Blue smoke vs gray smoke - oil vs fuel
 

Have a '00 S2000, 158k miles (4.56 gears for 90k miles). Have had the car since it had 31 miles on it!

Couple of years ago, Greg (tr6greg) started to notice blue smoke out of my exhaust pipes. Seems to only happen after I have been engine braking, and then accelerating slowly. If I accelerate hard, no smoke.

Changed PCV valve, installed a catch can (never has more than a drop of oil in it), had the valve guide seals replaced..... and the blue smoke continues. Greg is always the person behind me, so he knows what to look for! https://www.s2kca.com/core/smilies/0...lies/smile.png

Billman recently suggested to add a qt of 15w50 oil and see what happens (as he thinks it may be the rings). Did this, and the smoke continued.

His second thought was to add a 2nd qt.... here is the strange part.... now it is still smoking after engine braking, but the smoke is gray!

Why would the smoke change from blue to gray, after adding the 2nd quart of a higher viscosity oil??????

Also.... my exhaust tips really get sooted up after 100 miles or so.... doesn't seem to be oil on them, wipes off nice and clean with a wet paper towel.

Since now thinking its a possible fuel issue, have swapped injectors (thanks Andy for the injectors!) to see what happens. Weather has been sh*tty, so haven't been able to get the car out of the garage to see if the borrowed injectors help out!

Another thing that you should know... last year, was throwing P300/301/302/303/304/1399 codes - cylinder misfires. Sent the injectors out for cleaning last winter... and all came back cleaned and supposedly OK... still had the misfire. Swapped out injectors and found the injector in cylinder 2 was bad. Replaced it, and car hasn't thrown a code since.

Appreciate any and all thoughts or suggestions on what my smoking issue may be.... Thanks!!!!!

Sounds like worn rings/cylinder walls to me. I'd like to do a compression test and look at the plugs.

Ive heard of a few times a bad injector may wash out a cylinder, which is what may have happend in your case and caused some scaring to the cylinder walls allowing some oil to get by maybe. Dunno that there is anything you can do about it.Quick Reply

When I pulled the injectors, replaced plugs in 3&4 as they were dirty...

Recent compression test was 205/195/210/205. Leakdown test was done last year, 3%-5%...

I have to add a quart of oil maybe every 2k-4k miles... Seems like I use less oil than others I

But why the change in the color of the smoke?

That is one of the things driving me crazy...

Thinking if I can get rid of the gray smoke.... might only have a little blue smoke which I can live with.

"now it is still smoking after engine braking."

Sounds like this could be a valve seal issue, too. Does the exhaust pass more smoke the higher the RPM's, during engine braking. Esp, the first throttle application --- after this engine braking?

Seems like the longer you engine brake, the more smoke when you start up. Already replaced the valve guide seals, with little to no improvement.

When we came down Mt. Washington this past summer.... engine breaking all the way down. At the bottom, after we stopped for 15-20 minutes, then started back up, looked like I was blowing a smoke screen that would have been in a James Bond movie! :LOL:


No visible smoke during regular driving.

interested to know if you find out what is causing this.

If the valve guides are worn, new valve seals likely wont help, or if they do it will be very temporary. Did you replace the guides? Or were they found to be good upon inspection? It would not surprise me to find you have worn oil rings. 1 quart of usage per 2-4k miles is a pretty broad window. If you could narrow that down it would be better. If its every 2k id say for sure your burning it through the oil rings. At 4k it could be isolated, or mostly isolated to the guides/seals. It may just be what it is/not worth fixing if its the rings, and to continue to run the car keeping the oil topped off until it gets worse or you get sick of it and then replace the engine. Once you have to get into the bottom end, it doesn't become cost effective anymore, unless you are doing all your own rebuild work.

OK.... I use maybe a qt every 3k miles if that.

Valve guide seals were replaced, no difference in amount of smoke... was still blue.

Here is the big question....

Why did the color of the smoke change when I went to a heavier oil?

Blue smoke is oil, grey is fuel, white is antifreeze.

