New LS7 is hurting...
New LS7 is hurting... GM Crate LS7 Heads/Cam/MSD intake:
I was doing a highway pull in 3rd gear shifting at about 7,000 RPM and I heard something break up underneath. The car immediately bogged and lost a ton of power.
I was able to coast off the highway and limp it home to my driveway. I let it cool down, checked for any DTC codes with my HP tuner and none were found.
1. I started the car and there is a ton of white smoke for starters, could be an associated symptom but not main issue.
2. There is a wrap/or clanging can't discern if its valvetrain or bottom end.
Not sure if something let go during the pull, but I have to diagnose as best I can to see how screwed I am. LS3 dropped a valve last June. Brand new Crate LS7 installed in August. LME Brodix BR7 ported Heads/MSD Intake recently installed.
2nd motor in a year and not getting into another expense unless its top end valvetrain.
I have the Aftermath Startup clip from the engine bay and an undercar clip, so top and bottom. Depending on which you listen to, you might tend to say that direction, so I need a REALLY experienced ear, Please. I am not likely to be doing any manual diagnosis myself, I need to choose which direction I am going to go with it based on severity/costs.
Below is link to instagram of 2 clips. One under car and one from the topside.
kinda shitty i cant post these direct...
I was doing a highway pull in 3rd gear shifting at about 7,000 RPM and I heard something break up underneath. The car immediately bogged and lost a ton of power.
I was able to coast off the highway and limp it home to my driveway. I let it cool down, checked for any DTC codes with my HP tuner and none were found.
1. I started the car and there is a ton of white smoke for starters, could be an associated symptom but not main issue.
2. There is a wrap/or clanging can't discern if its valvetrain or bottom end.
Not sure if something let go during the pull, but I have to diagnose as best I can to see how screwed I am. LS3 dropped a valve last June. Brand new Crate LS7 installed in August. LME Brodix BR7 ported Heads/MSD Intake recently installed.
2nd motor in a year and not getting into another expense unless its top end valvetrain.
I have the Aftermath Startup clip from the engine bay and an undercar clip, so top and bottom. Depending on which you listen to, you might tend to say that direction, so I need a REALLY experienced ear, Please. I am not likely to be doing any manual diagnosis myself, I need to choose which direction I am going to go with it based on severity/costs.
Below is link to instagram of 2 clips. One under car and one from the topside.
kinda shitty i cant post these direct...
Last edited by Rich2342; Jul 24, 2023 at 02:56 PM.
TECH Enthusiast
Joined: Sep 2019
Posts: 532
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You are dealing with too much money to just rely on something online. Tear it down, starting with your intake, PCV, coolant, and that to find the source of the white smoke. Find the problem, and save your engine. Pray its just a head gasket or something.
TECH Resident
Joined: Mar 2012
Posts: 861
Likes: 404
From: Texas
I need to figure what the damage is top end or bottom or both and make some kind of decision.
I'm hating to even THINK about saying this, but knowing the LS7 pretty well, and with the reputation it has regarding dropping valves.....If the engine lost a ton of power, and is pouring white smoke out, sounds to me like a dropped valve. No LS7 is immune to this. Actually, no OHV engine is immune to it. But the LS7 has a bad reputation for dropping valves, and I don't like your odds on this one. Very sorry, it SUCKS. I've been wrong before, but whatever is wrong is more than a head gasket, IMHO...
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Seems louder on pass side from top view. But…video underneath says it’s a rod. White smoke would tell me coolant, so that’s a headgasket or cracked head…which could have hydro locked a cylinder and bent a rod…but not usually at 7k rpm. That rpm usually makes a big mess with holes…
Heres where you should start and it’s the easy stuff…
1. Pull valve covers and look for springs/valves, or rocker issues
2. Pull spark plugs and inspect plugs. Plugs tell a lot of data
3. Pull the oil filter off and cut it open with the correct $40 tool. The filter element tells a lot of data also.
4. Look for coolant in the oil, or oil in the coolant.
From these 4 steps, you should have a direction to go. Keep us posted.
Heres where you should start and it’s the easy stuff…
1. Pull valve covers and look for springs/valves, or rocker issues
2. Pull spark plugs and inspect plugs. Plugs tell a lot of data
3. Pull the oil filter off and cut it open with the correct $40 tool. The filter element tells a lot of data also.
4. Look for coolant in the oil, or oil in the coolant.
From these 4 steps, you should have a direction to go. Keep us posted.
