Oil Smoke - Input

[Ccmano]

Looking for some collective wisdom. Have to admit I’m a little stumped on this one. First some backgound.

My car is an ultra high mile (181k) one owner 1990 car I bought last year as a long term restoration project. Although, the car is generally in outstanding condition. Some of you may remember the photos I posted. I’ve be working on her and have recently replace the transmission, clutch and flywheel (presenting their own issues). Also, adding headers and exhaust. Last year, the compression test was excellent averaging 190-195psi across all cylinders (I’m at 4500ft so add few more psi for sea level). It idles smooth and runs very strong. No signs of smoke of any kind other than when flogging her at full throttle. Even then just a hint of smoke which I consider normal for a 1990. I run Mobile 1 10w40 High Mileage oil.

Dominic and I have been working since the first of the year tuning the engine for the current mods. The results have been outstanding. The car is responsive and strong. The weather here has been good allowing me to do several 40 mile data logging runs a week since then. The only issue has been an intermittent code 64 (right O2 Sensor lean) at idle after a long drive.

Suddenly, about three weeks ago I started noticing light wisps of blue smoke accelerating lightly from a stop, only when the car is hot. This started to increase since then. I noticed it particularly on a long coast down in 4th gear coming down a long grade to a stop at the bottom. No smoke while coasting but when I accelerated away from the stop I got a good cloud. I’ve been monitoring it since and it is to the point where once the car is hot I get a good plume if I goose the throttle. There is no smoke at static idle though. There is no smoke at all while the engine is cold, even under acceleration. The smoke comes exclusively from the right exhaust.

So I started looking at the usual suspects to try and find the cause. Valve guides are unlikely because they don’t fail suddenly like this and generally cause smoke at startup when cold. My car doesn’t do this. Next is the PCV system and the camcover breathers. Breathers are clean and generally dry. I removed the entire PCV system and found it to be in great shape with functioning PCV valves and no deterioration of the rubber pieces. All seals are good. I cleaned the PCV valves as a precaution. While there was oil in the system, there was not enough for concern. I even ran the car with the PCV system disconnected and still had the smoke. Related to the PCV system is excessive blow by caused worn rings. With the car idling there is no pressure or air being pushed out of either the oil cap opening in the cam cover or the dip stick tube. Nothing.

Today I conducted another compression test, to my surprise it was better than last time. Averaging 200psi on the right side and 190psi on the left. Again, I’m at 4500ft, so add a few psi for sea level comparision. None of the cylinders stood out. I’m thinking the right left difference is timing chain stretch.

Looking at the plugs, particularly the right side, #2 and particularly #4 show signs of soot but are not wet. They look different from the rest. See the fotos below. I did an endoscopic examination inside the cylinders particularly #4 and #2. All the cylinders show moderate carbon build up on the top, nothing unexpected. I’m not sure what to think of the cylinder walls though. All still exhibit the cross hatching, however all have vertical scuffing to one extent or another. See photos below. Given the mileage I’m not sure what to think of the scuffing.

My current thought is that it has developed a stuck oil ring, probably in #4. Possibly from carbon coming loose. I’ve done 2 Seafoam treatments in the past and I currently run an anti carbon additive in the fuel. Today I started soaking all the cylinders in Marvel Mystery Oil. It’s the old school method to try and loosen a stuck ring.

So what am I missing here? The car idles and runs great! Compression is good. The PCV system is good. My only other thoughts are the IH gasket leaking oil from the breather to an intake valve. Possibly a head gasket? Both of those a low probability.

Your input is welcome...
H
:cheers:

#2 Spark Plug
http://a66.tinypic.com/a42yir.jpg

#4 Spark Plug
http://a64.tinypic.com/2nsor49.jpg

#6 Spark Plug
http://a66.tinypic.com/4dbwm.jpg

#8 Spark Plug
http://a65.tinypic.com/2n22ufm.jpg

#2 Cylinder top
http://a66.tinypic.com/2igf3te.jpg

Cylinder Walls
http://a65.tinypic.com/212ffk5.jpg
http://a64.tinypic.com/34edqf7.jpg
http://a63.tinypic.com/x21khz.jpg
http://a65.tinypic.com/2gt2iis.jpg

[XfireZ51]

Hans,

Not sure if any of my experience applies but here’s the thread regarding what was found by Dr. Greekenstein.


http://www.zr1.net/forum/showthread.php?t=28220&highlight=Oil+consumption

[Ccmano]

Hans,

Not sure if any of my experience applies but here’s the thread regarding what was found by Dr. Greekenstein.