So why would the color of the smoke change after adding the heavier oil?

Just to keep this up to date... finally got the car out today, the different injectors or MAP sensor did not help. Still bowing grey smoke after engine braking, and accelerating gently....

PCV ok? Doesn't sound like you're burning much oil. O2 sensor? What you're describing can also happen if you install the seals backwards, you cannot put the intake seals on the exhaust side and vice versa as the valve stems are different diameters. The exhaust valves are smaller than the intake valves, and naturally are more prone to guide play as a result.

First of all, I wouldn't totally trust the more finite art of distinguishing the color smoke from bluish to whitish, especially if you aren't actually seeing it yourself, but relying on a friend behind you. That said, if its indeed whitish and your not burning coolant or emitting steam from a cold morning, then there is really only one other thing it can be and that's blowing unburnt fuel, and that can happen because of either a bad tune(not applicable in your case being oem) or because of incomplete combustion from either low compression in one or a couple of your cylinders, or possibly poor spark in one or a couple cylinders.

You still didn't answer my question on if the valve guides were replaced along with your valve seals? its not uncommon for the guides on these F20 to wear out, especially at 160k mark. Id almost guarantee you put good seals on bad guides and did virtually nothing to help.

I trust the guy behind me as to the color (grey, not white) of the smoke... he has seen it for 2+ years.

No coolant being burnt.... never is low on antifreeze.

Just the valve guide seals were replaced.

Compression is ok... Recent compression test was 205/195/210/205. Leakdown test was done last year, 3%-5%...

And I ask again, why the blue to grey change? What would cause me to blow grey smoke after engine braking?

Couldn't tell you, other then the thicker oil has reduced some oil burning, and you are now just seeing unburnt fuel. The 195 is a bit low and probably a sizable part of the burning issue, but If the car is using 1 quart every 3k and it has 160k on the clock, Id say your motor is generally fine and just showing some age. Again, continue to drive it and don't worry about it until the oil usage gets to a place where its ridiculous. Maybe in another 50-80k miles, who knows. There are some F engines with over 300k on them.

No person can obviously diagnose your issue over the internet, but here is some information based on what I've experienced in the past. I had similar smoke coming out of my exhaust, someone behind my car at the Dragon commented on it and I also noticed it once when backing up quickly into a parking lot. But my car always ran great and never had any oil or fuel issues.

The smoke was only noticeable when I was running a berk HFC, once I swapped back to the oem cat converter it went away immediately. My guess is if you have a HFC or test pipe then you may see that kind of smoke at times. The OEM cat converts hydrocarbons from unburned fuel to water or other non-noxious gasses, the berk HFC is not a three way cat and it doesn't convert hydrocarbons, and a test pipe won't convert anything. I am not sure if you have an oem cat, HFC, or a test pipe, but if you don't have an oem cat then I think your engine is probably running fine and this is not an issue, perhaps with just some unburnt fuel going out the tailpipe. Your oil consumption is decent and your leakdown test is good.

After I installed an air-fuel ratio gauge I also noticed that my car would go full rich for a brief second at very low rpms as I got on the gas from coast or idle situation or engine braking condition, and that was the point where the smoke would show up in the exhaust. At idle or coast or during engine braking the a/f would be around 14.7, then as I got onto the gas pedal it would spike rich very briefly between idle and say 1500 rpms for a brief second, then it would stabilize back to normal readings as I continued to accelerate. I am not sure what caused the rich reading for the brief period of time but I assumed it was a normal condition in the fuel delivery system, still very safe and not a cause of any engine issue, and the extra fuel just shows up as greyish smoke when running an HFC or straight pipe. .

Hmmm.... interesting.

I do have a Berk HF cat on. For some reason, can't find when I put it on, in my maintenance log.

Maybe I'll have to try and find a OEM cat and try it.

