TDIs blowing from the oil cap... WTF? (T5.1 and T5.2)

and_pir

Aktiv-Mitglied
Hello ppl. This post is abouth both the T5.1 and T5.2.
I had visited several sellers for both t5.1 and t5.2, and I alwais found a phenomenon that I knew is a problem.
I got Always told to do the following test: when you start the engine, you have to open the oil cap to see if there is sludge (head gasket broken) and to feel if the engine blows air from there. If you have an engine that blows air from there, you have to avoid to buy that vehicle since the engine is broken, it lost compression.
What made me aghast, is that I saw like 15 bus and all them had that problem.

I tested vans from 2007 to 2012, from 120.000 to 300.000 km, both PDE and Common Rail types, and it was Always the same... eventually some were blowing more than Others.
But the thing that to me doesn't look normal, is that I visited 2 bus: T5.2, 140ps: one runned 120.000km only and regoularly serviced by an official VW shop, and it was one with the strongest blows, like if someone was blowing air with the air compressor gun from the under of the oil duct. The other T5.2 runned 220.000km and was blowing a little less.

How could this be possible? A t5 with 120.000 km should not be blowing like that...

My question is: Is this test a valid test? or a bullshit? Because I can't understand how a 120.000km engine, that should be considered still new, could be already broken.
Did I exclude by mistake some worthly vans?

Our Vr6 T5 180.000km and 1.4 polo 160.000km don't blow from the oil cap...

Thank you ppl.
 
Marcus ist right.

There will always be an amount of blow-by-gas at the filler cap. Only to measure the amount of blow-by-gas by eye ist not very reliable. If the engine seems to run only on 4 Cylinders, has high oil consuption and or ist leaking massive amounts of oil at the seals or the turbo charger, there may be loss of compression and excessive crankcase pressure. In this cases, the pressure at the filler cap is another hint.
 
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