Zazz93

iTrader: (2)

Can you guys think of a reason why I would be burning oil through the PCV system with what seems to be a high compression low leak bottom end?

After a recent mild build I'm noticing that oil is still being burned 2,000 miles into use. Originally, my machinist said give it some miles to seat the rings but it is still an issue. The background on the problem is as follows...

Burning about a quart every 500 miles, and from what I can tell it is burning this directly through the PCV valve. No oil in the throttle body so this leads me to believe the number 2 bank is breathing and flowing gases ok but the number 1 bank is throwing oil directly out the PCV. The intake manifold collector is pretty saturated. The engine has been compression checked and every cylinder was in the 205-215 range. The engine has also been leak tested, but I'm a little leary of the leak tester I used but there was no sizable fluxuation in the needle. PCV valve has a good vacuum at idle. The engine pretty much only puffs smoke just off idle (leaving stop lights). Its throwing 1283 but I attributed that to HFC's.

Also the engine seems to be running strong otherwise.

Zazz93

iTrader: (2)

List of Mods-

Eagle Rods
Weisco 11:1 pistons .20 over
3 Angle Cut Valves
Balanced Assembly
Mishimoto Radiator
JWT Pop Charger
JWT Valve Springs
Motordyne 5/16 Spacer
Megan Headers
Jim Wolf Flywheel
Kinetics HFCs
M2 Exhaust

SGSash

iTrader: (3)

It honestly just sounds like a bad hone job or poor piston ring seal/file fit etc.

Sorry!

rcdash

iTrader: (18)

No catch can? That will allow you to measure oil coming out of the PCV. The OEM PCV valve is designed for the stock engine. I believe you are just pulling too much vacuum at idle. You can restrict with smaller tubing, but put a pressure gauge on your catch can and you can modulate until you find reasonable ventilation without sucking out oil.

Zazz93

iTrader: (2)

I didn't realize it was possible for the idle suction to be too strong (within reason of course). The comment makes sense because yesterday I scheduled a dyno run and on the dyno the car almost never went down to idle (1500-2000) and I didn't get a puff of smoke. I do have a catch can on order, also I've gone to a 20-50w oil (after the run) and it seems to be helping. Thanks for the response.

Zazz93

iTrader: (2)

I'm not ruling out error on my part, but it would be hard for me to believe the hone was off because the rings measured near perfect out of the bag at multiple points. I only had to adjust one ring because it was the same size as the preceeding ring. If i'm not mistaken, Wiesco rings for this app are square and aside from the numbers "going up" I can't see where it could have been a problem even if they were flipped. Trust me, this was on my mind the whole time so additional care was taken. But once again I not taking assembly erro r off the table, but before I tear it down I want to exhaust all other possibilities.

rcdash

iTrader: (18)

It is also possible that your PCV is not working as it should. At very high vacuum, it should actually drop flow. If it is sticky due to residue it may not function appropriately. Replacement is easy and inexpensive ($15 screw in part) and should probably be your first step before trying to alter the flow out from the valve.

Zazz93

iTrader: (2)

Forgot to say the first thing I replaced was the PCV. made no difference. I also inspected the valve cover and baffle and it was sealed pretty good. No leaks in the front seal or oil pans. I found some PSI figures for vacuum and I'm gonna try a vacuum test through the dip stick.

SGSash

iTrader: (3)

It's very frustrating for sure. Best of luck and hopefully it's not an internal issue!

Zazz93

iTrader: (2)

Your not kidding, hopefully it isn't internal or more specifically the block. but it is reacting better to a slightly heavier oil. Almost no consumption this week so I'm going to continue to monitor it and try the light weights again in a few months. I had it dyno'ed for an idea of whether it was making the power it was expected to and dyno operator said it was definitely stronger than a factory motor. For reference this mean dyno has HR's with intakes and exhausts in the 230 range. My DE turned out 242 untuned and what I thought was a little lean (didn't break out of the 14's until 5500). It's also done in 4th gear.

Time will tell,

Z1 Performance

iTrader: (564)

Did your machinist give you any specific oil recommendations? He should be able to give you some suggestions based on the bearing type/clearances he used. When you did a compression check did you try a few drops of oil during the process? Did the # change?

Zazz93

iTrader: (2)

The machinist didn't suggest a particular viscosity but he did recomend to usage of conventional oil until the rings were seated. I had been using a conventional 5-30 but ended up installing an oil cooler and going with a viscosity increaser. My best estimates suggest the heavier viscosity oil is not being thrown around as violently at and in the baffle on the valve cover and oil consumption is far lower (haven't had a noticable amount). Of course the viscosity increaser is merely a "Band-Aid" and is only buying me time to see if the rings truly needed an elongated seating period.

I haven't tried the oil'ed compression check, not sure why I didn't do it because I have heard of it before. I may try that test again as well drain the old oil and go to something like a 20-50 snythetic with no viscosity enhancers. From what I gathered, he machined everything a little on the tight and quiet side because I told him that street use was the priority. Because the rings were so close to perfect out of the bag I assumed it was a little free because a tight fit should require some ring working and I only had to adjust a single ring (which was within tolerences but had the same size gap as the preceeding ring).

1cockyZ

iTrader: (46)

A qt every 500 miles is major failure...sorry. Did you do new valve seals and one isn't seated right? But sounds like rings. If I remember right if the rings fit without filing, then the piston to wall must have been way out of spec. I have read if the ring gaps aren't staggered correctly the engine will use a lot of oil. But with compression that solid I am going oil control rings aren't right or valve seal. What did you use to square the rings?

Zazz93

iTrader: (2)

I used a purposed ring filer. And probably the only thing I can confirm without a doubt the adjustment was square allowing the ends to seal correctly. The valves seals could be bad but they are new as with most of the engine's internals. I didn't replace those personally (I left that to the machinist). The dispute I would have with the valve seal theory is it doesn't smoke on start-up. If I'm not mistaken that is a near pre-requsite for that type of leakage. Back to the rings, I made sure they were all staggered within spec (per FSM not Weisco), but the oil ring assemblies I left as they were out of the bag per my machinist's suggestion. Because I noticed most if not all the oil was going it through the PCV to manifold plumbing I started using a catch can. If i'm not mistaken this should isolate whether the oil is slipping past the rings or through the valve stems versus only through the PCV line.

1cockyZ

iTrader: (46)

smoke on startup can be rings if the piston to wall is excessive. Once the piston warms up it will grow a little and seal better. Did you pull all the plugs to see if any of them are oiled up?

Zazz93

iTrader: (2)

Yeah, good point about the rings. But there is no oil on the plugs (oddly). To be blunt I found it tough to even smell a lot of oil on the plugs. This I thought was really odd because of the amount of oil its burning. I was wondering how can I tell if a lot of blow by is physically in the oil? For example, in excessive blow by unburned fuel and exhaust can get pushed by the rings into the oil. Is there a test to confirm this?

1cockyZ

iTrader: (46)

oil analysis

JCat

iTrader: (4)

Compression check.

Generally, blow-by is caused by rings not sealing.

.

I have experienced rings not sealing correctly on newly rebuilt engines. It is not something that can always be explained.
.

Zazz93

iTrader: (2)

I was hoping there would be a more immediate method but I think I'm going to try that.

Zazz93

iTrader: (2)

Compression was high last time I checked, 208 was the low and 215 was the high (I think the FSM states 180 is average and 10% is the variation threshold). A leakdown test was also favorable, but I can't say the gauge was calibrated perfectly. However I did confirm there was little to no notible leakage in all of the cylinders.