I have a Komatsu site truck that I have been chasing an engine problem. I finally found it to be excessive crankshaft end play. Over .250. This is causing a clearance issue with the Ne sensor for eng RPM. I am wondering if anyone else has had thrust bearing failure with Komatsu SAA6d-140E engines or any others. I have not torn it down yet. A thrust failure does not make sense to me because there is no pressure against it. No clutch.
Seen the gears shear off..
Looks like this engine has three half moons for thrust, if there was some sort of issue one of them may have gotten sheared out of there, then I suppose the others would follow. Have you torn down the torque? Just because there's no clutch doesn't mean there isn't some fault that created severe thrust for a while. If something went wrong in the torque, or more likely either the engine or the transmission shifted in the mounts, there's only fraction of an inch leeway on the drive shaft between the torque and the transmission. Have a look at the front differential mounts, if they came loose I think the tranny would fall forward toward the engine. I'm just looking at online parts books, just throwing out suggestions.
Thanks for the replies. No torque converter on the engine. This thing has a drive damper like an escavator and a drive shaft to the trans. The trans has a PTO and torque converter built in like the Komatsu W500 loaders. In fact it is the same engine too. I looked in the service manual and the thrust bearing shells are sitting on roll pins. When I get time to pull the engine I expect to find them sheared off and the bearings in the pan .I have a good relationship with the local dealer and they looked for service bulletins on this issue, but did not find anything
I took a guess on the vintage of your truck, sounds like I missed! LOL. Good luck with her
I had some time today to pull out the engine and drop the pan. The bearings were in place, but the rear facing thrust is down to the steel and the crankshaft is severely scored. I also pulled out the drive damper and found no problem which could have put forward thrust against the crank. Anybody know someone who can spray weld and regrind this for me? Or a source for a reasonably priced crank? The engine is a SAA6D-140E3
If no luck finding someone closer try contacting these people: http://www.agkits.com/contact-us.aspx Call the phone number shown and ask to talk to Brian. I know they used to do crankshaft welding and fixed some for us in the past. Might help if you could take a couple pictures you could email him.
Thanks for the lead. I spoke with Brian and he may be able to grind the thrust for me. It depends on if the crank will fit on his machine. Also talked to a machine shop about milling out custom thrust bearings. Looks like this may work out if this one cant be welded. A new crank is $16k.
Force is coming from some place. That acts like a torque coming apart and pushing the crank. Look for force coming out of the trans. Later Bob
I finally got back to this and pulled out the crank. And found the cause. Whoever had this site truck before us had packed grease behind the pilot bearing. So much that the output shaft could not fully inserted. So when the drive damper cover was bolted up, it forced the crank forward and burnt out the thrust bearing and ruined the crankshaft. The end play went from under .010in. to over .300 in. and damaged the Ne crank position sensor. It is all back together with an aftermarket crank and just need time and space to reinstall.
Grease is like silicone sealer. If a little is good a lot more is betterer!