[studio54]

Hi,

I just made a spark plug change a few days ago and the spark plug #6 thread was wet, a bit darker than the others, smelled fuel but looked oily.
Only the thread was wet, not the tip, not the outter of the spark plug, and not the plug well.

It smelled fuel when i first pulled it out (car was sitting for a week) but i smelled it again today and it smelled more like oil so now i am not sure if it's oil or fuel

The car has no codes, or misfire.
Since 4 years i have it, idle has always got a kind of very small shake/hiccup/exhaust pop (very small) time to time randomly (lets say one 1 in a minute, when idling or at a stop)
I tried to chase this hiccup problem with changing coil + spark plug (at an indy) a first time to no avail , the tech guy didn't told me if a plug was wet or not...
I then cleaned myself the intake valves, to no avail, the small random hiccup still there... so i decided to live with it because it's barely noticable.
And then now, i decided to change the plug by myself because plugs were old since the last change, and discovered this wet plug.

Is it possible that it's symptoms of a leaking injector ?
Wet thread, after 1 week sitting

Does a lightly leaking injector make the exhaust to burble a bit on let off ? (without any MHD burble options activated)

Is it dangerous to drive with a leaky injector ?

If leaking injector confirmed, it is ok to change only one ?

Thanks for reading !

[mweisdorfer]

Originally Posted by studio54

Hi,

I just made a spark plug change a few days ago and the spark plug #6 thread was wet, a bit darker than the others, smelled fuel but looked oily.
Only the thread was wet, not the tip, not the outter of the spark plug, and not the plug well.

It smelled fuel when i first pulled it out (car was sitting for a week) but i smelled it again today and it smelled more like oil so now i am not sure if it's oil or fuel

The car has no codes, or misfire.
Since 4 years i have it, idle has always got a kind of very small shake/hiccup/exhaust pop (very small) time to time randomly (lets say one 1 in a minute, when idling or at a stop)
I tried to chase this hiccup problem with changing coil + spark plug (at an indy) a first time to no avail , the tech guy didn't told me if a plug was wet or not...
I then cleaned myself the intake valves, to no avail, the small random hiccup still there... so i decided to live with it because it's barely noticable.
And then now, i decided to change the plug by myself because plugs were old since the last change, and discovered this wet plug.

Is it possible that it's symptoms of a leaking injector ?
Wet thread, after 1 week sitting

Does a lightly leaking injector make the exhaust to burble a bit on let off ? (without any MHD burble options activated)

Is it dangerous to drive with a leaky injector ?

If leaking injector confirmed, it is ok to change only one ?

Thanks for reading !

Could be a leaking injector or it could be a leaking VC.

[studio54]

Ok, i thought if valve cover gasket leak, the outter white part of the plug, the plug well, and the coil should have been oily too.

If valve cover leak, is there any test, visual inspection, symptoms should i look for ?
Is it necessarly visible from the top engine bay ? or is it internal leak ?

That said, I am fully catless (dp + no secondaries), and the car isn't smoking.

Is it ok to drive ?

[Bimmer_Bro]

Originally Posted by studio54

Ok, i thought if valve cover gasket leak, the outter white part of the plug, the plug well, and the coil should have been oily too.

If valve cover leak, is there any test, visual inspection, symptoms should i look for ?
Is it necessarly visible from the top engine bay ? or is it internal leak ?

That said, I am fully catless (dp + no secondaries), and the car isn't smoking.

Is it ok to drive ?

It should be ok to drive if the leak is minor. You just might prematurely wear that plug.
Have you ever replaced your pcv valve? If your valve is old and leaking, it will pressurize the valve case causing it to leak. However once a leak has started, the gasket will need to be replaced.
If you have not done your pcv valve I recommend the rb turbo one. I did mine and it took 5 minutes to install.

[feuer]

Leaking injector won’t get the thread oily. Or wet with fuel. Spark plug threads aren’t protruding into the cylinder. Only leaking valve cover can do that to threads.

