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Old 05-10-2017, 10:26 PM
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Default 97 Rocker Valve Adjustment

I understand the rocker valves can't be adjusted, but some research I read said its a must if I removed anything removing the rocker arms, such as the heads, which I did to replace blown head gasket.

Any who, when I came to the point to reinstall the rocker arms and rods, I just placed them in and tightened them down, torqued at 40 lbs. Truck starts up then has loud knocking, then dies. Did more research and says I'm supposed to turn the engine to TDC #1 and finger tighten them, then tighten them until there's no play in the rod, then torque them to 20 lbs . So now I'm guessing I over tightened them, which is why it doesn't stay started after it fires up. So this time when I adjusted them today, I just watched the rods extend all the way just before they drop, then finger tightened them, then tightened them to what I thought was 20 lbs of torque ( No Torque Wrench ). Letting battery charge before I try to fire it up again .... ​​​Could that be right ? What happens when you over tighten the rocker valves and try to start engine ?

Also, just by watching the lifters, am I adjusting them right ? If not, can someone expierenced in this area please simplify how to correctly adjust the lifter/rocker arms, specifically on a 1997 Blazer VIN "W" 4.3 Vortec !? Thanks in advance !!
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Old 05-11-2017, 08:00 AM
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I think your engine probably has the bearings knocked out of it by running with no oil pressure as you previously described. Thought you was going to replace this engine (the one with the head gasket replaced that had a problem with the oil pump drive shaft).
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Old 05-11-2017, 10:26 AM
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I think your engine probably has the bearings knocked out of it by running with no oil pressure as you previously described. Thought you was going to replace this engine (the one with the head gasket replaced that had a problem with the oil pump drive shaft).
I just lifted it and took the pan off, the bearings were fine. My oil pressure sensor was broke and didnt realize it, causing no oil pressure on the dash gauge. Do you know how to do the proper valve adjustment on this year model ?
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Old 05-11-2017, 10:48 AM
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Originally Posted by Tynan Tha Real Dill View Post
I just lifted it and took the pan off, the bearings were fine. My oil pressure sensor was broke and didnt realize it, causing no oil pressure on the dash gauge. Do you know how to do the proper valve adjustment on this year model ?
With the net lash arrangement of these engines, you torque down the rocker arm nut and its done. There is no adjusting them. Simply torque the nuts to 20 ft lbs. 20ft lbs or 40 ft lbs, the nut comes up against a stop and doesn't turn anymore. As long as you don't twist or break the stud, it won't have made any difference in the adjustment. You will need to look elsewhere for your problem.

Last edited by Lesmyer; 05-11-2017 at 10:52 AM.
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Old 05-11-2017, 11:23 AM
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With the net lash arrangement of these engines, you torque down the rocker arm nut and its done. There is no adjusting them. Simply torque the nuts to 20 ft lbs. 20ft lbs or 40 ft lbs, the nut comes up against a stop and doesn't turn anymore. As long as you don't twist or break the stud, it won't have made any difference in the adjustment. You will need to look elsewhere for your problem.
I've had it scanned twice and no trouble codes came up both times. My uncle is a mechanic of 20+ years, he scanned it with a $300 Boshe Scanner, when he seen no codes he assumed the lifters were too tight. He said if their too tight the engine won't start and if it does it'll stall. So I'm going to charge this battery and try to start it. After that, I don't know where else to go...no trouble codes, no security light, no engine light, and crank but no start ? I'm stumped...
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Old 05-11-2017, 12:27 PM
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Quote:
Originally Posted by Tynan Tha Real Dill View Post
I've had it scanned twice and no trouble codes came up both times. My uncle is a mechanic of 20+ years, he scanned it with a $300 Boshe Scanner, when he seen no codes he assumed the lifters were too tight. He said if their too tight the engine won't start and if it does it'll stall. So I'm going to charge this battery and try to start it. After that, I don't know where else to go...no trouble codes, no security light, no engine light, and crank but no start ? I'm stumped...
  • Do you have correct compression on all cylinders (need compression tester)
  • Do you have correct fuel pressure (need fuel pressure gauge)
  • Do you have electrical pulses to your injectors (need noid light)
  • Do you have spark at 1) the coil, 2) at the spark plugs, and ) if 1,2 is OK then is the distributor oriented in a manner that will distribute the sparks correctly. (All of this can be checked with an extra spark plug and a pair of vice grips to hold it to engine ground)
Scanner will not tell you any of these things, but may be needed later for something else.

