My Tractor Forum banner

1 - 20 of 40 Posts

·
Registered
Joined
·
70 Posts
Discussion Starter #1
Due to the flywheels not aligned I started tearing down an L8 engine today. The engine had been rebuilt before I purchased the tractor and the out of alignment issue was caused when I was removing the starter clutch for repair. I felt the flywheel move as I was applying torque to the clutch.

Should be easy, the engine was rebuilt....not many hours on it. Sounded great, like a gravely should.

Teardown was going fine, then...

Let the fun begin!
 

Attachments

·
Premium Member
Joined
·
3,032 Posts
Due to the flywheels not aligned I started tearing down an L8 engine today. The engine had been rebuilt before I purchased the tractor and the out of alignment issue was caused when I was removing the starter clutch for repair. I felt the flywheel move as I was applying torque to the clutch.

Should be easy, the engine was rebuilt....not many hours on it. Sounded great, like a gravely should.

Teardown was going fine, then...

Let the fun begin!
I couldnt fix that, at least not in this decade. If something like that happens to mine its gonna be my other parts tractor.
Sorry and good luck.
P.S...Is that a piece or two of a bolt that broke?
 

·
Registered
Joined
·
70 Posts
Discussion Starter #4
The parts I was removing were in good shape and the workmanship showed a skilled level. Jug was a 7.6, lifters had been replaced, good interference with piston & wrist pin with light evidence of old oily residue.

I had performed the usual initial removal of the L/H axle housing and cleaned the sump of sludge when I purchased the tractor a few years ago. Got it running, no spark, and parked it due to the projects ahead.....

Removed the spreader bolt and found the second surprise inside the crankpin. Sludge, new sludge. Just some but enough. Took some of it and dissolved it in gas. Inserted a magnet in the mix and it looked like a porcupine. Something steel is wearing!

This prompted the disassembly of the crankshaft. Found the crankpin and rod in good shape. Minor trace of sludge behind the drive pinion allen head screw.

Time to located where the metal is coming from. In addition to the engine teardown have to look into the tranny.
 

·
Premium Member
Joined
·
3,032 Posts
A cpl things you mentioned are a lot like mine. I have a 1966 6.6 L but had to put a late 50's 7.6 L I jug on it.

God willing and the crick dont rise it might work.
Having a mechanic around wouldnt hurt either lol.

Of course I have limited time to work on it but Ive been 3 to 4 days just trying to get a belt on it. Meaning drive belt @ top & bottom pulleys.
 

·
Premium Member
Joined
·
4,338 Posts
Gerrard, that is a set screw that holds the drive pinion bearing in place in the engine casing. They can occasionally work loose, most of the time they are staked in place.
Right. It's not a big deal.

If this engine was rebuilt, it seems highly likely that whoever did the rebuild either didn't stake the setscrew, or didn't do it hard enough.

RI, if that's the biggest problem you have, you're in good shape. It does sound like something else in there is making metal, so you likely need to keep looking into it. If the the flywheels have been out of line, there are several candidates, for instance the ball bearing on the other end of the crank, or the gear drive to the oil pump.

The good news is that it's a simple robust engine. If you get it cleaned out and the flywheels aligned, I expect you'll be fine.
 

·
Registered
Joined
·
70 Posts
Discussion Starter #7
Cleaned up the crank parts and took measurements. Parts look great, the best I have seen. The lower end most definitely had been worked.

All are within tolerance except for the pin interference. Will need both dry ice and a press for this assembly. Pin interference are .019 and .013". Oddly the pin or the flywheel show no signs of forced interference. Disassembly was not difficult. With replacement pins, does one have to have the ends machined for the interference?

Time to place a parts order and clean up the rest of the engine.

RB
 

Attachments

·
Premium Member
Joined
·
3,032 Posts
OMG Sounds like surgery or something.
Are you a machinist or something like that?
I'll just read this thread and keep my opinions to myself because I know nothing that can help you thats for sure lol!
I cant even seem to manage to get the belt on LOL!!
 

·
Premium Member
Joined
·
4,338 Posts
Parts look great, the best I have seen.
+1. From that pic, those parts look real nice.

How's the clearance on the bushed ends of the rod? If you need to replace bushings, this is the time to do it :)
All are within tolerance except for the pin interference. Will need both dry ice and a press for this assembly. Pin interference are .019 and .013".
That sounds pretty high.

