Chevy and GMC Duramax Diesel Forum banner
1 - 11 of 11 Posts

· Registered
Joined
·
2 Posts
Discussion Starter · #1 ·
Hello! So I’ve got a 2007 LBZ no aftermarket. Yesterday it ran beautifully but decided to change the oil since I had recently bought it. I changed the oil to rotella T4 15w40 and used a Mobil 1 filter, after changing it had a slight abnormal vibration and the oil pressure was reading 60 at idle. Shut it down and drained some oil out of it then filled it back up to half way up the dipstick after that I turned it back on but now it was running with a hard vibration and a very loud rhythmic knocking that grew with RPM. Shut the truck down checked everything again started it and now it won’t turn over like it’s completely seized. Please help, I’m very worried about this…
 

· Registered
Joined
·
1,221 Posts
Hello! So I’ve got a 2007 LBZ no aftermarket. Yesterday it ran beautifully but decided to change the oil since I had recently bought it. I changed the oil to rotella T4 15w40 and used a Mobil 1 filter, after changing it had a slight abnormal vibration and the oil pressure was reading 60 at idle. Shut it down and drained some oil out of it then filled it back up to half way up the dipstick after that I turned it back on but now it was running with a hard vibration and a very loud rhythmic knocking that grew with RPM. Shut the truck down checked everything again started it and now it won’t turn over like it’s completely seized. Please help, I’m very worried about this…
60psi is not abnormal (at least for my LMM) when starting it from ambient temp. I dont have the knowledge that others have on this site but there is nothing there that would concern me.

Cant speak to the vibrations but when you pulled oil from the engine... did you see any discoloration in the oil or any flakes/debris? When i spun a rod bearing in my old DD the oil came out chocolate milk color and had 'glitter' in it.

You say you're stock. Any codes being thrown? Kinda nice being stock b/c you wont have to eliminate aftermarket stuff.
Check for codes regardless if no light is on (trust but verify).
Lastly, i know this might sound dumb but... check your fuses. They all look good?

Best of luck man.
 

· Registered
Joined
·
7,475 Posts
If it ran beautifully and then you changed the oil, your problem is not likely the kind that would cause a seized engine. Make sure your batteries are fully charged. You did nothing but change the oil and filter? When you turn the key to start what happens? Does this starter click or make any noise? You definitely have a problem, but it's probably solvable with some expertise.
 
  • Like
Reactions: BIOTEC and BoiseRob

· Administrator
Joined
·
19,360 Posts
Check your front pulley, typically these are either a broken crank (my first assumption) or could be a failed CP3 (would not cause vibration). There are some other potentials, but if it ran you could look at the harmonic balancer as you'll normally see the vibration.

I would try turning it over manually personally to see how it feels, if it turns over turn it over two full rotations.
 
  • Like
Reactions: BoiseRob

· Registered
2004.5 Chevy Silverado 2500HD LS. LLY Duramax, Allison Auto 5-spd. CCLB SRW 4x4. H2 Rims. Stockish
Joined
·
37 Posts
I'm guessing the engine wire harness. In particular, right around the oil filter. Maybe the entire bank of injectors is shorting out? I have lots of engine qire harness issues!
 
  • Like
Reactions: jfh00jfh

· Registered
Joined
·
621 Posts
Sounds like the fuel pressure sensor may be shorted which causes the CP3 to apply full fuel and can create one heck of a knock and load your cylinders. You may have hydraulic lock from too much fuel. Had this happen to my LBZ. Sensor is located on the PAX side above #5 & 7 but short could be anywhere.
 

· Registered
Joined
·
56 Posts
Since it is new to you, I also recommend taking it to a full service dealer experienced with diesels. Some small rural dealers are not. A goog dealer may be able to pull up the maintenance history on it. Maybe its because I'm retired LEO, but I'd suspect the previous owner saw failures of the crankshaft end coming and loaded it down with engine preservatives such as the old STP people used to use. (Haven't seen that in a long time.) When you removed these with the oil change, the old problems returned?
 

· Registered
Joined
·
7,475 Posts
If you are concerned about the engine being hydro locked, you could pull the glow plugs and that would allow compression, fuel, etc to escape from the cylinders.
 
1 - 11 of 11 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top