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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: 4x4orbust on February 08, 2009, 07:48:44 PM
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hey guys, i am trying to fix the leaking transmission in my truck (82 k10, 350/th350/np208) the current pan was chrome and pretty much rusted through (pin holes everywhere, major leaks). the tranny lines are rusted bad and leaking as well. already have a replacement pan and lines, and I got myself set up, rolled under the truck, and began my chore. only problem is, none of the bolts will come out. they seem rusted in, will not move, and i already snapped one bolt head off.
1: anyone know of a way to free "rusted/oxidized" bolts in a transmission?? specifically the pan bolts.
as it sits now it leaks about a pint a week, which is a pint too much to me.
2: if i can't get the bolts out, Would it be more worthwhile to pull the th350/NP205 setup out of my 73 and swap it into my 82? (82 currently has a th350/np208) would this be a direct swap, or would i have to change driveshafts, mounts, etc?
3: are the gears in the np205 relatively the same as the np208? (as in final drive ratio) i don't want to swap in the 205, then have to swap the gears in the axles just to make the truck move.
thanks for the help guys, i would like to get this done asap. also, if i have to swap the trannies, i would rebuild it at the same time, what does an average rebuild cost?
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Your pan bolts shouldn't be rusted since the tranny is aluminum. But the problem with iron and aluminum is it creates a chemical reaction that makes them stick. Anytime you have bolts going into aluminum whether it be a tranny, intake, head what ever, you have to rap the rachet handle with your hand in the direction you want it to turn to break it free.
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thanks for the advice, that's kinda what i was doing when i snapped the bolt, tried hitting it both ways with my hand, then tried a hammer, then....snap. that was this weekend. i then drilled out the center of the bolt, and proceeded to snap an easy out. got that out, and parked the truck, and have sprayed the bolts 3 times with pb blaster. gonna try again this week sometime. i figured the aluminum had oxidized to the bolts...
i know it's gonna suck if i break a few of the heads off. that means drilling and re-tapping, and there are a lot of bolts down there.
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1) You could try tapping directly on the bolt head. Is the bolt frozen to the pan?
2) Technically everything will swap over.
3) both transmissions have the same final drive, 1:1. The 208 has a more gear reduction.
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the bolt is not frozen to the pan, the threads are seized. i'll take a punch and tap on the heads, see what that does. would heating with a torch be ok? not sure if that would do anything to the aluminum...
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little update....
spent all day working on getting the bolts out, i only got 5 of the bolts to come out on their own. the heads snappedd off on the rest of the bolts. i ended up drilling and re-tapping the rest of them, which was suprisingly easy. the bolts drilled right out with little effot. i am now wondering if the guy that rebuilt it used some cheapo bolts on it. anyway, ran out of sunlight today, so i will finish the job tomarrow.
thanks again for all the help!!
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Man I hate fixing other peoples screw ups. He probably used something on the bolts so they wouldn't back out and not you are dealing with the problem.
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i hear ya russ130, whoever did the work really screwed some stuff up. especially the wiring!! this truck is harder to figure out than calculus!!
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couple differences between the 205 and 208. The 205 is gear drive and much stronger than the 208 which is chain driven. As far as gear ratios go, high range is the same but low range is different. If I remember right, the 208 has a 2.62:1 low range reduction and the 205 has a 1.96:1 low range reduction. The 208 shifts much easier. As long as you're not rock crawling or anything crazy, your current gears will work fine with the 205.
Sorry to hear about your tranny pan bolt fiasco, that sounds like a real PITA. Good luck with the rest of the job. If your cooler lines are already wasted you might think about cutting the lines as close to the fittings as you can (on the cooler and on the tranny) and using a 6 point box end wrench or socket on them from the start....before you round all the corners with an open end wrench...don't ask how I found this out.