1264 miles since my L98 383 build, supposedly standard oil rings.

i placed a catch can after the pcv, no oil there,very little

no oil out the tail pipe at coldstart up or driving acel and decel, nothing.

burns the same if i baby it or haul azz.

the car runs well, but seems to eat more oil that in the beginning. double actually

my shop ran some test and does not think it is an internal sucking of oil at the intake gaskets

i pulled one plug and itis not greasy.

using 10w-40 pennzoil dino

Expert comments needed< sorry but the corvette guys are stumped....

 

When you say it burns the same if you baby it or hammer it do you mean you can see smoke from the exhaust? If not, put the car up on a rack and see if the bottom of the car is covered in oil. Could be a rear main seal on the engine.

 

they told me the cat would get coated with oil and not smoke alot, i don't think so though,

I see nor smell no smoke whatsoever...

there is a intermittent leak at the bellhousing( it's a new engine what the heck?) they changed the distributor gasket, that's what they thought leaked, yes it slowed it.

I do have a leak at the bell housing, but the bottom of the engine is not covered in oil, just the drip every now and again.

I know I have to watch that rear main seal, what would make it dry one day and drip the next? frankly I don't think it is pouring out that much to lose a half qt every 100 or so miles.....

 

! how long has this been goin on for? I ask because high oil consumption is not uncommon for a freshly rebuilt motor. Though ide say more like 1 qt every 1k miles but hey every motors different i guess. The biggest thing ide want to know about is a compression test? I suspect maby a problem with the rings or the cylinders wernt properly preped. My first test would be to take the car and put it in first (Ithis is really for manuals but may work with autos as well) run the car up to a high rpm and like say 4.5k and just let off the gas letting the engin decelerate the car. This this is doing is creating very high vaccum in the motor because the motors running at a high RPM and the throttle blades are closed. This is typically when you see a big cloud of smoke if theres a problem because this high vacuum suck in air or oil from where ever it can places like valve guides and piston rings. Also try hooking up a vacuum gauge that is the single best indicator of a motors health i think.

 

it got worse, 400 mile 1 qt now 200 miles 1 qt,

i has a manual tranny, it decel all the time from highish RPM's no smoke whatsoever, do you think the cats are cleaning out the smoke?

no compresson test yet will that answer some questions?

i have a vacume gauge, where do i hook it up? at the plenum? manifold? or it does not matter? and what do i look for? at what rpm?

 

Well a compression test could answer some question or atleast confirm a few things like the condition of your rings although the readings may be decieving. Most compression tests pass/fail are based on a comparison to other cylinders. However in your case if say the piston rings were installed upside down for example the compression would probably be similar across the board and pass by a regular test of comparing them to other cylinders but would be a lower reading than it should be. So the compression test results will be interesting and will need to be looked at closely. For the vacuume gauge all youll need to do is hook it up to anypoint where theres just regular old manifold vacuum. Just let the car idle and atch your reading. Because this isnt a factory motor again well have to analize the results closely but just watch for needle movement steady quickly vibrateing ect as well as the actual reading.

 

the cam is choppy at idle 230/236 113LSA

 

Well thats what i mean with a cam like that i wouldnt expect the reading to be the normal 20-25 hg's but still if you cam up with a reading of 5 hgs we could say that that is bad safely lol. So a vaccum test would still be a good thing. And about your question about the cats cleaning up the oil smoke i forgot to answer that ide say no. I dont see a cat cleaning up all that oil so no smoke is present and it makes sence because how many old beat up cars do you see runnin down the road with blue smoke pouring out as bad a a ww2 destroyer. I just dont see it. Do you see any smoke comming out of the hole in the valve cover where the PVC would go when removed?

 

no smoke from pCV hole when running or oil filler.

i'll hook up the vacume gauge tommarrow, so I should look for a steady needle? what if it's not?

if you help me and write something, i can't thank you or answer back cause i'm tired and going to sleep, but rest assured i really appreciate you helping me tonight.

so thanks a mil in advance!

and i'll respond tommarrow...

