If the title sounds like you, and you have some ramps or suitable jack and axle stands, you might want to take a look at your PCV breather module on the back of your engine.

 

I took one off a couple of days ago, from an '05 9N3 Polo I saved from the scrappies, 85k on the clock, seemed to run OK, though there were signs of oil seeping from the oil-filler tube connection to the head, which had been bodge-sealed with silicone.  Radiator fan wasn't working at all either, and there was the seemingly universal coolant leak from the radiator thermoswitch (fixed by simply tightening to 30Nm).

 

Glad I did, but now probably needing to get the sump off too for a look-see.  I'll let the pictures tell the rest of the story, just off for a bath now.

 

 

 

 

 

 

Interesting, will have my mechanic do it as soon as the shop opens. Last time I had the car in service he thought the vacuum values were abnormal. I have no suitable tools for the job, but it's something I always wanted to check. 

I'm still out of luck about the MAP sensor, hopefully I'll see to sort that out when the shop opens.

12 hours ago, juanse_2691 said:

Last time I had the car in service he thought the vacuum values were abnormal

 

Lower or higher pressure than expected?  I guess if the breather system is mostly or completely blocked like the one photographed, although crankcase pressure will be higher, inlet manifold pressure might be lower than expected if the breather isn't returning vapour via the hose under the throttle body? (Won't apply to earlier versions of these engines where the output of the PCV went up to the airbox).

 

Edited 28 April, 20206 yr by Wino

Does anyone know if the 1.2 also suffers as well?

No, both 6-valve and 12-valve versions of the 1.2 engines feature quite different breather arrangements to this one, the 6-valve version being particularly simple and unlikely to block.

5 hours ago, Wino said:

 

Lower or higher pressure than expected?  I guess if the breather system is mostly or completely blocked like the one photographed, although crankcase pressure will be higher, inlet manifold pressure might be lower than expected if the breather isn't returning vapour via the hose under the throttle body? (Won't apply to earlier versions of these engines where the output of the PCV went up to the airbox).

 

Inlet pressure was ever so slightly lower than reference values. It was still within range, but in the lower side of the scale, enough to investigate a possible vacuum leak. Crankcase vacuum was excellent, if undoing the oil cap and having it sucked back into place is any indication, so no blowby apparently.

1 minute ago, juanse_2691 said:

but in the lower side of the scale, enough to investigate a possible vacuum leak

A vacuum leak would make the pressure higher, not lower

1 minute ago, juanse_2691 said:

if undoing the oil cap and having it sucked back into place is any indication

Well I thought that was enough indication, but this oil cap was still being sucked down reasonably well, even with that horrible mess in the breather box.  I think it was still passing some vapour, probably enough at idle when not much blowby is generated. I did log some MAP sensor values before replacing the breather box, so it'll be interesting to compare now.

Great, please let us know the results when you can! 

🙂 I might get a chance to do another log tomorrow.

 

I don't remember if the values were higher or lower, really, but still they left my mechanic puzzled.