Few things I wonder about.

[SpareParts]

What makes rear main seals go bad? Could it be the PVC system becoming partly plugged causing the crankcase pressure to rise slightly?
If you're rear main is leaking do you have the old or new style valve cover?

Most high mile 6.2s all seam to have low hot idle oil pressure and bad cam bearings. Is this caused by a bad O ring starving the cam bearings of the flow they need?
A new O ring and HV oil pump restores oil pressure but the damage to the bearings has already been done. Can the HV oil pump and O ring save it?
Seems like after a new HV oil pump and O ring they keep chugging along.

What happens if you take an old style valve cover and make the oil drain back holes slightly larger allowing the oil to drain better and not get sucked up into the PVC system?

I have a few more but these the top questions.

 

[mikez71]

I'm thinking crankcase pressure wouldn't cause a leak, if it did, once the PCV was fixed, it should seal again?

I don't think oil drains will help with the oil mist.. I thought it determined to be the location of the PCV to the the rockers?
Bigger drains might allow more blowby to cause more oil mist?

I always just assumed the more agressive 6.2 cam was putting more pressure on the cam bearings.

 

[Doubeleive]

one of these days I will probably throw a melling 10355hv on this 6.2 when the time is right to kill multiple birds with one stone
I wouldn't mind looking at higher oil pressure
when I had a rebuilt motor put in my 00 (5.3) that thing was solid at 68-71 psi no matter hot cold

 

[mikez71]

I'm at 23psi hot idle on a 237k mile 5.3.

 

[Doubeleive]

when I bought this 2012 low oil pressure was one of my concerns, turned out I was right but 3rd party insurance covered it. I guess these things are generally ok with low psi supposedly..... I don't care for it though.

 

[Scrappycrow]

Seals go bad mostly due to simple aging causing shrinkage and hardening. "High mileage" oils have additives that are supposed to rejuvenate them.

To improve the old-style valve covers, I'd lightly fill them with stainless or copper (real copper, not copper-plated steel) pot scrubbers. I've done this on other vehicles' PCV chambers/troughs and have seen significant improvement.

The main problem with the pickup o-ring going bad is the aeration of the oil. Not only does aeration effectively reduce the oil volume, more importantly the oil froths and loses its bearing capacity when it hits things like cam bearings which are "open" on the sides. At the delivery hole, the pressure is close to the system pressure, but by the time the oil gets to the sides, the pressure is zero (this is with or without aeration); with aeration, those bubbles expand and blow out, effectively leaving you with a frothy oil film at the center and no oil film at the sides. A somewhat poor analogy is that people drown in roiling water not only because they're tossed around, but because they lose significant buoyancy.

IMO, most situations don't benefit from an HV pump. Yes, I used them myself from when I started building engines in the early '80s, but testing in the last decade has shown that they mostly just waste power (and in the case of those driven by distributors, wear out your gears). Pressure is created by volume passing restrictions, and to put it simplistically, if you have sufficient pressure, you have sufficient volume. If you have low pressure due to excessive bearing clearances and/or low viscosity due to temperature, an HV pump might be beneficial (but remember that the HV pump itself will increase oil temperature).

 

[LsHart]

I do know there is a TSB on 2014ish silverados. That the timing chain guide has rubbed a hole in the feed side of the oil pump. New chain set and pump needed to replace ofcourse.

 

[03GMCYukonXL]

I don't know but I ordered this for this exact reason and it seems to have help tremendously

amazon.com/dp/B00754T6TK?ref=ppx_yo2ov_dt_b_fed_asin_title

 

[Fless]

I don't know but I ordered this for this exact reason and it seems to have help tremendously

amazon.com/dp/B00754T6TK?ref=ppx_yo2ov_dt_b_fed_asin_title

Might want to clean up that link so it points to one product.

 

[SpareParts]

Seals go bad mostly due to simple aging causing shrinkage and hardening. "High mileage" oils have additives that are supposed to rejuvenate them.

Is the same true for PTFE seals?

To improve the old-style valve covers, I'd lightly fill them with stainless or copper (real copper, not copper-plated steel) pot scrubbers. I've done this on other vehicles' PCV chambers/troughs and have seen significant improvement.

That's not a bad idea at all.

