mackdump600@yahoo.com Posted March 1, 2022 Share Posted March 1, 2022 hi is there any old-school mechanics that work on the 707 engines particularly 707 say having problems breaking ranks I have a seven day or 608 was 27,000 miles and it’s broke the rings twice and it wondering what could be doing it any ideas thanks Quote Link to comment Share on other sites More sharing options...
mackdump600@yahoo.com Posted March 1, 2022 Author Share Posted March 1, 2022 Dang auto spell I know I corrected that before I posted it breaking rings 707 gas engine it broke the rings initially at 24,000 miles and again at 27,000 miles what could be breaking them Quote Link to comment Share on other sites More sharing options...
Popular Post Onyx610 Posted March 1, 2022 Popular Post Share Posted March 1, 2022 Wrong size rings, manufacturing defect, heat fatigue, and detonation. How do the pistons, cylinder walls, and ring lands look after they break? 2 1 Quote Link to comment Share on other sites More sharing options...
Joey Mack Posted March 1, 2022 Share Posted March 1, 2022 are you re-using the pistons? jojo 1 Quote Link to comment Share on other sites More sharing options...
mowerman Posted March 2, 2022 Share Posted March 2, 2022 Man that’s messed up I know my uncle used to use a micrometer on brand new rings before he put them on he didn’t trust the manufacturers sorry I hope you find your problem… Bob 1 Quote Link to comment Share on other sites More sharing options...
mechohaulic Posted March 2, 2022 Share Posted March 2, 2022 are you saying the engine was done and rings broke 24k miles later , rings replaced again then broke after 27k (51k miles)or broke again after 3k mile , total engine miles 27k since rebuild? 1 1 Quote Link to comment Share on other sites More sharing options...
Onyx610 Posted March 2, 2022 Share Posted March 2, 2022 (edited) Sounds like engine was done and 24k miles on it they broke. Fixed then 3k miles later they broke again. Edited March 2, 2022 by Onyx610 1 Quote Link to comment Share on other sites More sharing options...
Popular Post theakerstwo Posted March 2, 2022 Popular Post Share Posted March 2, 2022 You need to give the guys some info like was the block bored and are you using same pistons and if block was not bored was the ring ridge cut back?Also which rings is breaking and are you sure the rings were not broke when installed and if old piston are used is the ring lands tight enough to support a new ring?Is the timing correct?Was the ring gap checked before rings was put on pistons?Also the man who is doing the work a mechanic? 4 Quote glenn akers Link to comment Share on other sites More sharing options...
mechohaulic Posted March 2, 2022 Share Posted March 2, 2022 another situation not being there to see / know all the facts. what type of truck are we dealing with;; older fire truck with only 24k miles . older road truck having a rebuild== why was it rebuilt ?WHO did the work,what parts were reused? etc... not degrading anyones work, just don't know what we are up against.. I like the part " any OLD mechanics" . YA someones looking for me 😀LOL Quote Link to comment Share on other sites More sharing options...
mechohaulic Posted March 2, 2022 Share Posted March 2, 2022 7 minutes ago, theakerstwo said: You need to give the guys some info like was the block bored and are you using same pistons and if block was not bored was the ring ridge cut back?Also which rings is breaking and are you sure the rings were not broke when installed and if old piston are used is the ring lands tight enough to support a new ring?Is the timing correct?Was the ring gap checked before rings was put on pistons?Also the man who is doing the work a mechanic? we are on the same page on this one. i was writing as you were posting. what was being used for a ring compressor; not granny's tuna fish can Quote Link to comment Share on other sites More sharing options...
mechohaulic Posted March 2, 2022 Share Posted March 2, 2022 where did he go ??? we are waiting for answers 1 Quote Link to comment Share on other sites More sharing options...
Onyx610 Posted March 2, 2022 Share Posted March 2, 2022 10 minutes ago, mechohaulic said: we are on the same page on this one. i was writing as you were posting. what was being used for a ring compressor; not granny's tuna fish can Yea they could be breaking during install, doesn’t take much to break one. Quote Link to comment Share on other sites More sharing options...
Onyx610 Posted March 2, 2022 Share Posted March 2, 2022 Tuna can isn’t a bad idea though… 1 Quote Link to comment Share on other sites More sharing options...
mechohaulic Posted March 2, 2022 Share Posted March 2, 2022 to break after 24k possible mechanical failure to break again after 3k ; install failure. were new rings put in second time or did someone pick the "best of the old" and reinstall. obvious when rings break ;; compression loss, oil blowby etc, who/ why broken rings determined . Quote Link to comment Share on other sites More sharing options...
mechohaulic Posted March 2, 2022 Share Posted March 2, 2022 4 minutes ago, Onyx610 said: Tuna can isn’t a bad idea though… new generation can't use a tuna can, new cans are easy open only on one end. have to find an app for instructions on removal of opposite end.hopfully instructions say empty can first. it's a mack might be better to use a dog food can!!LOL 1 Quote Link to comment Share on other sites More sharing options...
