Glitter in 6.2L oil ... please help

[rdezs]

.... And it's the cleaning I hate the most.

 

[rdezs]

On a side note, as it sounds like you're leaning towards keeping the AFM working.... The root cause of most failures is that VLOM manifold with the solenoids in it. Specifically it's usually one of those solenoids. One malfunctions, directs a lifter to do what it shouldn't do at the wrong time, and you have major engine damage. So if you're going to keep it it's probably good idea to go ahead and replace it, which should help somewhat with oil pressure as well as a preventative measure against a catastrophic failure. Even if you use one of the inexpensive devices that plugs into the OBD2 port to disable it, I would go ahead and replace it to address oil pressure issues. The genuine GM is about $260 on RockAuto. They also have one made by Dorman that supposedly is improved somehow, for about $180. I've got no experience or knowledge about the Dorman unit. The GM one, at least you know it's lasted however many miles you have right now.

When you're putting it back together, make sure you put a new screen in the hole where the oil pressure sending unit goes. And you might consider looking online, there's several sending unit relocation kits that move the sending unit to the end of a steel braided hose that you can wire tie up on the firewall. That makes it convenient way to swap in a mechanical gauge to verify pressures, and then just reinstall the OEM sending unit. Also makes future changes in checks a 5-minute ordeal.

And don't be surprised if you find half or more of the bolts securing the VLOM down loose. As in not even finger tight. That's pretty common. On assembly, a little bit of blue loctite on the threads will take care of that.

 

[j91z28d1]

The amount of peak horsepower you can get with the VVT cam is rather limited. A non BBT cam really opened the door up for higher horsepower. Generally as you add more horsepower with those cams, the power band is up high, and you lose the low end torque. The VVT.... Wether in an l92 without AFM or an old 94 with it.... Both make roughly 408 horsepower with lots of torque right off idle. It's sort of a compromise for driveability reasons. The best way to get the best of both worlds is with more displacement. Such as a 408 cubic inch stroker. There's so many choices in so many variables, it really does depend on what each person wants to use it for. For my wife's commuter and grocery getter, it's more than she'll ever need or use. (She gave it 3/4 throttle getting on the freeway and actually scared herself, LOL)
And if it's destined to be a family car, you might want to consider reliability. You start putting more lift on those valve springs, more pressure on the cam, result in a shorter overall engine life. But that's not a concern for someone after sheer horsepower.

One other veritable with cam shafts and low end torque is, Iobe separation angle, your stock cam is very wide, for smooth idle and clean emissions. the aftermarket can tightening that up, let it lope a bit and gain mid range(what most consider low end) and hp up top.


the ls7 stock cam shaft is a good example of this.. it's actually pretty big for a stock cam,( without looking it wouldn't surprise me if it's close to a stage 1 truck cam) it will allow a 7L engine with very very high flowing heads to pull cleanly to 7k rpm without dropping off. I actually smacked the Rev limiter passed 7k in one the first time I drove it, my ls3 car falls on its face well before redline and I never hit limiter. but idles dead smoothly and passes oem 50 state emissions. to do that it gives up mid range torque, but you don't gain as much hp up top as a normal mild cam shaft swap would.

you can take that 7L cam, drop it in a smaller size 6.2, which normally would allow the smaller engine to spin even more rpm. but a mild cam around the same spec but allows for a cammed out idle, but would never pass oem emissions would make more over all power from as little as 1500rpm up to the same redline.


so basically if your willing to swap in a small, say stage 1 truck cam with a good tune, it doesn't surprise me at all that you get more or the same low end power as a stock vvt setup does, and still make that extra 50hp up top most cam swaps are know for.

 

[Geotrash]

Generally as you add more horsepower with those cams, the power band is up high, and you lose the low end torque.

This is generally true, but truck cams are optimized for lower end power production. But of course there is significant variation between them in how well they do it. I ran 3 different "truck cam" grinds. One from Vinci, one from BTR, and the Cam Motion I have in there now, and it's superior to the others in both drivability and power output through the range. I chalk it up to the fact that Cam Motion sells a grind of each of their cams that's specific to the engine it's going into, taking advantage of the unique flow characteristics of the heads, etc. The others were ground as a compromise so they would "work" in the 4.8, 5.3, 6.0 & 6.2.

You start putting more lift on those valve springs, more pressure on the cam, result in a shorter overall engine life. But that's not a concern for someone after sheer horsepower.

