12 Valve Engine and Drivetrain Talk about the 12V engine and drivetrain here. This is for 1994-1998.5 engine and drivetrain discussion only.

If I had a Bent valve/Broken Lifter, how would I know?

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Old Jan 23, 2007 | 07:14 AM
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Txwelder's Avatar
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If I had a Bent valve/Broken Lifter, how would I know?

Any thoughts. Im still chasing this noise and dont want to pull the head unless absolutely necessary. Thanks.
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Old Jan 23, 2007 | 07:20 AM
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From: grand junction co
it wouldnt run right. u would have a dead cyl.
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Old Jan 23, 2007 | 08:04 AM
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with the valve covers removed and engine running watch the valvetrain for any abnormal movement.
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Old Jan 23, 2007 | 08:40 AM
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remove the valve covers and pull the pushrods out and take a look..... You then can remove the inspection cover on the drivers side on the block to see the lifters.

Doug
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Old Jan 23, 2007 | 12:54 PM
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Well the truck runs fine and I readjusted the valves (2nd time in less than 6k miles) and it still sounds like I have a bum lifter while Im going down the road. Cant really hear it with the window down while driving or at idle, only while in the cab on the road/windows up. Driving me crazy. Cracked all injectors and they all make the engine change pace, lift pump is less than two years old and doesnt seem to have any slack in it when I push down on the rod while the engine is running, if that means anything. Im stumped trying to find what is making that awful sound.
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Old Jan 23, 2007 | 01:38 PM
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Pull the valve cover and with the engine idling feel each of the rocker arms/springs for roughness or vibration.
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Old Jan 23, 2007 | 04:54 PM
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Not sure how easy that may actually be but I will just take your word for it. Sounds a little risky, and besides, what am I going to feel while the rocker is moving and the truck is making its normal amount of ruckus? Thanks anyhow.
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Old Jan 23, 2007 | 05:07 PM
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From: SunnyVale Trailer Park
Originally Posted by Txwelder
Not sure how easy that may actually be but I will just take your word for it. Sounds a little risky, and besides, what am I going to feel while the rocker is moving and the truck is making its normal amount of ruckus? Thanks anyhow.
Unless you want to pull the cam out and inspect each lifter , or pull the head and start with the valves , all you can do is pull the push rods out and check for a bent one.

The other option is to pull the valve covers off like everyone has said , look for anything that is not right (ie one valve spring sitting down lower than the rest without a lifter holding it down. If you don't find anything that way, start the engine , look listen and feel for problems.

If you want to rule out valves , rockers , push rods etc as problems , that's how your going to have to do it , unless you want to take it ALL apart.
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Old Jan 23, 2007 | 05:10 PM
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From: Fruitport, MI
I don't know, but that is exactly how the service manual says to do it. You should be able to feel it if the lifter is taping, it would transfer right though the push rod tubes and into the rocker arm. Only other way I can think of is to pull them all out and see if one collapses easy or won't collapse at all.
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Old Jan 23, 2007 | 05:22 PM
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A bent or burnt valve will cause the engine to shudder (not smooth during acceleration) you can also hear a chirp in the exhaust if it's an exhaust valve.
On the intake side if you remove the air horn from the head you might here a chirp when reving. If you think you have "one" and continue to drive, your playing a high dollar game. You can destroy the block, head and turbo in seconds.
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Old Jan 23, 2007 | 09:45 PM
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From: Wet Coast, Canada
TX ~ When you adjusted the valves were they out or you just check them?
Do you have access to a laser temp gun? Try shooting each exhaust port at the same distance from the head while some one else power brakes it for a bit to build some heat. There is nothing to these tappets so other than one wearing (or the cam lobe) not much can be wrong. A wearing lobe or tappet will show up in valve lash and temp on that cyl.
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Old Jan 24, 2007 | 09:48 AM
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When I checked all the valves, the majority of them seemed to be loose. Not alot of resistance on the feeler gauge when inserting between rocker and valve. The truck runs fine, so I dont really know what could be wrong. It seems like the majority think if I had a bent valve or broken lifter that I would have some performance issues, which I dont. I am getting my new exhaust next week, maybe I am hearing a leak or vibration in the system, (not all the hangers are there since the straight pipe).
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Old Jan 24, 2007 | 10:02 AM
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TX, have you checked the overflow valve? A broken spring sounds just like a lifter/pushrod.
Easy things first!
george
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Old Jan 24, 2007 | 10:10 AM
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From: Texas
just changed it yesterday. No change. Thanks
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Old Feb 6, 2007 | 01:02 PM
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I have all the valve covers off right now and have spun the push rods but cant really tell if anything is bent. I would love to pull them all and roll them to see if they are bent but I dont have a torque wrench to reinstall everything. Should I be able to tell a bent push rod while it is in the motor? Any thoughts?
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