Thread: update3 test results

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Hey all: Put an electric fuel pump and a fresh can of gas to eliminate the fuel pump as a source of oil. Not coming from there.
The compression test shows 152 psi on all cylinders. A mechanic lent me his leak down guage. I've never had the need to do a test myself, so I'll give you the readings and see what you think:
Pressure in-60 psi (all cylinders), reading on guage from cylinder averaged 70 psi, needle steady, did not gain or drop. If I turn up the incoming air pressure, the cylinder guage will go up. Same way if I lower the incoming pressure, the cylinder guage will drop in pressure. At no time will the guage from the cylinder drop below the incoming air pressure guage. I'm assuming if the cylinder guage reading fell below the incoming air guage reading you might have a problem. Correct or not? Air was only heard in the crank case. No signs of air in the cooling, exhaust, intake, etc. If the leak down test looks ok and I've eliminated the fuel pump, I've eliminated everyway oil could get into a cylinder, per say, but it's getting in there somehow!! I guess my only other option is to tear down and start over. In all honesty though, even the majority of some 25 people I've talked to (including all ya) really don't feel the grease would be a "major" problem, or would just delay the rings seating. I'm down to the only thing repeated on both rebuilds is the grease. Please let me know what you think about the leak down test. All 8 plugs are saturated with oil, and I swear it runs awsume like nothings wrong! By the way being so desperate as I am, I hopped on another forum and in over a week no one has replied! You guys (or gals if any on here) responded immediatly and helped me try to solve my problem! That's cool!! Thank you. I do have one other idea. I got to thinking about when the cover under the intake was remounted it was fastened in 4 new holes. (the cover mounted to the intake) The 4 old holes are not plugged. I assumed they don't go all the way through. What if for some reason they do? It would answer the oil I found under the carb, in the intake. It would then answer why all 8 cylinders could get oil. (2 holes each side so it would feed both planes of the intake). Anyone ever heard of such a problem?? The first time I seen the oil there is originally why I thought the fuel pump, although improbable. Also thought on the rarity of too much oil in cylinder escaping into the intake during overlap, again, improbable. Also, even with the road tube open, the oil fill tube, without breather cap on, blows smoke out of it like crazy. Ok, usually that points to blow by and rings, right? (the more you rev it, the more it smokes). Can you see why this is driving me a bit crazy? Better let ya go. Later

If you do have holes in the bottom of the intake that penetrate the plenum, it will suck oil from the lifter valley. I'd certainly check that out and would bet this is your problem.

Regarding the leak down test; Did you actually turn off the incoming air to see how long each cylinder would hold pressure? If the cylinders will hold pressure, and based upon the compression readings you describe, you probably do not have a ring problem - but it is also possible that excessive oil in the chambers will help seal the pistons against the cylinder walls and hide a worn ring problem.

if you have blow-by coming out of your breather, one of two things are happening. either you have a ring problem or your pvc stystem is not working. if you were sucking oil by the intake gasket it wouldn't come out of the breathers. if its compression in the pan then its rings.

Denny: The guage is a Mac Tool brand. Guage on left reads incoming pressure with a regulator underneath it. Guage on right is reading pressure back from the cylinder. I don't know about the percentage. Not doing this before, and not having the instructions that came with the guage I can't tell ya much. I assume I'll have a little bit of air in crank case by the gap of the rings, just a pinch. The air doesn't sound like it's gushing in there, you can hear a little though.

Hi MainCap: Yes, the cylinders will hold pressure for a moment and leak down really slow. I assume a cylinder isn't 100% sealable due to the ring gaps, (except maybe if you use gapless rings), so I assume the guage from cylinder will slowly drop once I shut off the air supply due to the gaps. (this set of rings only have 85 miles on them).

It1s10: We have an open system, no pvc valve. That would leave rings. Food for thought-if I'm sucking enough oil into the cylinders, overwhelming the rings, could cylinder pressure force the blow by by the rings thus letting it come out the breather? If I didn't have so much oil in the cylinders, right away I would guess rings with smoke out the breather cap in excess. (just a guess).

