Lm7 Build?

KIRK_PEAR

MEMBER
2001 CHEVROLET SILVERADO
5.3L
V8
4WD
AUTOMATIC
250,000 MILES

Engine will rotate both ways easily, then seizes in both directions. I have removed the starter, rockers, and push rods. During the installation, the engine rotated completely fine all the way after I installed the torque converter bolts. I completed the install, engine turned over and then seized. Now it only rotates roughly 5 rotations either way. Loved your LM7 build, followed it in my build, not sure where I went wrong.

7 Replies

RYAN L

ADMIN
261 POSTS

Hey thanks so much for watching!

So that is an interesting problem, if you let the engine sit for a while can you turn it over again easy?

My thinking is the oil pump relief valve is not working like it should. So, it is building pressure then locking solid. Then if you let it sit the pressure bleeds back into the pan and you can turn it over again.

Thanks for using 2CarPros!

Best,
Ryan

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Monday, September 11th, 2023 AT 10:15 AM

KIRK_PEAR

MEMBER
4 POSTS

The engine turns 5-6 rotations clockwise and counterclockwise and then binds. It will not rotate past those 2 points. It rotated fine after I connected the flex plate and converter, but now it has the bind at 2 separate points. The engine has never been started, just cranked over by hand. Can the oil pump and/or timing set dry out to cause a bind up like this?

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Monday, September 11th, 2023 AT 10:54 AM

RYAN L

ADMIN
261 POSTS

Right. But if you leave it alone for a few hours after it binds and come back, can you rotate it over again?

I do not think it is dry. I think the oil pump is building too much pressure and hydraulicly locking the rotating assembly. You can check for this by draining the oil out of the engine and then try turning it over by hand. Just do not forget to replace the engine oil before you start it.

Best,
Ryan

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Monday, September 11th, 2023 AT 11:59 AM

KIRK_PEAR

MEMBER
4 POSTS

I understand now. No, once it binds up, it stays seized, both directions. It will not turn any further no matter how long it sits. And it turned throughout the build.
Baffled.

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Monday, September 11th, 2023 AT 12:12 PM

RYAN L

ADMIN
261 POSTS

That is a real head scratcher!

Well, at this point I would take the oil pan off and look at the rotating assembly and see if you can find anything binding or any kind of witness marks.

If you cannot see anything then I hate to say it but, it might be time to take it fully apart and get to the bottom of this.

Best,
Ryan