I could swear I saw a manual saying what the interference fit is supposed to be, but I can't find it now. Beaner, are you listening?

But it was together before, it'll go back. I'd recommend heating the flywheels in an oil bath, in addition to dry ice on the pin. I've used that technique to avoid having to press at all, though in this case, I expect you'll still need it.

I love the pix :)
 

·
Premium Member
Joined
·
3,032 Posts
Its hard to tell size from pix but that connecting/piston rod looks like it came from a dang 440 big block or something! Sheesh... I didnt have to take mine out when replacing jug because I was just working from the top end and never even saw the rest of it.

Not to complicate things or muddy the water but does anyone know the dia. of a 6.6 or 7.6 piston?
I would like to try to confirm what an old man told me who used to work at the Gravely plant.
At anyones leisure of course
Later and thanks
 

·
Premium Member
Joined
·
4,338 Posts

·
Registered
Joined
·
433 Posts
If you are talking about installing the crank pin, all you need is some large washers and some all thread and two pieces of channel iron with a hole drilled in the center. Give your wife some money to go away for awhile, Then put the crank-pin in her freezer and the flywheels in her oven at about 250-300 degrees use the all thead/washer/nuts to press the flywheels together and the channel iron and all thread to align the the flywheels That should get you real close. Then you can use the straight edge method or center with a truing stand, lathe or drill press. Always use oil when pressing bearings, pins ect together. And make sure the kitchen is spotless when she gets home.
 

·
Premium Member
Joined
·
4,338 Posts
If you are talking about installing the crank pin, all you need is some large washers and some all thread and two pieces of channel iron with a hole drilled in the center. Give your wife some money to go away for awhile, Then put the crank-pin in her freezer and the flywheels in her oven at about 250-300 degrees use the all thead/washer/nuts to press the flywheels together and the channel iron and all thread to align the the flywheels That should get you real close. Then you can use the straight edge method or center with a truing stand, lathe or drill press. Always use oil when pressing bearings, pins ect together. And make sure the kitchen is spotless when she gets home.
Wow. Will that really work for that kind of an interference fit? .019"?

I guess I'll have to go brush up on my coefficients of expansion of steel.
 

·
Registered
Joined
·
319 Posts
Isn't the rod on the 7.6 different than earlier engines? It was made stronger and is heavier for the application? I was told that piston is same as 6.6 though.
 

·
Registered
Joined
·
433 Posts
I'm still guessing we are talking about the crank-pin. If all the parts came apart and no parts were changed, they should be able to go back together again.
 

·
Premium Member
Joined
·
3,032 Posts
I hope the rods are the same because I just put a 7.6 jug on my original 6.6 engine and used the same rod and all.
I used the 7.6 valves & springs because they came on the 7.6 jug ,wich I guess didnt really matter because I used my orig 6.6 head but I used 7.6 jug & 7.6 piston because my orig. 6.6 was bored .030 over and I wasnt about to get into all the .030 over piston measurements so I just used the 7.6 piston that came out of the 7.6 jug. And the piston had " STD" stamped in the center of it so I took that as a standard bore.
The reason I hope its the same stroke because TDC on it is pretty high, I mean I can touch top of piston w/first joint of little finger, and Im awfull glad that plug is tilted wich Im sure and/or hope is why.
 

·
Registered
Joined
·
70 Posts
Discussion Starter #18
If you are talking about installing the crank pin, all you need is some large washers and some all thread and two pieces of channel iron with a hole drilled in the center.
Toddnails,

I'll keep this in mind. I have a fixture for flywheel assembly, used it a couple of times already with good results.

RB
 

·
Registered
Joined
·
70 Posts
Discussion Starter #19
Cleaned up the crank parts and took measurements. Parts look great, the best I have seen. The lower end most definitely had been worked.

All are within tolerance except for the pin interference. Will need both dry ice and a press for this assembly. Pin interference are .019 and .013".
Need to retake the measurements on the crank pin. It is possible I read the mic wrong, using my bad eye.

RB
 

·
Premium Member
Joined
·
3,032 Posts
Ive got an electronic supposed micrometer and its the biggest piece of crap I ever got.

The Starett (sp?) dial type is no doubt the best one to have.
When you turn that dial on one you know youv'e got a thing of quality in your hands.
 
1 - 20 of 40 Posts
Top