Rebuilt LS2 - Burning Coolant and Oil in Exhaust
10-05-2012, 07:13 AM
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Rebuilt LS2 - Burning Coolant and Oil in Exhaust I just re-built a LS2 408. The block was decked, new PRC 6.0 heads, new LS9 gaskets, etc...
....during 1st break-in I had the usual white smoke from Oil and rings which went away soon and engine idled good, everything progressed nicely (No leaks, good oil pressure, good temp, etc...)...
...when I started to run at 2000 rpms, white smoke began slowly coming out of the exhaust (dual) , I shut it down and checked for coolant in oil and visa versa... all looked normal. So I let it cool down, and cycled through start up again...once it was at temp I went back to 2000rpms and it started puking more white smoke and white/blue again, getting progressively worse. I shut it down quickly. The coolant in reservoir was boiling.
After it cooled again, I checked the plugs and they all were wet with what appeared to be oil. I looked at/changed the oil it it looked just slightly milky...but real hard to tell. I pulled the intake and noticed oil pooled behind all intake valves.
At this point I believe I have the following issues:
1) - Oil is getting sucked into intake somehow and pooling behind intake valves. Burning out exhaust in white/blue smoke
2) - Coolant is somehow leaking into oil passages causing the excessive white smoke out of the exhaust above idle.
So right off I'm thinking the heads and/or gasket are causing the problem, but with oil behind all valves I'm wondering if it's a crankcase pressure issue (oil getting pushed up through valve stems into intake) and with coolant burning in exhaust thinking gasket is the problem there.
The Q's I have are:
Has anyone else had issues using the 6.0L/L92 gaskets on PRC 6.0L heads? (i.e.- coolant leaking into oil return passages)?
Would bad valve seals on the heads be the culprit for the oil getting sucked in behind intake valves?
Looking for a logical/reasonable place to start before pulling the heads....
....during 1st break-in I had the usual white smoke from Oil and rings which went away soon and engine idled good, everything progressed nicely (No leaks, good oil pressure, good temp, etc...)...
...when I started to run at 2000 rpms, white smoke began slowly coming out of the exhaust (dual) , I shut it down and checked for coolant in oil and visa versa... all looked normal. So I let it cool down, and cycled through start up again...once it was at temp I went back to 2000rpms and it started puking more white smoke and white/blue again, getting progressively worse. I shut it down quickly. The coolant in reservoir was boiling.
After it cooled again, I checked the plugs and they all were wet with what appeared to be oil. I looked at/changed the oil it it looked just slightly milky...but real hard to tell. I pulled the intake and noticed oil pooled behind all intake valves.
At this point I believe I have the following issues:
1) - Oil is getting sucked into intake somehow and pooling behind intake valves. Burning out exhaust in white/blue smoke
2) - Coolant is somehow leaking into oil passages causing the excessive white smoke out of the exhaust above idle.
So right off I'm thinking the heads and/or gasket are causing the problem, but with oil behind all valves I'm wondering if it's a crankcase pressure issue (oil getting pushed up through valve stems into intake) and with coolant burning in exhaust thinking gasket is the problem there.
The Q's I have are:
Has anyone else had issues using the 6.0L/L92 gaskets on PRC 6.0L heads? (i.e.- coolant leaking into oil return passages)?
Would bad valve seals on the heads be the culprit for the oil getting sucked in behind intake valves?
Looking for a logical/reasonable place to start before pulling the heads....
10-05-2012, 07:34 AM
#2
Rocker bolts leaking oil into the ports??
Water: Pressure test the system, and see if you can detect where it's going. Do this with the plugs OUT. W/psi on the system, spin the engine on the starter...Water out the plug holes?
I'd not troubleshoot it w/ antifreeze in the system. Bearings WILL take a hit. [We always do initial starts w/ strait H2O.]
What do you have for crankcase ventilation?
Water: Pressure test the system, and see if you can detect where it's going. Do this with the plugs OUT. W/psi on the system, spin the engine on the starter...Water out the plug holes?
I'd not troubleshoot it w/ antifreeze in the system. Bearings WILL take a hit. [We always do initial starts w/ strait H2O.]
What do you have for crankcase ventilation?
10-05-2012, 09:33 AM
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Ecellent Chuck...can't thank you enough that is exactly the kind of expert help I was needing ...
The rocker bolts are protruding into runners...I'm going to check and make sure they are sealed. Also going to drain coolant and refill with H2O and begin the troubleshooting for coolant leak as you outlined.
The PCV is basically a stock LS1 design....PCV valve on back of driver side valve cover going into lower intake ports. Clean air from TB into passenger side valve cover. The valve covers have baffles underneath.
The rocker bolts are protruding into runners...I'm going to check and make sure they are sealed. Also going to drain coolant and refill with H2O and begin the troubleshooting for coolant leak as you outlined.
The PCV is basically a stock LS1 design....PCV valve on back of driver side valve cover going into lower intake ports. Clean air from TB into passenger side valve cover. The valve covers have baffles underneath.
10-05-2012, 01:54 PM
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Well....I replaced the coolant with water and did the pressure test...it holds for a little while but then slowly lets out pressure at about 1psi per minute
I turned the engine over (starter only) and no water came thru the spark plug holes.
I removed the headers and the exhaust runners are full of black tar/gunk....just like what was on the plug electrodes. Is that indicative of coolant/water getting into the exhaust runners ? Normally oil wouldn't get the greasy/gunky on it's own...right?
I am going to seal the rocker bolts that protrude into the runners and see if that eliminates the oil in the intake issue....
Not sure what to do with the coolant leak....With no water/coolant showing up in spark plug holes....it could still be the gasket leaking into chamber...yes?
I turned the engine over (starter only) and no water came thru the spark plug holes.
I removed the headers and the exhaust runners are full of black tar/gunk....just like what was on the plug electrodes. Is that indicative of coolant/water getting into the exhaust runners ? Normally oil wouldn't get the greasy/gunky on it's own...right?
I am going to seal the rocker bolts that protrude into the runners and see if that eliminates the oil in the intake issue....
Not sure what to do with the coolant leak....With no water/coolant showing up in spark plug holes....it could still be the gasket leaking into chamber...yes?
