke the halves into) and am using #9639-003-1743. Of course, just my luck, our local Stihl Chainsaw Shop sold me Soft Seals and told me they were Hard Seals. When I went back and explained their foul up, they said “oops” and didn’t have “Hard Seals” in stock, so I had to wait an additional 10 days for eBay order to arrive.

However! I think I figured out the issue with all the sealing problems in that the “Bar Oil Pump” actually has a Ridge around the inside of it (to hold the bearing in place). Once I took a closer look…I now see that the process will be
#1. Install Sealant
#2. Install Hard Seals
#3. Clamp Halves together, Place Long Block in Chainsaw Housing and loosely install (4) Base Screws.
#4. Install Bar Oil Pump & Tighten the 2 mounting screws.
#5. Tighten (4) Base Screws and let Sealant Cure for +24hrs.

What is frustrating, is that in viewing several YouTube’s “How-To” videos on rebuilding the Stihl MS290…NOBODY mentioned anything about issues with the Seals and Bar Oil Pump! Grrrrr!

If anyone new to chainsaw mechanics (and finds themselves rebuilding a Stihl MS290)…I highly recommend jotting these Steps down before going through the headache I am going through!

Well, duty calls….wish me luck and I will report how it turns out!
 
cookies

cookies

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The cylinder is supposed to have a lip on each side to hold the seals in place, whn the case is bolted to the cylinder it bites into the seals locking them in place while also having sealant coating them. make sure you clean the sealing surfaces and wash your hands before putting the sealant on. sounds like you got a defective cylinder if it does not have a seal retaining lip on one side
 
Chevboy0167

Chevboy0167

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Ran into the hard/soft seal problem with my recent 290 rebuild also. Lesson learned.

I put 1/8" tall and wide Dirko sealant on on bottom pan only and thin coating on the outer diameter of the seals. ( Side note... you can use Permatex high temp red here also... same thing). And yes, I slipped the whole assembly into the lower unit housing then tightened the pan bolts. Seals stayed in place. I did thread lock the pan bolts as I re-used the original cylinder with threads already cut.

I let everything set up for 2 days then pressure tested with no leaks. YAY!

My first time on this style of saw and yes.... lots of swearing and questions but all said and done, not too terrible compared to some saws. Just the order of removal and re-assembly is very important.
 
Chevboy0167

Chevboy0167

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A few pics..
 

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Alaskan Stihl

Alaskan Stihl

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Hello All!

Well! I think I finally got it! Guess I should have took a picture of the “Outer Seal Saddle Ridges” on the Clutch Side that I was talking about.
Anyway, I put the Long Block in the Frame…inserted the (4) Base Bolts (lightly threaded) then installed the Bar Oil Pump (tightened) then finally tightened up the (4) Base Bolts. As mentioned, The Bar Oil Pump has a “Ridge of Sorts” that kept that Oil Seal in check from popping out. I found it very strange that the outer ridge (clutch side) on both the Aftermarket Cylinder & Stihl Base do not have that ridge (or lip…or whatever to call it) where they meet together.
Of course, nothing is mentioned in the service Manual other than “Use Hard Seals if Case is Split” and “Put Thin Bead of Sealant in Groove”. I guess they figure that the end user will figure it out eventually?

Or…just like user “cookies” stated…the Cylinder was suppose to have that ridge on both sides…and of course…mine didn’t…

Since Stihl’s Service Manual directions only gave me grief…I went ahead and Installed the Bar Oil Pump and Spread out the Sealant along the faces (figured aftermarket cylinder mated to Stihl base would probably not be a even fit)?

Well…for now it is Cross My Fingers and I now have to suffer the excruciating wait for 18 Hrs, 15 Minutes and 32 seconds for it to dry so I can test it! HAHA! Nah, Actually, I decided to let it cure for a couple days just to be on the safe side…

As for the stripped threads on the Cylinder that I fouled up, I went ahead and drilled out the remaining tattered threads on the Cylinder and installed a shanked bolt and cut it (and filed) to length as close as I could to keep it from bottoming out on the upper cooling fin.

Then, I was able to fit in a Tapered Locknut (not Nylock) and surprisingly it was able to get a Full Nut cinched on it. I was contemplating putting on some Hi temp Locktite, but it actually bore down pretty well to my astonishment! (See Pic).
Will report back in a couple of days with either a running chainsaw…or a bunch of spare parts pile for my other running MS290!

HEY! One more question anyone: While fiddling with the carburetor to see where the adjustments were…I noticed that the High Idle seems stuck (this carb has orange limiters in it). The Low idle threads in and out ok (I just moved it a smidge back and forth to make sure it turns). However, the High is clearly stuck. Obviously, before I start the engine, I will everything to standard settings…actually a little rich at first.

Question: Any tips here? If I rip out the Orange Limit Plugs…will it create another set of problems? Obviously, I am going to do some research on what needs to be done to get the carb ready…but any suggestions are more than welcome!
 

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Alaskan Stihl

Alaskan Stihl

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Gaudaost: Correct (Dirko). I was thinking about (after it cures), taking a razor blade and slicing off the spillage before the pressure/vacuum test…but knowing my luck…I fear it might root out some of the sealant (kind of doubt it though…I got the halves tightened up pretty well).
Question: Are you just saying that some leftover chunks inside the crankcase might peel off and burn through etc?
 
cookies

cookies

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yes, if you apply enough to squeeze out it will come off inside the crankcase and get blown out...its not a big deal. As far as limiter caps go, you may need to visit the service manual if it is too lean. FYI aftermarket cylinders/pistons may not fully rev out to 12,500rpm it may only hit 11k and thats ok since they can be ported to different timing numbers and use different casting styles. Congrats and enjoy your hard work paying off.
 
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