The main problem with the pickup o-ring going bad is the aeration of the oil. Not only does aeration effectively reduce the oil volume, more importantly the oil froths and loses its bearing capacity when it hits things like cam bearings which are "open" on the sides. At the delivery hole, the pressure is close to the system pressure, but by the time the oil gets to the sides, the pressure is zero (this is with or without aeration); with aeration, those bubbles expand and blow out, effectively leaving you with a frothy oil film at the center and no oil film at the sides. A somewhat poor analogy is that people drown in roiling water not only because they're tossed around, but because they lose significant buoyancy.

I get what you're saying

IMO, most situations don't benefit from an HV pump. Yes, I used them myself from when I started building engines in the early '80s, but testing in the last decade has shown that they mostly just waste power (and in the case of those driven by distributors, wear out your gears). Pressure is created by volume passing restrictions, and to put it simplistically, if you have sufficient pressure, you have sufficient volume. If you have low pressure due to excessive bearing clearances and/or low viscosity due to temperature, an HV pump might be beneficial (but remember that the HV

Once the O ring goes bad and it gets replaced some oil pressure might be regained.
If the O ring was not bad a new O ring does not improve anything. Because the #2 cam bearing is bad.
With at least one bad bearing the engine will benefit from a HV oil pump. With the increase volume there is more pressure. With the increase in volume it creates a band aid for the failed part.
Every 6.2 i have seen the cam bearings in were bad, without a doubt and #2 is always horrible.
I have no way to measure oil temp but i would imagine being a street driven engine that any increase in oil temp is negligible.
I think we are saying about the same thing just going about it different.

 

[OR VietVet]

What makes rear main seals go bad? Could it be the PVC system becoming partly plugged causing the crankcase pressure to rise slightly?
If you're rear main is leaking do you have the old or new style valve cover?

Most high mile 6.2s all seam to have low hot idle oil pressure and bad cam bearings. Is this caused by a bad O ring starving the cam bearings of the flow they need?
A new O ring and HV oil pump restores oil pressure but the damage to the bearings has already been done. Can the HV oil pump and O ring save it?
Seems like after a new HV oil pump and O ring they keep chugging along.

What happens if you take an old style valve cover and make the oil drain back holes slightly larger allowing the oil to drain better and not get sucked up into the PVC system?

I have a few more but these the top questions.

I'm thinking crankcase pressure wouldn't cause a leak, if it did, once the PCV was fixed, it should seal again?

I don't think oil drains will help with the oil mist.. I thought it determined to be the location of the PCV to the the rockers?
Bigger drains might allow more blowby to cause more oil mist?

I always just assumed the more agressive 6.2 cam was putting more pressure on the cam bearings.

I truly believe that lack of pcv venting because of whatever problems, causes oil leaks and the weaker sealing areas go first. Once the oil starts leaking, there is a "path" for the leak and just fixing the venting problem is likely not gonna fix the leak.

Regular oil changes, and I am not talking about 10-12k miles or once a year either and a quality oil filter, will go a very long way to keeping the oil leaks dry.

Mind you, not the only reason because age plays a big part, but initially, lack of proper maintenance is, again IMO, the biggest contributor to oil leaks.

 

[j91z28d1]

my 2 cents is it seems ls gm just used good gasket design with a bad rubber that doesn't hold up to oil long term. old Gen 1 with a single rear main lasted basically forever. the pan gaskets didn't thou, but a felpro oil pan gasket lasts the life of the car. so since the rear main plate leaks, the oil pan gasket, the front seal, the valve covers and vlom and afm lifter boss gaskets. they all seem to start leaking like clock work in these engines. in my mind it's gasket material.

as for oil pressure, the hybrid engine use a pump like the LT but without the pwm control, so they are max displacement at anything below the set pressure. so they basically run 60psi at all times, only time I see it under 45 is if I force it to idle after atleast 45mins of driving, finally it's warm enough on a 100deg day at 600rpm to drop off the max pressure. by a 1000 rpm it's back to 60ish. these trucks are not meant to idle basically ever so efficiency wise they didn't care. so they live life at basically what the afm bypass pressure is. and while I haven't pulled one apart to look at cam bearings, I will be curious what they look like if I ever do have mine apart. the afm goes out and kills these engines just like it does everything else. the Facebook groups are much more active and almost everyone ends up putting a engine in them just before the hybrid battery goes. so they have just dropped 5-10k on an engine to then be told they need a 3k battery a year later on a vehicle with zero resale value. so I honestly don't think the cam bearings are oil pressure related, the crazed performance guy did a whole hour long video on the cam bearings, he seems to think the stock bearings are garbage. I don't have any good reason to think he's wrong.


for the pvc, if you could put some of the mesh used in a catch can inside the valve cover pvc route, that would work much better. oil drains right back into the engine and you can just burn off the condensation. shouldn't hurt anything like burning oil does. my clean side separator on the ls3 car is like that, replaces the oil cap with a larger can filled with mesh and a vent port that runs to the intake, so at high rpm low vacuum if the blow by goes back up that side, it's filtered before getting pushed into the intake tube. Collects and drops back into the motor. at least that's the design and marketing.