 

Wel under normal circumstances I would expect the needle to be steady however because that cam probably has a fair amount of ovelap too it I suspect that the needle will vibrate quickly and evenly around some central value (+ or - a few hgs make note as to how far it swings from its central value) ide guess somewhere in the ball park of 17 hgs or so. The needle shouldnt drift around or anything funny like that.

 

alot of things come to mind

on a fresh motor like that you might think the rings werent properly seated, and its causing you to burn alittle oil.

rear main seal leak could be a culprit too

i would check compression to see the condition of the rings and valves

check for blue smoke while warming up

also did you use a stock sized oil pan? and a stock dipstick? ive run into problems where people get a dipstick thats too short, so they add extra oil to get it to the fill line, so then the car burns all this extra oil and when you check the dipstick it looks clean, so they add more oil thinking theyre low on it

 

A quart every 200 miles and it doesn't smoke? Gotta be leaking out then. If you can see a drop every few seconds or so, then that's where allot the oil is going IMO.

 

stock oil pan, stock dip stick

no smoke at warm up. i watch the tailpipes every time I start it up and during warm up.

how long before it's broken in?

what would cause the rings not to properly seat, i did the run it hard and decel hard routine for a few hundred miles...

 

not few drop every sec, not even a drop a day, perhaps a drop every 2 days

someone says oil evaporrates, some more than others, yeah right

 

Yea oil dosnt evaporate lol. Again look at any parking lot where severy stall has an oil stain about where the motor would be. It can be burned off but at that rate youde probably see and smell it being burned off. As for why rings would not properly seat, In order to seal rings and cylinders have to wear in together leaving you with a nice seal. This is why you have to run it through the hard accels/decel when you first get it running however thats only half of the story. A nice smooth cylinder bore wont allow for this wearing in process to take place so whats done any time the rings are replaced is they take a cylinder hone to the cylinder. This roughs up the cylinder walls with a nice cross hatch pattern and removes any glazing. This roughed up cylinder will now really wear in during the break in period giveing you a nice seal at the piston rings. If this was not done or not done properly or ive even heard but not confirmed that even if it was done and the engin was allowed to sit for long periods of time befor trying to break it in especiall in a not quite so ideal envionment it can cause problems as well. Heres a web site that has a briefe description of the proper cylinder wall, the break in procedure and the rhyme and reason behind it all.

http://www.stealth316.com/2-breakin.htm

 

the vacume gauge reads a steady 11 psi, and when i take the PVC off the stumbles and acts like a leak, the valve is suck closed so no air is getting thru the pcv valve.

does this mean there is an air gap in the intake manifold gasket, sucking air from that gap and into the cylinders?

should it not stumble? if it was sealed properly the valve cover area above the head should have positive pressure right? not a negative vacume right?, this is because the oil gallies equalize the crankcase pressure in the space and above and should be a net positive.....

comments?

 

Well one question the cam specs you told me earlier were thoes advertised specs or measured at .050 lift? If its advertised then the vacuum is way way too low if its at .050 i still think its low but not as horably low. Eather way ide say that reading is pretty low especially for a 383 which will tolerate cams better than their smaller counterparts. Now a low vaccum reading can be caused by a number of things like timeing being too retarded for example. However it can also be caused by things like low compression. I think at this point it might be a good idea to maby do that compression check.

Heres a link that you can look at to see what kinds of things it could be

http://www.earlycuda.org/tech/vacuum2.htm

 

oh and your other question yea it should be positive thats how the system works. That being said if sealed up it shouldnt build up like 30 psi and start shooting the dip stick out or anything but the only way it can work is to have ahigher pressure than the intake manifold. Now you said it stumbled when you pulled it out this isnt really such a good test of the PVC system but i would expect it to stumble as its just sucking in as much fresh air as it can basically acting like a vacuum leak.

