Oil burning 408 help....
02-14-2007, 11:55 AM
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Oil burning 408 help.... Hey guys,
I have a 408 that's been in my truck now for about a month and a half, and I have put about 4000 miles on the motor. It burns about 2 quarts of oil per 1000 miles, and it is most noticeable at idle. If I have been cruising around and stop and let it idle it is fine initially, no smoke or oil smell. After about 30-45 seconds though it starts to get a little bit of blue/white smoke out the tailpipe, and if I blip the throttle I get a nice sized puff of oil smoke come out. If I hold the revs up the smoke will clear, and when I drop it back to idle it will take another 30 seconds or so before it starts smoking again.
I have run a compression test (180-190 psi all the way around) and a leakdown test (5% all the way around). I swapped to an LS6 valley cover and PCV setup. I am in the process of replacing the valve seals (did bank 2 already, still need to finish bank 1). Nothing has helped so far, and I'm just about out of ideas. I have been running VR1 20w50 oil the whole time as recommended by my builder. When I pulled the intake manifold for the valley cover swap I had a decent coating of oil in the runners, but none pooled in the bottom of the manifold or anything.
Motor is as follows:
6.0L iron block, bored .03 over
Callies 4" Dragonslayer crank
Compstar 6.125" rods
Diamond 11576 dish pistons, custom cut for 1/16, 1/16, 3/16 rings
TotalSeal gapless stainless top ring, ductile iron second ring, standard tension oil ring STD OIL,20LB+/–. TotalSeal P/N MS0390 35
TSP PRC stage 2.5 LS6 heads
LS2 truck intake manifold
LS6 valley cover/PCV system
Anyone have any ideas? The wrist pin on the piston does go through the oil ring, but my builder said he has done a lot of engines with pistons like that and never once had a problem with it.
I have a 408 that's been in my truck now for about a month and a half, and I have put about 4000 miles on the motor. It burns about 2 quarts of oil per 1000 miles, and it is most noticeable at idle. If I have been cruising around and stop and let it idle it is fine initially, no smoke or oil smell. After about 30-45 seconds though it starts to get a little bit of blue/white smoke out the tailpipe, and if I blip the throttle I get a nice sized puff of oil smoke come out. If I hold the revs up the smoke will clear, and when I drop it back to idle it will take another 30 seconds or so before it starts smoking again.
I have run a compression test (180-190 psi all the way around) and a leakdown test (5% all the way around). I swapped to an LS6 valley cover and PCV setup. I am in the process of replacing the valve seals (did bank 2 already, still need to finish bank 1). Nothing has helped so far, and I'm just about out of ideas. I have been running VR1 20w50 oil the whole time as recommended by my builder. When I pulled the intake manifold for the valley cover swap I had a decent coating of oil in the runners, but none pooled in the bottom of the manifold or anything.
Motor is as follows:
6.0L iron block, bored .03 over
Callies 4" Dragonslayer crank
Compstar 6.125" rods
Diamond 11576 dish pistons, custom cut for 1/16, 1/16, 3/16 rings
TotalSeal gapless stainless top ring, ductile iron second ring, standard tension oil ring STD OIL,20LB+/–. TotalSeal P/N MS0390 35
TSP PRC stage 2.5 LS6 heads
LS2 truck intake manifold
LS6 valley cover/PCV system
Anyone have any ideas? The wrist pin on the piston does go through the oil ring, but my builder said he has done a lot of engines with pistons like that and never once had a problem with it.
02-14-2007, 04:35 PM
#6
You might do well to run a vacuum pump and catch can. I've seen applications of the total seal gapless ring really pump up crankcase pressure. CC pressure could be high enough to push oil past the seals and guides, hense the smoke when blipping the throttle.
02-14-2007, 04:40 PM
#7
Originally Posted by mr2guru
You might do well to run a vacuum pump and catch can. I've seen applications of the total seal gapless ring really pump up crankcase pressure. CC pressure could be high enough to push oil past the seals and guides, hense the smoke when blipping the throttle.
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02-14-2007, 05:07 PM
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Originally Posted by ls1408cp
+1 Do you have any oil leaks? I would run a open breather setup. Did you break in the motor hard or soft?
I don't have any oil leaks at all. I've been watching my garage floor and have not seen a single drop.
Why do the TS gapless rings cause excessive crankcase pressure?
