Intake Plenum and IRIS valve question

sicksubie · #1 10-22-2006, 08:41 PM

I have the top half of the motor apart and took the IRIS valve out today to just look. When I did that I saw nothing but crud and oil everywhere. The entire inside of the stacks, plenum even going out of the TB and even the top of the snorkel is coated with disgusting, brown, oily, crud. Any ideas what this could be coming from?

SVXRide · #2 10-22-2006, 08:46 PM

PCV valve....short of disabling the system, there's nothing you can really do about it.
-Bill

sicksubie · #3 10-22-2006, 08:57 PM

so this is supposed to happen?

ItsPeteReally · #4 10-23-2006, 12:57 AM

Quote:

Originally Posted by sicksubie

so this is supposed to happen?

Pretty much so, yes. It's all a question of degree. If what you see is a little oil 'misting' on the surfaces, but everything is essentially clean, unobstructed and free running, then you have little to complain about.

If, on the other hand, what you see is vast quantities of black gloopy crud, gumming up all the parts, then that is bad.

Probably you're somewhere between the two. What you are seeing is the accumulated results of 100,000+ miles of running. If the previous owner(s) maintained the car well, then it shouldn't be too bad.

But if they were of the 'change the oil when the red light comes on' mentality then the accelerated bore wear, with the attendant crankcase pressurisation it causes, is going to blow vasts amounts of dirty oil mist straight into your inlet - the only possible saving grace is that in really bad cases the PCV valve will clog up and protect you

In the 'bad old days', before PCV valves existed and crankcase pressure was vented directly to atmosphere, you could often see the vent pipe smoking.

sicksubie · #5 10-23-2006, 06:11 AM

Quote:

Originally Posted by SVXRide

PCV valve....short of disabling the system, there's nothing you can really do about it.
-Bill

STupid question.... Can you disable it to prevent it?

dcarrb · #6 10-23-2006, 07:35 AM

Quote:

Originally Posted by ItsPeteReally

In the 'bad old days', before PCV valves existed and crankcase pressure was vented directly to atmosphere, you could often see the vent pipe smoking.

I learned to drive in a tired 1962 Chevrolet Impala with a 283 V-8 that idled so smootly and quietly that we'd occasionally think it had stalled at a traffic light, if not for the blue smoke billowing from the crankcase vent tube.

On the SVX, oil vapor is also pulled into the intake by the cam cover breather hoses.

dcb

SVXRide · #7 10-23-2006, 08:08 AM

In theory, at least, you could route all of the PCV lines to a single catch can with a breather vent on it

-Bill (thinking old school...)

sicksubie · #8 10-23-2006, 10:31 AM

how hard would that be? I'm just thinking cuz I am spending time here cleaning it out and polishing and I do not want it to just go back to the way it is now.

dcarrb · #9 10-23-2006, 10:57 AM

It's normal to have oil residue in the intake... that's the way it's designed. If you route the breathers and PCV into a catch can, there will be no vacuum to evacuate the crankcase fumes (which probably makes no difference), and you'll be pointlessly defeating a key pollution control system, if that matters to you.

dcb

sicksubie · #10 10-23-2006, 02:52 PM

Global Warming??? Spend a winter up here and you will want global warming.

sicksubie · #11 10-23-2006, 02:53 PM

But it is seriously up in the TB and the top of the snorkel. Is that "normal" too?

SVXRide · #12 10-23-2006, 06:18 PM

Quote:

Originally Posted by sicksubie

how hard would that be? I'm just thinking cuz I am spending time here cleaning it out and polishing and I do not want it to just go back to the way it is now.

Shouldn't be too difficult -- check out Summit Racing for catch cans and breathers.
-Bill

oab_au · #13 10-23-2006, 06:57 PM

How about the one that is built in, at the back of the block, has that plastic cover over it. The fumes are drawn in there first to remove the oil, then to the PCV valve.

Harvey.

sicksubie · #14 10-23-2006, 07:05 PM

Quote:

Originally Posted by oab_au

How about the one that is built in, at the back of the block, has that plastic cover over it. The fumes are drawn in there first to remove the oil, then to the PCV valve.

Harvey.

Is that one that you are seeing in the Summit catalogue?

SVXRide · #15 10-24-2006, 02:19 PM

Quote:

Originally Posted by oab_au

How about the one that is built in, at the back of the block, has that plastic cover over it. The fumes are drawn in there first to remove the oil, then to the PCV valve.

Harvey.

Harvey,
I'll have to take another look at the system....wonder if we can improve on the system (i.e. remove more of the oil?)
-Bill