My Tractor Forum banner

1 - 11 of 11 Posts

·
Registered
Joined
·
14 Posts
Discussion Starter #1
I started getting my Lawnboy's ready for the winter and decided to perform a compression check on the 3 Duraforce's. Both the 10424 and 10550 read 115 psi with the 10525 about 25 psi lower at 90. I can definitely tell a difference in the power of the 525 and decided to install rebuild the engine. I am looking for some guidance....

How would you decide to replace the rings or the piston and rings?
What else should I replace while I have it torn down?
Is the service manual available online?

Thanks in advance!!
 

·
Registered
Joined
·
4,418 Posts
Welcome to the forum! I have rebuilt a number of duraforce engines, Replace the piston and rings, its just about the same price for the rings as it is the piston asm. Replace both the upper and lower seals, and id replace the head gasket while im at it...
 

·
Registered
Joined
·
443 Posts
Agreed. Replace piston and rings. They come in a set that also includes the wrist pin and snap rings. You don't really have to remove the head, but it makes Piston installation much easier vs. the older F and V engines that had to be installed from the bottom. The main bearings almost never go bad on a DF, but I'd also replace the bearings on the big end of the rod. The needles (683911) come in a strip of either 32 or 33 (it differs by when the bearings were made) and the rod liners come in a pair (677982) and usually have some wear after 10 years or more. The upper oil seal is the same as almost all other LB engines (611396), but the lower (94-5764) is bigger and is held in by a snap ring. Reeds (602588) are cheap and I'd replace them too. They get weak after so many years and don't perform properly. Make sure you use anaerobic sealer between the two halves of the crankcase. Overall, with a couple hours work and about $100, you can make your DF run like new again. Yes, the service manual is available on the LB website...or at least it used to be. I appologize if that's more info than you wanted.
 

·
Registered
Joined
·
4,418 Posts
Before you tear it down make sure you check the play in the crankshaft before you tear the motor down. I see alot of DF main bearing failures around here, and i have about 6 or 7 shortblocks with bad bearings in them.
 

·
Registered
Joined
·
443 Posts
Endplay: 0"-.017"
Sideplay measured at lower main bearing: around .0006"

Put plainly...you pretty much don't want any movement at all. I personally have never had a DuraForce with bad main bearings..and I've seen some that were really toasted. Others have had different experiences. Somehow the mains hold up...Being that they are large ball bearings rather than small needle bearings like all previous LB engines. DF's don't have endplay issues like the F and V engines because the lower main is also the thrust surface for the crank. The F and V engines relied on the crank running against the block and most, after years of use, have lots of endplay because the aluminum block wears.
 

·
Registered
Joined
·
395 Posts
Shoot me a PM if you want a cheap one around here, so I don't go and get it;)
LOL...The wife will kill me if I bring home anymore. I really wanted to go get those three DFs posted on CL the other day. Two running and one not for $60??? Oh well...

Still love the amount of help available on this site. So many random people willing to help out anyone and everyone.
 

·
Registered
Joined
·
2,350 Posts
LOL...The wife will kill me if I bring home anymore. I really wanted to go get those three DFs posted on CL the other day. Two running and one not for $60??? Oh well...

Still love the amount of help available on this site. So many random people willing to help out anyone and everyone.
I saw that one too, I was too late. Yeah this site is great. So many people around that are just so helpful and so smart. I would have never figured out how to fix my DF if it wasn't for this site. :thanku:
 
1 - 11 of 11 Posts
Top