Momentary white smoke (SEAT Leon Cupra 290 Manual 2016)

Apr 15, 2020
2
0
Hi everyone, a quick query, I hope someone might be willing to educate me a little further.

I noticed my cupra ever slightly under performing when accelerating. Just felt like an ever so slight loss of power but I thought I might be being paranoid.

After driving for 30 mins I hit a motorway was up at 70 and all of a sudden white smoke poured out back for a second or 2. stopped smoking for a second or 2, then smoking pouring out back for another second or 2. Then all stopped smoking again. No loss of power or anything. Im sure now the car has its full power back since this happened.

Im not knowledgeable about engines so forgive my lack of knowledge. Im guessing condensation buildup in exhaust systen am I guessing right? Would really appreciate some insight into how and why this happenned to put my mind at rest. Thought this happens in the cold winters rather than warm summer temperatures.

Thanks for anyone taking the time to hail an opinion.
 

CalJames

Active Member
Jun 25, 2019
174
84
My partner's Fiest had something very similar, turned out to be a crack in the cylinder head. Coolant was getting into the cylinders and causing misfires and poor performance, along with white smoke from the exhaust.
Check these things:
Coolant level
Remove oil cap and look for any "mayonnaise"
Smell the white smoke and see if it has a sweet smell.
 
Apr 15, 2020
2
0
My partner's Fiest had something very similar, turned out to be a crack in the cylinder head. Coolant was getting into the cylinders and causing misfires and poor performance, along with white smoke from the exhaust.
Check these things:
Coolant level
Remove oil cap and look for any "mayonnaise"
Smell the white smoke and see if it has a sweet smell.
So Ive suddenly become aware of the risks of seriously over filling the oil. Im getting it drained, hopefully I havent done any long term damage
 

SRGTD

Active Member
May 26, 2014
1,265
572
After driving for 30mins the engine would be fully warmed up, so I doubt it would be condensation build up suddenly being expelled in two second bursts. From the driver’s seat, exhaust condensation / steam is usually only visible (i.e. looking in the rear view mirror) during the initial engine warm-up period when the car’s stationary, or moving slowly.

Unfortunately, white smoke pouring from the exhaust does sound like something more serious than exhaust condensation - e.g. cracked engine block, cracked cylinder head, faulty head gasket. Usually, the thicker / more dense the white smoke, the more serious the issue - hopefully not too serious or expensive to rectify.
 
Last edited:

KXL

KXL
Dec 15, 2016
1,501
170
London, UK
condensation usually only happens in the first 10 mins of the engine, and you can easilly see it from your mirrors if you are stationary, and engine on, the 'steam' exiting on both sides (Cupra has dual spit exhaust). Was your tank very low at the time it happened? Maybe something at the bottom of the near empty tank? Hope you are using Vpower Nitro Plus or Momentum 99 petrol and not supermarket 95 RON. Else...it's as the other's say, perhaps more serious...
 

Two90Black

Active Member
Mar 3, 2019
38
12
Sounds very much like a gasket or cylinder issue.

get the coolant system pressure tested. Keep an eye on the coolant see if it’s dropping.

Another thing you can do is take the spark plugs out to see if any of them look like they are being fouled from the water getting into the cylinder. Whilst out you can get a camera down to check inside for any signs.

Also if you can smell the coolant from the exhaust. Anti-freeze has quite a distinct smell when it’s been burnt through the engine.
 
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