bob22z06

Hi guys , I finally started long waited project. The car :01 z06 ,with about 39k basic bolt ons(blackwing intake , LG super pros headers, no cats, X pipe and BBs oval tip cat back) . Oil consumption Id say 1 quart for 2k miles (with definitely noticeable spoting on the rear bumper when driving hard) My plan is to port the heads , install new stage 2 BTR cam with valve springs and other goodies that come in that kit, also meilling oil pump, ls2 timing chain, 92mm intake with ls2 ported throttle body, probably summit racing harmonic balancer and othe things that's laying in a box, lol. So here's questions I have since it's my first time tearing this engine down(I enjoy this ) I noticed lots of carbon build up on pistons (you'll see it on the pictures below) also there were build up around valves chamber especially the intake side and even build up around spark plugs . I know it consumed oil I even installed some cheapo ebay catch can and it was catching some oil (for this re build I already bought elite engineering catch can) I know 01 had bad oil ring from the factory based from my research, is this carbon and kinda oily residue cause of the bad rings or all this caused from blow by







???? So shuld I take the engine completely out and re do the rings while I'm at it ? I'm planning to change out the clutch too so everything already getting disconnected . In last picture shows after I cleaned everything of last night, that was fun!!took me few hrs , and I was about to remove the cam , looked and the clock it's 3am , lol went to bed.

ipuig

With the mileage being that low it is most likely ring flutter as described in the TSB. Did you perform a compression test and/or cylinder leak down test before disassembly? That would have given you an indication if ring replacement and/or cylinder resurfacing was needed. I had an 01 coupe with similar symptoms. I solved it by minimizing the driving conditions outlined in the TSB and switching to a lubricating oil with a lower volatility (Noack) index.

norcalace

ipuig is spot on. However you still can and probably should do a leak down test. Get a new set of head gaskets, clean up the head and block mating surfaces and reinstall the heads. Well worth the time and expense. 1 qt of oil every 2k miles with 39k on the odo is not normal. Before assembling the block and heads for the leak down test, while the heads are off, pour small amounts of lacquer thinner or acetone into the intake and exhaust ports to see if the valves are fully seated. If no leakage at the valves this will eliminate them as the cause of the oil consumption. Although the valve stem seals could be the cause they will be replaced when you perform your porting work. This way the leak down test will focus on the rings. A cracked block or head not withstanding but possible.

redzg

Any time the better half pops out of the door and asks if you know what time it is you can pretty much bet you don’t.
I’m not the expert others are, but that looks quite excessive for your limited mileage. To my mind the pistons and bores must be evaluated - we know they will be good, but due diligence requires a micrometer. Rings will have to be replaced, but do some research and see if one of the big known good suppliers has a set that doesn’t require honing. Can’t quote where, but I’ve seen or read of new rings in good low mileage bores before.

Cutlassmaster

Since you already have it torn down and will be doing clutch, take the extra step and tear it down completely. One and done is what I always say.
chris

bob22z06

Thanks for the reply guys any input appreciated!!!The thing about the leak down test, I could have done it if I had a problem with the car not running right.. the car ran perfectly fine no issues at all started fine pulled fine no bogging at all ...good thing I haven't taken my heads apart ill do the leak down on the valves for sure. So as far for replacing the rings what brand is better? or do most rings will have to be measured and filled down for clearance?also I forgot to mention on few of the lifter u can see on one of the pictures there a small scuff mark I ran my finger through it I can't feel anything I'm assuming it be same markings on the cam too, ill find out today when I pull the cam. So is that normal? Now do I need to change lifters too?

ipuig

Read the TSB carefully before you embark down the rabbit hole of replacing the rings. If you replace the cam, you should replace the lifters in my opinion.

Supercharged111

I've seen it myself in the 5.3 LH6 TSB which also addresses oil consumption, they advocate new rings in good, low mileage bores without a hone. Page 4.

https://static.nhtsa.gov/odi/tsbs/20...62524-7690.pdf

johnson-rod

I'll pass on my father's advice to me:"If you refresh the upper end of an engine, you need to refresh the lower end too or there will be problems down the line".

Even though he was a diesel truck fleet mechanic in charge of 166 over the road and delivery trucks for 20 years, I still ignored his advice. I regularly have thrown rods right out the side of the block.

Just sayin'.