http://www.zr1.net/forum/showthread.php?t=28220&highlight=Oil+consumption

I was thinking of your situation with the broken ring. Did you have good compression in that cylinder or was it low. Strange part on mine is the scuffing is in all cylinders and compression is good.
H
:cheers:

[32valvesftw]

Do cylinders 2 and 4 share the same coil? Maybe you have weak spark and incomplete combustion in those cylinders. The cylinders look ok as far as the hatch goes, but there is some minor scoring, no telling when that occured. Maybe oil starvation or overheating at some point in its life? I assume you did a static compression test? A leak down test may yield more information. Any lifter noises or seepage around the PCV piping?
Good luck with the Mystery oil. Does sound like a stuck oil ring at first glance, how high is oil consumption?

[Paul Workman]

:happy1:

[Ccmano]

Do cylinders 2 and 4 share the same coil? Maybe you have weak spark and incomplete combustion in those cylinders. The cylinders look ok as far as the hatch goes, but there is some minor scoring, no telling when that occured. Maybe oil starvation or overheating at some point in its life? I assume you did a static compression test? A leak down test may yield more information. Any lifter noises or seepage around the PCV piping?
Good luck with the Mystery oil. Does sound like a stuck oil ring at first glance, how high is oil consumption?

2 and 4 do not share a coil. The compression test was static with a warm engine. Since compression is not the issue I’m not sure a leak down test would provide any useful information. No lifter noises and no PCV seepage. Oil consumption is fairly high. A quart in 300-500 miles.

Good question. Keep the ideas coming guys...
H
:cheers:

[gtcollins@maxnet.co.nz]

Hi looks like oil sitting on top of the piston to the right

My engine will smoke if I decell hard from high rpm changing down the gears is this normal for LT5 engines

Sent from my SM-G930F using Tapatalk

[Ccmano]

Hi looks like oil sitting on top of the piston to the right

My engine will smoke if I decell hard from high rpm changing down the gears is this normal for LT5 engines

Sent from my SM-G930F using Tapatalk

I take it yours is the Black 90’. The 1990 came without valve stem seals. What you described is not unusual. I took the photos immediately after the compression test. I believe that’s fuel the piston.
H
:cheers:

[gtcollins@maxnet.co.nz]

Yes mine is the black 90 and I Will be rebuilding the original engine and will be fitting valve guide stem seals to the exhaust

Sent from my SM-G930F using Tapatalk

[XfireZ51]

I discussed oil consumption with Marc recently. He stated that 1qt. per 700miles or so I not unusual. Now that doesn't mean you end up w sooty plugs.
But its pretty common to have oil puff showing after hard accel and decel. You can take a ZR-1 to the track and go thru a quart with just a few passes.

[Ccmano]

Dom, all I have to do with mine is let it sit and warm up. Once hot and you rev the engine it will put a good amount of blue smoke out the right side exhaust.
Prior to this oil consumption was negligible. So something changed.
H
:cheers:

[XfireZ51]

Dom, all I have to do with mine is let it sit and warm up. Once hot and you rev the engine it will put a good amount of blue smoke out the right side exhaust.
Prior to this oil consumption was negligible. So something changed.
H
:cheers:

Hans,

My post was not intended to address your particular situation. It really was directed more to gt. You and I have discussed the similar symptoms my motor was exhibiting last year just prior to and during the MR5. And ultimately what Dr. Greekenstein diagnosed.

[Paul Workman]

Just following along here...

Assuming (for now) the "given(s)" are correct, the only thing exclusive to the one bank are the pistons/rings and the head (including valve/guides)

IIRC, when I did the compression check on Dom's car, compression average differed bank to bank, BUT there wasn't really anything that jumped out, far as static compression test goes.

And again, IIRC, Dom's oil consumption was similar to what you are describing.

I don't remember if Pete did a leak-down test, but I do recall Dom had a cylinder that did have fouling in excess of the others. (Dom remembers if that plug was in the cylinder with the broken ring.)

So, I don't think a leak-down test is out of line: hate to assume b/c static compression was good that a ring is eliminated. Has happened B4!

In the end, the motor was pulled and broken down and the broken ring was discovered upon disassembly. I know I was a little surprised at the broken ring. There wasn't any of the catastrophic "stuff" that usually goes along with a broken ring, far as I know.

Then too, it could be something off the wall - like...IDK...a valve seal breaking or the (off-the-wall) like? I'd want to eliminate everything I could to avoid pulling the motor - that being the last resort, but the best way to explore every nook and cranny. (Would be a good time to refresh the bearings and rings, etc., anyway, huh?)

Going back to my :happy1: now...

