White Smoke!! M20 B25 engine!
Moderator: martauto
Hi Everyone!
Recently my 325i cab has decided it wants to produce a nice big smokescreen from the exhaust. Now I know there are plenty of head gasket threads about but I am after some help troubleshooting from the guys on here that are the gurus!
The car has 161k miles and has been serviced regularly as far as I'm aware. I have had her for around two months now and the smoke has appeared in the last two weeks.
So a description of exactly what is happening. I start the car, no starting problems and no problems with the idle, after a minute or so of idling some white smoke starts to appear out of the exhaust. This gradually gets worse until the smoke is quite thick and doesn't really change when the engine heats up. It smells to me like fuel but I'm no expert.
Then when I start driving the car the smoke seems to disappear until I stop at traffic lights and then it re-appears! Producing a James Bond Aston Martin type smoke screen behind me! Lol.
Now I have had a look around on this forum and a few others but can't seem to find a problem that is exactly like mine. I have read that it could be The dreaded head gasket! Antifreeze and coolant leaking through a crack somewhere on the head and coming out of the exhaust as white smoke.
Also there is no mayo like substance on the dipstick, under the oil cap or in the reservoir. She isn't using any more oil than normal and she isn't losing coolant.
Could anyone shine some light on this for me? Any help would be much appreciated!! Any more details needed?
Recently my 325i cab has decided it wants to produce a nice big smokescreen from the exhaust. Now I know there are plenty of head gasket threads about but I am after some help troubleshooting from the guys on here that are the gurus!
The car has 161k miles and has been serviced regularly as far as I'm aware. I have had her for around two months now and the smoke has appeared in the last two weeks.
So a description of exactly what is happening. I start the car, no starting problems and no problems with the idle, after a minute or so of idling some white smoke starts to appear out of the exhaust. This gradually gets worse until the smoke is quite thick and doesn't really change when the engine heats up. It smells to me like fuel but I'm no expert.
Then when I start driving the car the smoke seems to disappear until I stop at traffic lights and then it re-appears! Producing a James Bond Aston Martin type smoke screen behind me! Lol.
Now I have had a look around on this forum and a few others but can't seem to find a problem that is exactly like mine. I have read that it could be The dreaded head gasket! Antifreeze and coolant leaking through a crack somewhere on the head and coming out of the exhaust as white smoke.
Also there is no mayo like substance on the dipstick, under the oil cap or in the reservoir. She isn't using any more oil than normal and she isn't losing coolant.
Could anyone shine some light on this for me? Any help would be much appreciated!! Any more details needed?
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e30topless
- E30 Zone Team Member

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most M20 engines tend to "steam" at this time of year, that's normal ..
is your heater ok and the temp needle sitting just below half?
is your heater ok and the temp needle sitting just below half?
Hi, thanks for the quick reply! I am totally new to BMW's especially old ones. The heaters are fine. Blowing hot and cold on all settings. It is a non AC model. And the temp needle sits just below half after warming up. Never goes any higher!
To be honest when I bought the car a couple of months back the weather was better and warmer, I didn't notice any smoke then. Maybe just the cold weather then?
To be honest when I bought the car a couple of months back the weather was better and warmer, I didn't notice any smoke then. Maybe just the cold weather then?
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maggspower
- Turbo Farmer Tractor Driver
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- Location: Nowhere near South Wales, ok butt
Is it any water?
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maggspower
- Turbo Farmer Tractor Driver
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- Joined: Wed Oct 12, 2005 11:00 pm
- Location: Nowhere near South Wales, ok butt
Well that didnt make any senseMafisher wrote:What do you mean?maggspower wrote:Is it any water?
Is it loosing any water from the cooling system. Much better
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e30topless
- E30 Zone Team Member

- Posts: 13598
- Joined: Wed Aug 23, 2006 11:00 pm
- Location: surrounded by scrap
sounds fairly normal to me, on very cold mornings they can really steam a lot !
Haha no it its not losing any water from the cooling system. It recently had a service, full coolant change and oil change around a month ago and the coolant hasn't budged.maggspower wrote:Well that didnt make any senseMafisher wrote:What do you mean?maggspower wrote:Is it any water?![]()
Is it loosing any water from the cooling system. Much better
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maggspower
- Turbo Farmer Tractor Driver
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- Joined: Wed Oct 12, 2005 11:00 pm
- Location: Nowhere near South Wales, ok butt
Yes I agree, the m20 is one of the most steamy engines when cold i have come across.e30topless wrote:sounds fairly normal to me, on very cold mornings they can really steam a lot !
I have also read the opening post again and there is no coolant loss.
I'll get me coat
Last edited by maggspower on Sun Dec 02, 2012 9:29 pm, edited 1 time in total.
Thanks mate, putting my mind at rest a little but! Blown head is all I need at this time of year!! Especially with very little mechanical skill!!e30topless wrote:sounds fairly normal to me, on very cold mornings they can really steam a lot !
Haha yeah best had mate! Been a long weekend? Lolmaggspower wrote:Yes I agree, the m20 is one of the steamy engines when cold i have come across.e30topless wrote:sounds fairly normal to me, on very cold mornings they can really steam a lot !
I have also read the opening post again and there is no coolant loss.
I'll get me coat
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HairyScreech
- Engaged to the E30 Zone

- Posts: 6265
- Joined: Sun Jan 21, 2007 11:00 pm
Yes found this myself after doing a head gasket on one only for it to chuck out huge clouds of steam. Had me worried for a while but its still running fine 5 years later as far as i know.
2.8 development thread http://www.e30zone.net/modules.php?name ... c&t=170822
m3.3.1 m20 thread - now running, chip needed - any volunteers?
http://www.e30zone.net/modules.php?name ... =viewtopic&
m3.3.1 m20 thread - now running, chip needed - any volunteers?
http://www.e30zone.net/modules.php?name ... =viewtopic&
Quick update, weather is a little better this morning and not as cold. Started her up and only a little steam which almost disappeared once the engine had warmed up! Cheers for the help though guys, put my mind at rest!



