4l60e cracked case for 3rd time

[VictoryRedK1500]

Hey everybody, I'm in a 1997 GMC Sierra K1500 single cab short box. Within the last 30,000 miles, I have gone through three transmissions. All of these have cracked between the pan and the transfer case adapter. I'm looking for any insight on what is causing this issue. The crack is located in the same place each time. The truck has had the motor mounts replaced and the transmission mount, along with the u joints, are also new. The transfer case has been looked at. The truck has no lift and the torsion bars are adjusted slightly up. They are nowhere near maxed out. Thanks in advance.

 

[Supercharged111]

Got pics? And are you jumping it or something? My guess is something is up with the way you drive or the truck itself. Do you have the little bars that bolt to the bellhousing cover and go to the motor mounts?

 

[Jglew82]

May sound like a dumb question, but do you by any chance have a solid trans mount?

 

[Hipster]

Fighting a vibration of some sort? Solid mount? Like others said driving habits.

Neutral drops from 6k rpm or matting the go pedal and forcing 4-2 shifts constantly is not the way to treat a 4L60.

 

[86454k30]

Mixing rubber and polyurethane motor/trans mounts can cause challenges like that. I'd also be checking hardware to ensure you don't have a bolt or stud that is too long.

 

[stutaeng]

Wow, that sounds bad!

Need more information... that's in the last 30,000 miles, but what about the rest? How many miles on the truck and what is the history with it? Did you buy it like that? Any information from the P.O.?

Any other mods? Do you off-road? Driveshafts been looked at?...need more information!

 

[VictoryRedK1500]

thank you everybody! i bought the truck second hand from the original owner with 165000 thousand miles. It was a daily driver and garage kept. current miles 233000 I dont drive wild and crazy the heaviest load the truck may tow is a 16 foot aluminum boat maybe 4-5 times a year. i use the old and trusty c3500 for work and this truck is treated like a grocery getter or something for me to wax and polish for me and the wife to take out. i did crank the torison bars a little bit and replaced stock wheels and 245 tires with 16x10 mickey thompsons and 285s around 200,000 the original 5.0 went to knocking. it had been leaking from timing chain cover and rear main so i chose to keep the truck because of how clean it really is inside and out. Had the local shop swap out the 5.0 with a 5.7 when they pulled the 5.0 they discovered the trans was cracked between the pan and the transfercase adapter. i knew it had been leaving spots in the garage but was hoping it was a seal they were going to change when they had it out so already had the motor ordered let do it as a package and got a new transmission as well. leaving the shop i felt i had done the right thing new motor and trans and the truck would now last forever lol.. boy was i wrong it didnt last maybe 5000 miles and cracked in the same spot with alot of headace about a warrenty they replaced it for free. but in doing so they went through my truck looking for something wrong they changed motor mounts with motor swap obviously. trans mount with trans u joints have all been replaced front and rear with transfercase being gone through. now its been to long and the warrenty is out and it has cracked again i dont want to keep replacing trans to just have it crack again i would LOVE to find the issue and fix it before having to buy a new transmission. till then it will sit in garage sorry for long post thank you everybody who has commented and took their time to read and help out. i will try and post pictures tonight

 

[someotherguy]

Do you have the little bars that bolt to the bellhousing cover and go to the motor mounts?

Any information from the P.O.?

Didn't see those two questions answered. My gut feeling was that possibly the support bars are missing, maybe from during the engine replacement? Also, that the P.O. got rid of a problem they couldn't solve. You've had it long enough; ask 'em to be honest with you about it before you chase the problem any farther.

Richard

 

[VictoryRedK1500]

yes the support bars are there from motor to trans. iv been trying to sync photos from phone to pc but cant seem to figure that out as well thank you all again ill be back on tomorrow.... hopefully with pictures!!

 

[VictoryRedK1500]

Wow, that sounds bad!

Need more information... that's in the last 30,000 miles, but what about the rest? How many miles on the truck and what is the history with it? Did you buy it like that? Any information from the P.O.?

Any other mods? Do you off-road? Driveshafts been looked at?...need more information!

no modes. no off road no mud bogs. this is really my daily driver. try to keep it dependable i have been leaning twords driveshaft i just have a gut feeling due to thats the only thing i know has not been tested...... but i also feel no vibration going down the highway or anything abnormal. even the transmisson drives like its suppose to. the case just leaks oil from the crack in it