 

yes at .050 for those durations

base timing around 6
advance with no load around 20.5

at idle

total around 26 degress

 

the timing sounds ok to me. I think its time for a compression test. Not sayin thats what it is neccessarily as theres still other possabilities but ive kinda suspected that your problems might be with the rings not sealing and the vacuum reading kinda suggest that as well.

 

how long does it take rings to seat?

how about my pvc question? when i unplug it?

 

Well how long can it take for a ring to seat thats a question depending on the type of ring used some types take longer than others. That being said i would say if you really used just standard run of the mill rings within the first 3000 miles they should be set pretty good. However even a ring thats in the process of being seated should only burn about 1 quart every per thousand miles or so and it should get better not worse. The PVC question you asked earlier i missed it first itme reading it but answered it in another post but again the stumbleing dosnt really supprise me as its sucking in pure air as opposed to blow by gasses and being that its unplugges the flow rates will not be metered properly as the flow rates of the PVC are a function of the differential pressure of the manifold when compared to the crank case.

 

no that's not the question, i put my thumb over the pcv and it still stumbles, as if the intake stroke is sucking air out of the crankcase....
and with thepcv removed it is a huge vacume leak.

does this verify that the intake manifold gaskets are not sealed properly?

again thanks for all the help....

 

Oh well putting you finger over the PVC open will cause it to stumble for sure. Reason being is that the PVC valve acts like a small vacuum leak but its ok because it is compensated for in the factory tune. If the PVC valve were plugged however then you have no air flow which will throw off things out of wack because again the comp is compensating for it still weather its there or not. This dosnt really mean that the intake manifold gaskets are sealed properly though. If you wanted too look deeper into that possability of a vacuum leak at the intake the best way i know of to check for vacuum leaks at the intake / vacuum lines is with something like a propane torch. If you spray propane or some equivalent over the intake and you spray it in one area and notice that the idle changes its because there is a vacuum leak there and when you spray it there its sucking in propane not just fresh air. Although i dont suspect this as a problem as something like that would cause some problems in the running condition of the car which in your case you have none correct?

 

what you are discribing are external vacume leaks, my question is about internal leak, if the intake manifold is not sealed properly to the crankcase wherever that may be, it could suck air from the crankcase, right?

and in doing so there would be a negative pressuure ( vacume) in the crankcase and wherever the oil gallys took it.

so when i pull the pcv and put my thumb over it i have plugged that vacume leak.

now the hole where the pcv valve should not suck air,it should theoretically blow air because, it is crankcase pressure, i'f i'm right crankcase pressure is caused by the pistons pushing air around in the crankcase.

do you understand my question? the stumble is not just a hiccup it is a massive decompression and the engine almost wants to die....

thanks again for the help....

 

Alright let me see if i got this right. Your pulling the PCV valve noticeing a huge stumble in the idle plugging the hole where the PCV valve would go cleans it up? Also when you pull the PCV valve your noticeing negative pressure sucking air in the hole? The way things should work is + pressure is developed inside the crank case by gasses that blow by the piston rings which is normal as even in a motor in good condition rings will never be a perfect seal so there will always be some blow by gasses. If your describeing the opposite scnario where you feel negative pressure in the crank case then that means somehow the motor is sucking air in from the crank case and with the PVC valve dissconnected that should have been the only place air should have been sucked in from. Now is it possable you have a vacuum leak at the intake manifold internally causeing a negative pressure i suppose it could but that would probably have other symptoms as well like a water leak. Also it may make the motor run alittle rough but would at most effect 1 cylinder or so because it would have to be pretty small imperfection to again allow air to leak and nothing else. In other words althogh its not impossable ive never heard of that happening. Especially concidering the rate that it would have to leak to cause that huge amount of vacuum when you pull the PCV valve. What i think is more likely is the the pistons sucking in air from the crankcase. I say this because theres a few places that pistons can suck air from the crank case as on the intake stroke causes alot of vacuum and can suck oil/air through things like the valve guides or past piston rings if things arnt in good shape. Another possability i havnt talked about is late valve timing again if the cam wasnt installed correctly and the intake valve opened too late the cylinder would generate huge amounts of vacuum and have no where to suck air from but the crank case atleast untill the valve opened. This condition is also a cause of low vacuum and would probably cause a negative pressure in the crank case.

