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Old 12-19-2009, 10:48 PM
 
Location: Earth
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Wanted to see how common it is to have lifter bleed down, and how does it affect engine idle/runability? Does it basically make the hydraulic lifters dead/not work?
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Old 12-20-2009, 08:20 AM
 
Location: Fly-over country.
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Hydraulic lifters?

Here's a site with sound clips of good idle and bleed down idle...
Hydraulic Lifters

Problem is, when the site loads, both files (MP3s) will play so you have to stop one, listen to the first, then start the second.

If you've got rollers, what are they doing? I don't think it's common unless they are flawed (???) You'd know it though.

I'm not too up on internals myself.
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Old 12-20-2009, 10:56 AM
 
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Your only going to get bleed down if they are worn out.. springs get weak, cylinder bore gets worn and widened out, etc. What it will do is give you slop between lifter to pushrod or pushrod to rocker arm, since it can no longer keep pressurized and take slack out of the system like its supposed to do. This slop allows the pushrods to start slamming against the lifters and rocker arms this makes other things get slammed, valve timing is off... engine will run poorly.

Hydraulic lifters are great for non-high performance applications... in the high performance, the engine RPMs get too high the lifter's internal springs and bore can't keep up with increased force of the oil pressure and the high frequency of oscillation. They will not adjust fast enough, give you slop and will probably break apart.

Solid lifters... are solid! Not ideal for the average engine. Solid lifters are pretty much unaffected by heavy loads and high RPMs however they do not constantly take the slack out of the system like hydraulics do and routinely need to be adjusted for.

Rollers are available in both flavors... instead of having a flat tappet interface between the lifter and cam lobe you now have a wheel. Great for reducing friction and wear, but the added complexity makes them a weaker design IMO.
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Old 12-20-2009, 02:12 PM
 
Location: Earth
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Thanks...the issue I'm having is when the engine is started when cold, it will lope like if it had a HUGE cam installed...for about 10-20 seconds then the idle clears up. Once cleared up it will idle smooth as butter.

It's a '91 model 4.3 liter V6 engine vin code Z. It's throttle body injected and not an actual Vortec engine. The ECM only has 2 codes, one for a MAP sensor and the other for a brief low voltage to the fuel pump but that was a direct result of the loping, at least I believe so.

Someone reported the brief rough idle could be from lifter bleed down and then someone else thinks it's an IAC issue. The valve train doesn't make any racket like the one in the video in the link you posted. Also I believe the camshaft used in my engine was a roller.
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Old 12-20-2009, 02:54 PM
 
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Quote:
Originally Posted by Deez Nuttz View Post
Thanks...the issue I'm having is when the engine is started when cold, it will lope like if it had a HUGE cam installed...for about 10-20 seconds then the idle clears up. Once cleared up it will idle smooth as butter.

It's a '91 model 4.3 liter V6 engine vin code Z. It's throttle body injected and not an actual Vortec engine. The ECM only has 2 codes, one for a MAP sensor and the other for a brief low voltage to the fuel pump but that was a direct result of the loping, at least I believe so.

Someone reported the brief rough idle could be from lifter bleed down and then someone else thinks it's an IAC issue. The valve train doesn't make any racket like the one in the video in the link you posted. Also I believe the camshaft used in my engine was a roller.
Yep, thats a hydraulic roller system with that motor. You may want to check how quick they are bleeding down by taking the motor up to temp, shutting it off and then starting it an hour later, hour and a half later, two hours later... etc. My 350 L05 used to do the same in very cold temps, never had a problem. You want to look into getting new lifters if the valvetrain is rackety all the time... they are cheap and easy to replace.

For now, I would say your just fine.
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Old 12-20-2009, 02:58 PM
 
Location: Earth
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Usually if the engine is restarted within a few hours of shut down it restarts no issues. It's usually when it sits overnight is when it lopes. Depending on how cold it is seems to determine how long it lopes for.
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