[studio54]

Originally Posted by Bimmer_Bro

It should be ok to drive if the leak is minor. You just might prematurely wear that plug.
Have you ever replaced your pcv valve? If your valve is old and leaking, it will pressurize the valve case causing it to leak. However once a leak has started, the gasket will need to be replaced.
If you have not done your pcv valve I recommend the rb turbo one. I did mine and it took 5 minutes to install.

Ok thanks interesting. Nop i never replaced the PCV valve.
I got a turbo blown some months ago, any oil could have going there and damage or clogged PCV or something ?
I read that #5 & #6 are often worst than other plugs due to the PCV system.

Found a very similar interesting thread :
https://www.e90post.com/forums/showthread.php?t=675388
And finally found out the end of OP story (themyst) on another forum we cannot link here ()..
According to OP, it was because of a restrictive oil catch can he installed..when he removed the OCC, everything went fine again, dry plug, however i haven't oil catch can, but since it's connected to the PCV system, maybe a faulty PCV valve can cause similar problems ?

Originally Posted by feuer

Leaking injector won’t get the thread oily. Or wet with fuel. Spark plug threads aren’t protruding into the cylinder. Only leaking valve cover can do that to threads.

Ok, I understand that it cannot be a leaky injector, but i was looking at valve cover gasket DIY on Youtube, and in my particular case, i don't understand how a leaky valve cover can leak in spark plug threads only, without soaking the well, the coil and the outter side of the plug ?

[feuer]

Originally Posted by studio54

Ok, I understand that it cannot be a leaky injector, but i was looking at valve cover gasket DIY on Youtube, and in my particular case, i don't understand how a leaky valve cover can leak in spark plug threads only, without soaking the well, the coil and the outter side of the plug ?

Probably because if it is the valve cover (sometimes is the little plastic pipe that go into back turbo intake) leak is still minimal so oil only wet the threads.

[studio54]

Originally Posted by feuer

Probably because if it is the valve cover (sometimes is the little plastic pipe that go into back turbo intake) leak is still minimal so oil only wet the threads.

Ok thanks, those leak on the plug thread are weird, because i assume that if spark plug is correctly torqued, oil shouldn't pass the gasket of the plug and fall down to the thread.

Can you elaborate on this little plastic pipe ? what part are you talking exactly ? Are you talking about the pipe that goes from the PCV to the rear turbo inlet with the angled heater connector ?

I remember having broken one plastic tab/clip of this connector when mounting back my intake manifold when i cleaned my intake valves. The connector have a o-ring and i assumed since it was connected to the inlet, it was under vacuum, so i just taped it tightly and forgot about that. Should i be concerned about that ?

From my understanding, under boost, the PCV valve opens and rear turbo inlet assists to vacuum vapors, and under low load or idle, the PCV valve is closed, and oil vapors goes to intake manifold.

[feuer]

Originally Posted by studio54

Ok thanks, those leak on the plug thread are weird, because i assume that if spark plug is correctly torqued, oil shouldn't pass the gasket of the plug and fall down to the thread.

Can you elaborate on this little plastic pipe ? what part are you talking exactly ? Are you talking about the pipe that goes from the PCV to the rear turbo inlet with the angled heater connector ?

I remember having broken one plastic tab/clip of this connector when mounting back my intake manifold when i cleaned my intake valves. The connector have a o-ring and i assumed since it was connected to the inlet, it was under vacuum, so i just taped it tightly and forgot about that. Should i be concerned about that ?

From my understanding, under boost, the PCV valve opens and rear turbo inlet assists to vacuum vapors, and under low load or idle, the PCV valve is closed, and oil vapors goes to intake manifold.

If o-ring doesn’t seal oil would drip. Inspect the area.

[studio54]

Originally Posted by feuer

If o-ring doesn’t seal oil would drip. Inspect the area.

Ok, i will remove the tape and check it with a light.

But when you say, "sometimes is the little plastic pipe that go into back turbo intake", what do you mean ? the check-valve in the hose stays in the closed position causing a restriction ? or there is leak causing a lack of vacuum ?