 

thanks i finally took another look, the brake booster just broke so now i have that problem, of leaking vacume, but i capped it off and not using vacume for now.

i put my finger over the pcv hole and and another finger over the pcv itself and pulled on the trottle , I can't feel any sucking in that hole, but at the pcv yes

i guess the bad idle and possibly the low vacume reading was from the bad brake booster.

so if there is a leak it is minor and you have a point that not every cylinder will be affected, but i did read elsewhere if the bolts holding the intake to the heads are even a little loose it can be a source of an internal leak.

i will have to take it to the shop for a leak down, to rule out the rings and valves. my shop put the cam straight up, and aligned the dots, didn't degree it but would installing the cam wrong be a real amateur move considering these people work on chevy small blocks all day long?


where is the oil going? it is not smoking?

can it burn off like a diesel engine without smoking? is that possible?

 

I think i get what your saying now. You felt vaccum at the PCV and were expecting to find none there because you were under the impression that the postitive crank case pressure was what causes the gasses to flow into the intake correct? Vaccum at the PCV valve is normal becase a PCV valve is like a controlled vacuum leak. Inside the PCV valve is a valve obviously held in place by a spring. Manifold vacuum pulls the valve against the spring forcing it to open. At high vacuum it pulls the PCV valve into a position that allows a small amount of gases to be pulled into the intake to be burned and the more throttle the less manifold vacuum the weaker the force acting on the valve is allowing the spring to open the valve further allowing for more gasses to flow through the PCV valve. Now again because the computer expects this controlled leak, it has accounted for it. However by plugging it its like covering 1 barrel of a carb (not really but it gets the idea across). It will throw off the tune and cause it to run poorly. Pretty complicated little system for something so seemingly simple.


Now yes the bad break booster could cause some problems with the vacuum for sure. Now that its dissconnected and capped ide check the vacuum again to see what your looking at now.

Yea intakes manifold gaskets can leak if not done properly but usually something like that would cause some running issues like a bog or hesistation and your car runs seemingly fine its my understanding. Usually though with intake manifold leaks though i see water leaks because the cooling system is under a fair amount of pressure up to 16 lbs or so depending on the car. Again not sayin it cant happen just that with your symptoms i dont really think it is.

As far as the cam goes yea it would be a real amature move to install it wrong as its not really a complicated procedure to say the least lol. But it does happen i guess.

As far as where the oils going thats a good question. Really though theres only 2 places it can be going an internal leak or an external leak. If only it were as simple as it sounds lol. On a serious note really i dont see oil being burned off without giveing off any smoke. I mean maby if it was small enough you might not notice it but i have never seen a car that burnt off oil in your kinds of quantities and didnt smoke and smell weather it be burned off in the motor or on the exhaust manifold. However if you have no external leaks there arnt really many other options. Just out of curiocity its a long shot but have you checked your coolent? Ive heard of a case or two where oil was actually pumped into the cooling system but water was not seen atleast in the oil. Also one other long shot try letting the motor with parked revving the motor at a constant higher RPM (like 2500-3500) for a few mins like 5 or so (oil has a nasty tendency to pool up in areas delaying the appearnce of oil leaks) and watch under the car. This is because again another thing that ive seen thats rare is leaks that dont really appear at idle. Leaks that may worsen with pressure or leak only when something like the valve cover gets backed up with oil due to a drainage problem. You might want to also consider oil leaking from something like a timing chain may hit a belt and be thrown around or the fans could be blowing the oil into strange places.

