Will a Turbo still boost okay with leaking oil seals?

DrewCole

Spannering the Cupra
Oct 19, 2015
697
1
Braintree, Essex
I have a 2002 Leon Cupra 180 that recently started to see some smoke from the rear in slow moving traffic.

The car is just over 100k mark now and has been well cared for up to this point.

I have just completed a minor oil service with 5w30 oil and new filter.

I suspected not all was well when I caught site of a 'cloud' lingering out the back of the car in slow moving (10mph) traffic a few weeks ago, and then the other day my oil light came on and the level had dropped a fair amount.

I put the car up on ramps and found that the Turbo looked wet and there was oil residue on the inner CV joint and on top of the CV joint cover plate, it was nice and clean oil so I assume it was that which I had just filled the engine with!

The car still drives and boosts as it ever has and I can't seem to spy any smoke when driving, and it hasn't been smoking in traffic all of the time...

My initial thoughts are that the oil seals have gone on the Turbo, but would that impact on the performance of it at all?

I'm still seeing 0.7bar on the boost gauge, so about 8-9psi?

Any advice out there greatly received, before I go and buy a new unit!
 

efeballi

1hp Biker
Jan 9, 2018
2
0
Milano/Istanbul
I would say definitely it's something to be investigated further. Whichever side the turbo's leaking oil, it will harm the cat (if you didn't decat it) and it will mess with combustion if the intake side seal is leaking, reducing the octane rating and possibly causing knocks. Not to say it's terrible for you and others inhaling the oil, either burnt or unburnt.
Though if the oil was clean the leak might well be elsewhere.
 

Muttley

Catch that diesel!
Mar 17, 2006
4,987
31
North Kent
Turbo oil seal failure will show as oil in the exhaust or inlet, not externally. If you have oil dripping, find out where it's coming from. The oil pipes to and from the turbo would be a good place to start, as they are under high pressure - the turbo needs a lot of oil to keep it cool, as well as to lubricate it. But if you have a big enough leak to show up as a substantial drop in oil level, then it needs to be found. My guess is that a leak that big would show up as massive amounts of smoke in the exhaust, but it hasn't happened to me so I can't be sure.
 

DrewCole

Spannering the Cupra
Oct 19, 2015
697
1
Braintree, Essex
I can confirm, my top oil feed to the turbo has gone... this results in a fair amount of oil dripping and I also have oil/smoke in the exhaust too, so suspect internal brearing failure too.
 
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