Just installed a Supra PCV valve, which was suggested by another Canadian.. :)

If this doesn't work, I'll try the OEM cat.

yeah see how the new pcv works, I think it is more than likely unburned fuel rather than oil, l, but see if things improve or not. An oem cat will help since it will convert the hydrocarbons, but I prefer the performance of the berk hfc so if I'd keep running that after you decide to test out an oem cat. It's not an engine issue it is just that the oem cat will better convert the hydrocarbons and make it less noticeable out the tailpipe, the engine will still run the same with either cat, the oem cat just better deals with the hydrocarbons. .

If it is fuel all you can do is make sure that your plugs (plug gaps), and coils are fresh so that you are burning as much of the air-fuel mixture as possible. I always ran a bottle of Redline fuel injector cleaner once per year (one bottle treated 2 fuel tanks) , which I would recommend to keep injectors performing their max maintaining proper spray patterns. Redline is one of the few products actually strong enough to work with one treatment which contains PEA for maximum effectiveness. Good luck bud !

Put in the Supra pcv, and changed the oil to get rid of the 15w50 oil.

Took it for a drive with the better half following.

Last time we did this, the first time I engine braked, she saw smoke, this time, she did not.

Drove it around for a bit, and she did definitely saw gray smoke once, and maybe a second time, out of 15-20 attempts.

I guess I'll wait until the Leprechaun run when hopefully Greg will be behind me to watch....

Keeping my fingers crossed! :fingerscrossed:

what was your reason for changing the valve seals? and any information about why the guides were not changed? can we confirm no installation error on the seals, does the smoke occur after the seals were changed?

maybe it's the valve guides.

if you think it is fuel, how is your gas mileage?

Local shop that is well known for S2000 and NSX work, thought it was the valve guide seals. Smoke still occurs after seals replaced.

Since the smoke is now grey, thinking it is not an oil issue.

Seems like I need to stop for gas at the same time as everyone else, and I am running gears (4.44) so I should use more than everyone else.

This is probably a crazy idea - but - maybe reset the ecu?

Nice, was likely the unburnt gases as mentioned by Joey. Boy knows his stuff. :tipwink:

Done..... :)

One of the 4,946 things I tried! :D

I'm hoping that is the case...

Might even find a used cat to throw on, in place of the Berk HF cat I have on now.....

I would really like to get this behind me!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!! :)

what kind of spark plugs are you running, how old are they?

Spark plugs are brand new.
NGK Laser Iridum

one check you can do since you're already done 4,835, a wet compression test.

new injectors, new plugs, compression good, oil consumption not bad, gas mileage not bad...i say carry on and let it be.

I hate the smoke clouds! :nono:

You need the stock cat back on the car then. Otherwise i tend to agree, it is what it is. Nothing amiss.

Hope to get the car out in a few weeks, and hit some backroads to see if the Supra pcv valve has corrected the issue.

If not, will be trying a stock cat.... just need to find a S2000 parked on the street, or in a garage so I can borrow their cat! :LOL:

The ap1 has poor valve cover baffling which is more prone to allowing oil to splash through and enter the front breather and get combusted, but most report this on left hand turns on the track which doesn't sound like your issue, but thought id mention it anyway. The ap2 valve cover baffle was improved and ive never personally experienced this on the street or track but some have still. Ive heard of running the supra pcv before, back in the day I even ran one myself, but it was for boosted applications to help hold the added positive pressure the stock ap1 plastic one couldn't. In NA form i'm not sure what the thinking is since your not making any positive pressure.

If we ever get some dry, no salt 50's weather around here... can't wait to see if the PCV valve takes care of it.... :)

Good luck with that. It was looking good here a week ago. I pulled mine out of storage and drove it home to my garage on a sunny dry, but cold, day. Literally the next day we got another 3 inches of snow and they laid salt all over the roads again after it had pretty much all washed off. No end in sight. Ugh.