Probably so, but there is precious little information out there with which to assess the tradeoffs between performance and probable durability, so folks like me end up choosing something in the middle that doesn't seem to push the limits too much. The lift on the Cam Motion cam is .553/.553 so I went with springs designed to handle the higher lift and did a trunnion upgrade, though the latter probably wasn't necessary. Stock is .500/.500 but lots of guys are running cams with .601/.601 lift from TSP and others. I was afraid to go that high because I had no way to assess the impact on durability, even with dual springs.

 

[thefrey]

On a side note, as it sounds like you're leaning towards keeping the AFM working.... The root cause of most failures is that VLOM manifold with the solenoids in it. Specifically it's usually one of those solenoids. One malfunctions, directs a lifter to do what it shouldn't do at the wrong time, and you have major engine damage. So if you're going to keep it it's probably good idea to go ahead and replace it, which should help somewhat with oil pressure as well as a preventative measure against a catastrophic failure. Even if you use one of the inexpensive devices that plugs into the OBD2 port to disable it, I would go ahead and replace it to address oil pressure issues. The genuine GM is about $260 on RockAuto. They also have one made by Dorman that supposedly is improved somehow, for about $180. I've got no experience or knowledge about the Dorman unit. The GM one, at least you know it's lasted however many miles you have right now.

When you're putting it back together, make sure you put a new screen in the hole where the oil pressure sending unit goes. And you might consider looking online, there's several sending unit relocation kits that move the sending unit to the end of a steel braided hose that you can wire tie up on the firewall. That makes it convenient way to swap in a mechanical gauge to verify pressures, and then just reinstall the OEM sending unit. Also makes future changes in checks a 5-minute ordeal.

And don't be surprised if you find half or more of the bolts securing the VLOM down loose. As in not even finger tight. That's pretty common. On assembly, a little bit of blue loctite on the threads will take care of that.

So after the new o-ring, the tick is still there but doesn’t seem to be as frequent or loud. I’m thinking one of my next steps is to replace the VLOM as you mentioned to not grenade the lifters.

Will a bad VLOM contribute to low pressure? The research I see is that it will but I’m not sure how much pressure will change with a new VLOM.

 

[thefrey]

Now you get to explain to your other half about the long list of stuff...."while we are in there"

Make sure you use the word 'we' so she feels part of everything

New water pump, serpentine belt, the pulley and tensioner, new hoses. Lol, everything is connected to something so the list is as long as you want to make it. Knowing when to stop is the most difficult thing!

I told my wife about this and she died laughing. It was even funnier when she realized it wasn’t about a random forum and it was about our Yukon

 

[rdezs]

Lol

Yes, the VLOM can be responsible for huge oil leaks. First off, it's pretty typical to find several of the bolts that hold it down barely finger tight. And it has to seal down against towers that have oil coming up through them.

It's also pretty common in your OEM oil pump, for the relief valve to get weak and bleed off oil at too low of a pressure, or to get a buildup of sludge and crud that interferes with its operation. Another good reason to go in for that timing chain, since the oil pump has to come off anyway.

"We" need to order some parts

 

[thefrey]

Lol

Yes, the VLOM can be responsible for huge oil leaks. First off, it's pretty typical to find several of the bolts that hold it down barely finger tight. And it has to seal down against towers that have oil coming up through them.

It's also pretty common in your OEM oil pump, for the relief valve to get weak and bleed off oil at too low of a pressure, or to get a buildup of sludge and crud that interferes with its operation. Another good reason to go in for that timing chain, since the oil pump has to come off anyway.

"We" need to order some parts

“We” need to order parts

“We” need to install them (this would never work lol)

Good to know. I’ll might as well do the VLOM soon since it’s a fairly easy install. I doubt the last owner replaced it when he did the lifters.

Is it worth just installing a new tensioner or a new chain + tensioner and not replacing the sprockets, etc?

 

[rdezs]

By the way, you'll see the eight towers with an oil port coming up through them when you lift off the VLOM. In an AFM delete, I plug those ports with steel plugs pounded in.

This is the underside of a VLOM that was bleeding off oil pressure. It ran for two oil changes on Valvoline restore and protect as an experiment to see if it actually cleaned anything. The clean spots are clearly where it was bleeding off oil pressure, and did a good job cleaning. The seal is that orange circle that goes over the oil port. Now when you find loose bolts you'll have a good idea.....

And when you remove your oil pump, take out the oil pressure relief valve and see if there's crud inside. Here's what the parts look like on an oem pump. Note the spring seems kind of corroded.

 

[rdezs]

I would do the sprockets, chain and tensioner. It's not overly expensive, and you really don't want to have to go back in there later on