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1G Excessive Exhaust Blue Smoke

cmp1516

Proven Member
52
20
Aug 2, 2021
Quezon City, Asia
Some background: Had my engine (4g63 NT) overhauled since Oct 2021 due to leaking gaskets, for the following months I keep getting back jobs since the shop was very incompetent (Wrong belt timing, blaming parts they purchased etc.). So after my 3-4 back jobs my Galant became an embarrassing smoke machine that spits enormous white/blue smoke on idle and every rev, the incompetent mechanics said that it's just spitting the last few remaining oil stuck at the exhaust, but boy did I not believe their terrible lie.

The valves were bent, the head had clearance issues and the piston rings were leaking! (They even broke off my trunk badges, scratched my paint and broke my gauge RPM!)

Forward to Feb this year, I found a better shop that fixed the last job's crappy mistake, they machined the head, resurface valves, adjust valve clearance, replaced valves and seals and replaced some of the piston rings, (I didn't had the budget to fully replace all rings and the piston sleeve since they said that the pistons had some play but said it can be solved by just replacing some rings), the car smoked a little bit then it was FINALLY gone.

BUT the timing was off (bucking when off throttle and pressing 1/4 of the pedal) so the next 2 days I gave it back for them to adjust the timing, they fixed it thankfully however THE SMOKE IS BACK and it's just as bad as before!

So the question is, did the wrong timing caused the engine to break the valves and the rings again?

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Edit: Added video
 
Last edited:

waltah

10+ Year Contributor
369
154
Mar 2, 2011
fairfield, Virginia
Blue smoke is of course oil smoke. There is more than one way for oil to get into the cylinders. Was the car smoking before the overhaul in October?

What exactly was the reason for the overhaul? 'Leaking gaskets' doesn't seem like a reason to do more than just replace that gasket and be sure everything is correctly tightened.

If the idle is smooth now then bent valves are unlikely. When does the car smoke most? When cold but stops when warmed up? When accelerating? When going downhill with foot off the gas? What's the mileage on the engine?

Answers to those questions will be clues but the next step to find out where the oil is getting in would be to do some tests. It sounds like you're not able to do that: Maybe someone here could recommend a skilled mechanic in your area? You're probably going to need one to actually fix the car anyway.

It seems to me that it's getting tougher and tougher to find mechanics who can actually fix things on our cars without breaking something new pretty much every time. One reason why I'm still doing my own work at age 83.

Edit: I did not notice "Asia." You still need a good mechanic but I've no idea how to find one in your area.
 

cmp1516

Proven Member
52
20
Aug 2, 2021
Quezon City, Asia
Blue smoke is of course oil smoke. There is more than one way for oil to get into the cylinders. Was the car smoking before the overhaul in October?

What exactly was the reason for the overhaul? 'Leaking gaskets' doesn't seem like a reason to do more than just replace that gasket and be sure everything is correctly tightened.

If the idle is smooth now then bent valves are unlikely. When does the car smoke most? When cold but stops when warmed up? When accelerating? When going downhill with foot off the gas? What's the mileage on the engine?

Answers to those questions will be clues but the next step to find out where the oil is getting in would be to do some tests. It sounds like you're not able to do that: Maybe someone here could recommend a skilled mechanic in your area? You're probably going to need one to actually fix the car anyway.

It seems to me that it's getting tougher and tougher to find mechanics who can actually fix things on our cars without breaking something new pretty much every time. One reason why I'm still doing my own work at age 83.

Edit: I did not notice "Asia." You still need a good mechanic but I've no idea how to find one in your area.
Hey thanks for your reply, It did smoked a little bit before the overhaul when starting up the car then goes away when warmed up (probably the valve seals). Reasons I did the overhaul was because it did smoked a little and all gaskets were just worn and didn't ran quite well.

Engine mileage is around 230k, right now it smokes a bit a little bit at idle and gets extremely worse if revved higher. Another note is that it smokes right after revving, I managed to record it and I'll attach here.

Agreed to finding mechanics is a lot tougher these days, I'd want to fix it myself but I just don't have the area and tools to do it (parking area is public and in gravel).

