Help: LB7 overheat and burning oil

[bmemmott]

I need some help / opinions. I have an 03 Chevy dually with 215,000 miles. Friday I was driving along and all of a Siddons the coolant temp shot up and it started bellowing white / blue smoke from the tailpipe. I pulled over and shut it down. I checked the oil to see if there was a coolant oil mix but it was so low it didn't read on the stick. So I let it cool off and started it up to pull off the hwy. it ran good and made good oil pressure but still blew a lot of smoke. I slowly drove off the hwy and right before I shut it off I heard a little "pop" and oil started dumping out the back of the motor.

The overheating was caused by a broken heater core quick connector. But I can't figure out why it was blowing smoke / burning oil. I did a compression test today 7 were at 375 and 1 was 325. Now I am going to pull the transmission to see where the oil is coming from.

Any opinions or suggestions? Is 325psi bed enough to burn a lot of oil?

Thanks
Brian

 

[Balindir]

I'm not sure why low compression would make it burn oil? Almost sounds like a head-gasket, but that doesn't explain the oil running out. Unless its leaking around the cylinder where the gasket might be blown.

 

[bmemmott]

I was under the impression that if a cylinder had low compression it could mean bad rings which would allow oil to get into the cylinder.

 

[ironmax]

i think your turbo went out. bad seal could allow oil to be shot into the motor. that much oil could of made its way through intercooler.
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[bmemmott]

I forgot to mention that all boost tubes are clean. No oil.

 

[ripmf666]

Check to see if your pcv valves in the valve covers are working fine. The spring inside can screw up and also the line can back up. This would cause more crank case pressure and if you look we're the oil is coming out from most likely its the rear main seal blew out.

 

[bmemmott]

I got the trans out Monday night and finally got the flex plate off (WOW are those bolts tight) and the rear main was just hanging there. I'm going to try and buy new PVC valves. Any other suggestions?

 

[ripmf666]

I got the trans out Monday night and finally got the flex plate off (WOW are those bolts tight) and the rear main was just hanging there. I'm going to try and buy new PVC valves. Any other suggestions?

The flywheel bolts there tty so they will need replaced now. Also you will need a new rear main seal.

Is the rear main seal damaged at all ? Also when removing the pcv check valves from the valve covers see if the spring has life left in it. Check to see if line is pluged shuts going to front vent. There is a reason for this so you want to hunt it down.

 

[bmemmott]

The flywheel bolts there tty so they will need replaced now. Also you will need a new rear main seal.

Is the rear main seal damaged at all ? Also when removing the pcv check valves from the valve covers see if the spring has life left in it. Check to see if line is pluged shuts going to front vent. There is a reason for this so you want to hunt it down.

Thanks. I already ordered new bolts and seal from the Chevy dealer (won't be here until Friday) The rear main looked fine, like it just popped out. I am going to check the pcv valves and lines tomorrow. Hopefully I will find the problem.