Problem Diagnosis?
12-13-2009, 07:05 PM
#1
Problem Diagnosis? So a while back, I broke my #7 intake rocker arm (6000 miles on the 408" motor). The rocker showed signs of interference, so I got a whole new set from Jesel.
Here's the thread.....
https://ls1tech.com/forums/generatio...m-failure.html
I got the new rockers, installed them, and there was a noticeable tick going on. I disconnected the coils, pulled the driver side valve cover, and turned the motor over. The #7 intake rocker sounded like it was making the noise and it felt very "jittery" while it was opening. I removed the #7 rockers and the noise went away.
I pulled the cylinder head expecting a bent valve or something, but the valves moved smoothly after I disassembled the #7 valvesprings. The roller on the #7 intake lifter looks fine and the cam also looks fine. The pushrods are also straight. The only other possible problem I can think of is something internally wrong with the lifter.
If the lifter was collapsed, would it be exhibiting these symptoms? If there is a problem with it, I think it is also what caused the rocker to break. I'm looking for what direction to take now. I can buy a new set of lifters and replace them on the driver side just to see, but if there's something I'm overlooking, I'd like to know before I put the head back on.
Also, after I ran the motor for 10-15 seconds and pulled the valve covers, oil had not yet begun to come out of the push rods. As we were cranking it over with the coils disconnected, oil began to seep out of the 1-3-5 pushrods, but not the #7 yet. Is it possible that there just wasn't enough oil in the #7 lifter to pump it up yet? It was sounding bad enough for me to do a tear down. The motor sat for 2 months or so before I tried running it with the new rockers.
Here's the thread.....
https://ls1tech.com/forums/generatio...m-failure.html
I got the new rockers, installed them, and there was a noticeable tick going on. I disconnected the coils, pulled the driver side valve cover, and turned the motor over. The #7 intake rocker sounded like it was making the noise and it felt very "jittery" while it was opening. I removed the #7 rockers and the noise went away.
I pulled the cylinder head expecting a bent valve or something, but the valves moved smoothly after I disassembled the #7 valvesprings. The roller on the #7 intake lifter looks fine and the cam also looks fine. The pushrods are also straight. The only other possible problem I can think of is something internally wrong with the lifter.
If the lifter was collapsed, would it be exhibiting these symptoms? If there is a problem with it, I think it is also what caused the rocker to break. I'm looking for what direction to take now. I can buy a new set of lifters and replace them on the driver side just to see, but if there's something I'm overlooking, I'd like to know before I put the head back on.
Also, after I ran the motor for 10-15 seconds and pulled the valve covers, oil had not yet begun to come out of the push rods. As we were cranking it over with the coils disconnected, oil began to seep out of the 1-3-5 pushrods, but not the #7 yet. Is it possible that there just wasn't enough oil in the #7 lifter to pump it up yet? It was sounding bad enough for me to do a tear down. The motor sat for 2 months or so before I tried running it with the new rockers.
12-13-2009, 07:27 PM
#3
Well my main question is if I do have a problem with that lifter (internally), is there any way to check now that I have it out of the motor? Most of the time, people have to diagnose lifter while they're in the car. I thought it was valves, so everything is already pulled.
12-14-2009, 10:20 AM
#6
Casey, sounds like a #7 lifter problem. If it turns, it can do all kinds of damage to your cam and rockers. If the heads are still off, pull the lifter trays and inspect #7 lifters and look at the cam lobes for unusual wear.
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2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
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2018 Cadillac Escalade 6.2L A10 Pat G tuned.
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2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2018 Cadillac Escalade 6.2L A10 Pat G tuned.
LS1,LS2,LS3,LS7,LT1 Custom Camshaft Specialist For custom camshaft help press here.
Custom LSX tuning in person or via email press here.
12-14-2009, 11:12 AM
#7
There are some known issues with Jesel and higher lift cams, but based on your description and the fact that only one rocker/cylinder appears to be the issue then I would look into why no oil. Have you looked at the oil supply on the passenger side?
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12-14-2009, 11:22 AM
#8
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Lifter could be getting starved by crud in the block bore
/ orifice that feeds it? Maybe pull the lifter and try to
pressurize the oil system somehow, see if anything can
be flushed out?
On my old SBCs that was easy, just pull the dist and
get the drill out with a junk distributor shaft. Dunno if
there is any such handy access on LS1s. But maybe
adapting up to that oil cooler port, or something?
/ orifice that feeds it? Maybe pull the lifter and try to
pressurize the oil system somehow, see if anything can
be flushed out?
On my old SBCs that was easy, just pull the dist and
get the drill out with a junk distributor shaft. Dunno if
there is any such handy access on LS1s. But maybe
adapting up to that oil cooler port, or something?