Where is my oil going?

[Pir0San]

I put my motor back together with another head, and so far the car has been running fantastic. No water and oil mixing, but I am noticing that my 1st and 4th plugs have black crisp buildup on them, where the black buildup is all cracked, like the plug has leprocy.

My oil level has also been slightly sporadic. I put in 4 1/2 quarts initally when I did the engine build, and the motor took a little while to prime before it was spraying oil out of the oil distrubution rail on the head. I then checked the oil a few days after that, and it looked 1/2 a quart low, so I added the rest of the 1/2 quart I had. A few days ago, I noticed the oil was down by a quart, or at least as far as I could read it was, so I added another quart of oil. I checked the oil again today, and it seemed a little low, but I was driving the car around before I had checked it, so I am assuming that the oil level is probably close to fine, and that it was stuck up in the head.

I am also noticing white smoke on acceleration, and I know it not to be water leaking into the combustion chamber, because my coolant is at the same level it has been the whole time the car has been running, so I'm thinking it's either oil related, or the car is running too rich (which I doubt is the case, because all of my other plugs are burning just right). What could cause my problems?

[Ed]

Did you rebuild the motor and the head? Replace the valve stem seals? New rings? New bearings? Valve job?

It sounds like the valve stem seals are shot. Oil leaks down the valve into the combustion chamber. Gunking up your plugs. The white smoke could be oil burning.

[Pir0San]

the head is rebuilt everything (valve seals, guides, seats, valves, reground rocker arms, reground cam, the works). I was thinking maybe bad/poor piston rings, but is it plausible for 2 out of the 6 rings to be shot? The head has only 300 miles on it...could the seals not be totally sealed? I've read about people doing head gaskets and having problems like I described that eventually went away over a short amount of time...does this sound plausible at all?

Oh, and the block seems to be in good condition, guy at the local machine shops that knows his Z stuff said it was in good condition, no cylinder ridges at all, so I'm assuming everything is okay on the bottom end...

[Pir0San]

I just went outside and did a "dry" compression test. The car was only slightly warm (in the middle of the T in temp) and I held the throttle wide open. My numbers came out to be 140-140-145-140-135-140. I had read about doing a leakdown test, and I was unsure how to make a leakdown tester, but I had also read that a "wet" compression test would allow me to be able to tell somewhat if the rings are the culprit. I went down and bought a quart of oil, and poured what I thought to be about a teaspoon in the first cylinder, then attached the pressure gauge, and cranked the motor over. The gauge shot up to 250 psi, and this is where all hell broke loose. I released the pressure, thinking that was a huge amount, but didn't sweat it at that time. I went to crank it over again, same 250, but when I went to bleed the pressure, a milky white substance came out of the release valve. It was oily, so I started freaking out, thinking that I blew the crap out of the head gasket. I took the compression gauge out of the spark plug hole, and turned the motor over to see what came shooting out. A bunch of oily fluid came spraying out. I started freaking out, not knowing what was going on. I checked my oil, my water level, everything that would indicate a water leak into the cylinder, and thank god, no dice so far. I kept turning the motor over until most of the crap was out of the cylinder, then I decided to put the plugs back in and allow the cylinder to burn the oil out of the combustion chamber. The car started up, and immediately began to smoke. I let it run until it stopped smoking, and then checked the oil and water, and they looked ok. I then took the plugs out again, and turned the motor over again, a slight bit of smoke from the oil burning out came out of the 1st plug hole, and then stopped. I turned the motor over again, no oil shot out. After that, I gave up for now and came in.

Can too much compression kill my rings?

[Ed]

What concerns me is that you have build up on your plugs. If the valve was not leaking oil then where is the oil coming from that is fouling your plugs?

Try installing some new plugs. Drive your car for about 20 minutes until everything is nice and hot. When you pull in to your parking spot rev the engine to about 3k and turn it off at 3k. Check the color of your plugs they should all be a nice cool grey color and hot so be careful . If any are darker or black you might have a air/fuel mixture problem. Especially if 1-3 are a different color than 4-6. Next let the engine sit overnight and check the plugs again. Are any of the plugs wet?

Your compression looks pretty good. It won't tell you the condition of the rings but it does tell you that all the cylinders are in the same condition.

I'm wondering if enough blow by is getting by the rings into the crank case which is then blowing oil up to the pcv valve and into the combustion chamber causing the white smoke.

Check your oil under the same conditions. Like after she has sat all night. The engine holds five quarts so you were underfilled the first time.

