Can Glow Plugs cause blue smoke?

MrSweet1991 · 01-11-2022, 07:52 AM

Good afternoon peeps!

Been a while since I've been on here with the 330d off the road, been driving a 7 seater Nissan Qashqai to accommodate our new earthling, my gosh when my claims drop off in a month or two I'll hopefully be able to insure both as I miss it.

Anyway back to the point, I had a chap comment on my YouTube video, it's a blue smoke video I took to see the smoke prior to adding a crankcase breather, in another video I done another cold start and all smoke was clear so the breather was a success. However, a chap said that faulty glow plugs/module can cause blue smoke as well leaky injectors. However, from my knowledge the smoke it's quite specific that being:

Blue is oil related

Black or greyish white is unburned/partially burned fuel due to various fueling/air issues

White steam/vapour is coolant

So to me both injector and glow plugs would fall under the fueling category resulting in one way or another black or white, but no way to cause blue.

The video and comments can be seen here:

I'm always up for learning about my car, maybe I am wrong and have overlooked something so if anyone would like to explain how either a leaky injector or faulty glow plug and or controller could result in blue I'm all ears

chrissyw · 01-12-2022, 05:13 AM

Whilst it's not ideal, with that amount I wouldn't be overly concerned.

Is that from freezing cold this morning?

Yes blue smoke can be caused by the glow plugs.

It can also be caused by a leaking / lazy injector that weeps overnight in the cold weather.

It can also be caused by a perished valve cover gasket.

My 320d does the same on freezing cold mornings and I personally feel it is an injector slightly leaking overnight.

I've done all the glows, new controller and replaced two injectors.

I have also gone back to the old loo roll style breather - to try and stop and inlet manifold oil leak not really the blue smoke.

It used to run really rough on a cold morning before I replaced the two injectors, sometimes throwing a rough running code. Blue plooms of smoke and the whole car would shake for 30 seconds. Two injectors didn't look great on INPA so I whipped those out. The seals on all 4 injectors were completely shot.

I'll get the two I removed checked and rebuilt at some point I think.

White smoke out the back is generally a sign of unburnt diesel from an overfuelling injector.

MrSweet1991 · 01-12-2022, 10:56 AM

Quote:

Originally Posted by chrissyw

Whilst it's not ideal, with that amount I wouldn't be overly concerned.

Is that from freezing cold this morning?

Yes blue smoke can be caused by the glow plugs.

It can also be caused by a leaking / lazy injector that weeps overnight in the cold weather.

It can also be caused by a perished valve cover gasket.

My 320d does the same on freezing cold mornings and I personally feel it is an injector slightly leaking overnight.

I've done all the glows, new controller and replaced two injectors.

I have also gone back to the old loo roll style breather - to try and stop and inlet manifold oil leak not really the blue smoke.

It used to run really rough on a cold morning before I replaced the two injectors, sometimes throwing a rough running code. Blue plooms of smoke and the whole car would shake for 30 seconds. Two injectors didn't look great on INPA so I whipped those out. The seals on all 4 injectors were completely shot.

I'll get the two I removed checked and rebuilt at some point I think.

White smoke out the back is generally a sign of unburnt diesel from an overfuelling injector.

My car's sweet mate, popped a CCV filter in and no more smoke, that video was taken a couple of years back I think. I was just posting as a chap mentioned a leaky injector and glow plugs/controller could cause blue smoke but from my understanding it's not possible to produce blue smoke from either as blue is one way or another oil burning, white/black is partially or unburned fuel. I've never had working glow plugs since I've owned the car, it's just something I never did get around to doing lol.

But as your stating the same as the chap in the YouTube comment, could you elaborate how either a leaky injector or glow plugs can cause blue smoke, it doesn't make sense to me as neither relate to oil.

chrissyw · 01-12-2022, 11:25 AM

Quote:

Originally Posted by MrSweet1991

My car's sweet mate, popped a CCV filter in and no more smoke, that video was taken a couple of years back I think. I was just posting as a chap mentioned a leaky injector and glow plugs/controller could cause blue smoke but from my understanding it's not possible to produce blue smoke from either as blue is one way or another oil burning, white/black is partially or unburned fuel. I've never had working glow plugs since I've owned the car, it's just something I never did get around to doing lol.

But as your stating the same as the chap in the YouTube comment, could you elaborate how either a leaky injector or glow plugs can cause blue smoke, it doesn't make sense to me as neither relate to oil.

There are a load of Youtube videos on diesels without glows puffing blue smoke when starting - not just BMW, which is why people generally point towards the glow plugs.

I had two dead glowplugs on mine and the controller was covered in oil yet it has always started first time in the winter but rough, really rough. Colder the temp, the worse the start. In the summer, no smoke at all. The blue smoke being emitted was pretty embarrassing.

Since changing all glows and the controller, it does now show the coil / glow symbol on cold mornings and the car starts fine, with a small puff of blue like yours in that video.

Since changing two injectors, the INPA values are now pretty much perfect but I still get the blue puff of smoke.

Now I know blue generally means burning oil but why when it has been left overnight in 10 degree weather does it not do it? That's the bit I can't get my head around.

It has to be temperature related.

MrSweet1991 · 01-12-2022, 11:44 AM

Quote:

Originally Posted by chrissyw

There are a load of Youtube videos on diesels without glows puffing blue smoke when starting - not just BMW, which is why people generally point towards the glow plugs.

