Low compression 5.3L gen IV Cylinder 7

[Marky Dissod]

@donjetman, is it reasonably possible for a Gen3 V8 (L59) to make use of the Gen4 post-TSB valvecovers?

(Always thought that the conceptual logic of the Oil Life Monitor was sound, except that it was simply too lenient.
It's nice to know that, at some point in time, GM agreed with me.)

 

[donjetman]

@donjetman, is it reasonably possible for a Gen3 V8 (L59) to make use of the Gen4 post-TSB valvecovers?

A TSB valve cover should work good.

2.5 yrs ago I bought a stock 2002 C5 Corvette w/gen3 LS1 w/60k miles. When I started driving it the 1,000 miles each way between our TX & CO homes I was bummed to see it was burning 1 qt of oil per 2,500 miles.
I replaced the stock pcv valve on the stock 2002 gen3 LS1 with a "fixed orifice" pcv valve, #12572717. I also installed a catch can and did a piston/combustion chamber soak. These measures have reduced consumption to 1/2 qt per 5,000 miles.

If these changes hadn't work as well as they have I was gonna install one of the improved TSB gen4 valve covers.

 

[solli5pack]

Shouldn't the shop have done a leakdown test to see where the loss of compression is going?

 

[j91z28d1]

A TSB valve cover should work good.

2.5 yrs ago I bought a stock 2002 C5 Corvette w/gen3 LS1 w/60k miles. When I started driving it the 1,000 miles each way between our TX & CO homes I was bummed to see it was burning 1 qt of oil per 2,500 miles.
I replaced the stock pcv valve on the stock 2002 gen3 LS1 with a "fixed orifice" pcv valve, #12572717. I also installed a catch can and did a piston/combustion chamber soak. These measures have reduced consumption to 1/2 qt per 5,000 miles.

If these changes hadn't work as well as they have I was gonna install one of the improved TSB gen4 valve covers.

in theory the ls6 valley cover swap would be better than a newer valve cover. but I just spent a few days in the mountains with my buddy 04 ls6 zo6 and his 30$ Amazon catch can was full at the end of each day. so I'm not sure it's any better in practice.


I feel like the best LS I've been around for not drinking oil was by 02 ls1 camaro. got it new, left it bone stock, over a 100k of very hard miles. I never changed oil before the light popped up, beat the car to death and don't ever remember adding oil between changes. and literally used any oil that was cheap to free except the one before a trip I knew it would be extremely abused, including towing the bike trailer there.


how or why gm consistently made the ls pvc system worse and worse as the years when by is byond me.


have you considered a catch can on the clean side of your c5? or maybe the clean air separator they call it that replaces the oil cap with a mesh filled housing before running to the air box port? with such low mileage and lack of abuse. I feel like it's gotta be using the half qt thru the pvc system and not the rings?

 

[rdezs]

I think it was simply too much PCV the way they had it set up. I have a 2003 lq4 in a Hummer, that always had the typical little pool in the intake manifold of oil. Updated to the same valve cover as on our 2014 Escalade, at the same time I went through the heads.... Under 113,000 miles, I thought the deposits on the intake valves stems were a little excessive. Started chasing a problem with condensation building in the crankcase, verified by oil sample analysis. Then I realized the new valve covers have a real small orifice.... With engine running I put a vacuum gauge on the fresh air side and it took about 1 minute to even register a couple inches of vacuum. Drilled that orifice out to 3/16ths.... Condensation issue disappeared, and a nice steady vacuum on the fresh air side. The fresh air intake to the engine is downstream from the mass air flow sensor, which apparently adjusted and it runs just fine. Also, I don't get the oil pulling in the intake. Uses zero oil in 3500 miles. My guess.... Just a guess.... Is that excess oil in the intake drips down into cylinder one or seven when the engine shut off, maybe causing the issue with the rings in those cylinders. This is way before AFM existed, no relief valve in the pan to be spraying oil upwards under the piston.

Not 100% sure of the dynamics behind GM's problem, but it does seem to be an issue with the right amount of crankcase ventilation.

On most modern engines, if you pull the dipstick with the engine running you should hear the idle change as you create a vacuum leak. That's why you have that little o-ring around the dipstick. That was my first clue the updated valve cover wasn't quite adequate...

 

[j91z28d1]

I think it was simply too much PCV the way they had it set up. I have a 2003 lq4 in a Hummer, that always had the typical little pool in the intake manifold of oil. Updated to the same valve cover as on our 2014 Escalade, at the same time I went through the heads.... Under 113,000 miles, I thought the deposits on the intake valves stems were a little excessive. Started chasing a problem with condensation building in the crankcase, verified by oil sample analysis. Then I realized the new valve covers have a real small orifice.... With engine running I put a vacuum gauge on the fresh air side and it took about 1 minute to even register a couple inches of vacuum. Drilled that orifice out to 3/16ths.... Condensation issue disappeared, and a nice steady vacuum on the fresh air side. The fresh air intake to the engine is downstream from the mass air flow sensor, which apparently adjusted and it runs just fine. Also, I don't get the oil pulling in the intake. Uses zero oil in 3500 miles. My guess.... Just a guess.... Is that excess oil in the intake drips down into cylinder one or seven when the engine shut off, maybe causing the issue with the rings in those cylinders. This is way before AFM existed, no relief valve in the pan to be spraying oil upwards under the piston.

Not 100% sure of the dynamics behind GM's problem, but it does seem to be an issue with the right amount of crankcase ventilation.

On most modern engines, if you pull the dipstick with the engine running you should hear the idle change as you create a vacuum leak. That's why you have that little o-ring around the dipstick. That was my first clue the updated valve cover wasn't quite adequate...

it's a problem across the board too. my neighbor has a gm 4 cyl ecotech or whatever they are called. the pvc port in the head is plugged up. very common from my research and messes everything up. blows out crank shaft seal and stuff. fix seems to be pull half the engine apart to poke it out with a wire and then install a catch can.

I Just pulled the intake off a v10 Ford at work to replace a leaking intake manifold gasket. poured what felt like a qt of oil out the intake.


I still feel like the old rattle pvc valve was good at blocking oil, or at least helped.

 

[donjetman]

have you considered a catch can on the clean side of your c5? or maybe the clean air separator they call it that replaces the oil cap with a mesh filled housing before running to the air box port? with such low mileage and lack of abuse. I feel like it's gotta be using the half qt thru the pvc system and not the rings?

No
My dirty side catch can doesn't catch much between oil changes.