[Ccmano]

Paul,

I have found only two instances of this documented previously. One was Doms with the broken ring. The other was back in 2014 on a 368. That turned out to be a collapsed oil ring. If I’m not mistaken Pete diagnosed and repaired both. So it’s trending in that direction. I’m keeping my fingers crossed it’s stuck oil ring that can be loosened.

I may run a leak down in a few days when the temps here climb over 40 again and my back, which I put out this morning, gets better.

Btw, no valve seals, it’s a 90’.
H

[Ccmano]

For those following this thread. Lee (Lgaff) and I have been talking off line. He has 2 sets of low mileage stock liners. All show the same vertical scuffing mine seem to show. Appears unlikely that this is related to the current condition discussed here.
H
:cheers:

[A26B]

Do you still have the original exhaust manifolds/cats installed?

[Ccmano]

Do you still have the original exhaust manifolds/cats installed?

No it has headers and exhaust. This started after I installed them. One of the reasons I did that was because of my concern at the cats breaking up.
H
:cheers:

[DRM500RUBYZR-1]

No it has headers and exhaust. This started after I installed them. One of the reasons I did that was because of my concern at the cats breaking up.
H
:cheers:



Interesting.
Could oil somehow be getting introduced into either the combustion chamber or into the exhaust stream somehow?
Seems awfully coincidental and odd that the problem appears simultaneously to the installation of the headers.
There is an answer there somewhere.
Hmmm...........................
Marty

[Ccmano]

The only remotely possible area of oil introduction that I am aware of is at the header stud. No way to get into the combustion chamber from there. Generally just causes a leak or oil burning off the header. I my situation oil is getting into the combustion chamber and causing smoke out the exhaust.
H


Sent from my iPhone using ZR-1 Net Registry (http://r.tapatalk.com/byo?rid=90383)

[XfireZ51]

Maybe the correlation is that after 28 years, something is going to give when u push it a bit. My motor had about 70k on it when this happened. And I recall seeing puffs of blackish-gray smoke upon harder acceleration right at the beginning of the season last year. I thought it was just the motor blowing out some carbon.

[gtcollins@maxnet.co.nz]

I had the left catalytic converter go on my 1990 #0308 you say it's on the right side when my cat went it made the exhaust white the left bank often had a white to gray look to it compared to the right side well before the big white out in hindsight this was the cat just starting to go bad did noy know enough about the cars then had a steep learning curve after that.
Justs a thought l wonder if the headers are making more vacuum in the exhaust port and pulling the oil down the guide dose the oil smoke clear after you drive of my car can blue smoke when I decel hard thought the gears you see the oil smoke in the rear view mirror once the smoke clears from the decel you don't see it again the engine doesn't use alot of oil I think the reason the oil smoke can take a few seconds to clean is that it's in the exhaust port and exhaust not always in the combustion chamber so once back on the gas the oil burns of I need to put my gopro back there and film it to see if the engine smoke under hard acceleration just an idea hope this can help put your mind at ease I will be rebuilding #308 engine soon as I would like to put it back in the car as the engine in the car is #3026 and was rebuilt and dynoed and shipped to NZ by Doug Rippy back in 1995 It was never run till I got it going in 2017


Sent from my SM-G930F using Tapatalk

[Ccmano]

Interesting thought. This did not happen immediately when the headers were installed. At first everything was normal. I probably put 700 or so miles on the car with the headers before this started about 3 weeks ago. If the MMO treatment doesn’t work I will check the IH gasket and will pull the right cam cover to check for obstructions. Failing that or some other as yet unknown issue, it tear down time.
H


Sent from my iPhone using ZR-1 Net Registry (http://r.tapatalk.com/byo?rid=90383)

[gtcollins@maxnet.co.nz]

I would also do a leak down test as well as a compression test another idea is if you think the ring are carbon up you could run diesel engine oil in it as it has detergent in it and will clean out carbon I ran it in my wife's car when it had noises hydraulic lifters fix the noise lifters

Sent from my SM-G930F using Tapatalk

[gtcollins@maxnet.co.nz]

Also all the cleaning products could have washed out the carbon that was helping seal up the engine if I put diesel oil in gas to clean them up sometime it will ruin the engine as it wash a the carbon but they are not that good anyway if fail after that I haven't had 1 fail yet

Sent from my SM-G930F using Tapatalk

[Ccmano]

A leak down test is also in the schedule for this weekend. If it turns out to be an oil ring I suspect my aggressive decarbonizing may have contributed. The Marvel Mystery Oil has the same affect as diesel. It’s in all the cylinders as we speak, soaking. I may add the remaining half quart to the fuel as an added precaution.
H
:cheers:

[gtcollins@maxnet.co.nz]

Hi I don't use diesel I use diesel engine oil that is petrol engine rated it has a higher detergent percentage level than petrol oils and this keeps the engine clean can sometimes help l don't run this in my LT5

Sent from my SM-G930F using Tapatalk

[gtcollins@maxnet.co.nz]

Hi all I brought a gopro awhile ago haven't used it before I thought I would check out the exhaust smoking on decel and I found that there was none I have seen some big clouds of blue smoke from in the car at times and when I think back about it the smoke has been after I have had extended times of quite driving my engine was overhauled by Doug Rippy back in 1995 and it was dynoed then as well it was not run till I got it going in November 2017 so I suppose I am still running it in I have done just over 4000 miles since getting it going again have been having awesome time driving my ZR-1 and after last night I feel even better about it here is a clip from the video I pushed the loop button on the gopro and didn't get much video but will get the general idea of situations if you like I will make some more videos here's the video let me know what you think

Regards Glen Collins
https://youtu.be/vsdywrkycwc

Sent from my SM-G930F using Tapatalk

[gtcollins@maxnet.co.nz]

Hi again if you copy and paste the link it should work

Sent from my SM-G930F using Tapatalk

[jss06c6]

Hans,

What's the verdict after the MM oil treatment?

Steve

Sent from my QTAIR7 using ZR-1 Net Registry mobile app (http://r.tapatalk.com/byo?rid=90383)

[Ccmano]

Hans,

What's the verdict after the MM oil treatment?

Steve

Sent from my QTAIR7 using ZR-1 Net Registry mobile app (http://r.tapatalk.com/byo?rid=90383)

Steve,

After putting my back out early last week (getting out of bed...lol) I ended up leaving the MMO in the cylinders till Sunday. Feeling somewhat better Sunday I cleared the remaining (surprisingly) oil out of the cylinders and buttoned her back up. Started her up and commenced the mosquito fogging. After warming up I took her out for a short drive. We at least had weather in the 40’s. Did have a good chance to blow out the oil and loosened carbon. By the time I got home the smoke had cleared.

Since I didn’t have a chance to do an extended drive I will say I am cautiously optimistic. By the time I got home I was unable to reproduce the smoking I referred to earlier. Reving the engine from idle no longer produced the smoke I had previously seen.

I’m hoping to get out for a longer drive tomorrow. If this holds up it would appear that a stuck oil ring was cleared. At this point I’m not prepared to go that far.

I’ll report back after some further testing.
H
:cheers:

[XfireZ51]

Let’s hope Hans

[jss06c6]

Good news so far buddy!! Will be watching..

Sent from my XT1585 using ZR-1 Net Registry mobile app (http://r.tapatalk.com/byo?rid=90383)

[Paul Workman]

Fingers CROSSED!

MMO... huh! I assumed that stuff was on the shelf with the STP and all the other miracle cures. To hear it may actually have worked!? Well, I'l B!:jawdrop:

[XfireZ51]

Have used MMO many times in tank and oil. Helpful for sticky lifters.

[Ccmano]

Fingers CROSSED!

MMO... huh! I assumed that stuff was on the shelf with the STP and all the other miracle cures. To hear it may actually have worked!? Well, I'l B!:jawdrop:

Again, I’m not convinced yet. Should have a better idea later today. This treatment is nothing new. Some do it with Seafoam today, filling the cylinders and letting it sit for 48hrs. In my case it was 4 days. I’ve done this before with a Saturn I bought for $500 for one of my kids. Similar situation, spewing blue smoke. Saturns were known for coking up the cylinders. Ran great after. My kid drove it for another two years.
H
:cheers:

[gtcollins@maxnet.co.nz]

Good to hear you are on the right path hopefully all is well with your engine

Glen

Sent from my SM-G930F using Tapatalk

[Ccmano]

Well.... the verdict is in and as in all things it’s not clear cut. Drove the car on my 40 mile datalogging loop today. For most of the drive all was well. Then, towards the end I came off the freeway to a stop. As I accelerated away from the stop I saw the smoke again. Not as bad as before but definitely there. Getting home I let it idle in the driveway. Goosing the engine once again produced smoke. Again not as bad as before, I’d say 50%. Strange how it’s only there after a half hour or so of driving.

Given the mileage on the car I’m leaning towards a rebuild or replacement depending on what I find.

At this point it will have to wait a few weeks. I’m going into the hospital Friday for a gallbladder removal. Nothing major but it will put me out of commission for a week or two. Gives me time to consider the options and possibly start buying what I need.
H
:cheers: