i suddenly started having excessive oil consumption. i burned 1qt in under 500 miles! i pulled off the air cleaner coupler to the TB, and i had oil leaking out from behind my TB blades!!

i was thinking maybe PCV problem, but my PCV valve was just replaced less than 10k ago, and i didnt see any excessive oil in the pcv hoses. how else can oil get into the plenum besides the PCV system? should i just replace the PCV valve again for the heck of it?

two side issues i just started having around the same time i noticed this issue, which may/maynot be related:
1) car doesnt want to turn over unless i tap the gas repeatedly while cranking (might just be struggling because of the oil fouling the ignition)
2) TCC doenst always want to disengage when releasing the gas pedal. it acts like cruise control is on. i was thinking maybe the TB blades were a little sticky (which is the original reason why i pulled the TB coupler off, so i could spray the TB). i checked the TPS with the car off using tunerpro, and it is reading like it should.

 

I would do a compression test on all cylinders and inspect the sparkplugs while you're at it.

You can put a clear fuel filter on your PCV line. That will help keep oil out of the intake and allow you to monitor the amount of oil passing through.

 

I would check the pcv hose for excess oil. Also see whats coming out of the breather line. Hopefully the pcv is just picking up more oil than it should. A compression check is also a good idea.

 

ok, i just performed a dry compression test.

here are the results, along with a description of the plugs. this was done with a very cheap compression tester that i got for $20 from harbor freight tools... so i dunno how accurate it is, but at least the results are consistent. the plugs have 18k on them, and were installed when the head gaskets were replaced. the engine itself has 190k on it.

#1 - 150psi - plug looked like normal wear, tiny bit on the white side
#3 - 150psi - plug looked ok, little bit of white crusty stuff, but not enough to raise concern
#5 - 150psi - plug looked ok, little bit of white crusty stuff, but not enough to raise concern
#7 - 120psi - plug looked ok, little bit of white crusty stuff, but not enough to raise concern

#2 - 150psi - plug looked aweful, possibly bridged gap
#4 - 150psi - plug was kinda oily, had some significant buildup on it, but not as bad as #2
#6 - 150psi - plug had a good amount of white crusty stuff on it
#8 - 120psi - plug had a good amount of white crusty stuff on it

i found it intersting that the rear two cylinders scored lower than the rest. at first i thought maybe i didnt have the tester hose screwed in well when i did #8, and was going to re-test it until i saw the results for #7.

also interesting to note that the pass side plugs were much worse than drivers side. they all had to be cleaned up with a dental pick before i reinstalled them. i will state that this was the side that had the bad head gasket... is it possible that it was bad for so long and having a good seal freaked out the valves?

 

Hello slayer_taunu!!

Your excessive oil consumption is ring related, unless of course your leaking a lot of oil!!

 

oil in your plenum, or air filter box; I would say is blowby... I had a similar situation with my Carb 5.0 ... Oil would pool in the air filter...

 

Hello KNBlazer!!

Isn't that what I said above???





P.S. Talking about blowby!! I had a 1974 Chevy Nova with a 350 that would put a quart of oil in the air cleaner every 500 miles or so!! At first I thought that I had a fancy oil bath air cleaner system, nope, no such luck, I found out that all the top rings were broken in half!!

Something about ridge reaming the cylinders that the previous owner didn't think about doing, during an engine rebuild!!

 

it's probably the intake manifold gaskets failing, and not the bottom end in any way. If you get a cracked/failed gasket, engine vaccuum will pull oil from the valley, and coat everything down. furthermore, looking at the plugs, I would say the leak is occurring somewhere between cylinder 2 and 4.

 

Its common for tpi and lt1 engines to pass some oil through the manifolds in your case it sounds like it a little to much i run catch cans on my pcv line and my crank case line i fabricated them out of two inch black pvc pop pip caped on one end with a screw on cap on the other end with two brass hose barbs one on top of the screw on cap that's the output and one about one inch down on the side that the input line.
One is mounted next to my battery the other is mounted next to my charcoal canister on the camaro i think it cost about 25 dollars at the hardware store for the extra house pipe glue and fittings about every two months i disconnect the side hose unscrew the canister and pour the oil back into the crankcase it works great my intakes are clean as a whistle and my spark plugs last longer.
You can make them as big or long as you want in your case i would make them on the big side.

 

I would also be looking at the valve seals, very common in these cars.

 

manifold gaskets were replaced when the head gaskets were replaced 18k ago.

 

Rings washed new gaskets on old motor= sucked out rings sooner or later

Had same prob with oil cleaned my TB n intake when i was porting with some good break clean, cheap stuff took 3 cans and barley took any residue off. Replaced my valve seals guy had exhaust ones on intake and so on, stopped smoking as much. Still just tore the motor down and rings are washed(too bad that's not all that is messed up). Figured it was rings too, cause it smoked bad under hard accel. In my case the guy didn't know crap bout anything tried too rebuild it, but failed too hook up a single sensor of the few that was on the car an no air filter, motor was doomed from the start. Still car was dirt cheap and it's been fun learning bout efi. Betting you got some spark knock issues too.

Prob suck out my rings again shortly, using an old shortblock that's seen a few cars cause I can't afford the full rebuild atm. This one has seen less than 10k of hard miles, but this will be the 5th set of heads on it, hopeing it last 2-3k of weekend crusing n raceing.