Any news?Same exactly problem.Jdm f20c motor with 100k miles on it.Changed seals,guides but nothing happened.Compression test 225 all 4.It burns 1.5 qt per 3k miles with normal driving.I'm ordering penzoil platinum 10w30 to see if something is going to change(tryed the amsoil sgt 5w50 but didn't notice any dramatic change).The mechanic diagnosed "oval" cylinder walls when we took off the head for changing the valve guides.But my question is,why it isn't smoking if i drive it hard,or driving on the highway?Only at traffic situations and when i take off a traffic light or when decelarating for some time and then hitting the gas

I'd say that the oil control rings are most likely stuck. You'd have to remove one piston to confirm.

do you have an oem cat, aftermarket cat or no cat (test pipe) ? When you take off from a stop you go from very lean to rich very quickly in less than a second, only a stock cat can effectively deal with the increase in fuel , the other two options will show light grey/ whitish exhaust. If you are running an oem cat then I am not sure what is causing your issue.

I have no cat(test pipe).But i don't think it's fuel what i see and what i smell.It's oil for sure.Also it consumes enough oil for normal driving.I'd expect to see smoke all the time and especially in vtec with broken rings but it doesn't happen.Only after idling for a while at the traffic and then hit the gas or after braking the motor by gear(downhill with gear braking-no gas) and then hitting it again.It's strange but there is nothing left for me,the head is ok so it is the rings or cylinder walls.All others checked.Pcv,egr e.t.c.Hope the oil will help a little.Any ideas about penzoil platinum 10w30?I've read somewhere it helps with f20c's that consume a lot of oil.Any other suggestion?
Thank all the guys for the answers.

Those symptoms sound like worn valve guides and/or seals. I experienced those exactly on a non-S000 car, but without a significant change in oil consumption.

I see you changed the valve guide seals, but did you check the valve guides for wear? With my previous car, seals alone didn't solve it - eventually I had the head rebuilt with new valve guides and the smoke ceased.

I've also changed the valve guides.Nothing changed:(

peace of mind test - swap in an oem cat, if the smoke goes away you are all good. If the smoke continues you have a mechanical issue. If it goes away with an oem cat then go back to your test pipe and no need to worry about it any further, enjoy the drive.

The concern is the amount of oil consumption. Cat or not has no influence on this.

^ I couldn't tell how much oil consumption he was referring to, other than saying it consumes enough oil for normal driving ? It might help to know what oil consumption level the motor is experiencing though, in quarts / 1000 miles.

The Original poster said 1Q in 3k miles. But my response was in regard to the most current poster a few back "Nippon" who stated 1.5Q in 3k miles and did a full valve guide/seal replacement with still no change in consumption reduction.

Finally got the car out this past weekend.

Had gone back to 10w30 oil in it.....

Still getting smoke, and its back to blue.

Only other thing left to try is the OEM cat instead of the Berk HiFlow cat.

You have to change the valve guides.It's the last you should do to make sure the head is ok.The misfires you saw back then is a common symptom of worn valve guides/valves.You'll be lucky if the problem is the head.Otherwise you are messing with the cylinders/pistons/rings which is difficult to repair and very expensive.Hope that's the cylinderhead.

The OP said he changed them. I still think they are suspect as the symptoms fit worn valve guides.

To the OP, are you sure the guides were replaced and not just the seals? Are you sure the machinist actually did the work? I had a machinist try to convince me once to knurl the guides instead of replacing them because it was easier for him. Hope you don't mind me challenging you on this, but as I said above, the symptoms fit so well, especially for a higher mileage head, I wanted to be double check that you don't think they were changed when they were not.

I'll have to see if I can find the paperwork for when the valve guide seals were replaced, but I'm pretty sure it was just the seals, and not the guides.

my information was in regard to grey/whitish smoke, if you have blue smoke it is oil getting into the combustion chamber somehow. If it smells like burning oil then it likely is.

Thanks for the info :thumbup: Consumption rates aren't too bad, perhaps more than what the owners expected though given their attempted repairs.

I recently bought my first old school Honda that does not burn oil, it is a 2000 Acura GS-R with 190,000 kms on it, it does not burn a drop much to my surprise and I've been putting it through its paces. My 10 previous Hondas all burned some oil. My newest Hondas - 2016 Civic turbo and 2017 Hr-v don't burn any oil yet, so far so good.