[Pir0San]

I'm thinking that the oil is coming from the rings while the car is running. My mixture is right, because my plugs come out looking cleanly burned. The only plugs that look strange are the 1st and 4th ones, due to the buildup. I decided to switch the 1st and 4th plugs to see if by driving with them in other plug holes if they would clear up, and they are burning the way they are supposed to be. The other plugs I swapped into the 1st and 4th now come out looking black and sooty.

Since this is a new head, with a 3 angle valve job, new guides, seals, etc., would it be plausible that it would be leaking?

I just want my Z to run again, and to run well!

[LanceM]

Just on a chance I would bring the engine up to temp and retorque the head. You do have some strange symtoms going there. Ed has some good ideas, try them to help narrow things down...

[Pir0San]

thanks for all of your help guys. I don't believe that the head is bad, considering it's been gone through, and the guy I bought it from (I got it from ebay) has awesome feedback, and the head was in excellent condition when I got it (fresh rebuild), so I don't believe it to be the valves. I'm going to jack the car up and inspect the bottom of the engine for oil leaks to see if that is where the oil is going, then I will run the car and retorque the head to see if it helps out any. Thanks again!

[240ZMan]

... when I went to bleed the pressure, a milky white substance came out of the release valve.

I hate to be thinking bad thoughts for you, but if you started with clean oil, and it's mixing with coolant, it's going to look milky. I don't know anything else that's going to cause a white milky oily substance to come out of the cylinders during a compression test.

I know from recent first-hand experince. In my case the culprit in the end was a small hole that developed in the head near one of the valve springs that allowed coolant to leak onto the top of the head and drain back down into the crank case with the oil. I couldn't see the hole until I had the head pressure tested. Then it was obvious

What does the oil look like on the dip stick? Is there any sign of milkiness? You could have a pin hole leak somewhere that isn't going to noticeably drop the coolant level in a short period of time but will cause the oil to become milky.

Until you're absolutely sure coolant isn't mixing with oil I wouldn't run the engine. Coolant may be slippery, but's no lubricant.

[Pir0San]

I haven't posted this here on this site, but the original Z head I had was had a very small crack around the 4th cylinder valves. It was so small that even when pressure tested at 35psi, it would not leak. After putting a junk head on the block that was given to me (it had bad valves) the car ran and didn't leak water whatsoever. The original head had been pressure tested as I stated above, shaved, everything to fix it, and it still leaked after the car had warmed up slightly, causing the crack to open. I now have a totally new, rebuilt head, and the new head hasn't had any of those problems, so I'm sure it's not leaking water and oil. When it comes to milkshake mix, I'm like a f-in expert

The milk mix ended up being the white assembly grease/lube that most gauges come packed with. The oil I put into the cylinder had mixed with the lube (which is 2 very different weights), which created the milk mix that I had seen. No milk mix shot out of my cylinder, just out of the pressure test gauge.

I checked the oil dipstick just a little while ago, no milkshake in this motor, .

it's been about 330 miles so far with the new head and old block. Right now, the car is down by a quart or so after 5 days...so I'm imagining I've either got a leak or it's burning off in the cylinders.

I talked to one of the guys at Kragen's today while I was getting some oil, and he said that the reason he thinks my motor is eating oil is because the new head is so "tight", that it is creating better compression, which is sucking oil past the rings. Does that should right?

[Ed]

I talked to one of the guys at Kragen's today while I was getting some oil, and he said that the reason he thinks my motor is eating oil is because the new head is so "tight", that it is creating better compression, which is sucking oil past the rings. Does that should right?

I've never heard of this. Possible? Maybe. But when the engine "sucks" the intake valve is usually open.

In my car I've got 150psi in all six. 9.65:1 compression and I have no eating oil problems.

[LanceM]

I'm with Ed, maybe, but bad rings and high compression would cause excessive blow by in my book. A quart in 300 miles is excessive, a leak would be a mess, burning it would look like a smoke bomb I would think!

I'm thinking though that this oil use didn't start until putting this new head on right? If it didn't use oil before the head change then the only thing I would be looking at would be the head or head gasket. Compression is good so that would pretty much rule out the gasket in my book, time to look at the head. Yeah, I know all new, but maybe not done right, or seals left off, or seals torn. With bad seals on the exhaust valves you'll burn a lot of oil but not see it on the plugs, bad intake will show on the plugs. The only way to check the seals it to pull them out and look at them, might as well replace them if you look at them...