mcratchet1 Posted August 7 Share Posted August 7 Hello I have a 2013 mru 613 with T310 10 speed tranny. Couple times a time I cannot get it to switch to low gears. When I stop sometime I toggle gear switch up and down then I can. Other times no luck and I take off in 6 gear. I replaced hi/lo valve thinking maybe internal leak but no change. Also new oil, check for air leaks nothing . Does this sound like an internal problem. Any help would be really appreciated Quote Link to comment https://www.bigmacktrucks.com/topic/74427-no-low-gears-intermittent/ Share on other sites More sharing options...
Joey Mack Posted August 7 Share Posted August 7 Do you hear it try to down shift? Any chance one of the spaghetti lines is kinked? Does the range button feel like it is not moving right? Quote Link to comment https://www.bigmacktrucks.com/topic/74427-no-low-gears-intermittent/#findComment-556602 Share on other sites More sharing options...
mcratchet1 Posted August 7 Author Share Posted August 7 Yes I can hear it shift but when I take off in low gear sometimes it does not grab a gear like it’s in neutral. It’s not shifting all the way to low gears. I can flip the button back and forth and hear it though Quote Link to comment https://www.bigmacktrucks.com/topic/74427-no-low-gears-intermittent/#findComment-556606 Share on other sites More sharing options...
mcratchet1 Posted August 7 Author Share Posted August 7 The range button moves good I did not see any kinks. It does not do this all the time but probably 5-6 times a day Quote Link to comment https://www.bigmacktrucks.com/topic/74427-no-low-gears-intermittent/#findComment-556607 Share on other sites More sharing options...
Joey Mack Posted August 7 Share Posted August 7 Did you check the range cylinder on the rear of the tranny above the yoke? Quote Link to comment https://www.bigmacktrucks.com/topic/74427-no-low-gears-intermittent/#findComment-556608 Share on other sites More sharing options...
mcratchet1 Posted August 7 Author Share Posted August 7 No I did not is there orings inside that cover? or what should I look for Quote Link to comment https://www.bigmacktrucks.com/topic/74427-no-low-gears-intermittent/#findComment-556612 Share on other sites More sharing options...
fjh Posted August 7 Share Posted August 7 2 hours ago, mcratchet1 said: Hello I have a 2013 mru 613 with T310 10 speed tranny. Couple times a time I cannot get it to switch to low gears. When I stop sometime I toggle gear switch up and down then I can. Other times no luck and I take off in 6 gear. I replaced hi/lo valve thinking maybe internal leak but no change. Also new oil, check for air leaks nothing . Does this sound like an internal problem. Any help would be really appreciated Try leaving it in gear and pulling the range shift before you move the stick! Quote Link to comment https://www.bigmacktrucks.com/topic/74427-no-low-gears-intermittent/#findComment-556613 Share on other sites More sharing options...
mcratchet1 Posted August 7 Author Share Posted August 7 Yes I flip the button before taking it out of high gear to go into low. I tried it in neutral as well no difference Quote Link to comment https://www.bigmacktrucks.com/topic/74427-no-low-gears-intermittent/#findComment-556638 Share on other sites More sharing options...
Joey Mack Posted August 7 Share Posted August 7 As far as the range shifter, remove the back cover from it, you will see a 2 peice piston. All is sealed with o-rings, the piston nut can loosen over time. If you need new pistons, PAI has a good low cost product. Use seal glide or equivelant on the o-rings when you go back together. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74427-no-low-gears-intermittent/#findComment-556640 Share on other sites More sharing options...
fjh Posted August 7 Share Posted August 7 check to make sure the yoke bolt is tight and yup pull the lid and check piston nut! for tightness! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74427-no-low-gears-intermittent/#findComment-556643 Share on other sites More sharing options...
Mark T Posted August 7 Share Posted August 7 Sounds like it needs to be taken out and repaired ( synchro and range cylinder components in the transmission ). Keep start'n out in sixth ??? you'll be taking the transmission out anyway to replace the clutch. Like F and Joey mentioned, those items can be the issue, but if it is and you're seeing issues, probably after repairing those you'll be wondering why it won't stay in low range and keeps clunk'n in and out. Quote Link to comment https://www.bigmacktrucks.com/topic/74427-no-low-gears-intermittent/#findComment-556659 Share on other sites More sharing options...
Joey Mack Posted August 7 Share Posted August 7 I was thinking about that Mark,, I assume that most who post are mechanics. Obviously in a shop on a concrete floor with the right tranny jack and something to support the engine when the tranny is pulled, then able to tip the tranny on its bell housing, would be the way to go. It is am MR chassis which makes it easier and an hour or so shorter of a removal job, that is what I would do after my trials that I do first.. Of course I have pulled , many,, transmissions, so for me it would be routine.. Quote Link to comment https://www.bigmacktrucks.com/topic/74427-no-low-gears-intermittent/#findComment-556661 Share on other sites More sharing options...
