dominicbeesley

Well-Known Member

• Mar 15, 2016

• #1

I had some idle problems on my s3 petrol recently after a brisk 200 miles on the motorway. I've just cleaned the idle jets and that seems to have more or less sorted it but I noticed something else.

The engine breather used to very gently blow (if you put a thumb over the outlet on the Dalek head it would give a slight puff after holding it a few seconds). Now it constantly sucks, not hard, but noticeably with a constant sucking noise.

Any ideas what the cause is likely to be? Piston rights, valves?

I won't have time to strip it down for a while so hopefully it wont do any immense harm...

D

 

Bobsticle

De Villes Advocaat

• Mar 15, 2016

• #2

Im sure thats a Hebden Bridge thing. I hear half the women there cant make their minds up these days.

 

LandyMan

Well-Known Member

• Mar 15, 2016

• #3

blow is just a figure of speech!

 

SpringDon

Well-Known Member

• Mar 15, 2016

• #4

Constant sucking? Interesting.i would guess valve guide specifically inlets. Piston or rings should cause pressure.
But there should some other symptom like smoke or compression loss. So I don't really know (he says helpfully)

 

A

ajb403

Active Member

• Mar 15, 2016

• #5

Pure guesswork but if you've not got a hardened head could the 200 miles at motorway speeds have caused damage to the valve seats 'lead memory'? May cause issues?

 

D

divie

Well-Known Member

• Mar 15, 2016

• #6

I doubt if 200 miles will cause valve seat recession. My P4 Rover has never had the head off in the last 40 years.

 

dominicbeesley

Well-Known Member

• Mar 15, 2016

• #7

Thanks lads, it has got hardened valves and seats so it shouldn't be that. I think I'll whip the rocker box off and see if I can see where it's sucking from. The tappets all sound ok and it's not running lumpy. All I can think of is a piston ring but then I'd expect it to be blowing...

 

L

lynall

Well-Known Member

Full Member

• Mar 17, 2016

• #8

If its got the crankcase breather routed into the inlet tract could that be causing your suck?

 

wammers

No longer with us, RIP

Donater

• Mar 17, 2016

• #9

Yep a suck or blow depends which end you have your thumb over.

 

mistericeman

Active Member

• Mar 17, 2016

• #10

Worn inlet valve guide/s?
Inlet side is the only bit that is under a vacuum.

 

dominicbeesley

Well-Known Member

• Mar 18, 2016

• #11

Sorry lads, turns out I am an idiot .... I'd still got the PCV pipe to the carb attached - what a knob! Still having idle issues so looks like a full carb strip down / new manifold gaskets are in order.