Combines A C diesel engines

[big_orange]

Were all new rod bolts usedIJThat could be the problem if they weren't.

 

[augerhead]

Years ago AC said you should replace rod bolts when you remove them . They are streched when you torque them and will weaken if used again. In the 2900 and the 3500 engines I always thought they could stand larger bolts.A set of rod bolts are not cheap,but a new short block cost a whole lot more. Standard in engine H_O's rod bolts out,new one's go in.Why take a chanceIJ PSA good torque wrench that is accurate and proper tighting procedure is important also.)

 

[kirk]

all new rod bolts,torqued to book specs. book says every other overhaul use new bolts but how do you know , so always new bolts are used from agco

 

[Tom_Russell]

In addition to using a good torque wrench, frequent calibration is required on some wrenches. Secondly, if the mechanic uses a clicker type torque wrench, does he turn the setting down for storage according to the wrench manualIJ It sounds like your guy knows what he is doing, however there could be some obscure factor that is causing problems, Good luck.

 

[John_W]

My two bits worth. I think your confidence may be misplaced if this wrench turner has had another similar failure lately. There maybe a good reason he is a "former" mechanic. I have been surprised by alcoholics that hid there problem for years, not that this is the case. Marriage or family problems have messed up a lot of good men too. Have you considered replacing this AC engine with a modern CumminsIJ This might be a good time. Or at least a different mechanic.

 

[max_doubt]

Make sure he knows about the newer torque specs on the newer rod bolts. I think there is a sheet included with the bolts, so he probably knows. It seems that they lowered the torque to an odd figure 37.5 ft lb.s or something like that. Anyone know more on thisIJ I had a 7580 throw a rod out the side after 40 hours. New bolts, magnafluxed, correct torque. My 7050 seems to be surviving fine with 300+ hours. Wish I could offer more. Mike

 

[Gleaner_mechanic]

The new torque that should be sent with All new rod bolts is 67.5 ft. lbs. using a drop of oil on the threads and under the head of the bolt. I would definitely make sure he knows and did this. Hope this helps! Gleaner_mechanic P.S. i would definitely look into a cummins repower, at least give it some thought and research!

 

[Dan]

What a shame. Was breakin oil changed at 50 hoursIJ Does engine warm up without reving and was tractor allways allowed to warm up before revingIJ Was oil filter element blown inward on either filterIJ Can you see if either bolt had backed out a noticable amount compaired to its mateIJ Had bearing spun out in rodIJ If it looks like bearing had spun awhile it is likely that bearing went and then bolts broke off. We allways pressure feed our engines full of oil after overhaul to help insure bearings and journals are flushed well before cranking. We have fancy Snap On torque wrenches that we keep calibrated but I wonder if I don't still prefer the old bending arm type torque wrench. We replace the bolts on maybe 10% of the engines we do and have never thrown a rod after recent overhaul. 100's of engines (Knocking on wood). Had a private guy who overhauled high reving old N6 last year and it blew a rod out within 50 hours. The engines I have seen blow a rod are usually just a short distance from where engine was started (this tells me it was reved cold and quickly took out bearing and then it hammered until bolts broke and rod come threw side. I wish you the best and hope you can figure out the reason exactly. Be sure to use the 74037047 long AGCO filters for they will allow more cold oil to pass without bypassing unfiltered oil into oil galley.