Autopsy of dead LS6
Thread Starter
Teching In
Joined: Sep 2010
Posts: 5
Likes: 0
From: Tucson, AZ
Autopsy of dead LS6 I had an LS6 motor that self destructed about 2 weeks ago, this engine was in a short course off road truck. The motor had the oil changed just before that fatal race. I put Mobile 1 5W30 oil in the engine, this engine is mostly stock a fairly mild Comp cams, just a bit larger than the "Hot Cam" nothing too radical. I had the rev limiter set a 6300 RPM. I've never had any oil pressure issues with this engine.the oil pump is stock I believe.
When the engine let go I was running just under the rev limiter and had been for maybe 20 seconds. I don't usually push the RPM that high for that long but I had to that time. Water temp was normal . No unusual noises until it let go.
When I pulled the engine down I found two broken rods, both of the respective pistons had totally exploded both rods were in numerous pieces. it looks to me as though I spun # 5 & 6 rod bearings. My inspection found some minor scoreing on 2 more of the rod bearings, the rest of the rod bearings looked good. the main bearings all showed some scoring, but no melting of the bearing material.
The oil pump looks ok, there was some light scuffing of the cylinder walls on all cylinders except # 5&6 The block is wasted, the heads have some light damage but should be salvageable, at least one bent valve. The cam is damaged on a few lobes, one lifter was damaged,
This all looks to me as if it is an oil related issue, but I'm not sure. I'm going to have to build another engine but I don't want this to happen again. Where do I go from here? What weight oil do you guy's run? could this have been an issue. I've always run mobile 1 10W30 befor this.
When the engine let go I was running just under the rev limiter and had been for maybe 20 seconds. I don't usually push the RPM that high for that long but I had to that time. Water temp was normal . No unusual noises until it let go.
When I pulled the engine down I found two broken rods, both of the respective pistons had totally exploded both rods were in numerous pieces. it looks to me as though I spun # 5 & 6 rod bearings. My inspection found some minor scoreing on 2 more of the rod bearings, the rest of the rod bearings looked good. the main bearings all showed some scoring, but no melting of the bearing material.
The oil pump looks ok, there was some light scuffing of the cylinder walls on all cylinders except # 5&6 The block is wasted, the heads have some light damage but should be salvageable, at least one bent valve. The cam is damaged on a few lobes, one lifter was damaged,
This all looks to me as if it is an oil related issue, but I'm not sure. I'm going to have to build another engine but I don't want this to happen again. Where do I go from here? What weight oil do you guy's run? could this have been an issue. I've always run mobile 1 10W30 befor this.
TECH Addict
Joined: Sep 2009
Posts: 2,481
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From: PA/MD
All I'd be doing is guessing, but my guess would be stretched rod bolts.....or the dropped valve, but once you lost one rod the whole assembly was thrown off balance and that's what lead to the rest of the carnage
I don't think the weight of the oil was the problem bc 10w-30 and 5w-30 are the exact same viscosity once they heat up to operating temp, the only difference is that when cold the 5w is a little thinner than the 10w
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Verdad Gallardo Thread Starter
Teching In
Joined: Sep 2010
Posts: 5
Likes: 0
From: Tucson, AZ
I was running the truck pan, the angle was just about flat side to side and front to back, but pulling some G's not awhole lot. I was airborn for a second or two just prior to the only noise I noticed.
Yeah, I'd invest in an aftermarket dry sump system, 3 or 4 stage pump, with 10 quart tank. It will pricey up front, but it's the only way to ensure oil control, for what you are doing.
That truck pan isn't doing anything for you. It's designed for highway usage. There is a nice set up for sale here in the classifieds.
That truck pan isn't doing anything for you. It's designed for highway usage. There is a nice set up for sale here in the classifieds.
