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  1. J

    60/40 Bench to Standard Bench Swap?

    I've got a 60/40 bench in my '98 extended cab right now. The D/S seat is busted at one of the hinges and sags off center. My Dad is scrapping a '95 with a regular bench that's in good shape. Is that a straight bolt-in swap? I searched the forum but all the swaps I found were taking out a...
  2. J

    4L80E Intermittent Leak, Morning Sickness

    I will note that I always park this truck nose uphill so the bed doesn't collect water/crud. That may well be exacerbating the situation. Sent from my moto g(6) using Tapatalk
  3. J

    4L80E Intermittent Leak, Morning Sickness

    That's good to know. I'm not especially bothered by it so long as it isn't a sign that something is gonna let go. Clearly it hasn't bothered me enough to go digging into it in the last couple years :)
  4. J

    4L80E Intermittent Leak, Morning Sickness

    Having some issues with the 4L80E in my '98 K2500. The truck has 265k miles on it and I'm not sure if it's the original trans but I'm sure it's got a lot of miles on it because just after I bought the truck I had to replace the pump pressure spool valve (used the Sonnax kit) due to high line...
  5. J

    Blown up rear axle, what years fit?

    Too optimistic. Carrier is cracked, although R&P look fine. Pricing parts out (carrier, spiders, hardware) vs junk yard rear now. Sent from my XT1585 using Tapatalk
  6. J

    Blown up rear axle, what years fit?

    The axle is a GT4 code (3.73). Might not need a whole axle though. Turns out what happened is that one of the pin/bolts that holds the spiders in backed out. The truck dropped a spider gear and that's what blew out the back of the cover. Wrecked all the spiders, but the r&p is fine and I haven't...
  7. J

    Blown up rear axle, what years fit?

    I think I have the semi-float. I don't have to pull the axles to get the drums off. Also if the truck had a G80 it never worked. I know it'll spin (or rather would spin) one tire on wet grass. I'll have to check the ratio and see what the damage is. Can I put a 2wd heavy rear in it even if the...
  8. J

    Blown up rear axle, what years fit?

    My Dad's been driving my '98 K2500 for a couple months while his truck was getting fixed up. Today he called me and said the rear blew something out the diff cover and locked up while he was driving it. Won't know for sure what went til I get it opened up, but I'm anticipating the worst and...
  9. J

    '98 K2500 surging at idle, can't figure it out

    From what I read the 4L60E can have the same problem I did. If you want to confirm it's a transmission issue you need to do a line pressure test when the issue is occurring (so warmed up, in reverse). When I revved mine up in reverse the line pressure became excessive and erratic. I bought an...
  10. J

    '98 K2500 surging at idle, can't figure it out

    Just this past Friday I finally got the truck buttoned back up. I took care of a number of things while the trans was out including the rear main, oil pan gasket, trans input/output seals, t-case output seal, new exhaust gaskets at the CAT and the manifold, new trans cooler fittings, etc. The...
  11. J

    '98 K2500 surging at idle, can't figure it out

    So I didn't feel like laying on my back pulling a trans again. I bought a used 2 post lift a couple years ago and kept putting off installing it because I thought it was going to be a pain, but this was good motivation. Lift is up, truck is up. I spent 4 hours the first day getting the stupid...
  12. J

    '98 K2500 surging at idle, can't figure it out

    Here's the sonnax kit for the leaking boost valve: https://www.sonnax.com/parts/1985-boost-valve-kit and attached is the service bulletin I found with the additional info about drilling the passage.
  13. J

    '98 K2500 surging at idle, can't figure it out

    I borrowed my uncle's lift and got the line pressure gauge installed. Idle pressures were all in-spec (60 psi in park/neutral, 120 psi in drive, and 150 psi in reverse). 2,500 rpm in drive was about 280 psi and stable. Reverse the pressure gets really unstable as the rpm's go up and pegged...
  14. J

    '98 K2500 surging at idle, can't figure it out

    The only way you guys don't find the answer is if I get sick of this thing and junk it before it's fixed... Sent from my XT1585 using Tapatalk
  15. J

    '98 K2500 surging at idle, can't figure it out

    I found one trick to diagnosing it is to loop the cooler lines to eliminate the cooler in the circuit. If the problem stops it's a cooler restriction. I don't think this is my issue since I just changed the radiator with the cooler inside, but something else to consider. Sent from my XT1585...
  16. J

    '98 K2500 surging at idle, can't figure it out

    Might have found something. Apparently it's more common on '99+, but it seems that if the torque converter isn't supplied enough fluid the TCC will drag, and the stock PR valve in the trans is set for too much line pressure stock. Also a restriction in the cooler lines will starve the converter...
  17. J

    '98 K2500 surging at idle, can't figure it out

    I can read engine temp and it's 192-194. It isn't changing when the truck starts to act up, it'll hit 192+ in the first 5 minutes Utes of driving but the truck won't start surging until a drive of at least 20 minutes. I'm really leaning toward a trans problem at this point. The problem with...
  18. J

    '98 K2500 surging at idle, can't figure it out

    Today's results: Capped off PCV at intake tube and manifold, removed PCV from valve cover, no change. New MAP sensor didn't fix it. Cleaned MAF and swapped one from another truck, didn't change anything. Cleaned battery and ground connections, replaced battery bolts; no help. Tried a...
  19. J

    '98 K2500 surging at idle, can't figure it out

    Side note, a friend suggested a possible test. What if the truck didn't know it was in reverse? It's not like it needs to control shifts or anything. If the signal from the trans range sensor was interrupted in reverse only would the transmission still function properly? If so, does anyone...
  20. J

    '98 K2500 surging at idle, can't figure it out

    Still fighting with this. Although I had already switched the IAC out with one from another running truck I decided to replace it anyway since after all my digging it still seemed like the most obvious solution. New AC Delco IAC made no difference. I also unplugged the EGR valve when the...
  21. J

    '98 K2500 surging at idle, can't figure it out

    Ok, it's officially getting weirder. I swung by the shop today to use the scanner and fiddle with the truck some more. It's only about a 10 minute drive if I go straight there from my house, so I took the long way to make sure the truck was warm enough to exhibit the issue. When I get to the...
  22. J

    '98 K2500 surging at idle, can't figure it out

    Below 400 rpms the engine shakes at just the right frequency to make the door panel rattle. In the truck it's not that bad, but it must have been like right next to the phone mic because it picked it up way louder than the engine noise itself. I never noticed it before because I never turned...
  23. J

    '98 K2500 surging at idle, can't figure it out

    Just for grins, here's a video of the issue. It is extremely consistent, 100% of the time it does this after the truck has been driven for more than 15-20 minutes. It does not do it necessarily as soon as the engine reaches operating temperature, that happens in 5 minutes. It does have to be...
  24. J

    '98 K2500 surging at idle, can't figure it out

    I'll have to borrow the better scanner to see CMP offest. Maybe Friday afternoon. Thermostat is a new 195 F unit. Radiator is new too (and it's about to get a new water pump). All unrelated to the current issue, the truck had several annoying leaks when I got it. A/C doesn't work. Needs a...
  25. J

    '98 K2500 surging at idle, can't figure it out

    The scanner shows a reasonable engine temp, usually around 197 F. I assume the scanner sees the same ECT as the computer? Trans shifter position shows as correct on the scanner when shifted through the gears. Again I assume this is the same signals that would be going to the computer...

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