I bought a used head(perfect condition),took it at a specialized machine shop with new ferrea valve guides and oem honda valve seals.After 3 days i took the cylinderhead from the machine shop(the new guides were easy to see) and went to my mechanic.He swapped the "new" head with the original one.I was there all the time,just in case...Unfortunatly,nothing changed:(.I was sure that the guides were the problem but i was wrong.The thing that drives me crazy is that if i got worn piston rings or worn cylinder walls,how the hell the compression test was fine(3 times checked/225-230 all 4)????

Some cases early ap1/F20 burned up to 1Q in 1000miles right off the showroom floor so keep that in mind when gauging some perspective here. No deck plate was used to precisely hone the cylinders and so you can get some less then ideal consistent clearances that effect oil consumption. Your usage is more typical then not. The F22 addressed this. Its possible to have poor oil control ring seal but good compression rings. Also some oil in the combustion chamber will raise compression, showing otherwise more favorable numbers then mechanically what the state of the engine is in. But thats where looking at consistency across all cylinders is important to look at, as well as other signs such as oil fouling on the spark plugs. If the plugs look tan and dry, thats a very good thing. Some will show variances of this, with some severe cases of oil consumption displaying dark and white caked deposits on the electrode with a wet look around the threads and base.

Junky is correct: my F22 had good compression but drank oil. When I took it apart, discovered that the oil control rings were gummed up and stuck in the ringlands, while the compression rings were perfect. This is why I suggested to remove one piston to inspect the rings.

I wouldn't do anything bottom end related with the consumption quoted. Wast of time and money. When you start drinking a quart every 500 miles you got a clear bottom end problem and you will get tired of dumping in oil, changing plugs and cleaning off your rear bumper, so dig into it then or just pick up a lower mile used engine. Until then, drive it like you stole it.

my s was drinking a quart every 350 miles. i still dump in oil. granted, it's no longer my daily driver, which helps a lot.

funny thing is, the rear bumper is not more dirty than compared to when the car was new.

i've since got it back up to a quart every 800 miles by mixing in 15w50.

I had issues with black oil dots and crap all over my rear bummer when I had motors that were drinking that much oil. I've had 5 engines in the span of time in my S2k. Sadly an expert on this haha.

Thanks all the guys!I don't intend to do nothing with the bottom end.I'll just try the penzoil premium10w30 and hope for a little less smoke at traffic situations.The only solution is a new oem short block from Honda.I'll add a full rebuilt head(new valves,valve guides,seals) and enjoy a brand new motor with zero miles.

How about combining f22 bottom end with jdm f20c head and jdm ecu.I know the 9000 rev limiter is a bit high for the f22 but some guys have done it.Any info for the reliability of a combination like this.I suppose it'll be a real fast motor.

Wear increases exponentially with each rpm. Even if you managed to get the f22 to spin to 9000 rpms and make any decent power above 8000 rpms the rate of wear would be higher. Seeing where you are right now you might not want to experience higher wear later down the road. But anything is possible, you can throw all the money in the world into any setup and make it work. Speed costs money, how fast do you want to go ? lol

With my f20 ap1 I almost never revved it beyond 8500, there was no point as it stopped making power by then and I was already in the sweet spot for the next gear change by 8000 rpms.

You got a point.:thumbup:

You don't have to remove the engine to swap out piston rings. If you're going to go through the trouble of pulling the head, might as well toss new rings on there while you're in there.

i had no idea that it's possible to replace piston rings with just the head off. do you have a quick explanation of how this is done?

it's pretty easy actually. Just ream the upper ridge of the cylinder if needed first, then disconnect the connecting rod caps with the oil pan removed, and then pop the pistons through the top of the block. Reinstall in reverse.

shoot. i should have done this the last time i had the head removed.

argh.

HELP!!!!
 

PLEASE HELP ME ASAP. I just did a oil change today 5.0 quarts of castrol edge high mileage and white smoke started coming out the engine head immediately. I read it could be from head gasket, to burning coolant, to piston problems. Can someone give me an answer tonight as to what might be happening? This never happened before and im very worried. Smoke is white not blue and comes directly out engine head not exhaust. Like what could i have done oil changes are pretty standard and ive always done my oil and even torque the bolts to factory spec idk wtf happened tonight. Oh and its not like a crazy amount of smoke just a little coming out the red block. My car has been running rock solid till this and i just reached 150k.