If you want to go through these things, collect the tools and we can begin. Many can be borrowed with deposit from a local parts store. Otherwise I'm not going to be able to help you.

Last edited by Lesmyer; 05-11-2017 at 12:34 PM.
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Old 05-11-2017, 12:57 PM
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Quote:
Originally Posted by Lesmyer View Post
  • Do you have correct compression on all cylinders (need compression tester)
  • Do you have correct fuel pressure (need fuel pressure gauge)
  • Do you have electrical pulses to your injectors (need noid light)
  • Do you have spark at 1) the coil, 2) at the spark plugs, and ) if 1,2 is OK then is the distributor oriented in a manner that will distribute the sparks correctly. (All of this can be checked with an extra spark plug and a pair of vice grips to hold it to engine ground)
Scanner will not tell you any of these things, but may be needed later for something else.

If you want to go through these things, collect the tools and we can begin. Many can be borrowed with deposit from a local parts store. Otherwise I'm not going to be able to help you.
Ok I appreciate the list of tools I need, I have a light tester and a multimeter, can any of those be substituted for the noid light ?
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Old 05-12-2017, 08:06 AM
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Originally Posted by Tynan Tha Real Dill View Post
Ok I appreciate the list of tools I need, I have a light tester and a multimeter, can any of those be substituted for the noid light ?
It's possible, but quite difficult to make the connections with a test light. Better to get or borrow a noid light (they're quite inexpensive) and be sure to get the correct spacing to fit your wiring harness where it plugs into the MPFI Spider.

The first three things to check are so easy and quick.....

Test the fuel pressure at the Schrader valve with key on engine off. Should go up to around 58-60 psi for 2 seconds when the key is first turned on and then drop back maybe 5psi when the fuel pumps shuts itself off. System should hold this pressure for a while. If you find a problem - we will have to fix it.

If Fuel pressure is OK - then remove the connector that goes into the top of the MPFI spider. Inspect the pins in the Spider for any bent ones, and the connector for any damaged or backed out wire terminals. If OK, install the noid light across the circuit of your choice and have someone crank the engine while you watch. If light flashes you're good on a lot of things. If not, we will have to fix it.

If first two tests are OK, disconnect the coil wire at the distributor and install a spark plug into the end. Ground the spark plug to something metal by clamping lightly in place with the vice grips. Have someone crank the engine while you watch. You should observe spark out of the coil. If not, we will have to fix it.

Go through this stuff and report. These are the quick easy things that can send us in the right direction. If all of this is OK, we can go on to more difficult things to do. If you find a problem with the easy checks, then we can focus on that.

Last edited by Lesmyer; 05-12-2017 at 08:14 AM.
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Old 05-12-2017, 02:21 PM
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Quote:
Originally Posted by Lesmyer View Post
It's possible, but quite difficult to make the connections with a test light. Better to get or borrow a noid light (they're quite inexpensive) and be sure to get the correct spacing to fit your wiring harness where it plugs into the MPFI Spider
Ok I'll buy a noid light kit, where exactly would I plug in the noid light ? Do I need to remove the upper intake to get to it or is the wiring connected on top of the spider ? Or the name of the piece so I can google it. I really appreciate the info man, real big help !!
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Old 05-12-2017, 07:59 PM
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Originally Posted by Tynan Tha Real Dill View Post
Ok I'll buy a noid light kit, where exactly would I plug in the noid light ? Do I need to remove the upper intake to get to it or is the wiring connected on top of the spider ? Or the name of the piece so I can google it. I really appreciate the info man, real big help !!
Its just the connector that plugs into the top of the spider. Unclip it on both sides, disconnect it, and turn it over to plug the noid light in. Just pick any pair of the 12 terminals (2 for each cylinder). You'll see when you do it. If not just ask. Don't forget to inspect the pins in the tp of the spider that push into the connector for being straight - and the wiring terminals for in the connector for not being pushed back.

PS I'll be flying out of state starting early tomorrow morning to attend my son's wedding. Be back Sunday eve. So don't get discouraged it I don't answer in the meantime, but I might get on my cell tomorrow night if things break up early. Can't promise.

Last edited by Lesmyer; 05-12-2017 at 08:03 PM.
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