Here is the video:

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cmp1516

Proven Member
52
20
Aug 2, 2021
Quezon City, Asia
More info: Before doing the job on Feb, the mechanic shared a video showing that my pistons has play, however he suggested that it can be fixed by replacing the rings (we didn't buy new rings, they had some leftovers from a previous SOHC 4G63 overhaul which they used on my car).

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DSMPT

DSM Wiseman
2,128
1,693
Jun 12, 2014
Japan / Mexico, Arizona
More info: Before doing the job on Feb, the mechanic shared a video showing that my pistons has play, however he suggested that it can be fixed by replacing the rings (we didn't buy new rings, they had some leftovers from a previous SOHC 4G63 overhaul which they used on my car).

You must be logged in to view this image or video.
I don't know how exactly your mechanic rebuilt the engine but maybe you should look for another mechanic again, and inspect/measure all parts to rebuild. It looks like he doesn't know what he is doing... He doesn't want to fix that play by "replacing" the rings and it's not the proper way. The pistons are designed like that. So that play is normal and necessary unless it's too much. Without the play, you may damage the pistons, rings and/or cylinder wall when the engine gets hot.
You may have mismatched cylinder bore/pistons/ring size. or some rings installed upside-down/damaged, or worn/wrong finished/damaged cylinder wall. Also maybe the valve guides are damaged and causing the smoke as you said you bent valves before.
There are many factors that would cause smoke, so it can't be 100% sure but according to what you stated above, so far it sounds like an assembly/installation error to me.
 

waltah

10+ Year Contributor
369
154
Mar 2, 2011
fairfield, Virginia
The pattern of smoke shown in the video is typical of a well-worn engine and at 230k miles that's entirely reasonable. I don't think you're going to find an easy answer and I would not trust someone saying "I can fix that for just ... dollars." The standard answer would be a new or rebuilt engine or at least a complete overhaul by a competent machine shop. I don't know prices but in the U.S. certainly over $5000, maybe $10,000 or so. You might find a good used engine and get it installed for anywhere from $2500-up but that's a crapshoot --- if the engine isn't that good, even if it's covered by a meaningful warranty you've still got to pay for the labor. The places that have good warranties are more expensive, of course.

If you are going to try to repair this, find a new mechanic. CMP1516's comments above are exactly what I'd say. You had a worn engine, now you have a worn engine that may have been made worse by doing stuff that shouldn't be done. Fixing that is almost surely beyond 'diagnose a problem and fix it.'

And of course the cost numbers have to be compared to the value of the car. Maybe that matters to you, maybe not.
 

JusMX141

Moderator
15,092
1,136
Dec 13, 2005
Greensburg, Pennsylvania
If the valves were bent and they didn't replace the guides or at least inspect them to verify they weren't cracked, that's likely where the problem lies. That much oil leakage should show up on the spark plugs if it's being introduced into the combustion chamber so if the plugs are clean it's more than likely a valve guide issue.
 

cmp1516

Proven Member
52
20
Aug 2, 2021
Quezon City, Asia
I don't know how exactly your mechanic rebuilt the engine but maybe you should look for another mechanic again, and inspect/measure all parts to rebuild. It looks like he doesn't know what he is doing... He doesn't want to fix that play by "replacing" the rings and it's not the proper way. The pistons are designed like that. So that play is normal and necessary unless it's too much. Without the play, you may damage the pistons, rings and/or cylinder wall when the engine gets hot.
You may have mismatched cylinder bore/pistons/ring size. or some rings installed upside-down/damaged, or worn/wrong finished/damaged cylinder wall. Also maybe the valve guides are damaged and causing the smoke as you said you bent valves before.
There are many factors that would cause smoke, so it can't be 100% sure but according to what you stated above, so far it sounds like an assembly/installation error to me.
That mismatched idea may be the problem, since they used leftover piston rings from a previous overhaul, it may not have matched the bore size that my engine has. Sure the rings are for a 4G63 but maybe that mm difference could cause it to leak?

Although the first Feb job made it smoke significantly less (though it still smoked nonstop when revving), but after the last back job (adjusting the timing) made it worse for some reason...
 

cmp1516

Proven Member
52
20
Aug 2, 2021
Quezon City, Asia
The pattern of smoke shown in the video is typical of a well-worn engine and at 230k miles that's entirely reasonable. I don't think you're going to find an easy answer and I would not trust someone saying "I can fix that for just ... dollars." The standard answer would be a new or rebuilt engine or at least a complete overhaul by a competent machine shop. I don't know prices but in the U.S. certainly over $5000, maybe $10,000 or so. You might find a good used engine and get it installed for anywhere from $2500-up but that's a crapshoot --- if the engine isn't that good, even if it's covered by a meaningful warranty you've still got to pay for the labor. The places that have good warranties are more expensive, of course.

