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View Full Version : air coming from breather, oh no!



cdn_w_sr20
08-04-2005, 11:48 AM
I had the car running nicely today after re-wiring the fuel pump and adding an extra ground for the ignitor. When all of the sudden, oh no, i stick my hand over the crank case vent which i had a breather on before and noticed air being pushed out instead of sucked in.

Last time i checked this should not be happening unless rings or something else are screwd correct? I was sure it should be constant vacuum. I then check my boost gauge to see my vacuum sitting at -10 to -11 psi instead of where it was before around -18 to -19 psi. I get the feeling that could be the cause of the problems and why i'm some reason able to make boost in neutral.

there has never been oil come out of the breather though, there has been residue but thats about it. Sound normal?

EDIT: Just found oil over all 4 spark plugs.

_Def_
08-04-2005, 12:02 PM
I have air coming out of my oil cap at idle, but it's not a huge amount(engine idles a hair rougher with it out). It still pulls about -19 to -21 in-Hg of vac at idle(stock cams).

I think the oil on your spark plugs is bad news though...

Time for a compression check.

cdn_w_sr20
08-04-2005, 12:04 PM
Compression was 140psi across the board, engine warm, throttle open and such. I'm thinking of going to an RB25 now since i can get one for a little under $2000 complete.

cardriver
08-04-2005, 12:16 PM
how much you wanna sell your sr for? http://forums.freshalloy.com/images/graemlins/tongue.gif

cdn_w_sr20
08-04-2005, 12:23 PM
the entire motorset? with all the goodies i have on it? Would be looking to get around 2k or so for the motor with the turbo/driveshaft.

Brad
08-04-2005, 04:25 PM
checked timing at least? that will make your vacuum drop at least. same with cams

JimStinksAtDorifto
08-04-2005, 04:42 PM
I then check my boost gauge to see my vacuum sitting at -10 to -11 psi



There's your real alarm.

(even if you meant inches of vacuum) http://forums.freshalloy.com/images/graemlins/smile.gif

cdn_w_sr20
08-04-2005, 05:17 PM
Here is the thing, i think the oil was coming from up top some how, since i could see oil on the top of the spark plug wells.

The vacuum issue is making me wonder a little too. When i try to get the engine in timing mode it doesn't seem like there is any difference at all. Today i had the engine idle itself with the tps unplugged. the idle was at around 1200 rpm and when i checked the timing it was nearly on TDC. Then when i plugged the tps back in and rev'd it up it would go to around -15 BTDC. I'm going to clean the IACV out and try it again and use a different compression gauge this time.

It still stumps me how the motor will not rev'd past 3,500 rpm at all. Even if the compression is at 140psi on each cylinder it should still be driveable. Am I right? i'm pretty sure i am lol. Right now i know it is not a fuel issue or a spark issue.

How does the IACV work though? does it close when the throttle is open or something? I'm getting the feeling the IACV is the source of the issue here, but i think none the elss the motor may be done for soon.

RB25 tIME!!!

Enthalpy
08-04-2005, 05:30 PM
ok i love this one.

does it never occur to people that the exact opposite of what is happening in the combusiton chambers is also happening in the cankcase? the pistons are moving up and down. moving air IN and OUT of the crankcase. AND all motors have some amout of blowby. SO if the engine is blowing by just a bit and the pistons are moving up and down. Doesnt it make sense that ther is going to be air movement felt at the breather.

i would think so...

but what do i know?

cdn_w_sr20
08-04-2005, 05:44 PM
Does make sense yes. The vacuum going so low though i dunno. This timing crap is starting to piss me off. It was not this hard when we did the headgasket. I have a really bad feeling that the IACV is causing some problems though.

When you go to start the car it will not start unless you keep hitting the gas over and over. then you need to give it lots of gas to make it idle. I'm not sure if the IACV has any effect when the motor is under load or not but it seems as if something is wrong.

Then again, uhmmm we did use GTIR pistons when we did the rebuild, so that could effect the compression since they are 8.3 to 1 or something like that right?

asad
08-04-2005, 09:26 PM
Then again, uhmmm we did use GTIR pistons when we did the rebuild, so that could effect the compression since they are 8.3 to 1 or something like that right?



No. The compression difference in the GTi-R comes from the cylinder head, not the pistons.

Asad

Enthalpy
08-04-2005, 09:39 PM
Then again, uhmmm we did use GTIR pistons when we did the rebuild, so that could effect the compression since they are 8.3 to 1 or something like that right?



No. The compression difference in the GTi-R comes from the cylinder head, not the pistons.

Asad



Ding ding ding...we have a winner!!

54c pistons are in most newer and some old RWD det's and they all have 46cc cylinderheads adn 8.5:1 CR thus the GTiR has a larger cylinder head cc.

cdn_w_sr20
08-04-2005, 10:04 PM
you know the line that runs from the intake manifold to the pcv in the valve cover, if per say that was loose with it cause low vacuum like this?

Enthalpy
08-04-2005, 10:05 PM
yes

cdn_w_sr20
08-04-2005, 10:22 PM
this is likely the vacuum leak then. I was checking things over and noticed it was like 1/2 on the pcv valve. Not sure why but whatever, i'm sure once i tighten it the vacuum issues will go away, not sure about driveability.

Is the $2000 for a full RB25DET swap a good price? i still need moutns and the intake mani of course.

_Def_
08-05-2005, 03:55 AM
Crankcase volume remains the same since for every piston going up, there is one going down. Moving the air around does cause a power loss, which is one reason why vac pumps on the crankcase make more power.

The air felt at the breather should be all blowby.