02-14-2007, 06:24 PM
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Call me an idiot, but how can increased Crankcase pressure have anything to do with an increased Cylinder pressure which could possibly be the cause of our friends problem.
I'd be all over that motor with a flashlight versus looking at your garage floor. Have you spoken with the person who built your motor? I guaruntee they can tell you a lot more about your motor than the people here who in some cases are only capable of proving how well they type.
And not to diss your mechanical ability, nor the original engine builders. But I'd have someone double check your valveguide seal job. I've heard of talented mechanics ripping motors apart due to this same issue when in reality, they barely slipped up while intallation of the guide seals.
..just my $.02
I'd be all over that motor with a flashlight versus looking at your garage floor. Have you spoken with the person who built your motor? I guaruntee they can tell you a lot more about your motor than the people here who in some cases are only capable of proving how well they type.
And not to diss your mechanical ability, nor the original engine builders. But I'd have someone double check your valveguide seal job. I've heard of talented mechanics ripping motors apart due to this same issue when in reality, they barely slipped up while intallation of the guide seals.
..just my $.02
02-19-2007, 07:31 PM
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I have spoken with the machinist who built the shortblock, and he wasn't able to help me much. Sounds like it's a problem with the heads and valve guides from what all of you are saying. If it's still burning oil after I replace the rest of the valve seals I'll have to get in touch with TSP and see if they can work with me on figuring this out.
02-21-2007, 07:26 AM
#13
Please keep us up to date on this and let us know when you figure it out. I am having a very similar problem. I burned almost a quart of oil last Friday night just from going to the track, beating it at the track and driving home. That's a shitload of oil if you ask me. I do have a small leak but it is like 4 drops on the garage floor from sitting over night. I have a small breather on the driver's side (back) valve cover and a large one on the passenger side (front) valve cover. I do still have the one hose attached that goes from the passenger side front valve cover up to the side of the TB. All others are capped.
02-21-2007, 07:43 AM
#15
Originally Posted by 98Z28CobraKiller
Please keep us up to date on this and let us know when you figure it out. I am having a very similar problem. I burned almost a quart of oil last Friday night just from going to the track, beating it at the track and driving home. That's a shitload of oil if you ask me. I do have a small leak but it is like 4 drops on the garage floor from sitting over night. I have a small breather on the driver's side (back) valve cover and a large one on the passenger side (front) valve cover. I do still have the one hose attached that goes from the passenger side front valve cover up to the side of the TB. All others are capped.
cobrakiller, dont forget about the possiblity of that thing dripping oil more heavily while driving down the road. if you have a crank case pressure problem, that will push oil out all the time will off idle under load, and maybe all your seeing is whats dripping off the oil pan afterwards. if you were burning oil that bad, you would def. smell it AND see the smoke behind you. my iroc did this and its very annoying. the smell is very strong. plus you'd see oil coming out your tailpipes and getting all over your rear bumper at the rate your describing. mine burned oil very bad at idle and it didnt go through oil like that. also pulling the plugs would be a good indication if your really burning it or not.
02-21-2007, 11:00 AM
#16
The first thing I would do is completely ditch the PCV system and run a breather.This will rule out any oil in the intake.I've seen alot of 408's suck in alot of oil in the intakes.
After 1k miles if it still uses excessive oil then I would look at the heads.
After 1k miles if it still uses excessive oil then I would look at the heads.
02-21-2007, 11:48 AM
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cobra killer... mine does the exact same thing... check your rear crank freeze plug next time you have a chance. mine leaks 4 drips off the back and when i dyno'd my car and tuned it that night i lost about the same amount of oil.. im not burning any oil.. its all leaking out.
02-21-2007, 11:49 AM
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Originally Posted by Slowhawk
The first thing I would do is completely ditch the PCV system and run a breather.This will rule out any oil in the intake.I've seen alot of 408's suck in alot of oil in the intakes.
After 1k miles if it still uses excessive oil then I would look at the heads.
After 1k miles if it still uses excessive oil then I would look at the heads.
02-22-2007, 09:38 AM
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I had already plugged off the driver's side port because I went to an LS6 valley cover - I capped off the PCV ports on the manifold and throttle body, left the driver's side valve cover port plugged, ran a hose straight from the valley cover to the passenger valve cover where the hose to the TB used to be, and put a cheapo breather in the oil cap. Hopefully that does the trick.