Landarose

So, first post here and I'm trying not to look like a clueless jackass, here's the facts:

I have a 2003 350z enthusiast model, 6 speed MT boosted at 60k miles, was running strong until about 90k on 6psi with greddy 18g twin kit, intercooler, 440cc injectors.

I run royal purple 5-40 synthetic, and have never had a problem its 30k miles boosted, just recently ive smelled burning oil, with NO BLUE/WHITE SMOKE FROM EXHAUST, Checked my oil today and noticed it was burned/smelled burned and was brown, which sounds normal but when I change the oil every 3k its usually still purple as ****, almost like it could be reused, however that was not the case. Oil level and pressure have remained normal.

The vehicle is a daily driver, not severely beaten on, but sometimes I just get an itch to booooossssttt. Originally I suspected rings, but without smoke I was unsure what the cause may be. I have a compression tester and could check all my cylinders but was not sure if it was necessary yet at this point.

I've been around the forum for about a year now and try to search for my problems well before I post and have never had to do so with that advice, until now.


Any help, suggestions, ideas would be greatly appreciated.

Resmarted

iTrader: (2)

Well my brain is fried, and nothings coming up but I can throw a few things to check out at you (which you should check out anyway...)

PCV? Are you running a catch can, vents, or stock system? A stock system would probably be fine on 350whp, but It's a really easy mod to switch to open evap

What do your plugs look like?

What do your turbo's look like? Could be a seal starting to go bad on a turbo. A buddy of mine bought brand new gt28's from garret and they were leaking out of the compressor side, so I've realized NOTHING is out of the ordinary anymore. Although it wouldn't just kind of smell and not come out your exhaust.

Sounds like its an external leak onto something hot. It's possible that it's your valve-cover, or maybe another serviceable seal is letting go and dripping down onto a header or something.

Landarose

Im running a stock system, but I suppose Catch cans or a vent would be a better alternative, haven't taken a look at the plugs yet but will probably later tonight.

My turbos appear alright externally, they do look well used though, a good amount of rust/heat discoloration on the exhaust portion of the turbo. After thinking about it(although I try to allow a good amount of cooldown time before shutting it off) I was thinking possibly from killing the engine with turbos still warm could cause the oil to lose viscosity and basically cook into the the turbo in a still warm oil line that could be the source of my internal oil burning?

I guess next step at this point is to pull plugs and do a compression test while I'm at it so I could at least rule out a couple of things... while i was underneath the car, I noticed the smallest drip of oil ready to drop from back behind my last header on the driver's side, seeing as how tight everything is in there with the turbos in it was hard to get a good look at, and ill have to do a little more searching and sniffing in the engine bay.

I appreciate the suggestions and I'm open to anything else that comes to mind from experienced Z guys, Thanks.

BriGuyMax

iTrader: (4)

If your oil is noticeably dirtier and you smell burning oil with the same interval and usage pattern, I would suspect you have a small ring issue beginning in one or more cylinders. I would highly doubt the turbos are the issue since you would see a plume of oil smoke if seals were the problem and you wouldn't have dirtier oil. A leakdown test would give you a good idea how your rings are sealing.

Have you ever had an oil analysis done? Might be good to do on your next oil change.

binder

iTrader: (8)

Sounds like rings. 90k on the motor with 30k of that being boosted means the rings are probably toast. It will allow more blow by down into the crankcase which will contaminate the oil with carbon. It doesn't have to smoke out the exhaust to have a ring issue.

Check the plugs for any other issues and do a compression test. With water cooled turbos I doubt the turbos cooked the oil so it's probably just extra contamination.

Landarose

Really appreciate the input guys, and its feeling more and more like a ring issue at this point.

However, these greddy turbos do not have any water cooling, they are entirely oil cooled which is what led to my suspecting of that problem.

Either way though a compression test and good look at my plugs should be able to determine what my real problem is. Ive been expecting the rings to go sometime soon so this wouldnt be a large surpise I just moreso expected a large cloud of obvious blue smoke out of my exhaust.

Ill have my compression test results up tonight or tomorrow and hopefully that shows some results.

zach711f

iTrader: (11)

Loose dipstick? Had it happen once.

binder

iTrader: (8)

Would cause engine bay smell but I think he's talking about actually smelling the oil once it was removed from the car.