666lisa

Cleaning that carbon off u probably loss 50hp. U lowed the compression.

bob22z06

Pulled the cam out, also did pour some acetone inside exhaust and intake ports , only cylinder 1 small leak on both and exhaust leak only on cylinder 7, on second picture shows passenger side head after springs and valves removal, exhaust valves seems gunky to me, what do guys think?

bob22z06

So, I after reading at the write up about this oil consumption and the links you guys posted . My brain about to explode 🙃 😫!!lol..this can't be that hard , I hate when "it's may be this or may be that, if u do this u need to to do that" Why can someone just make post to simplify it (take it apart in this order , order this part in this case would be the rings .) I still don't understand with the honing thing , is it necessary? Whuld i replace pistons and connecting rods? Do I replace the all the rings ? Because according to that bulletin they only want you to replace 2 and reuse old ones. I need someone to chime in on this one who was in similar situation as me with this rebuild . Thanks

666lisa

That is extreme oil buring ,surprised u didn't notice blue smoke from decel or accel. Anyway since u didn't do a leak down. I would ,this is just me but like was said up above i would hone and get new rings made sure the gap is with in spec. Thats builder work who every u go with and get there number per cylinder of ring gap and piston cleans. THAT Will eliminate bottom end . That will put ur bottom end to new condition with honeing. If for some reason the ring didn't set proprobly the first time this would burn oil. This time break in as what rings are used and gap pre ring spec. Should be no more then about .016ish tp .02 thou. There is no way pvc sucks all the oil ur plugs will be trushed with in 100 miles or so. Thats what i would do and i bet ur oil consumption will be gone every friend did these and oil consumption was back to normal every 5 to 7k about 1/2qt mile depending on hard u push it. Buddy 25lbs of boost over 1khp consumption about 1/2 qt every 5k with .03 top and .028 second ring. Good uck whjich any way u go. JMO this is the only way to go or ur chancing it to be right back where u are.
For got honeing schuiffs the to walls to break in ring if walls where glazed from bad break in the frist time.

RonSSNova

Did you find oil in the intake manifold? If so, that’s a clue. These engines will get some even with a catch can.

On honing, engine needs to come out for that. And it needs to be done if you replace the rings.
Modern rings need a need a finer hone job than the old school stuff.
I’d say use GM rings, but horribly expensive. The aftermarket will have what you need.
No need to replace pistons or rods. With those low miles, probably not even bearings.

The valves leaking when you poured fluid in the ports is not good. The good news is a simple lapping of the valves to the seats will fix that. Unless the valves are bent…..
Just keep each valve with the hole it came out of.

If this is all beyond your comfort or skill level, better find some help.

Ron

natchamp

It certainly looks like the carbon is oil. I do not see much crosshatch pattern on the cylinder walls. But that could be just the angle of pic. The lifters do look galled on the bore side. What does the oil smell like. If it smells like gas, then the oil is being diluted, possibly washing the rings down. Which could wear the rings and open the gaps. 3 out the 4 intake ports look clean, which I suppose means the injectors are working as intended. The forth could be next to the PCV port, or that seal is bad. You did not mention if there were any codes in the system. Would have been nice to have more testing before teardown. Remember, now that you want to add more "improvements" the engine will produce more crankcase pressure adding to the oil consumption. I concur with others that the engine should come out, and be properly checked. Find a machine shop you are comfortable with and have them check and at least do the block cleaning, honing, ring gaps, and maybe pistons. Or the whole bottom end. Unless you think the oil pump is bad, I would not replace it. Seems like there is enough oil floating around. You could put a windage tray kit in, and trap door for the pick up.

666lisa

Thats a lot of gas if washed walls, the bearing would go before it washes walls. Seen this many time with carb car that amateurs change the set up with diff carbs that are bigger CFM'S then change ignition wires and so on and have no clue what that changes drastically change tune then try to start the car after a rebuild They pump the gas so much to try to start the engine. They bring the engine back after they barely get it running but just enough to toast earing in engine and blame on builder. The stupid thing they don't do is dump the oil then there is no prove, Thats the first thing the builder check. You can literally put a match to and it will light.(exaggerating) But easy smell how much gas is in the oil.

PS the builders i know which is one, always tell them put all the same set up, that was on the engine because it was running before build, then make changes one at a time.

natchamp

Mr lisa, Your right, that would be a lot of gas. And back in the day there was, with everyday street vehicles, depending on conditions, driving habits, different vehicles, there was consistent gas dilution. As I am sure you are aware, the oil pressure switch's back then came on around 4-10 lbs. As long as there is liquid in the engine there will be pressure. Maybe not too much lubrication, but it does take quite awhile to wear the bearings down, depending on that dilution. With the advent of injection, computer controls, this has brought this issue down quite a bit. The only thing I can say is, I still smell gas dilution on everyday cars when I change oil on them. These people travel on average anywhere from 6 to 30 miles a day round trip. It usually takes extended trip/time, higher speeds, to get the oil hot enough to burn off any residue in the oil. This would also include condensation in the top most part of the engine and pvc system if living in a colder climate, or just chillier mornings when driven. Short trips, lower rpm's, getting on the gas for speed, all contribute to less efficient burning of fuel, even with today's systems. If someone would like to log an oxygen sensor reading from cold to hot over a period of time (with the air pumps disabled) that would give an indication of how the engine is running. As well as how the driver is using the car. When I was going to track days and depending on the interval, I would be changing the oil every 2-3 times out. And because the gas pedal is pretty much on the floor, there was a distinct odor of gas in the oil. Also, made sure the oil was changed before putting the car away. There is sediment that settles on the bottom of the pan with old oil.