08 Sierra Won't Turn Over Following Cam Swap---Help Diagnose
06-08-2017, 06:16 AM
#1
08 Sierra Won't Turn Over Following Cam Swap---Help Diagnose
Alright, need a little help here guys. My brother called me a few weeks ago with a chirping noise coming from his motor. He had replaced a couple of pulleys and his belts thinking it may be a pulley bearing going bad, but that didn't fix it. Ended up taking it to a dealer to check it out, and they told him it was a lifter going bad. It didn't sound like a normal lifter tick, but I pulled both drive belts, and the chirp was still there. Ok, so maybe it is a lifter...
The dealer wanted to charge him $4400 to replace the cam and lifters in it. I told him nah, bring it by the house and I would take care of it for him.
Fast forward to today. I have everything swapped out, it was in fact a no good lifter. I replaced everything with factory spec parts (he's not into hotrodding). I went to crank the motor a couple of nights ago, and it won't turn over. The starter just clicks once or twice, and then stops. Things I have done so far...
1)I have checked the battery, even tried a new one. Battery is fine.
2)I have turned the motor over by hand, spins over just fine. No interference or anything causing it to bind up.
3)I jumped the starter to check it in the car, it engages but just barely wants to spin the motor over (if it spins it at all). Took it out, bench tested it at Advance, checked out good. Got back home last night, swapped the starter from my 03 Sierra to his truck, and it just clicked once and stopped. Starter isn't the problem.
I'm thinking it has to be a ground issue or something, but I can't think of one that I took loose that I haven't hooked back up. The only ones that I can think of that I disconnected were the harness ground by the passenger side injectors that connects to the front of the passenger side head and the ground strap that runs from the back of the driver's side head to the firewall by the brake booster.
Any ideas? The truck is a 2008 GMC Sierra with a 4.8. I'm really hoping it's just a wiring/electrical issue because I'd hate to dig back into this thing again.
The dealer wanted to charge him $4400 to replace the cam and lifters in it. I told him nah, bring it by the house and I would take care of it for him.
Fast forward to today. I have everything swapped out, it was in fact a no good lifter. I replaced everything with factory spec parts (he's not into hotrodding). I went to crank the motor a couple of nights ago, and it won't turn over. The starter just clicks once or twice, and then stops. Things I have done so far...
1)I have checked the battery, even tried a new one. Battery is fine.
2)I have turned the motor over by hand, spins over just fine. No interference or anything causing it to bind up.
3)I jumped the starter to check it in the car, it engages but just barely wants to spin the motor over (if it spins it at all). Took it out, bench tested it at Advance, checked out good. Got back home last night, swapped the starter from my 03 Sierra to his truck, and it just clicked once and stopped. Starter isn't the problem.
I'm thinking it has to be a ground issue or something, but I can't think of one that I took loose that I haven't hooked back up. The only ones that I can think of that I disconnected were the harness ground by the passenger side injectors that connects to the front of the passenger side head and the ground strap that runs from the back of the driver's side head to the firewall by the brake booster.
Any ideas? The truck is a 2008 GMC Sierra with a 4.8. I'm really hoping it's just a wiring/electrical issue because I'd hate to dig back into this thing again.
06-08-2017, 07:05 AM
#2
Do you have a volt meter? Are you familiar with volt drop testing? Not trying to be a smart ***. I try not to assume anything when helping. If you can perform a volt drop on the +starter cable during a cranking attempt and then a volt drop from the starter to the negative battery post, this should tell you what portion of the circuit is bad. I can explain volt drop if needed but I'm sure YouTube has far better examples. If you have any more questions let us know.
06-08-2017, 07:25 AM
#3
You're not being a smart *** at all. I am mechanically minded, not electrically. Just before I saw this response I had just run across a page about checking the voltage drop across the positive and ground circuits. I will check that this afternoon. I have a feeling this will point me in the right direction. Thanks for the response. My Dad left me his volt meter yesterday, so I have one to check it now.
06-08-2017, 02:07 PM
#4
There are two grounds coming from the main harness that connect to the block and behind the drivers side head as you stated (g103 & g104)
Has to be dropping a ground somewhere for the voltage to fall off. Best advice is to check everything you touched on the electrical side again...best bet it's in there.
Last edited by darkirish63; 06-08-2017 at 02:14 PM.
06-09-2017, 05:58 AM
#5
Sorry I haven't been back on since yesterday morning. Didn't have a chance to do any troubleshooting last night because my parents came over for dinner. I was sitting there talking to Dad about it after dinner, and I had an epiphany when I was telling him about the plans to check the voltage drops...I didn't remember ever doing anything with the main ground wire coming from the battery. Didn't remember ever taking it off when I tore the motor down, but figured I might check just in case...
Went down and checked it....yep, it was just hangin there. Apparently it was also grounded to the spot on the front of the passenger side head, and I just didn't make a note of it when I took the other small harness ground loose from there.
I didn't have the starter put back on the truck last night, and it was already about 9:30, so I'm going to try and crank it tonight. Thanks for the help guys. I told my brother it was going to be something simple causing it...just didn't think it would be that simple.
Went down and checked it....yep, it was just hangin there. Apparently it was also grounded to the spot on the front of the passenger side head, and I just didn't make a note of it when I took the other small harness ground loose from there.
I didn't have the starter put back on the truck last night, and it was already about 9:30, so I'm going to try and crank it tonight. Thanks for the help guys. I told my brother it was going to be something simple causing it...just didn't think it would be that simple.