^^^ If you have whitish vapor/smoke coming out of the front valve cover breather you have piston ring failure. Its called blow by. Its when the compression rings no longer are sealing enough and the gasses that are suposed to be combusted are instead blowing by the rings, entering the crank case and coming out of the vent system ie front brearher and pvc. The smell is a distinct oil and fuel vapor.

There is only so much that can be sertain over the internet when troublshooting, unlike being there in person. But no, burning oil happens out the exhaust, not get pushed out the crank case. A video clip would help. But if the symtoms of what I said about vapor coming out of the valve cover breather is indeed happening then near 100% the problem is what I said, with bad rings and loss of compression. You should perform a compression test to further verify this. You can easily perform this yourself with the proper gauge. You can pick one up from amazon for about $40.

I would challenge you to think through how you performed the oil change and also anything special that might have occurred shortly before it. For example, was the oil level low before you changed it and perhaps you just decided to not refill before a hard drive because you knew you were going to change it anyway? Are you sure it was the proper filter and not the wrong one that might be restricting oil flow? How many quarts did it take to refill? You get the idea - don't take anything for granted.

I'm challenging you because I am having a hard time imagining how healthy rings would lose compression immediately after a properly executed oil change. I'm not disagreeing with S2000Junky's diagnosis; rather there's likely a clue in the recent driving history and/or details of the oil change.

After having the valve seal guides replaced, catch can put on, Supra PCV valce installed, heavier oil, mystery oil used, and I forget what all else I did.... I think the issue of blowing blue smoke after engine braking has been solved.

One of our locals, Jason Baur suggested putting an OEM cat on in place of the Berk High Flow cat that I am running.

2 weeks or so ago, picked up another local's cat (Andy Ferger) and put it on.

Just spent the weekend down at Rock the Dragon event down in TN/NC.

Greg, the guy who is always behind me, saw zero blue smoke!!!!

Not sure if the Berk didn't create enough back pressure or what.... but no smoke when Greg would have seen it in the past.... I say, its solved! :)

Not sure if the Berk didn't cause enough back pressure or what..... but it looks like the issue may be fixed.....

I suggested that fix one year ago.

The OEM cat works better because it is a true three-way cat converter, so it will convert unburned hydrocarbons, the Berk is not a true three way cat, it does the bare minimum possible, hence the reason Berk needs to add an anti-fouler on the 02 sensor bung.

Just to close this out.... the blue smoke issue has been taken care of by getting rid of the Berk hi flow cat, and putting an OEM cat back on.

Same would/could apply if you are running a test pipe.

That's what I suspected. There is a reason why OEM catalytic converters are worth a lot of money in the scrap market (and by thieves) , yet aftermarket cats are worthless . OEM cats have higher levels of precious metals to convert the hydrocarbons, the others do not.

Anyone want to chime in how many S2000 cars they know about have had the catalytic convertor stolen?

I don't know of any in my region, they are too low to reach under the car without access to a good jack.

The blue smoke is oil burning either through the piston rings or valve guides/seals or both, which is an engine issue, not a cat issue. Yes the OEM cat does a better job at hiding the emissions from the car whether that's unburnt fuel and or some level of oil combustion, but the oil combustion (ie blue smoke) shouldn't be there to begin with cat or no cat. That said, most high revving motors like the S2k will go through some amount of oil burning, but to the point of seeing it out the tailpipe is not typically normal or a favorable sign for "normal" consumption levels. Definitely more prone to see higher levels of oil burn on a early F20 vs an F22 and higher mileage or course contributes. But if the oem cat helps knock down the visible signs you are finding then great, as it should to some amount, just keep in mind that oil is still being burnt and traveling down into the exhaust where that oil residue is collecting on the 02 sensor and front end of the cat, eventually gumming up.