If you boost the car and heat the turbos up then shut it off without letting them idle or drive around in vacuum then that would cook some oil in the turbo housing.

Landarose

Ok so havent gotten to a compression test yet, only managed to pull my driver side plugs to take a quick peak at them, all 3 are white as hell, which I know could be a couple things, among running to lean to burning coolant. Now since i havent checked the plugs in almost 10k miles its hard to say what this came from, my car is tuned pretty rich and usually idles around 16 for my afr. so i have some more investigating to do tonight, and will post back as soon as i can.

I really dont believe its the dipstick being loose im pretty careful about that, and the oil burning definitely appears to be something internal.

iideadeyeii

iTrader: (6)

What's your afr under boost and cruising?

unvmyg35

iTrader: (15)

I have 40K miles on a replacement engine on my 2004 G35 coupe. I've been boosted now for almost 20K on a vortech supercharger running 11psi. My car at times smells just as you described above. I have checked pcv and all other connections (oil cooler, sandwich plate, belly pan, vortech drain line, vavle covers ect.). I have no leaks, but I do get blow by into my catch can. My car burns about 1/2 quart every 3K and this has been happening before the vortech and its the same now being boosted.

These are the results of my compression and leak down test performed by ZCarGarage last month.

Cylinder 1 195PSI 1%
Cylinder 2 185PSI 4%
Cylinder 3 190PSI 6%
Cylinder 4 190PSI 4%
Cylinder 5 190PSI 4%
Cylinder 6 185PSI 6%

The test results show a healthy engine. For now, I just ignore the smell.

rcdash

iTrader: (18)

Try disconnecting the manifold from the passenger side PCV and just run catch cans with open breathers.

binder

iTrader: (8)

Plugs on most street driven vehicles will be white since most of the driving will be at 14.7 (stoich).

You said the car is "rich" yet you mention 16 a/f at idle. 16 is very lean. It should be 14.7 all times driving until you are in boost. You are actually lean in your driving map which means you need a tune.

350zjason350z

iTrader: (15)

I didn't read all the posts but.. Did you check if there was oil in the intercooler... I had a problem with the Pcv system .. I thought my seals were bad in my turbos but it was the pressure from the crank case while boosting

unvmyg35

iTrader: (15)

My a/f is 13.5-13.9 at idle and 11.5 during boost. Should I be needing a tune to lean it out during idle and cruise? I have noticed my gas consumption go down too.

Landarose

"16" was a typo, my bad, kind of important number to have right for diagnostic purposes, it should have read 15, it idles roughly between 14.8 and 15.2 about averaging out at 15. And yes you're right the larger the ratio the more lean, i had it mixed up thinking the higher meant richer, and apologize.

my afr cruising sits at about 14.5-.14.8 and at full boost (6psi) is somewhere around 12.

I havent checked the intercooler for oil but I can if that would give me some clues to whats going on

@unvmyg35 appreciate the post I'm kinda playing the safe game to prevent a catastrophic failure somewhere in my rotating assembly by any means I can before it were to happen.

I keep hearing about catch cans and it being a possible crankcase pressure issue under boost...never thought it was much of a problem under low boost, but i suppose for future goals having that can't be bad upgrade right? I'll have to look into it further as a possible problem solver.

still on 60hr work weeks and im trying to squeeze in work on the car, appreciate the input and patience from you guys, and I'm open to all suggestions.

binder

iTrader: (8)

You need to be under 12 on pump gas for sure when in boost. Probably more like 11.5. anything around 14.7 is ok for cruise and idle.

At low boost stock pcv will work just fine but when you come out of boost oil will get into the plenum through the front pcv vent hose so you will notice oil being burned as it is sucked back into the engine.

Landarose

alright finally got my compression test done and I can't say im surpised with the results, did 3 tests on each cylinder, in all but one range was 189-193psi, with a saddening 140psi in cylinder one. Suspicions confirmed... apparently a ring issue all along.

binder

iTrader: (8)

bummer but at least you figured out the problem.

bmyles

So what's the plan, built block or find a low mileage stocker?