One thing I forgot to mention on the compression test. I went ahead and added oil to the cylinders, (as if I need more in there!) and got 0 more pressure on the guage. Again though, with so much oil it could be possible to get false readings as you say.
I hope it would be as easy as the intake. If that's not it, it puts me back to the rings and tear down. All for now.

smoke coming out of a breather closed or opened is compression getting pass the rings and the smoke you see is oil being blow out of the pan. the smoke is oil. there is something wrong with your rings, pistons, and or block. sucking oil from anywhere above the pistons has no effect on the breathing. just make it smoke out the tail pipe.

Withe the grease on the cylinders at the time of the assembly, I still think the cylinders are glazed over and not allowing the rings to seat. IMO, pop it apart, re hone it, end gap and install a new set of rings. Like Mike said, smoke coming out the breather means compression is getting past the rings.......JMO

What kind of heads are you running, you might have stated but don't remember. Do you have screw in studs in your heads?

Originally posted by 73RS
What kind of heads are you running, you might have stated but don't remember. Do you have screw in studs in your heads?

WHAT DOES SCREW IN STUDS HAVE TO DUE WITH OIL CONSUMPTION?

hey all: Correct on oil out the breather and rings. Got the leak down test figured out. The average percentage is 12%. From research, it seems 5-10% is ok, at 20% or more you probably have a problem. If the compression is good like it is, and the leak down seems ok, then how can it be the rings? The only thing these two tests can't show is if the oil rings are doing their job. We have smoke out the exhaust, and the blow by out the breather. Both ring companies I spoke to said if you saturate the cylinder enough with oil, no set of rings in the world will seal. That's why I'm wondering if I had a leak large enough top side to overwhelm the rings and get blow by that way. The kicker is on the first rebuild the cylinder walls appeared normal, no sign of glazing. Also, Hastings rings said they found no residue of grease on the rings I sent them from the first rebuild. I think I've got it down to the rings or intake. I'll eliminate the intake and then have no choice but to tear it down. The heads are stock, no screw in studs.

if you are getting that much oil on top of your pistons you should be able to find out where its coming from. oil on top of the piston helps seal the rings,(wet comp. check) any more than that should lock the motor up. i agree if your comp. check is right you shouldn't have this problem.

Is it possible that the grease is blocking oil drain back? The upper rings seal,but also scrape and drain back through the slots behind them. The only other way to get all that oil in there past the rings is with positive crankcase pressure. Are you certain the oil isn't coming past the valve guides,or being drawn through a portsomehow?

as far as that much oil being sucked into the cylinder from the intake it would have to be a sizeable hole in the intake, which should give you a bad vac. leak, which you should be able to see or hear, or the motor should show low vac. reading. also if you had a hole in your intake with a vac. leak, then it wouldn't be blowing oil out of the breather, it would have a suckion at the breathers as if you had a pcv valve on it.
if you dont have a pcv valve hooked up you are gonna get some blow by out of the breather, so i think you have a small vac. leak at the intake, or valve guides, thats causing the tail pipe smoke and the breather smoke is normal.

How about the PCV. Problems with those can cause oil consumption.

Hey all: Your all right. (except we have no pcv valve). It wouldn't run as good as it does if there was a hole in the intake. The maker of the grease states it's melting point is 300 degrees. On the bench I heated up some on a metal plate and it would melt and slide off the plate at 190-200 degrees. I'm assuming the grease isn't blocking the drain back holes if it melts fairly ease. (no plugged holes on the first rebuild). I guess that does leave me with rings not sealing because of the grease. You all helped me realize that, thank you. I'll let ya all know when I tear down and get it back together. Thanks again for all your help!!!! It is appreciated. Later

Hmm.

I'm still betting that your unused holes in the bottom of the intake are sucking oil - and would probably seem to run fine if they are not too large with relatively balanced leakage across both plenums.

Since you are planning to tear it down, why not pull the intake first and eliminate this as the problem before you pull the motor?