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Verdad Gallardo Definitely a bent rod. Exactly what mine sounded like after it went lean under an over boost condition on a pull during tuning session.
In my case, It bent #2 and #7 in the direction of the rod pin and the counter weight was hitting the bottom of the piston's. I was able to put 2 used pistons and rods in along with new gaskets. Reused the bearings and rings from there respective hole's with a light 320 Ball hone and sent it...
In my case, It bent #2 and #7 in the direction of the rod pin and the counter weight was hitting the bottom of the piston's. I was able to put 2 used pistons and rods in along with new gaskets. Reused the bearings and rings from there respective hole's with a light 320 Ball hone and sent it...
Jay I bet your right about the cracked sleeve…would explain the white smoke and the LS7 blocks are notorious for cracking a sleeve. Spark plug should show coolant on that cylinder.
GM Crate LS7 Heads/Cam/MSD intake:
I was doing a highway pull in 3rd gear shifting at about 7,000 RPM
Not sure if something let go during the pull, but I have to diagnose as best I can to see how screwed I am. LS3 dropped a valve last June
2nd motor in a year and not getting into another expense unless its top end valvetrain.
I was doing a highway pull in 3rd gear shifting at about 7,000 RPM
Not sure if something let go during the pull, but I have to diagnose as best I can to see how screwed I am. LS3 dropped a valve last June
2nd motor in a year and not getting into another expense unless its top end valvetrain.
Pulling the dipstick would tell you if there was coolant in the pan. Seriously doubt it has anything to do with the cylinder heads but coolant into the crankcase or in a cylinder is all bad. Very much sounds like a rod knocking to me..
Just pulled both valve covers.
Looks like some milkiness??
All valves, rockers and springs are accounted for. At a minumum these are salvageable!. 5 k or more in top end alone.
I wont attempt much else on my own.
What can we conclude are the culprits? And issue?
1. If not a dropped valve what would cause the bottom end to go with under 5k?
2. Granted this was a crate, this engine sat on the shelf. There was rust on cylinder walls when the oem heads were removed. The fact that driving wouldn't have removed it, is concerning. The installed consulted Chad Gollins, Gollins engines, and he scuffed it out and installed my heads.
3. I had some exhaust work a few weeks ago and the tech said he smelled antifreeze. Car was fine at that point.
Thoughts?
Check the oil dipstick like suggested earlier. If the oil is tan then there is water in it. If the oil level is high then there's something other than oil in it.
At the end of the day the engine is going to have to be opened up, so the things you're doing right now are really just for your own curiosity because whoever does the work is going to redo everything you just did and more.
At the end of the day the engine is going to have to be opened up, so the things you're doing right now are really just for your own curiosity because whoever does the work is going to redo everything you just did and more.
Looks like chocolate milk on the rockers. So many times guys say white smoke, and it isn't, it's whitish with blue tint. In this case, I'm glad I was wrong about the dropped valve, but I didn't see where you'd swapped heads. The only way this could be on the head builder, and I'm certainly not saying that it is, but the only way would be that if they set up the guide to stem clearance too tight. Example: If new guides were pressed in, and the press was too tight, the guides would collapse more than they should. If they didnt size the guides/check guide to stem clearance, that would be the only way you could blame them. This would create possibilities that the valve stems stuck in the guides. If the valves were hitting the pistons from the moment the engine was first fired, you'd hear it sounding like a typewriter from the get-go, if you know what a typewriter is, LOL!! You nailed it on the chocolate milk when you stated "looks like some milkiness. However, I still think PTV wasn't checked, and there wasn't any, or enough....
Last edited by grinder11; Jul 28, 2023 at 01:18 PM.
Just pulled both valve covers.
Looks like some milkiness??
All valves, rockers and springs are accounted for. At a minumum these are salvageable!. 5 k or more in top end alone.
I wont attempt much else on my own.
What can we conclude are the culprits? And issue?
1. If not a dropped valve what would cause the bottom end to go with under 5k?
2. Granted this was a crate, this engine sat on the shelf. There was rust on cylinder walls when the oem heads were removed. The fact that driving wouldn't have removed it, is concerning. The installed consulted Chad Gollins, Gollins engines, and he scuffed it out and installed my heads.
3. I had some exhaust work a few weeks ago and the tech said he smelled antifreeze. Car was fine at that point.
Thoughts?