I am talking about this pipe (part : 11157553949) :



And the plastic tab i broke only one side on the rear inlet:
(maybe i will zip tie it tightly instead of using tape)

[feuer]

Originally Posted by studio54

Ok, i will remove the tape and check it with a light.

But when you say, "sometimes is the little plastic pipe that go into back turbo intake", what do you mean ? the check-valve in the hose stays in the closed position causing a restriction ? or there is leak causing a lack of vacuum ?

Yes, sometimes, and that little plastic pipe you have on the photos. Leaks oil where is attached to the valve cover. Other end attaches to rear turbo intake. I have one at home that leaks. One of the clips is broken.

[studio54]

Originally Posted by feuer

Yes, sometimes, and that little plastic pipe you have on the photos. Leaks oil where is attached to the valve cover. Other end attaches to rear turbo intake. I have one at home that leaks. One of the clips is broken.

I seen that Rob from RB recommend to add a worm clamp just after the plastic connector on the valve cover.

[feuer]

Originally Posted by studio54

I seen that Rob from RB recommend to add a worm clamp just after the plastic connector on the valve cover.

That would not know about what they recommend. I broke this during removal to replace valve cover gasket and now is getting oily.

[studio54]

Originally Posted by feuer

That would not know about what they recommend. I broke this during removal to replace valve cover gasket and now is getting oily.

Hehe i didn't understand your first sentence.

Maybe you can try it for your leak, pic attached.

[feuer]

Originally Posted by studio54

Hehe i didn't understand your first sentence.

Maybe you can try it for your leak, pic attached.

I will most definitely try this.

[studio54]

Originally Posted by Bimmer_Bro

It should be ok to drive if the leak is minor. You just might prematurely wear that plug.
Have you ever replaced your pcv valve? If your valve is old and leaking, it will pressurize the valve case causing it to leak. However once a leak has started, the gasket will need to be replaced.
If you have not done your pcv valve I recommend the rb turbo one. I did mine and it took 5 minutes to install.

I read a bit about the PCV valve to have a better understanding about the system.

I understand it can create a small boost leak via intake ports if a old/leaking PCV check valve isn't closing properly during acceleration, however i don't understand how it can pressurize the crankcase since next to it, there is the flapper that is supposed to vent crankcase positive pressure with the big hose connected to the rear inlet. If the flapper hose isn't plugged or defective, it shouldn't be possible, am i wrong?

I may buy this kit :
https://shop.ez-p.de/bmw/3er-e90-e91...-deckel-v2?c=6
It's the upgraded PCV + the cap (the stock cap seems to often be damaged when opening it the first time) but the brand is FTP and i don't know yet if it's good or not, the price is ok and the shipping from Europe seems convenient for ppl in Europe like me.

[Bimmer_Bro]

Originally Posted by studio54

I read a bit about the PCV valve to have a better understanding about the system.

I understand it can create a small boost leak via intake ports if a old/leaking PCV check valve isn't closing properly during acceleration, however i don't understand how it can pressurize the crankcase since next to it, there is the flapper that is supposed to vent crankcase positive pressure with the big hose connected to the rear inlet. If the flapper hose isn't plugged or defective, it shouldn't be possible, am i wrong?

I may buy this kit :
https://shop.ez-p.de/bmw/3er-e90-e91...-deckel-v2?c=6
It's the upgraded PCV + the cap (the stock cap seems to often be damaged when opening it the first time) but the brand is FTP and i don't know yet if it's good or not, the price is ok and the shipping from Europe seems convenient for ppl in Europe like me.

I am definitely no pcv expert. It is quite complex inside the valve cover. I just know it's common to get a valve cover leak due to a bad pcv. Yes the valve cover can be pressurized from this... maybe if the pcv is stuck closed ?

