I've never solved oil consumption issues by replacing valve stem seals.

The valve guides have always been ovaled out, allowing for oil to slip by a distorted new valve seal.

My suspicion is the valve guides are worn past tolerance.

High oil consumption is badly worn oil control rings or oil being directly sucked into the intake by ring blowby through the PCV.

I think at the lab we have both valve guides and seals. Might be a good plan to replace both.

quote:

Originally posted by Mars_Attacks:
I've never solved oil consumption issues by replacing valve stem seals.

The valve guides have always been ovaled out, allowing for oil to slip by a distorted new valve seal.

My suspicion is the valve guides are worn past tolerance.

High oil consumption is badly worn oil control rings or oil being directly sucked into the intake by ring blowby through the PCV.

Mine too, usually the worn guides allow the valve stems to eat up the seals. Only real fix is pulling the head and having a complete head job done. New seals will have a very short life with sloppy valves before they start leaking again.

OP- Bad guides and seals at your mileage are fairly common on the 5.3. Only real fix is to pull the heads and have a head job done. But, I'd do a compression test first and make sure you have good compression and fairly even compression between all cylinders before tearing it apart.

With the resources at my lab, I think I'll start with seals. We test this model engine time and time again, every day, in the lab, and have all sorts of spare parts.

quote:

Originally posted by 4MUL8R:
With the resources at my lab, I think I'll start with seals. We test this model engine time and time again, every day, in the lab, and have all sorts of spare parts.

Have you done an oil sample on the oil to see what wear you're getting?

7. Many times before the PCV hose was replaced, the engine did not have any power, the transmission would not properly downshift, and the brake boost was minimal.

In answer to question 7, 4L60E and 4L80E automatic transmissions are completely electronically controlled, no vacuum source is used for controlling upshifts or downshifts in those. Been that way since the early 1990's. In that case something else is/was going on there. Was it accompanied by a Check Engine light?

I'm still in the worn valve guide/valve stems/bad valve seals camp but there could be excessive carbon buildup on the rings too. This part of the TSB addresses that:Cast-Iron Block - Oil Getting Past Piston Rings
- Free Up Piston Rings on All Models
1. Remove the spark plugs and ensure that none of
the pistons are at top dead center (TDC).
2. Clean the pistons by putting 118-147 ml (4-5 oz) of
Upper Engine and Fuel Injector Cleaner, GM P/
N 88861803 (in Canada, use 88861804), in each
cylinder. Allow the material to soak for at least
2.5-3.0 hours, but no more than three hours and
then remove the cleaner. A suggested method of
removing the cleaner is cranking the engine over.
Make sure to unplug the ignition coils and fuel
injector before cranking the engine over. Also
make sure that the painted surfaces are covered
so no damage is done.
Important: Ensure that the engine cleaner is
thoroughly removed before reinstalling the spark plugs.
Failure to do so may result in a hydro-lock condition.
3. Reinstall the spark plugs. Replace the spark plugs
if necessary due to full of carbon. Refer to the parts
catalog.
4. Re-evaluate the oil consumption. Document on the
repair order. If the oil consumption is still greater
than 0.946 L (1 qt) in 3,200 km (2000 mi),
replacement of the pistons and rings will be
required.

If you decide to try that as a last ditch effort DO use the the GM Top Engine Cleaner referenced in the TSB. Normally not sold over the counter (retail) but that stuff is aggressive and it does work with stuck piston rings.

quote:

Originally posted by shovelhead:
In answer to question 7, 4L60E and 4L80E automatic transmissions are completely electronically controlled, no vacuum source is used for controlling upshifts or downshifts in those. Been that way since the early 1990's. In that case something else is/was going on there.

True that the transmissions have no direct connection to a vacuum source, however their is one sensor that does. The two main inputs that the transmission will use to effect shifting is the Throttle Position Sensor and the Mass Airflow Sensor. With a large vacuum leak there is a big mass of unmetered air getting into the intake system, thereby causing the MAF sensor reading to be off. This will confuse the PCM, and erratic shifting can and does occur.

I think this is what the PCV hose leak created. Weird MAP (manifold absolute pressure).

I also discovered the battery, nearly three years old, was not charging. I replaced it yesterday with an AGM by Interstate.

I would try what Shovelhead is recommending, He was a GM parts counter guy for decades and knows his GM's explicitly. I'd just add to his instructions, to change the engine oil a day after running it and doing that procedure. Personally I feel it's valve guides and seals, over piston rings, but you never know without doing a leak down test.

I am still suffering from oil consumption.

I have attacked stuck rings with a custom-blended fuel cleaner made for me at my lab. Five tanks of fuel with a very specific chemistry. Although Shovelhead has prescribed the correct path, I am not able to do the top engine cleaner method.

I have deduced that idling the engine for some time, such as in an automated car wash, results in some oil being delivered to the combustion chamber. Then, leaving the place of idling, the engine stumbles and bumbles. Blue smoke is evident. I believe the valve guide seals are needing replacement. Thankfully I can get these from my workplace.

Sounds like you need an old fashioned Valve Job.

Funny you should mention this.

I have a '99 Chevy S10 4 Cylider I purchased new in March of "99. I still have it. It has been a fantastic truck to keep around. It's not my daily driver, it gets driven about once a month or so to Home Depot, Lowes or the Garden Center. I just haven't been able to justify a new pickup at this time.

It's always started on the first turn of the key and ran just fine. It might have helped that I'm the only one who ever drove it and I've always driven as an adult and not some kid.

Anyway, I got back from Home Depot and parked it. It was running fine. Got into it a few days later and it would crank but not start unless I pushed the accelerator pedal down halfway. Then it would start but run raggedy and die if I let off the gas pedal.

Got it towed to the shop, assuming it was an ignition or fuel problem.

Nope.

#1 Cylinder had zero compression, further investigation revealed #1 Intake Valve was stuck open. The shop says they have to pull the head off to see exactly what went wrong.

Basically it fix this it amounts to an old fashioned Valve Job.

Weird, huh?

The truck isn't worth much, the repairs will cost about half of what it's worth.

I'm going to get it fixed anyway. I just can't justify the price of a new or newer-ish new truck at this time.

If it has tires or transistors it's troubles, lol.