Jetstar seriies rear main

molinegb

Well-known Member
What wrench is used for removing the two 5/8 head size bolts on rear main? Always have tough time getting them out especially if rusted. Has to be 6 point and have 45 degrees. Boxend just doesn't handle torque.
 
I'm guessing you are wanting to change that bearing with the blocks still on? Or is it a frozen engine and you can't get it apart and need to relieve the pressure so you can roll the crank?

The older manuals (R,Z,series) show using an offset box end wrench to remove those bolts. One where the box end offsets an inch or so from the main handle of the wrench. I bet it would be tough to do if the engine was built only last week. But if its really rusty, you may have to make-(heat and beat)-a wrench that will work.
 
I just tore apart a 206 combine engine that was completely locked up, that was a bear, I finally got the jugs off but the crank still wouldn't turn. I had to use that offset box like you said and hit it with a piece of iron and a hammer to crack that back one loose, then one notch at a time until it came off. Probably took a half an hour for the back bolt alone. I saved a good crank and crankcase anyway. Blocks will never be any good though.
 
My motor was stuck. Got blocks off. Removed other two mains and crank rusty. Have it moving but don't want to score crank. Will have to make a wrench of some sort.
 
Hi f-mm wondering where you are located and if the 206 crankcase is for sale if it would work for a replacement for a 220 in a u302.
 
Jet 2 crankcase not same as U302 or Jet 3. Have Jet 3 crankcase that is not smashed. Getting hard to find! Manitoba. Governor stuck,over revved and knocked out # 2 ?
 
I think my crankcase could be for sale and the crankshaft too but like he said it probably won't work in that model. I'm in South east ND. though incase anyone is interested.
 
Is that a three bolt starter or a single bolt starter. Do you have a part number of the crank and crankcase?
 
It's a single bolt starter, I wrote down all the serial #s when I tore it down and put everything in a storage box. Engine was a 206C-4. I have to locate the sheet with all the serial numbers yet if you still want that info.
 
Apparently there is no MM tool made to remove the bolts. To do properly according to book is to pull motor and push crank out back. This is the way it was torqued in factory. Talked to MM dealer and says he uses a 6 point socket on a swivel wrench. It is type that is open end wrench with socket on end. If swivel will take the torque! I ended up taking a brand new 6 point socket and shaving top sides off and vice grips to hold. Still was tough.
A 1/2 drive socket with a 3/8 nut welded on top may also have worked. not alot of room!
 

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