368 LT5 Drinking oil

[Mitsumark]

Just to address a few of the statements above..When I picked up this car in Virginia last July,it ran strong to the point that it actually scared me.I've owned some quick high powered Mitsu's that made power on boost.However I wasn't used to the instant power just tapping the gas like in this car.It was a fun ride back to NJ..The car had a rock steady idle,pulled hard,and just ran great.The one thing I noticed that I hated the most was a 1100rpm idle.The previous owner had all the documentation on the car.The build sheet stated that idle was set high to quite the inheritant noise that comes with a light flywheel..I hated the high idle as it was very loud,I was putting a ton of gas in it,, and getting out of 1st sometimes was a pain with the CC stage 3 clutch..So I contact Marc H for one of his tunes.I told him what I had and he burned me a chip for a 368 with my bolt ons..After speaking with him,I also relocated my IAT sensor from the airhorn to under the front bumper..while waiting for the chip to arrive I also installed plugs that were a step colder than stock..Once the chip arrived, I followed the directions and started it up..I don't know which of the things I did that did it,but the car hated it..Although the idle was where I wanted,the car hunted for idle, ran very rough,and developed misfires.I even listened to it ping many times under light throttle on premium fuel.I drove it for a month thinking the computer would relearn and things would get better..They didn't..The misfires and hunting idle were driving me nuts so I started replacing everything..Coils,back to correct HR plugs,new IAC valve,new MAP sensor and hose,Jerry's PCV rig with new valves,new Delco 02 sensors,and I checked high and low for vac leaks under and around the whole engine..Non found..Installed new 2ndary vac pump and turned the key.. Worked like it should..Ran 3 sec and shut..Would continue to run when I pulled a vac hose the way it should..The car now ran again without any misfires.The idle still does hunt from 800-1200 rpm while rolling in neutral until I completely stop where it settles around 700..The smoke started a few weeks ago.. I hammered it a bit getting onto a highway and held on..It took off but I noticed a nice cloud behind me..Didn't think nothing of it.I had it idling in my driveway a few days later and I noticed after running for about 10 min it started smoking faintly out of the tailpipes..It has smoked everyday since then..Currently,sometimes I can be sitting in traffic for 10 min and there is no smoke at all..Then all of a sudden,even without throttle,I'll get the smell,look behind me and theres the smoke..It comes and goes at random..Again, I don't know jack about these cars..But I did drive through a few bad misfires before I discovered I had a bad coil.. I honestly think I burnt a valve up with the dead cylinder being dumped with fuel,the plugs being to cold and loading up(they were covered sooty Black when removed)..Just a bad combination of things..For the record,the build sheet says the car dynoed 459 WHP and it stated 'recommend customer returns after break in for more tuning'..The chip I removed and sent to Marc did say B Kirchoffer on it..

Ya know I was thinking maybe the oil got so thinned out from dumping fuel with the dead cylinder and cold plugs that maybe it thinned out enough to get past valves and rings.. I'm gonna try changing the oil again but I did not smell any fuel in the crankcase with the cap removed..

[bradley]

is there a place you can run her on the dyno to get what the air fuel is ????kinda sounds like she is pig rich . you can pull the plenum the pull the injectors out while still attached to the fuel rails . have a friend turn the key on while you look at the injector sand see if you have a leaker . oh put a towel under the injectors before doing the test

[scottfab]

As you mention in the original post your oil light came on so I agree, it's smoke from oil. What you did not mention (or maybe you implied it) is that the oil comes from both sides? If it does not have a crossover or H pipe and smoke is from both sides then you'd be burning oil on both sides. If it's a burnt valve then there are burnt valves on both sides. (less likely) If the oil burning is due to lack of valve guide seals then it would come from both sides.

FWIW
I know for sure what is in my engine.
I have an almost bone stock 90 with >90k on it. It has no valve seals. It burns a bit of oil at each WOT. It burns hell of a lot more on the track when I use the wrong oil. (1qt of 0w30 in 20mi). It burns more when I inadvertently overfill it. (don't let the oil settle)
When I let it sit overnight and top it off it burns about 1qt per tank full with lots of WOT.

