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Ls7 lifter not staying pumped up

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Old 07-10-2018, 07:53 PM
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Default Ls7 lifter not staying pumped up

Alright heres the deal. A friend and myself have been building a 370 for my TA for about 2 months now. FINALLY we go to start the car and notice a pretty loud valvetain noise. He says its normal because the lifters are pumping up so give it some time. Well its been almost a week now, found out that he measured wrong preload, swapped out the 7.38" pushrods for 7.400. Made some difference but not enough. Today we found out that I need 7.425 based off the pushrod checker we got.
We also noticed that a lot of the valvetrain noise is on the driver side. Cant hear anything on passenger hardly. He told me that the GM ls7 lifters were not pumping up and were bleeding off.
Also, while it on the lift we lifted it up, and we are hearing (on the driver side) loud clattering from the header into the y pipe. Like an exhaust leak.
Mods are: btr stage 4 cam, btr dual springs, 7.400 chromemoly comp cam pushrods (switching to 7.425), ported 706 heads
Is there something im missing here?
I think my friend is at a pretty big loss right now on what to do. He said he has never seen this and is saying maybe the lifters are bad.
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Old 07-10-2018, 08:01 PM
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How is your oil pressure?
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Old 07-10-2018, 08:02 PM
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Originally Posted by G Atsma View Post
How is your oil pressure?
Its great. 60lb when started up, 50 when hot
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Old 07-10-2018, 08:11 PM
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Dash gauge or mechanical?
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Old 07-10-2018, 08:15 PM
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Originally Posted by G Atsma View Post
Dash gauge or mechanical?
Its dash gauge. It has always ran fine before, so I never hooked it up to a mechanical one.
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Old 07-10-2018, 08:28 PM
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Need more info. Was the block decked? Were the heads milled? Are the lifters new? Was a valvejob done on the heads? What headgasket?
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Old 07-10-2018, 08:39 PM
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Originally Posted by Che70velle View Post
Need more info. Was the block decked? Were the heads milled? Are the lifters new? Was a valvejob done on the heads? What headgasket?
Block was not decked. Heads were not milled. Lifters are brand new. No valve job. GM .048 head gasket.
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Old 07-10-2018, 08:50 PM
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Originally Posted by lsx4thewin View Post
Block was not decked. Heads were not milled. Lifters are brand new. No valve job. GM .048 head gasket.
That rules out a machining error that would require you to use different length pushrods. Throw the 7.425Ē pushrods at it and see what happens. Iíve seen where these lifters wanted shorter pushrods to quiet themselves also.
Are they GM lifters, or the eBay units?
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Old 07-10-2018, 08:54 PM
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Originally Posted by Che70velle View Post


That rules out a machining error that would require you to use different length pushrods. Throw the 7.425Ē pushrods at it and see what happens. Iíve seen where these lifters wanted shorter pushrods to quiet themselves also.
Are they GM lifters, or the eBay units?
They are GM. We were going to go with a shorter one because we were told a 7.350" might work better, but it didn't measure out to be that we needed shorter.
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Old 07-10-2018, 08:57 PM
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Try the other and keep us posted.
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Old 07-10-2018, 09:00 PM
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Originally Posted by Che70velle View Post
Try the other and keep us posted.
Could the pushrod be the cause tho of the lifter not staying pumped up??
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Old 07-11-2018, 10:42 AM
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Originally Posted by lsx4thewin View Post
Could the pushrod be the cause tho of the lifter not staying pumped up??
Probably not a pump up issue...unless you got a bad batch, which is doubtful. Itís more than likely just lifter tick due to wrong pushrod length, but itís tough to guess at this stuff without being there and hearing first hand.
Your oil pressure readings override bearings or lifter clearance issues. Rocker bolts were torqued to 22 ft lbs, correct?
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Old 07-11-2018, 06:30 PM
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Originally Posted by Che70velle View Post


Probably not a pump up issue...unless you got a bad batch, which is doubtful. Itís more than likely just lifter tick due to wrong pushrod length, but itís tough to guess at this stuff without being there and hearing first hand.
Your oil pressure readings override bearings or lifter clearance issues. Rocker bolts were torqued to 22 ft lbs, correct?
I remeasured for pushrod length and got 7.425. Swapped some in, and now im hearing noise from the whole valve train rather than the driver side. It really sounds like the lifters are no good. Even though I know its unlikely that all 16 are bad I think several are. Noise is getting louder now. Going to check oil pressure mechanically and then pull heads if oil pressure is good.
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Old 07-11-2018, 07:05 PM
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Originally Posted by Che70velle View Post


Probably not a pump up issue...unless you got a bad batch, which is doubtful. Itís more than likely just lifter tick due to wrong pushrod length, but itís tough to guess at this stuff without being there and hearing first hand.
Your oil pressure readings override bearings or lifter clearance issues. Rocker bolts were torqued to 22 ft lbs, correct?
And yes they were torqued to 22 ft lbs
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Old 07-11-2018, 07:14 PM
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Here is the video


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Old 07-11-2018, 08:33 PM
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Geesh man...the video makes it almost sound like an exhaust leak. Pull the covers and see if it’s oiling well up there.
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Old 07-11-2018, 09:08 PM
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Originally Posted by Che70velle View Post
Geesh man...the video makes it almost sound like an exhaust leak. Pull the covers and see if itís oiling well up there.
Its got 50lbs of oil pressure on mechanic gauge.
Also it is oiling when I pulled the covers.
When the car was on a lift, the headers were making the clattering sound that you hear in the video. But I didnt know an exhaust leak could be that bad where im hearing it in the engine bay??
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Old 07-11-2018, 09:19 PM
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Here is another video. We are trying to see where this is coming from and its from the rear of the engine.

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Old 07-11-2018, 10:17 PM
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Exhaust leaks can be sneaky to figure out. It’s amazing the tricks that they can pull concerning where the sound is coming from. I’m not saying that you don’t have a valvetrain issue, but the videos sound like exhaust leaks to me. I’d chase the rabbit down that path first. Replace both header gaskets if you have to. The GM MLS exhaust gaskets are great. I run ARH headers on my Chevelle, and one of my flanges requires that I double up exhaust gaskets to make it seal. Those are $1300 headers. Don’t take anything for granted here. Check your flanges under the car as well for tightness. Once your sure it’s not an exhaust leak, then re-visit the valvetrain.
I went on a 100 mile drive once, and developed an exhaust leak. Or so I thought. I had the carbon stain above my drivers side header flange, so I changed the gasket. Still there. Turned out I had a rocker bolt loosen up. I’ve read several threads on here, and other sites, concerning the same issues, with valvetrain noise being exhaust, and vise-versa.
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Old 07-16-2018, 01:42 PM
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The best way I've found to check the manifold gaskets for leaks, or really any exhaust leak, is to get a mechanics stethoscope and pull the end off leaving the rubber hose, then stick a piece of metal brake line in the end and bend the end a little for getting up under the manifold. Trace the whole manifold flange edge with it, you'll know when you find the leak, you'll hear it and it'll blow in your ear a little. It doesn't blow hot air up the tube it just blows air toward the air that's already in the tube.. I could see someone reading this and getting worried they will burn their ear lol.


And to most, exhaust leaks sound exactly like lifters
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