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Thread: Troubleshooting Lift Pump

  1. #41
    Join Date
    Feb 2007
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    2,926

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    When the lifter is in the back of the cam position, any force from the push rod, will overcome the weak spring in the lifter, and push the tiny piston down, releasing the oil back into the gallery. So yes, they automatically adjust. I can't see why it isn't, unless it's piston is already fully depressed, meaning the valve stem is to long. Get cyl one valves both closed, and try getting a screwdriver between the rocker and valve stem, see if it moves the pushrod down and leaves clearance. Otherwise try my shim experiment, if the compressions stay good, you are stuck with grinding the ends off the valve stems or using permanent shims. I can't imagine seized lifters, unless you bought + 10 thou ones, or installed them turned so they were damaged by the retaining plates.
    Grant H.
    1995 6.5 turbo GMC K2500 extra cab 4x4 pickup, PMD under bumper, mechanical wastegate, 228,000 miles, rebuilt engine, 4.10 diff, 16 mpg
    1994 6.5 turbo GMC K2500 4x4 suburban #9 resistor, PMD in the bumper, mechanical waste gate, 226,000 miles, 3.73 diff, 16 mpg
    1982 4x4 shortbed 6.2 Chev 260,000 miles untouched motor 17 MPG 4.27 diff. Best thing I ever owned, since 1992.

  2. #42
    Join Date
    Mar 2009
    Location
    Folsom, CA
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    194

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    Here’s the latest:
    Compression with rockers in place:
    Cyl 1,2,3,4,5,7 = 0psi
    Cyl 6,8 = 300+psi (gauge doesn’t go higher than 300)

    I couldn’t get a screwdriver between the valve stem and rocker.

    I made sure the lifters weren’t turned and that the guide plate was secure before I tightened the retainer.
    Mike
    1994 K2500 Suburban 316,000 mi., F VIN, 4L80E, 3.73 w/posi., 3" turbo back, no cat, FSD Heat Sync, #9 resistor, SSD heads, SSD intake, fuel miser injectors, Bastard IP (5068), 4x4 posi, Cooling upgrade w/duel 180° t-stats and d-max fan

  3. #43
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    Feb 2007
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    It is now more confusing because both heads have a compression problem. You need to measure a push rod length, and compare with an old one. Where did the parts come from?
    Grant H.
    1995 6.5 turbo GMC K2500 extra cab 4x4 pickup, PMD under bumper, mechanical wastegate, 228,000 miles, rebuilt engine, 4.10 diff, 16 mpg
    1994 6.5 turbo GMC K2500 4x4 suburban #9 resistor, PMD in the bumper, mechanical waste gate, 226,000 miles, 3.73 diff, 16 mpg
    1982 4x4 shortbed 6.2 Chev 260,000 miles untouched motor 17 MPG 4.27 diff. Best thing I ever owned, since 1992.

  4. #44
    Join Date
    Mar 2009
    Location
    Folsom, CA
    Posts
    194

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    All the push rods on the drivers side are the same length as the old one I kept. I’ll pull the passenger side out tomorrow and check them.

    I bought them from SSDiesel. As well as the lifters, valves and head.
    Mike
    1994 K2500 Suburban 316,000 mi., F VIN, 4L80E, 3.73 w/posi., 3" turbo back, no cat, FSD Heat Sync, #9 resistor, SSD heads, SSD intake, fuel miser injectors, Bastard IP (5068), 4x4 posi, Cooling upgrade w/duel 180° t-stats and d-max fan

  5. #45
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    Feb 2007
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    I bought the lifters rods and rockers from rock auto because SSD didn't stock all of the parts, they worked fine, then bought 2 heads from SSD and used one for a few minutes, it worked fine. I am mystified as to why the valves won't close on your engine. I shouldn't ask this, but did you use head gaskets?
    Grant H.
    1995 6.5 turbo GMC K2500 extra cab 4x4 pickup, PMD under bumper, mechanical wastegate, 228,000 miles, rebuilt engine, 4.10 diff, 16 mpg
    1994 6.5 turbo GMC K2500 4x4 suburban #9 resistor, PMD in the bumper, mechanical waste gate, 226,000 miles, 3.73 diff, 16 mpg
    1982 4x4 shortbed 6.2 Chev 260,000 miles untouched motor 17 MPG 4.27 diff. Best thing I ever owned, since 1992.