Now here is the interesting part.
When I use a 20% mix of 10w40
AND
only fill the oil to the bottom of the dip stick line I get very little oil burn.

Just food for thought.
Hope your wife's fall was not serious. We're all pulling for ya.
We all have weeks like that.

PS unrelated but 3sec between secondary pump cycles is not good. That is too much leak down. When you're below 10sec cycling then you're on the slippery slope toward 1sec cycles and failure of the secondary to hold in.

[Schrade]

Originally Posted by scottfab

...

It burns more when I inadvertently overfill it. (don't let the oil settle).
...

This is a good point Scott:

Some engines, when you put too much oil in the crankcase, the crankshaft spins IN THE OIL, and makes a foamy, frothy, jammy mess.

It will make the oil light come on, when the system pickup tube starts suckin' up the froth.

I can't imagine WHAT goes through the PCV plumbing when this happens.

And who knows what would go through the cylinders. And the exhaust...

I don't know how LT5 dynamics would handle too much oil...



(good job Admin on editing - some people don't know a tactful way of telling another that they THINK another MIGHT be wrong. Even if they KNOW they're wrong. 'Cause they might NOT be wrong)

Like so:

Originally Posted by Schrade

That's what it ALL ABOUT - learning. No one knows it all.

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Slightly more tactful ways exist of telling someone they might be wrong too...


ed.:
That's a good attitude there Franke. And good restraint. Responses like that start arguments. Right or wrong...

[GOLDCYLON]

Originally Posted by PhillipsLT5

I usually wait 24 hr to check oil, you can not get a accurate read immediately

A true statement, I always pull the dipstick in the morining however 2 qts is telling I think the guide/seals are the key

[geezer]

Just to throw in my 2 cents worth here - the PCV valves are new but as we know each has very different characteristics to deal with 'no load' plus WOT conditions. A lot of blowby at 'no load/ low load ' Could the PCV 's be reversed? LH is AC 913. GM info. has this reversed.
???

[GOLDCYLON]

Originally Posted by geezer

Just to throw in my 2 cents worth here - the PCV valves are new but as we know each has very different characteristics to deal with 'no load' plus WOT conditions. A lot of blowby at 'no load/ low load ' Could the PCV 's be reversed? LH is AC 913. GM info. has this reversed.
???

I doubt it as the Stock PCV 2 piece hose is stepped as are each of the PCV valves with a body stop to avoid reversal. To reverse it would be rather odd and look of it would be Odd as well. In the non stock Samco replacment that could be done however I would tend to say no as the stock one was designed to give the mechanic a clue. In the correct position both PCV valve will be flush in the hose as intended. Actually a neat little bit of engineering by GM if I must say so

[Mitsumark]

PS unrelated but 3sec between secondary pump cycles is not good. That is too much leak down. When you're below 10sec cycling then you're on the slippery slope toward 1sec cycles and failure of the secondary to hold in.

Maybe I was mis understood..The 2ndary vac pump is brand new and cycles on for only 3 sec when the key is turned..It does NOT cycle on at any time during running unless I pull off the vac hose that controls secondaries..Then it will run nonstop.Although its irrelevant to my issues,I've already established the complete secondary system is fully functional.

Re: 368 LT5 Drinking oil
Just to throw in my 2 cents worth here - the PCV valves are new but as we know each has very different characteristics to deal with 'no load' plus WOT conditions. A lot of blowby at 'no load/ low load ' Could the PCV 's be reversed? LH is AC 913. GM info. has this reversed.
???

Good guess..However as stated above they really only fit one way correctly.I second guessed myself with that and double checked it yesterday..I really appreciate all the ideas and advice on what to do..I have about 2 hrs to play with tomorrow so I'm gonna change the oil with M1 15W50..I will also do a compression check..Standbye fellas..

[Pete]

Can you try using the old PCV valves, of course clean them first.

Let us know how the thicker oil works out.

Pete

[LGAFF]

I run 15-50 all the time and ran it in the car prior to installing the new engine with valve seals; reduced smoking at idle