CANNOT Get My Crankcase To Split - Newbie In Trouble Again

Lads - am attempting to split the case on my '76 175 GP.

Followed the steps in the shop manual precisely: removed head and cylinder. Removed magneto & sprocket covers. Removed sprocket. Removed magneto. Removed transmission cover, with shift lever & kick starter pedal attached. Pulled off the drive gear. Removed all 8 crankcase retaining screws. Did not remove clutch since shop manual says that's not necessary to split the cases.

I built my own crankcase splitter based on drawings of the official Husky part and pictures of the many fine home-made fabrications found on this forum. I cranked on that baby until the 3/16" steel plate on my puller began to bow and is now permanently distorted. I thought I was going to rip the threads out of the case. I pounded on the case with a rubber mallet and pounded on the shift shaft and the sprocket shaft.

Could see a little split on top of the case, aft of where the cylinder would attach. Cannot see a split developing forward of the cylinder gasket or anywhere along the bottom of the case.

What else can I do? Binx

I am not familiar with that model. If you leave the clutch on then you would create pressure on the other side of the crankshaft with attachment in tension to the case. The crank for me always pushes out of the bearing. There are locating pins on the ones I take apart, a larger one at the rear that may be making things harder. Of course look closely and make sure there is not a 9th bolt holding the things together. Heat can help a few minutes with an electric heat gun can make a difference. For me the transmission bearings and shafts offer little resistance.

From memory you shouldn't have to take the clutch off as the tool pushes on the mag side of the shaft. Make sure your tool is pushing on the the shaft and not bottoming on the case in some way. That said, I.m not sure why you haven't pulled the clutch off as you will need to eventually to replace the crack seals properly.

I've had the same issue on a couple of my bikes and it's usually I've left the screw in that sits just in fron of the sprocket. Double check they are all out. I'd remove the clutch as it's easier to work with it off and you can check condition of the baskets and plates easier with it off.

Bending the plate should not happen, so have a good look for screws that the heads might be difficult to see.

Good luck..

Put some tension on the seperator tool and then stick it all in an old oven, the heat should free things up, i would put the oven on and heat to say 180c then switch off the oven and place the entire engine into it, after about 30 mins you should be ok to split the cases without running the risk of a catastrophic breakage.
Suggest buying an old electric wall oven and doing this outside.

sometimes the case pins corrode and get like bonded in. but should not hold it up...just not a smooth easy split. there are only 8 6 x 75mm bolts fron right to left. take the darn e clip off and pop out clutch anyhow. got to to put back together also.. I prefer to build the older non primary kick into the right center case and not the left but that is just me. like to be able to see the shift drum and shaft conections rather than buried.

and try splitting from primary gear side too/ After clutch off

As Joe said, sometimes the dowel pins get corroded and stuck, and sometimes the shaft is extremely hard to get to move out of the main bearing. Once it starts to move its not bad, but that first "pop" is difficult.

Your puller should not bend, I recommend you buy a proper case splitter. I use this one and it works on vintage and modern engines.

https://www.rockymountainatvmc.com/...se-Splitter?term=tusk tools crankshaft puller

the tusk unit works well and is cheap

I got a universal from Phillip at Husqvarna-parts. He asked me why not buy the Husqvarna specific unit. I told him the universal will do the Husqvarnas I own and everything else as well. It has not failed me yet after 5 case splittings thus far. Last one was a 390WR engine, same structure as your 175.

3/16 inch steel and permanently distorted? Hammer and flat surface.

There is only so much force that can be put on the threads chances a stronger puller isn't the answer. I pull off four small perhaps 4mm threaded holes just a couple inches from the crank. There are lots of kinds of rubber mallets the way to hammer is so as to get some seperation force, hitting on an angle but with the face parallell. Put as much force as you feel safe with and then hammer in that fashion, within reason. I would work on the rear of the engine. If both the front and rear locating pin/dowel/case pin are stuck it might crack apart a tiny bit like you describe. I have only had to battle with the rear one and on some the engine has rattled around so much that locating pin doesn't really locate any more. Yours probably isn't a swingarm pivot like mine. Look at the parts sheet and see where the pins are and apply heat there. It is almost 40 years and dis similar metals for the pins.

If you really still have problems I guess some sort of seperation devece needs made to put some force more to the rear either attaching to threaded holes or glued on hard points.

Send us pics please, and there is no need for heat. Why is that the first thing that everyone tries ? I will never know . Heat is not the answer to old bikes...
Send us pics of your puller as well . Most likely it will do the job but lets see it. It will let out a nice pop and then it moves a little bit as you crank on the puller and you can see the motion in action as your cranking.

An increase in temperature makes most things expand. Probably everything of note in this scenario, cases bearings, and locating pins. A ring in a ring of the same material get a space between them if the temperature increases. I know aluminum expands more than steel and suspect Magnesium is similar. The Workshop Manual for my 1955-1969 BMW actually has temperatures to heat things to in the various steps of getting the crank out. There is Heating the whole thing which works as described above and heating only the outer part as best as possible when possible which works better.

I suppose the question should be asked does the crank turn. If the whole crank cavity is full of corrosion not all of the posted stuff is on target.

heat can be a very useful tool that prevents damage, but of course can be abused or mishandled. dont how many times i glanced at my smaller propane torches or my oxy/acetylene ones and been lazy, only to struggle with the task at hand. after using some heat things quickly come apart (or go together)
im not saying this is the problem here yet however...we need info on the permanently damaged 3/16 plate splitter

I appreciate all the advice and comments. Hope to get out to the barn tomorrow to implement some of the suggestions. I should mention that the crank spins freely. The bike is a "genuine" barn find. Sat in a barn, unused, for 34 years. I got the engine to start after some MAJOR work on the carb and the air cleaner. After a little clean-up it started second kick when cold and first kick when warm.

Here it is. My '76 175 GP.


The air cleaner. Replacing the Twin Air with a mouse nest was a trick race mod back in the day.

My home-made crankcase splitter attached to right-side case.

Put enough pressure on that 3/16" steel plate to permanently distort it. Any additional force and I'm sure I'd pull the threads out of the case.

Did I mention I traded a 12-pack of Fat Tire Ale for the bike? Relevant?

Would imagine some corrosion to the crank and bearing would stop the crank pulling through the bearing and releasing the cases better to heat the cases and pull the crank with the bearing attached, magnesium expands slightly more than aluminium, without knowing what area is not releasing localised heating may not help, if the cases show signs of corrosion the above may be more true.
Bent a homemade puller and stripped a 6mm thread trying to force the cases mechanically but after being in the oven they came apart.

Does the official tool only use two of those 6mm bolts/machine screws?

I found a picture of what I made without the help of any official literature. the ring that I made is drilled for the similar small bolts/machine screws on the other side as well. The tapped holes in the ring are 1/4-20.

Note how easy it is to get some heat onto that inner race of the bearing.

Do yourself a favor and buy a proper case splitter.

When the plate is distorted that much, give the bolt head a sharp crack from a lead or hardwood mallet. Sometimes a little impact will do it for you.

Spray PB Blaster on possible corrosion spots