Onyx610 Posted March 2, 2022 Share Posted March 2, 2022 Big soup can, they are taller so you can get all the rings in it at once, rookie…hahaha 1 Quote Link to comment Share on other sites More sharing options...
mackdump600@yahoo.com Posted March 2, 2022 Author Share Posted March 2, 2022 Hi thanks all for the replies and yes you’re all right I should I give more information here’s the story I bought the truck in 04 . 21,000 miles on it took the fire bed off put a dump bed on it started hauling Sand and gravel ,at 24,000 miles the Pistons melted down through the side on one piston all the way through the rest of them was halfway burned through, sent them to a machine shop on the West Coast, they tig welded them up re-cut the rings ,supplied rings and racing shop that I had put it together took the cast strings and threw them away and put in chrome Molly, I run it from 24,000 miles to 27000 and they broke all the rings in it every cylinder , had it board out ,honed 20,000 over with no’s pistons,in a machine shop in Harrisburg PA , he had built these engines in the 60s did a great job on it brought it home ,started it up had less than one hour on it idling and running part throttle, and all six cylinders cracked the rings all three sets of rings ,I believe I had an out of time too much ,so it’s my fault ,I was just wondering what everybody else thought about it thank you very much for your replies and the help Quote Link to comment Share on other sites More sharing options...
mackdump600@yahoo.com Posted March 2, 2022 Author Share Posted March 2, 2022 Sorry it won’t let me put any more reactions today Quote Link to comment Share on other sites More sharing options...
mackdump600@yahoo.com Posted March 2, 2022 Author Share Posted March 2, 2022 I will reply to everyone who answered thanks again Quote Link to comment Share on other sites More sharing options...
doubleclutchinweasel Posted March 2, 2022 Share Posted March 2, 2022 Wrong ring groove in the piston. Wrong ring end gap. Cylinders not round. Cylinder ridge. Cylinders warping at temperature (improper cooling). Detonation. This is a biggie. Can damage LOTS of stuff. (refer back to original melted pistons) (too lean, too much timing, too much compression, too low octane fuel, etc.) Improper piston/cylinder fit. Rings installed upside down. Woods sprites. Gremlins. 1 Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment Share on other sites More sharing options...
theakerstwo Posted March 2, 2022 Share Posted March 2, 2022 Lean fuel mixture can sure do that.I saw this happen years back with a Giesel engine which was a V cummins converted to gas.I was am city truck and would burn one piston in a weeks time over and over.When some one found it the intake manifold was warped and letting it suck air in on one cylinder. 1 Quote glenn akers Link to comment Share on other sites More sharing options...
doubleclutchinweasel Posted March 2, 2022 Share Posted March 2, 2022 1 hour ago, theakerstwo said: Lean fuel mixture can sure do that.I saw this happen years back with a Giesel engine which was a V cummins converted to gas.I was am city truck and would burn one piston in a weeks time over and over.When some one found it the intake manifold was warped and letting it suck air in on one cylinder. From his original description, that's what it sounds like to me. Cookin' the Puppy! 1 Quote "Eagles may soar, but weasels don't get sucked into jet engines." Link to comment Share on other sites More sharing options...
theakerstwo Posted March 2, 2022 Share Posted March 2, 2022 I worked for the mack dealer here in the mid 60s and dont remember any problems with this engine like that.Some were on propane and i remember the drivers talking about how many years they would run burning propane.They were hard on plugs and points. 1 Quote glenn akers Link to comment Share on other sites More sharing options...
mackdump600@yahoo.com Posted March 2, 2022 Author Share Posted March 2, 2022 Thanks guys for the thoughts on it I’m leaning towards the carburetor was too lean that it in , plus I might’ve had the timing off too much. OK appreciate input I’m going to try it one more time and see what happens thanks a lot I’ll let you know ,hopefully get it back running in the next two weeks Quote Link to comment Share on other sites More sharing options...
mechohaulic Posted March 2, 2022 Share Posted March 2, 2022 more detail sure does make a difference on diagnostic ideas. Thank you for update. that's sure is alot of $$$$$ into that engine. 1 Quote Link to comment Share on other sites More sharing options...
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