If you are going to try to repair this, find a new mechanic. CMP1516's comments above are exactly what I'd say. You had a worn engine, now you have a worn engine that may have been made worse by doing stuff that shouldn't be done. Fixing that is almost surely beyond 'diagnose a problem and fix it.'

And of course the cost numbers have to be compared to the value of the car. Maybe that matters to you, maybe not.
Damn, I was thinking of that earlier to either buy a used one or completely rebuild my current. In other words, burning lot's of cash and time :cry:

Thanks for the input, I'll wait for other replies to see their perspective on this case like DSMPT mentioned, it might be just installation error and most likely the rings. Due to it having a chance on having the wrong mm since it was meant for a different engine overhaul.
 

cmp1516

Proven Member
52
20
Aug 2, 2021
Quezon City, Asia
If the valves were bent and they didn't replace the guides or at least inspect them to verify they weren't cracked, that's likely where the problem lies. That much oil leakage should show up on the spark plugs if it's being introduced into the combustion chamber so if the plugs are clean it's more than likely a valve guide issue.
The guides were machined from previous back jobs while the recent Feb job machined the head, resurfaced valve and seat then adjusted the clearance.

I'll check the plugs later and send some photos.
 

DSMPT

DSM Wiseman
2,128
1,693
Jun 12, 2014
Japan / Mexico, Arizona
I missed this part.
I am not sure what SOHC ring set your mechanic used or I don't know about all SOHC ring set spec, but I am almost sure that NOT all SOHC ring specs are the same as DOHC's. So, there is a possibility that the SOHC ring set on your DOHC piston may also be the cause of smoke, due to less oil controlling, less sealing, because of too much ring groove clearance. You should confirm with your mechanic what ring sets are used.
 

cmp1516

Proven Member
52
20
Aug 2, 2021
Quezon City, Asia
I missed this part.
I am not sure what SOHC ring set your mechanic used or I don't know about all SOHC ring set spec, but I am almost sure that NOT all SOHC ring specs are the same as DOHC's. So, there is a possibility that the SOHC ring set on your DOHC piston may also be the cause of smoke, due to less oil controlling, less sealing, because of too much ring groove clearance. You should confirm with your mechanic what ring sets are used.
From what I've heard the SOHC and DOHC variants of the 4G63 are practically the same, only the head is different therefore some SOHC owners here convert their heads into DOHC then change harness and whatnot.


I'll try to find a reputable shop to diagnose my problem, but I'm really starting to suspect the rings are either installed incorrectly or have incorrect diameter since the symptoms check out...
 

DSMPT

DSM Wiseman
2,128
1,693
Jun 12, 2014
Japan / Mexico, Arizona
only the head is different
This is wrong. There are more differences and not all 4g63 have the same pistons and ring set. But as I stated that I don't know what ring set your mechanic installed, so it's just one of possibilities.
 

cmp1516

Proven Member
52
20
Aug 2, 2021
Quezon City, Asia
This is wrong. There are more differences and not all 4g63 have the same pistons and ring set. But as I stated that I don't know what ring set your mechanic installed, so it's just one of possibilities.
For real? I'm talking about the carbureted 8 valve SOHC 4G63 and the MPI version that were released in lower 6gen Galant models. Maybe the one you're talking is the 16 valve EFI SOHC version that looks like the 4g92/3 engines that came with the 7th-8th gen Galant?

Asking out of curiosity since local tuners here use SOHC blocks when they cracked theirs.
 

