3800Pro Forums banner
1 - 7 of 7 Posts

·
Registered
Joined
·
4 Posts
Discussion Starter · #1 ·
I have a 2000 Pontiac Bonneville and I just put a used motor in it. I got it all installed and it was running great. I turned the car off and went to restart it and nothing. It just sounded like the starter was freewheeling so i bought a new starter and same thing. I pulled the inspection cover off and then had my wife try it again. The flexplate was spinning with the starter but the serpentine belt wasnt. So i that the motor was locked up. I can turn it over by hand with ease and it also is turning the flexplate. So my question is why cant i get the car to start?
 

·
Super Moderator
Joined
·
875 Posts
Sounds like you didn't quite get the flexplate bolts right, and they sheared off or backed out.

You'll need to lift out the engine and put new flexplate-to-crank bolts in, along with fresh flexplate-to-converter bolts since those will have to come off to get it on the engine first. Torque to spec (they are meant to stretch, so need to drop $5-10 each install) and use red loctite for a little peace of mind. This has worked for me on 3800's from stock to 500+whp that have been on the road 10-15yrs since.
 
  • Like
Reactions: Budd3800

·
Registered
Joined
·
4 Posts
Discussion Starter · #3 ·
Sounds like you didn't quite get the flexplate bolts right, and they sheared off or backed out.

You'll need to lift out the engine and put new flexplate-to-crank bolts in, along with fresh flexplate-to-converter bolts since those will have to come off to get it on the engine first. Torque to spec (they are meant to stretch, so need to drop $5-10 each install) and use red loctite for a little peace of mind. This has worked for me on 3800's from stock to 500+whp that have been on the road 10-15yrs since.
Thank you i was thinking maybe the crankshaft positioning sensor too?
 

·
Super Moderator
Joined
·
875 Posts
You said it wasn't spinning the belt while the starter turned the flexplate, so my reply is based on that.

If the belt/crank/balancer is turning, you can pull one plug and ground the side to see if it's firing while cranking. Just be careful to not touch it while it's cranking, or you'll risk a shock. You can rest or tape it somewhere stable for this.
 
  • Like
Reactions: Budd3800

·
Registered
Joined
·
4 Posts
Discussion Starter · #5 ·
You said it wasn't spinning the belt while the starter turned the flexplate, so my reply is based on that.

If the belt/crank/balancer is turning, you can pull one plug and ground the side to see if it's firing while cranking. Just be careful to not touch it while it's cranking, or you'll risk a shock. You can rest or tape it somewhere stable for this.
Good point. Ill start pulling the motor tomorrow. I just knew i was gonna have to mess with the one pain in the ass bell housing bolt again. Lol
 

·
Super Moderator
Joined
·
875 Posts
Long extension thru the passenger wheel well after the diff bracket is off... Or I think a GearWrench works when the exhaust is off.
 
1 - 7 of 7 Posts
Top