I have a track tensioner leaking bad on cat 311b ex. I'm a newbie to excavator and have not crawled under it yet to check it out much. Does an excavator have the big coil spring like a dozer has, through which the tensioner passes? If anyone could share a schematic of track tensioner for cat 311b, I would appreciate it. Also, some place I could get an aftermarket replacement tensioner or seal kit thanks Stacy
On your 311 the adjuster and the recoil spring assembly are two separate asemblies. The recoil spring assembly is part of the front idler and you will have to remove the whole thing complete in order to get the adjuster out because it's behind the recoil spring. You will not have to disassemble the spring. The method is pretty simple. 1. Open the grease valve in the adjuster and push the idler as far back as it will go. 2. Either split the track and pull it away so that the idler is completely exposed, or if the track is worn you will probably be able to get it off far enough to one side to be able to remove the idler/recoil spring assembly without splitting it. 3. Pull the idler and recoil assembly out of the front of the track frame. 4. The adjuster assembly is fastened to the track frame with 2 bolts (circled) that you access from above, they are located in a hole just to the front of the track carrier roller. Remove the bolts and the adjuster will come out through the front of the track frame. There is no seal kit for the adjuster, only separate seals. Altogether there are 7 seals/rings required to reseal it. 099-0172 x 2 (Ref #9), 099-0173 x 2 (#10), 095-1607 x 2 (#11), and 095-7101 x 1 (#8). The price for the lot is around $40 from Cat.
On my 312 I can remove my adjuster out the bottom with out taking the idler out its not as big as it looks in Niges picture it will fit out the hole under the top roller also but it has to be collapsed all the way and line it up just right ... I found it easier to remove it out the bottom Sent from my iPhone using Tapatalk
It may well be that the adjuster can come out of the bottom. The procedure I quoted above it how the Service Manual says to do it, but never having done one personally I would defer to someone who had. Obviously if it can be removed through the hole in the track frame that's a lot less work.
The first time I had problems with mine I couldn't get my track apart so called cat service .... 20 min after the guy showed up he had it out . He put a couple blocks under the track frame on top of chain for room to work . Made it look pretty simple Sent from my iPhone using Tapatalk
you guys are life savers. I appreciate you both very much. I have the excavator about 20 miles from home right now, trying to finish with loading some really big limestone rocks. Hope I can manage to not run a track off until this job is done and I can bring it home to work on it.. BTW, Both track tensioners seemed to have 'busted' through the seals at about the same time. I was traveling with really heavy rocks (one at a time), traveling on really hard hard ground (like concrete). I did have to turn some, to change direction and line up with the truck. Could that have been what caused the old seals to give way near the same time. IE, they were already old and weakened and then I put a lot of pressure on them by twisting, turning with heavy load on ground so hard that tracks had very little 'slippage'? (It just seemed like too much of a coincidence that within 5 minutes of me noticing 1 tensioner had gone out, I notice the other one had also leaked down badly) Respectfully Stacy Whetzell
I got the cylinder off. I will post pictures later. Now I trying to figure out hw to get it apart. do I just pump it full of grease until the body and pjston separate?
You could probably do it with compressed air and make less mess.......
thanks Nige. I had already tried that and immediately blew my grease hose. lol. after that, I found that just by pulling on the end, it came out pretty freely. I replaced the seals, put tensioner back in and tracks are good 'n tight now. Hanco is right. Take it out bottom and you don't have to take tracks off. If need more room, can remove 1 bottom carrier roller. 1 thing I learned: Don't push front idler as far back as it will go before removing tensioner. If you do, it will probably retract a little farther when you remove the tensioner. Just enough that the tensioner is 1/4 inch too long to go back in. Getting that front idler to move forward even just enough to sqeeze the tensioner in, was not fun. One other thing: I did this by myself and I found myself wishing for a short time that God had blessed me with 3 arms/hands instead of 3 legs.
thanks for the 311b track tensioner diagram Nige, thanks so much for the schematic showing what order to place the seals and orings. Without that, I would have been lost as goose in hail storm My old ones had pretty much crumbled and no way to tell which order they were in.
Glad it came apart as I said , different models you never know , pretty simple repair once you've done it , but looks a lot bigger then it is Sent from my iPhone using Tapatalk
The first track tensioner took me 5 to 6 hours. second tensioner took 1 hour 36 minutes, working by myself. almost an hour was trying to hold it in place with one hand and get the bolts started back with the other, and tightening the tracks back up with manual grease gun. Actually I found that I would not even have had to loosen the tracks very much. the tensioner came right out through the hole where you reach through to connect grease gun. All it took was reaching in, twisting and turning a bit and wall, it came right out. Had I know that, I could have saved some sore arms (from pumping manual grease gun). Two men should be able to do this in well under 1 hour, WITHOUT removing the tracks. Thanks to everyone for your help Stacy Whetzell