  6. #46
    Join Date
    Mar 2009
    Location
    Folsom, CA
    Posts
    194

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    It’s a worthwhile question... yes I did.

    I’ve been thinking about it a lot and what has changed during rebuild, considering it did run before I pulled it apart. Only thing I can think is that I soaked the lifters in mineral spirits to remove storage oil and then immediately soaked in clean motor oil. Is that the possible cause of all of this? Only thing I can think is that this caused the lifter plunger to seize but I would have thought even then, they would flush out. For what it’s worth, I couldn’t compress them by hand prior to installation.
    Mike
    1994 K2500 Suburban 316,000 mi., F VIN, 4L80E, 3.73 w/posi., 3" turbo back, no cat, FSD Heat Sync, #9 resistor, SSD heads, SSD intake, fuel miser injectors, Bastard IP (5068), 4x4 posi, Cooling upgrade w/duel 180° t-stats and d-max fan

  7. #47
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    Feb 2007
    Posts
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    There is so much "use silicone instead of gaskets" these days, I had to ask. The mineral spirits question ......? What is it other than a non viscous liquid, well low viscosity. I don't think that is the problem, I had one apart, but years ago, so I don't remember well how it functions, but there is a valve system at the top, as well as the piston and the oil gallery hole below, for when the lifter is down to release pressure. However, I could not see why the lifter was failing to hold pressure. Is there oil in the head area, when the lifters function, they bleed a lot of oil up the inside of the push rods, that will indicate something. A lot of pressure is needed to compress the spring in a lifter, difficult to re-assemble. I may not be able to respond until tomorrow night, you need to try to push the lifters down when the valves are closed.
    Grant H.
    1995 6.5 turbo GMC K2500 extra cab 4x4 pickup, PMD under bumper, mechanical wastegate, 228,000 miles, rebuilt engine, 4.10 diff, 16 mpg
    1994 6.5 turbo GMC K2500 4x4 suburban #9 resistor, PMD in the bumper, mechanical waste gate, 226,000 miles, 3.73 diff, 16 mpg
    1982 4x4 shortbed 6.2 Chev 260,000 miles untouched motor 17 MPG 4.27 diff. Best thing I ever owned, since 1992.

  8. #48
    Join Date
    Feb 2007
    Posts
    2,926

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    Send SSD an email, they are helpful, the parts are theirs, and they may have seen the problem before.
    Grant H.
    1995 6.5 turbo GMC K2500 extra cab 4x4 pickup, PMD under bumper, mechanical wastegate, 228,000 miles, rebuilt engine, 4.10 diff, 16 mpg
    1994 6.5 turbo GMC K2500 4x4 suburban #9 resistor, PMD in the bumper, mechanical waste gate, 226,000 miles, 3.73 diff, 16 mpg
    1982 4x4 shortbed 6.2 Chev 260,000 miles untouched motor 17 MPG 4.27 diff. Best thing I ever owned, since 1992.

  9. #49
    Join Date
    Mar 2009
    Location
    Folsom, CA
    Posts
    194

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    Thanks Grant. I’ve been in contact with Walt. He’s been really helpful. I’ll let you know what I find out. All indications point to the lifters not compressing enough to allow the valves to close.

    Thanks for all your help.
    Mike
    1994 K2500 Suburban 316,000 mi., F VIN, 4L80E, 3.73 w/posi., 3" turbo back, no cat, FSD Heat Sync, #9 resistor, SSD heads, SSD intake, fuel miser injectors, Bastard IP (5068), 4x4 posi, Cooling upgrade w/duel 180° t-stats and d-max fan

  10. #50
    Join Date
    Feb 2007
    Posts
    2,926

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    Good, Walt was helpful with my engine, I hope he comes up with a solution, I'll wait for results.
    Grant H.
    1995 6.5 turbo GMC K2500 extra cab 4x4 pickup, PMD under bumper, mechanical wastegate, 228,000 miles, rebuilt engine, 4.10 diff, 16 mpg
    1994 6.5 turbo GMC K2500 4x4 suburban #9 resistor, PMD in the bumper, mechanical waste gate, 226,000 miles, 3.73 diff, 16 mpg
    1982 4x4 shortbed 6.2 Chev 260,000 miles untouched motor 17 MPG 4.27 diff. Best thing I ever owned, since 1992.

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