Vacuum Trees & PCV/EVAP

[S2central.net]

After MUCH searching, I finally found the right box containing a CD with some stuff I archived off a computer from a previous life...

The originals are still there in MS-Visio format. I did this over two years ago. I have uploaded three diagrams in JPG format onto S2central.net for posterity. I shall add words and more beef later this month.

- 3B Vacuum Tree
- ABY Vacuum Tree
- ABY PCV System (Which is largely identical to 3B - except for different parts used)

http://s2central.net/images/Vacuum_and_PCV/


Paul

[ThatGUY]

I think it would be helpfull to have P/N here with these great diagrams

#3 PCV valve 034 129 101A (old) 034 129 101B (new)
#5 Flame Trap 025 103 477A

[4WheelDrifter]

Also worth noting that there should be a vacuum diagram on a sticker on the underside of your bonnet. Quite handy I have found.

[Crawford_S2]

Are these part numbers still correct for ABY? Think i might need them!

[S2central.net]

Let me check later tonight Crof... I just replaced my PCV valve and flame trap last night - seemed only right when the rad and fan is out to tackle the firkin sump and oil switches.

I got some photos to share - man that flame trap was gunjed - 15yr old gunje.

Paul

[Crawford_S2]

Cheers paul

[macspring]

Paul,

Do either of the small little on way valves ever go faulty and require replacement? The two that I'm thinking of are the light blue coloured valve at the rear of the head and the yellow and black one also at the rear of the head and which is close to the middle of the strut brace?

Additionally, while I asking, whereabouts is the moisture trap on an ABY Avant? Does it ever need replacing?

Thanks for your time.

p.s. - Might see you tomorrow, can you bring crank "spanner"?

Kind regards.

[S2central.net]

The parts I used are -

Flame Trap 035 103 477A - bout 6 quid
PCV Valve 034 129 101 B - bout 10

Those numbers were current & correct in Jan '08

[Crawford_S2]

Sweet, going to get them on as soon as i get back off hols, finally think i have found my boost leak

[JamesHarrold]

Hi Crawford_S2....Where was your boost leak in the end....I cannot track mine down at all

[Crawford_S2]

Well, not certain yet but all signs are pointing to the PCV valve and breather system. I have replaced loads of sensors recently and tested for leaks on all inlet side but forgot about the breather system and how it can cause boost leaks and funny fault codes. Penny dropped the other day when i found the PCV valve all covered in oil and smeg. Will update when i find it.

[A80Avant]

Just trying to clarify one little bit again here:

according to the schematic, there is a lower crankcase hose which bypasses the PCV valve and an upper one, through the PCV valve.

Can someone explain to me the workings of the small tube (13mm) going to to the lower crankcase? it seems to me that this is permanently connected to the blowby, so when ON boost, you would have both PCV valve OPEN + blowby going through that smaller tube to the lower crankcase. Correct?

I found that when i only used the catch tank with a connection to the hose that the PCV valve is connected, and the tank connected to the MAF hose, i was still getting near to none blowby through the tank, but most of it went through the smaller tube into the lower crankcase area, which eventually made my rubber crankcase seal to leak.

Once i got a T piece hose fitted in conjuction with the smaller metal tube, then towards the tank, the tank started to fill up quite quickly.

So what is the deal with the smaller of the 2 metal tubes which bypasses the PCV valve?

[Rusty]

Maybe best to copy the diagram above and modify it show what you're enquiring about. The smaller bore pipe connects the head breather with the crank case breather and is a major contributor to oil getting into the system, as oil is pushed out of there under hard acceleration and then blow into the system by the crank case blow by.

[A80Avant]

this is what i am inquiring about.

so oil is pushed from the head downwards to the block where it meets the rest of the system and the PCV valve route.
thanks

[Rusty]

Yes. I did some investigations into it and for 8 first gear runs, 50-100ml of oil went down the pipe. Best option is to relocate the head breather - something I'm working on a bolt-on solution for right now