I tthink we are just dealing with mass production at the lowest cost with a 30k warranty and most people that buy new vehicles don't run much past 100k before trading them in. gm has to build vehicles for the people that buy new cars. Sadly that's not really enthusiast. I've had one new car in my life and would never buy a new one agian. always something used. so I'm not the focus group.

 

[rdezs]

The number 2 Cam bearing in the VVT engines is probably the main contributor to somewhat low oil pressure in higher mileage engines. There is a groove in the cam journal for oil to access the VVT actuator in the end of the cam. That leaves less of the journal putting the same amount of pressure on a smaller area of the bearing. That alone justifies changing the oil every 4000 miles or less with only a full synthetic oil.

Of course, aging pick up tube o-rings, sticky oil pressure relief valves in the oil pump or the one in the oil pan are common contributors. In an AFM equipped engine, that VLOM plate has a lot of places for internal oil leaks.

Regular oil changes do help preserve the rear main seal over the life of the engine. I think it has to do with thrust bearing wear on the crankshaft. Once it gets worn enough, and the crankshaft starts moving forward and back, the seal is no longer riding in the exact same spot and gets disturbed. Just my theory though, no proof. Wife's Escalade at 182,000 mi, rear main is still bone dry. Oil changes about every 3,500 miles over its entire life.

 

[Scrappycrow]

Is the same true for PTFE seals?

I don't have the knowledge to address that. Is the rear main seal PTFE anyhow?

 

[rdezs]

Yes

 

[B-train]

What makes rear main seals go bad? Could it be the PVC system becoming partly plugged causing the crankcase pressure to rise slightly?
If you're rear main is leaking do you have the old or new style valve cover?

Most high mile 6.2s all seam to have low hot idle oil pressure and bad cam bearings. Is this caused by a bad O ring starving the cam bearings of the flow they need?
A new O ring and HV oil pump restores oil pressure but the damage to the bearings has already been done. Can the HV oil pump and O ring save it?
Seems like after a new HV oil pump and O ring they keep chugging along.

What happens if you take an old style valve cover and make the oil drain back holes slightly larger allowing the oil to drain better and not get sucked up into the PVC system?

I have a few more but these the top questions.

It's not normally the RMS that fails, it's the rear engine housing cover gasket - the type of gasket that is permanently molded to the aluminum. It gets stiff with age and then allows some seepage due the high quantity/psi of oil that passes next to it.

 

[SpareParts]

It's not normally the RMS that fails, it's the rear engine housing cover gasket - the type of gasket that is permanently molded to the aluminum. It gets stiff with age and then allows some seepage due the high quantity/psi of oil that passes next to it.

Could be but either way the fix is the same.

 

[hagar]

A restricted pcv system on these engines for sure can cause oil leaks. If it is enough to cause the engine to blow blue smoke (it is,) it is enough to cause oil leaks. It only gets worse with higher mileage as the piston rings allow more compression past the rings and into the crank case.

For an extreme example of the effects. Way back when I built my first big power car, a c6 corvette with a 416 stroker and an f1 procharger, I didn't realize the importance of getting the pressure out of the crank case. I ran a stock sized pcv system configured how you traditionally set one up for boost.

The very first pull resulted in a massive smoke screen. I shut it down, looked under the hood, and the dipstick was hanging by its tip, and there was a huge puddle of oil under the rear main. I ran a larger pcv system, and the car has been bone dry ever since. The system simply couldn't keep up because it was never designed to alleviate that much pressure.

Example 2. Buddy and I were on a road trip with his Cummins diesel, and it got super low on oil. Oil was all over the place under the hood. It was so bad we had to add a liter every 30 miles. I pulled the oil fill cap off, and the truck didnt burn another drop for the rest of the trip. The pcv system was plugged solid.

 

[setha8]

I have a 2012 Suburban which has the "upgraded" rocker cover. I also have a rear main seal leak, so maybe not a connection there. I also note that even with the upgraded rocker design, I had oil in my intake manifold, so it doesn't stop the issue entirely. I put a catch can on it recently.