Mark T Posted August 7 Share Posted August 7 IDK seems like Mack synchros and trunion bars, everyone is reluctant to accept when they're done. Can't fault a person for remaining optimistic though. Quote Link to comment https://www.bigmacktrucks.com/topic/74427-no-low-gears-intermittent/#findComment-556662 Share on other sites More sharing options...
Joey Mack Posted August 7 Share Posted August 7 I get it Mark... weak points for sure.. they do fail early relatively speaking,, It hurts my heart, because of my love of the Mack Truck's. its easy for me to say that if you own this set up and have a mechanic brain, you can maintain it and prolong the failure interval.. Still the best Trucks in the dirt.. !! Hands down.. Quote Link to comment https://www.bigmacktrucks.com/topic/74427-no-low-gears-intermittent/#findComment-556664 Share on other sites More sharing options...
fjh Posted August 7 Share Posted August 7 Yup I agree how ever never had to work one! Just experience working on! And my experience tells me I would have a fuller over a Mack 18 any day of the week!If I was ever to own a truck! Quote Link to comment https://www.bigmacktrucks.com/topic/74427-no-low-gears-intermittent/#findComment-556665 Share on other sites More sharing options...
Mark T Posted August 7 Share Posted August 7 Absolutely. They go a long time if used correctly and maintained as they should be (or even not) but when those things need help, it's usually the whole thing. They're expensive repairs when it comes to it though. 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74427-no-low-gears-intermittent/#findComment-556666 Share on other sites More sharing options...
Mark T Posted August 7 Share Posted August 7 1 minute ago, fjh said: Yup I agree how ever never had to work one! Just experience working on! And my experience tells me I would have a fuller over a Mack 18 any day of the week!If I was ever to own a truck! IDK. If you ask me , Mack hung on way too long to the belief people knew what to do with extended range transmissions and multiple PTO options. Fuller was by far more driver and maintainence friendly, and in most applications did a fine job. It makes me sad they're all going the same direciton as injection pumps and two sticks. Oh..... and a pipe from a turbo that went to a muffler. 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74427-no-low-gears-intermittent/#findComment-556667 Share on other sites More sharing options...
Joey Mack Posted August 7 Share Posted August 7 Yes guys, I worked them both in the dirt.. Eaton is better, and easier to do a synchro repair.. fixed many of them, I could do an eaton repair in 1 shift at the shop, from first test drive, to last test drive.. ( of course parts were in the parts room back then) .. I still have my shop made jig in my shop here.. it held many Eaton back boxes.. and a few Meritors too.. 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74427-no-low-gears-intermittent/#findComment-556668 Share on other sites More sharing options...
Joey Mack Posted August 7 Share Posted August 7 Dammit !!! Mack should have been the Best.!!!! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74427-no-low-gears-intermittent/#findComment-556669 Share on other sites More sharing options...
fjh Posted August 8 Share Posted August 8 A true patriot! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74427-no-low-gears-intermittent/#findComment-556670 Share on other sites More sharing options...
mcratchet1 Posted August 8 Author Share Posted August 8 Is this it under back cover the attached pic Quote Link to comment https://www.bigmacktrucks.com/topic/74427-no-low-gears-intermittent/#findComment-556695 Share on other sites More sharing options...
fjh Posted August 8 Share Posted August 8 yes remove the cover and check bolt 13 for tightness ! also check the yoke bolt! 1 Quote Link to comment https://www.bigmacktrucks.com/topic/74427-no-low-gears-intermittent/#findComment-556697 Share on other sites More sharing options...
mcratchet1 Posted August 11 Author Share Posted August 11 Just to clarify the cover we’re talking about removing is on the back side above yoke? Four bolts to remove, I tried to pull that one off but does not want to move back. Didn’t want to try to pry it off. Never removed that one before is it ok to tap it back with a rubber mallet? Quote Link to comment https://www.bigmacktrucks.com/topic/74427-no-low-gears-intermittent/#findComment-556886 Share on other sites More sharing options...
Joey Mack Posted August 11 Share Posted August 11 that is the range shift cylinder, did you try to pull the rear cover? Quote Link to comment https://www.bigmacktrucks.com/topic/74427-no-low-gears-intermittent/#findComment-556890 Share on other sites More sharing options...
Mark T Posted August 11 Share Posted August 11 NO that's your range cylinder. F's 13 he's talking about is under the cover on the top of the transmission and the bolt on the yolk is the one in front of the universal joint it'll be below your picture and it's like inch and five sixteenths Quote Link to comment https://www.bigmacktrucks.com/topic/74427-no-low-gears-intermittent/#findComment-556891 Share on other sites More sharing options...
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