I had two dead glowplugs on mine and the controller was covered in oil yet it has always started first time in the winter but rough, really rough. Colder the temp, the worse the start. In the summer, no smoke at all. The blue smoke being emitted was pretty embarrassing.

Since changing all glows and the controller, it does now show the coil / glow symbol on cold mornings and the car starts fine, with a small puff of blue like yours in that video.

Since changing two injectors, the INPA values are now pretty much perfect but I still get the blue puff of smoke.

Now I know blue generally means burning oil but why when it has been left overnight in 10 degree weather does it not do it? That's the bit I can't get my head around.

It has to be temperature related.

I'm not entirely sure what the answer to yours is, but I do feel that the glow plug/injectors are indirectly related to the blue smoke. There's a good few ways to get oil into the chamber including CCV, valve cover gasket and valve stem seals and maybe working glow plugs reduce the crank time and somehow that prevents the visible blue smoke and when it's colder and it has to crank longer maybe during the crank cycle something is happening to pull more oil into the chamber maybe?.. I honestly don't know but my purpose for the post is to try and see if there is a clear explanation as to how either glow plugs or injectors can cause blue smoke because from my current knowledge they cannot be directly related, they will always create some sort of fueling issue whether that be longer cranking or incorrect fueling during startup die to a leaky injector which results in black/white smoke but I'm yet to see how blue can be produced.

Take my car for example, this video was a day or two afterwards the video posted above, the only difference is a CCV Filter, but every single glow plug is still faulty and there's no DPF but there's not a smidge of blue smoke which to me makes sense as glow plugs are (at it's worse) fuel related black/grey but the CCV filter specifically related to the separation of oil and vapour which I can understand why no more smoke would occur.

Hopefully you get an answer to yours as I'm intrigued why it happens as well. But this is my next startup with CCV filter, no glow plugs and no DPF Cold start

https://youtube.com/shorts/NKlHo4fE4wM

chrissyw · 01-12-2022, 01:51 PM

In my case I'm 99% sure it's not oil, it has a smell to it and as it doesn't happen when the weather is mild to warm, that pretty much confirms it for me.

It's most probably my two remaining injectors that are original and have done nearly 180k.

Since switching to the old loo roll breather my oil consumption is a lot lower.

If it is the rocker cover gasket I'd expect it to do it every single day, just like if it was the valve stem seals.

01-11-2022, 07:52 AM	#1
MrSweet1991 Captain 129 Rep 828 Posts Drives: BMW E90 330D M Sport Join Date: Apr 2017 Location: West Midlands iTrader: (0)	Can Glow Plugs cause blue smoke? Good afternoon peeps! Been a while since I've been on here with the 330d off the road, been driving a 7 seater Nissan Qashqai to accommodate our new earthling, my gosh when my claims drop off in a month or two I'll hopefully be able to insure both as I miss it. Anyway back to the point, I had a chap comment on my YouTube video, it's a blue smoke video I took to see the smoke prior to adding a crankcase breather, in another video I done another cold start and all smoke was clear so the breather was a success. However, a chap said that faulty glow plugs/module can cause blue smoke as well leaky injectors. However, from my knowledge the smoke it's quite specific that being: Blue is oil related Black or greyish white is unburned/partially burned fuel due to various fueling/air issues White steam/vapour is coolant So to me both injector and glow plugs would fall under the fueling category resulting in one way or another black or white, but no way to cause blue. The video and comments can be seen here: I'm always up for learning about my car, maybe I am wrong and have overlooked something so if anyone would like to explain how either a leaky injector or faulty glow plug and or controller could result in blue I'm all ears
	Appreciate 0 Tweet Quote

01-12-2022, 05:13 AM	#2
chrissyw Second Lieutenant 36 Rep 242 Posts Drives: 2006 E90 320d M Sport Join Date: Mar 2014 Location: Midlands iTrader: (0)	Whilst it's not ideal, with that amount I wouldn't be overly concerned. Is that from freezing cold this morning? Yes blue smoke can be caused by the glow plugs. It can also be caused by a leaking / lazy injector that weeps overnight in the cold weather. It can also be caused by a perished valve cover gasket. My 320d does the same on freezing cold mornings and I personally feel it is an injector slightly leaking overnight. I've done all the glows, new controller and replaced two injectors. I have also gone back to the old loo roll style breather - to try and stop and inlet manifold oil leak not really the blue smoke. It used to run really rough on a cold morning before I replaced the two injectors, sometimes throwing a rough running code. Blue plooms of smoke and the whole car would shake for 30 seconds. Two injectors didn't look great on INPA so I whipped those out. The seals on all 4 injectors were completely shot. I'll get the two I removed checked and rebuilt at some point I think. White smoke out the back is generally a sign of unburnt diesel from an overfuelling injector. Last edited by chrissyw; 01-12-2022 at 08:59 AM..
	Appreciate 0 Quote

01-12-2022, 01:51 PM	#6
chrissyw Second Lieutenant 36 Rep 242 Posts Drives: 2006 E90 320d M Sport Join Date: Mar 2014 Location: Midlands iTrader: (0)	In my case I'm 99% sure it's not oil, it has a smell to it and as it doesn't happen when the weather is mild to warm, that pretty much confirms it for me. It's most probably my two remaining injectors that are original and have done nearly 180k. Since switching to the old loo roll breather my oil consumption is a lot lower. If it is the rocker cover gasket I'd expect it to do it every single day, just like if it was the valve stem seals.
	Appreciate 0 Quote