I am hoping someone can give me some guidance on my problem. A few years back I came across a couple 644-A's somewhat cheap and me not knowing better, bought them. I guess thats not really fair since I have used them enough to justify buying them. However, I have ran into some trans/eng problems so I took the worse one out of service to use for parts. To make a long story a little shorter, after rebuilding the engine and replacing the crank I developed an engine oil leak in the flywheel housing. Its hard to tell exactly where the leak is coming from since the flywheel slings it all over the place. However there doesn't appear to be too many places for it to leak. I have replaced the rear main seal 4 times now, including the last time using the expensive install tool. So I am somewhat convinced its not the rear main seal. However I can start the engine without the housing installed, and the oil gets slinged off the backside of the flywheel. Does anyone have any ideas what this might be? Anyone heard of a defective crankshaft that leaks oil like this? I am starting to run out of ideas on this machine. On the plus side though I now have experience taking the machine down to the flywheel and can tear it down in less than a hour now. Thats about the only good thing I can come up with so far. Can anyone help me with this antique?
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Oil Leak on Deere 644-A
- Thread starter Jperry
- Start date
Countryboy
Senior Member
- Joined
- Jun 8, 2006
- Messages
- 3,276
- Location
- Georgia
- Occupation
- Load Out Tech. / Heavy Equipment Operator / Locomo
Welcome to Heavy Equipment Forums Jperry! :drinkup
That's a possibility. The shaft might not of been machined to exact specifications causing the seal not to make good contact. There really aren't too many other places for oil to get onto the flywheel unless its leaking from the top of the motor somewhere, as in valve covers, intake manifold,etc.
Is there any sign of oil on the motor above the crank that you can see? Was that a new crank or is it crank that has been machined? Are you 100% sure that's the correct seal you're putting in?
I know nothing about your machine but I do know about motors. Maybe someone esle knows of a specific problem with that specific machine series.
That's a possibility. The shaft might not of been machined to exact specifications causing the seal not to make good contact. There really aren't too many other places for oil to get onto the flywheel unless its leaking from the top of the motor somewhere, as in valve covers, intake manifold,etc.
Is there any sign of oil on the motor above the crank that you can see? Was that a new crank or is it crank that has been machined? Are you 100% sure that's the correct seal you're putting in?
I know nothing about your machine but I do know about motors. Maybe someone esle knows of a specific problem with that specific machine series.
steve931
Active Member
644 oil leak
If you are sure about the seal and oil pan,clean the back of the block and apply some machinist dye for cast iron cracks.This should tell you if you have a small stress crack in the block.
Thanks for the replies, Its definatly not leaking from the top of the flywheel housing. The stress crack is something I haven't thought of, but I have bought a couple bottles of dye to put into the oil right before I tear it down again. If I could just figure out someway to run the engine without the flywheel I would be able to see more. The engine is a 6404T if that helps anyone. Thanks again for the replies and please keep the ideas coming
bolt thrower
Well-Known Member
OK, Heres my contribution for what its worth. A procedure I've used for this type of problem is to seal off the engine's crankcase and pressurize it with compressed air. I like to use my radiator tester because it has a hand pump and I dont have to worry about putting too much pressure in there and blowing the oil pan off or something. Once the thing has a little pressure you can spray soapy water over the back of the engine and watch for bubbles. I would want the flywheel off for this.
One other idea..............last week I treated a 631 scraper engine with a rear main leak. A close inspection of the old seal showed that the guy who installed it didn't lubrucate it. The sealing lip surface looked like it had been on fire. It was black and crumbly, rest of the seal rubber was like new. Just a few ideas. Al.
One other idea..............last week I treated a 631 scraper engine with a rear main leak. A close inspection of the old seal showed that the guy who installed it didn't lubrucate it. The sealing lip surface looked like it had been on fire. It was black and crumbly, rest of the seal rubber was like new. Just a few ideas. Al.
pressurizing the crankcase is a good idea. I haven't thought about that one.
On the seal though JD uses a two part seal so I don't think thats the problem but a good thought. I may try that pressurizing idea this weekend, I think I can rig up a small regulator to the crankcase vent or something.
Thanks for the help
On the seal though JD uses a two part seal so I don't think thats the problem but a good thought. I may try that pressurizing idea this weekend, I think I can rig up a small regulator to the crankcase vent or something.
Thanks for the help
jughead
Senior Member
oil leak
i am not a heavy equip tech. but if the crank doesnt have a flange and the flywheel bolts screw into the end of the crank its self maybe sealer on the bolt threads would help. a lot of automotive flywheel bolts have to have a sealer to keep crankcase oil in.
i am not a heavy equip tech. but if the crank doesnt have a flange and the flywheel bolts screw into the end of the crank its self maybe sealer on the bolt threads would help. a lot of automotive flywheel bolts have to have a sealer to keep crankcase oil in.