 

the engine just sings along past 6000 rpm, i really don't think it's the cam.

the 700 mile new flowkooler WP blew a seal and i had to change it under warrantee, RPITA and $$$ to the shop but they did warrantee it for life

i had the shop put it in without adding coolant, my ratio was too high to begin with, yesterday i drained the radiator and topped it off with coolant, now i think it is a good ratio. so to answer your q, the cooling system is oil free.

the car has no evidence of external oil leaks other than the bell housing caused by 1/ the distributor gasket( has been fixed) and what could be reisdual oil MIGRating to the end of the bellhousing, so no there is no drip anymore and no greasy residue anywhere under the car, on the tailpipes, around the engine nothing.

this is just plain strange...

I know one thing, I have to pinch myself I know I go to the store and buy oil , I know I write everything down as far as added amounts and mileage and even dates when topped off, i know i have the reciepts to prove my buying the oil.


BUT WHERE does it go? what brsnd should i use and what weight? I think i will top it off one more time and then change the oil with something you recommend that won't disappear.

I would like to stick with dino tho.

 

Well one other thing you could try is have you ever seen the dye you add to your oil that makes your oil glow under a UV light? Makes finding external oil leaks real easy to find if they exsist which even though they dont seem to be any maby its worth a try at this point. I really dont think the oil your useing is causeing you all this grief it should be fine and if thats whay you like to use ide stick with it. Becides you shouldnt use synthetics during the break in anyways or atleast the experts havnt to my knowlede definitivly decided that its ok to break a motor in on synthetics. Becides the weight of oil your useing is less likely to dissapear than what i usually use (mobil 1 synthetic in modern roller type motors and valvoline VR1 or Rotilla T desil oil in older flat tappet motors all in 10w-30 for street driven applications in a moderate climate). All and all though at this point ide be curios too see what your leak down test reads and maby give the engin oil dyes a try. I think one of the two will turn up something interesting. However this problem will be solved its only a matter of time as a few quarts of oil dont just dissapear without a trace as hard as that might be to believe at this point lol.

 

I've been following this thread for a while now (plus over on CF). I have a very similar problem; 383 stroker and 1qt every 150 miles, regardless of the driving style. Absolutely no leaks (not a single drop under the car in the garage) and last weekend I was followed by an ASE Master tech and he confirmed that absolutely no blue smoke could be seen (some black at WOT due to running a little rich with my tune, I have a Vortech supercharger).

The compressions are good (all at 170-180).

One plug is much darker than the rest (#7). I think you may also have mentioned this over on CF...

I have split BLMs in the datalogs, "false lean" on the drivers side

The problem on my car is that the intake isnt sealed to the heads properly due to milling issues; and as a result #7 sucks oil from the valley. I removed the injectors a few days ago to switch them from side to side to try and track down the split BLMs (easy job on my LT1) and I could clearly see a pool of oil sitting on the intake valve. Note again that there is zero blue smoke at startup.

I lifted the intake and there it was - clear evidence of oil across the gasket at #7.

The same ASE tech had previously performed a smoke test on the intake and concluded "no intake leaks". However our theory is that engine vacuum is pulling oil across the gasket and the smoke test only operates about 1-2psi.

So.... my advice to you is to have the builder pull the intake and check the gasket seals. As a potential "quick and dirty" check you might try spraying TB or MAF cleaner around the edges of the intake while the car is idling - if there is a gap across the intake gasket then the engine will surge.

Good luck.,.,....

 

last week or so the shop sprayed brake cleaner in the pcv and the valve cover make up air hose, and in the valve covers, they said and i understand , he is introducing a combustable/ flamable into the crankcase and if there was a leak internally the idle would be affected, this made sense to me. instead ot going up the idle went down, i don't know how "right" that was but that is the theory.

a valve sguide seal was ajar at #8 hopefully that was the problem, if it still eats oil, the next step is intake (super ram ) removal.

now i understand why it got worse, the engine was new and when the rings progressively sealed over time the oil sucking got worse( path of least resistance), what doyou think?
good morning, thanks on the phone now with the shop...