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Thread: Clutch issues w/swapped in NV4500

  1. #1
    Join Date
    Oct 2001
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    Granby, Missouri, USA
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    Default Clutch issues w/swapped in NV4500

    I have a friend who has an '88 Chevy 1500 4x4 that originally had a 350 gasser w/NV3500. He swapped in a 6.2L and a later model NV4500. I've helped him get the engine running, but he can't seem to get the clutch to work. I don't know a lot about these systems, but I know that he has a hydraulic setup. The pedal pumps up firm, but it doesn't seem to move the clutch far enough to disengage from the engine. He's pumped and pumped, and bled and bled, but it doesn't seem to help.

    What should I check for first? I've never messed with the NV4500 setup. I'm an auto guy, myself.

    I'm not sure what flywheel or clutch combo he used.

    Casey
    1995 K1500 Tahoe 2 door, 6.5LTD, 4L80E, NP241, 3.42's, 285/75R16 BFG K02's; 1997 506 block; Kennedy OPS harness, gauges, Quick Heat plugs, and TD-Max chip; Dtech FSD on FSD Cooler; vacuum pump deleted, HX35 turbo, Turbo Master, 3.5" Kennedy exhaust, F code intake; dual t/stats, HO water pump, Champion radiator; Racor fuel filter

  2. #2
    Join Date
    Dec 2003
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    Yukon Canada
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    Default

    Hi
    A guy i know was having the same issue with a GM gasser last year.Turned out he had the clutch plate in backwards.He tried changing the slave,master cyl and line with no luck.
    The clutch system is bled differently than the brake system,that may be the problem as well.
    Good luck
    Thomas
    90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews

  3. #3
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    Default

    I know that I had a devil of a time bleeding my clutch when I replaced it the other year. IIRC, the bleed screw is on the side of the slave and I had to jack the passenger front side of the truck up to get the bleed screw to point "up" enough to get all the air bubbles out.
    '94 GMC 6.5TD K1500 4L80E 2-Door Yukon SLE 221K
    '93 Chevrolet 6.5TD K2500HD NV4500 Std. Cab Longbed 187K
    '85 Toyota 22R RN60 4x4 Std. Cab Shortbed 178K (Currently retired for rebuild)
    Diesel Page Member #2423

  4. #4
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    Oct 2001
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    Granby, Missouri, USA
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    Default

    Quote Originally Posted by Yukon6.2 View Post
    The clutch system is bled differently than the brake system,that may be the problem as well.
    Could you explain further please?

    Thanks

    Casey
    1995 K1500 Tahoe 2 door, 6.5LTD, 4L80E, NP241, 3.42's, 285/75R16 BFG K02's; 1997 506 block; Kennedy OPS harness, gauges, Quick Heat plugs, and TD-Max chip; Dtech FSD on FSD Cooler; vacuum pump deleted, HX35 turbo, Turbo Master, 3.5" Kennedy exhaust, F code intake; dual t/stats, HO water pump, Champion radiator; Racor fuel filter

  5. #5
    Join Date
    May 2005
    Location
    SE Wisconsin
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    488

    Default

    Bleed screw is on the top of my slave cylinder. I just opened it up and let the air out. Pumped the clutch a few times and let more air out.

    Are the clutch fork and ball in good shape? Installed correctly? Are they the right parts?
    1993 K3500 - Peninsular 18:1 engine, marine injectors, high capacity cooling, AL Core Radiator, 3" DP and 4" exhaust, ISSPRO Gauges, Girdle, AMSOIL Dual Oil Filter System, 1997 Air Filter(trashed the K&N), 395K on Body, 165k on engine.
    1997 GMC Savana - 6.5 TD
    1966 CJ5 - V6 Gas - highly modified
    1967 Jeepster - Stock
    1986 Jeep CJ7 - Stock
    1993 Grand Cherokee - 6.2 diesel
    2007 Grand Cherokee - 3.0 diesel

  6. #6
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    Windham, ME
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    Default

    On my Ford you have to fill and bleed the slave cylinder before installation. This is a real PITA, but it's the only way to get something even remotely resembling a firm pedal.

    Assuming it's a late-enough model not to have the concentric slave cylinder, I'd remove the master, hose, and slave as a unit, clamp the slave in a vise with the hose port as close to the top as possible, and have someone else hold the master high enough to take any bends or kinks out of the hose while you work the slave pushrod in and out. You'll know when the last bit of air is gone.
    Phil

    '90 Jeep Wrangler, 4.2l, AX15, Dana 30 & 35 with 3.07s (for now!) 4" Rough Country lift, 33x10.5x15 BFG KM2s

    '91 F350 XLT Lariat crew cab, 2WD SRW, 7.3l IDI, ZF S5-42, 3.55 LSD.

  7. #7
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    Dec 2003
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    Hi Casey
    I'v had the best luck letting gravity do the bleeding on clutch systems.I open the bleeder and watch the fluid coming out for air,close the bleeder and cycle the pedal a couple of times.Repete as nessesary, The first one i tried to bleed like brakes we used two bottles of fluid and never did get a firm pedal.
    Sometimes they can be a real pain.
    Good Luck
    Thomas
    90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews

  8. #8
    Join Date
    Dec 2000
    Location
    Walla Walla WA
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    Default

    I contacted LUK clutch tech folks on my swap. I had a military rig with the 6.2. I installed a 98 NV4500 with internal slave cylinder setup. The clutch they had me buy was not the standard 6.2, 6.5 found on the web. Had everything to do with the length of the bell housing, internal slave cyinder setup and a 6.2 vs a 6.5. So maybe the clutch diaphragm needs to be a certain height. Food for thought.

    Sounds easy but I do believe LUK clutch was purchased by another company.
    1994 K2500 ext cab. Recently repowered with; Non-cracked 599 block, factory compression, used old DSG girdle for main caps. Factory for what remains. Changed diffs to 3.42. Fuel economy Hwy 22.5 mpg US, in town without lcokup in 2nd/3rd - 18 mpg US.
    1994 K3500 CC LB Silverado. Next project. Built for endurance, power and gearing. Plan on opened up intake and exhaust sytem, best cooling mods, 4.11 gearing 4L80E, followed by Gear Vendors OD. Need to be able to split all gears and have lockup in 2nd/3rd/4th. Tan interior cloth, Bad ass dark blue (coming) aluminum wheels and air ride (coming)

  9. #9
    Join Date
    May 2015
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    Ct
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    1

    Default

    Quote Originally Posted by jggiedeman View Post
    I contacted LUK clutch tech folks on my swap. I had a military rig with the 6.2. I installed a 98 NV4500 with internal slave cylinder setup. The clutch they had me buy was not the standard 6.2, 6.5 found on the web. Had everything to do with the length of the bell housing, internal slave cyinder setup and a 6.2 vs a 6.5. So maybe the clutch diaphragm needs to be a certain height. Food for thought.

    Sounds easy but I do believe LUK clutch was purchased by another company.
    I know this thread is very old but how can a clutch from a 6.5 not work on a 6.2? Do you have a part number on the clutch you used?

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