DSMPT

DSM Wiseman
2,128
1,693
Jun 12, 2014
Japan / Mexico, Arizona
I don't know what 4g6 you have in your country and which one you were talking about. What I said is a common thing. 4g6 had been used on so many equipments, from fork lift to EVOs. There are many variants. Do you think SOHC 8v pistons and DOHC 16v pistons are the same? What do you think is going to happen if you would have a 1.2mm thickness 2nd piston ring on a piston that utilizes a 1.5mm 2nd ring. You would have too much ring groove clearance and the ring wouldn't probably function as it should. 2nd ring is more for scrape oil on cylinder wall, so that would let more oil go up into combustion chamber than usual. That's what I meant in post #11 as one of possibilities.
 

cmp1516

Proven Member
52
20
Aug 2, 2021
Quezon City, Asia
I don't know what 4g6 you have in your country and which one you were talking about. What I said is a common thing. 4g6 had been used on so many equipments, from fork lift to EVOs. There are many variants. Do you think SOHC 8v pistons and DOHC 16v pistons are the same? What do you think is going to happen if you would have a 1.2mm thickness 2nd piston ring on a piston that utilizes a 1.5mm 2nd ring. You would have too much ring groove clearance and the ring wouldn't probably function as it should. 2nd ring is more for scrape oil on cylinder wall, so that would let more oil go up into combustion chamber than usual. That's what I meant in post #11 as one of possibilities.
Ahh I get what you're saying, I misunderstood that the engine blocks aren't compatible on either heads may it be DOHC or SOHC variant.

I understand that you're saying that the mechanic that worked on my engine used a different 4G63 variant piston ring that can cause incorrect diameter therefore burning oil, sorry for the misconception!
 

cmp1516

Proven Member
52
20
Aug 2, 2021
Quezon City, Asia
Welp very late update, motor is fixed now and no more blue smoke. However the shop I went to had little to none experience with 4g63s so it's idles like crap when I got it and had fully synthetic oil so its leaking from time to time (high mileage engine problems LOL).

Though the good news is the idle got better by tinkering the TB sensors and BISS screw, although it "chugs" when at 1k rpm when off throttle plus without any load at idle the rpm bounces around 950-1k rpm which isn't too bad. Also for the oil I'd guess I'll change it into conventional oil

Off to more fixing I guess...
 

waltah

10+ Year Contributor
369
154
Mar 2, 2011
fairfield, Virginia
Welp very late update, motor is fixed now and no more blue smoke. However the shop I went to had little to none experience with 4g63s so it's idles like crap when I got it and had fully synthetic oil so its leaking from time to time (high mileage engine problems LOL).

Though the good news is the idle got better by tinkering the TB sensors and BISS screw, although it "chugs" when at 1k rpm when off throttle plus without any load at idle the rpm bounces around 950-1k rpm which isn't too bad. Also for the oil I'd guess I'll change it into conventional oil

Off to more fixing I guess...
Wow, that's a lot of good news. Quite likely all you have to do is set up the throttle body adjustments correctly. The stop screw is 1-1/4 turn in from contact (opens the throttle a bit), then set the closed throttle position switch so it's just closed when the throttle is closed and goes open with just a little opening of the throttle. I wrote the directions for these settings on another thread tonight.

Most likely that'll end the 'chugging' -- that's caused by the ECU not knowing the throttle is closed (because switch isn't closed) so it doesn't take charge, there's too much air going through the BISS and fuel cut then shuts 'er down at 1500 ... repeat ... repeat. If the idle is still a bit fast when the above is done, crank the BISS down a half turn at a time until the idle is correct and behaves properly when A/C or headlights are turned on.

(High beam headlights should give no change, A/C a slight increase of RPM.)

Tweaking the BISS is adjusting the fixed amount of air for idling so that the Idle Speed Control (driven by the ECU) can cover the whole necessary range -- BISS too far out, the ISC goes closed too soon and the idle speed will be too high under hot conditions, BISS too far in the ISC cannot open far enough and you won't have enough fast idle for a cold morning and the car will stall when starting.

Just to add to the pistons and rings discussion, as stated these engines are used on many kinds of machinery -- not just cars. And on cars, every thing from 'slightly sporty' SOHC N/A models to DOHC turbo. These differences in engine output mean big local differences in internal temperatures even with the same thermostats and cooling system. Pistons and rings expand; the really high output models need more space (smaller pistons, bigger gaps in rings) so they wind up a correct fit rather than seizing. So swapping anything around without pretty expert knowledge is risky. High output pistons and rings will work but will give more oil consumption in lower output engines.

Really glad things got straightened out. Congratulations!
 
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