I stole the info below from another thread on here but it has some good points.

https://www.e90post.com/forums/showthread.php?t=1592468

"With the the N54 PCV valve when the engine is operating under vacuum (vs. boost), crankcase gases are pulled through the center of the PCV valve outward into the cap, then over the tip of the PCV valve nipple and back into channels in the valve cover. A small amount of fresh air is admitted into the crankcase via the small hole in the flapper valve. These ventilation channels lead to six (6) individual small ports in the aluminum head right before each cylinder's intake valves. This is the most direct cause for carbon buildup on the intake valves and the need to periodically walnut blast the intake valves. You can plug the ports in the head with a tap and setscrews. This eliminates the vacuum side PCV unless you install an external PCV valve arrangement (either aftermarket or DIY).

When the engine is under positive boost pressure, the 6 ports in the head and channels in the valve cover provide this positive pressure to the PCV valve which closes if it is working properly to prevent pressurizing the crankcase. Under boost with the PCV valve closed, any need for crankcase ventilation is through the flapper valve into the rear turbo inlet pipe."


As for the parts, I'm sure those would be fine if you don't want to ship from the US. Anything is better than the stock plastic one.

[studio54]

Originally Posted by Bimmer_Bro

I am definitely no pcv expert. It is quite complex inside the valve cover. I just know it's common to get a valve cover leak due to a bad pcv. Yes the valve cover can be pressurized from this... maybe if the pcv is stuck closed ?

I stole the info below from another thread on here but it has some good points.

https://www.e90post.com/forums/showthread.php?t=1592468

"With the the N54 PCV valve when the engine is operating under vacuum (vs. boost), crankcase gases are pulled through the center of the PCV valve outward into the cap, then over the tip of the PCV valve nipple and back into channels in the valve cover. A small amount of fresh air is admitted into the crankcase via the small hole in the flapper valve. These ventilation channels lead to six (6) individual small ports in the aluminum head right before each cylinder's intake valves. This is the most direct cause for carbon buildup on the intake valves and the need to periodically walnut blast the intake valves. You can plug the ports in the head with a tap and setscrews. This eliminates the vacuum side PCV unless you install an external PCV valve arrangement (either aftermarket or DIY).

When the engine is under positive boost pressure, the 6 ports in the head and channels in the valve cover provide this positive pressure to the PCV valve which closes if it is working properly to prevent pressurizing the crankcase. Under boost with the PCV valve closed, any need for crankcase ventilation is through the flapper valve into the rear turbo inlet pipe."


As for the parts, I'm sure those would be fine if you don't want to ship from the US. Anything is better than the stock plastic one.

Thank you for your answer

From what i understand (at the bolded quote above), if your OEM PCV valve leak (meaning not closing properly), when in boost, you have a boost leak from the intake manifold / head hole tunnel ports to crankcase cover (probably resulting in a bigger PSI delta than usual between boost mean and boost in logs?).
So the boost will leak and pass the PCV valve and will go to the crankcase, then will be immediatly evacuated via the flapper hose to the rear inlet. IMO it would need a big big leak or big big PSI figures to cause a crankcase pressure issue, but i am not an expert too.

[semper]

Hi did You fixed your problem?

[studio54]

Originally Posted by semper

Hi did You fixed your problem?

Hi,

I am not sure yet, I just replaced spark plugs with NGK ones a few weeks ago, and old spark plugs were all dry, and the #6 cylinder thread wasn't black and oily this time ?!?

Concerning the slight random hiccup during idle, for now it's ok but spark plugs are brand new.

[rismo]

I just had the a similar observation on plug 3-4-5, I think it has been caused by me overfilling the engine with oil prior going to the race track. (My poor man human sump pump solution).
I think it just drips into the sleeves left or right when you spoil while filling up the engine, my plugs did not had any containment on the cylinder side.

[rismo]

I just had the a similar observation on plug 3-4-5, I think it has been caused by me overfilling the engine with oil prior going to the race track. (My poor man human sump pump solution).
I think it just drips into the sleeves left or right when you spoil while filling up the engine, my plugs did not had any containment on the cylinder side.