Too Much Crankcase Pressure

[Cruzn620]

for some reason my little truck (L20B) is building up a lot of crank case pressure. i have a vent type air filter on the valve cover spigot instead of the stock routing to the air cleaner. i dont know how else i could be building up this much pressure. thanks for the help in advance!

[banzai510(hainz)]

you running a PCV on the crank to the intake manifold???????

you know the hose the comes from the block to the lower part of the inatke under the carb. This can suck some of it up!!!!!!!!!!

 

Usually you have more pressure at idel then when going faster it will start sucking IN.

 

maybe you have worn rings!!!!!!Blowby

[Cruzn620]

i talked to one of my NZ buddies last night and he suspects shot rings. The PO said he rebuilt the motor 8000 miles ago, but this is the same idiot who removed smog stuff and just twisted wires together under the hood and left them exposed. If the rings were shot, wouldnt i be burning oil? i am not burning any oil at all that i can tell. about the PCV, i know its possible for these to clog, i think i need to check that out. as for it going from the crank to the intake mani, i need to check my manual and see the routing, but i don't remember a line going from the crank to the mani. the line i am thinking about is like 3/4"-1" and it goes into a spigot kind of underneat the carb. i wish i had a picture or a better description, but the truck is 40 miles away and i am sitting at my desk at work. my uncle says the motor is going to blow before i get it running right, but this is the same guy who has built a lot of cars, but only when they were in perfect condition when he got them...i'm trying to prove him wrong here! Thanks for all the help hainz

[banzai510(hainz)]

here my photo should be similar to this or some sort(L20s) have more stuff but still should be hooked up

see the hose going to the lower part of the intake(there is a PCV valve.)

 

most PCV can be cleaned and just is it wiggel back and forth.thats about it.

 

also the aircleaner deal you out on your valvecover spout. I would remove that and just route a hose down below the trans so it doesnt blow oil on the fire wall. or route it toward the ground somewhere. This is my sidedraft eguipt cars since I just open vent the crank case. (NO hose. No PCV valve)

 

On my 521 I route the valve cover spout to the lower part of my aircleaner. Weber has a L shaped tube that routes inside of the aircleaner to get burned up. You could try this

[hang_510]

there should be a pipe (likely the 3/4" - 1") from the block under the IN mani. a hose from there to the PCV valve, which is attached to the IN mani.

 

do a compression check to verify bad rings. low pressure? add oil into the cylinder-redo check. if it goes way up=bad ring(s)

[datsunaholic]

Blowby doesn't necessarily mean burning oil... the oil rings could be fine, but the compression rings bad. With a lot of blowby there won't be a lot of oil left on the walls to burn.

[Cruzn620]

hang, i know the pipe you are talking about now. I think i may know my problem. on my truck, the PO took off all the EGR stuff and sealed it up with God-knows-what. it looks like the stuff you use to seal up conduit. anyway, there are two spigots side by side. one was plugged off, and one went into the EGR stuff. i think in the 2 years i have been tinkering with this truck, that i may have the two reversed. from looking at hainz's pic, i think i might. i'll do a compression check on the truck. i did the easy old "thumb on the spark plug hole" and it seemed to be acceptable...but i'll get a real test if i can get some equipment borrowed for the weekend and post my findings. if i end up with low compression, i already have a spare sorted out to use while i rebuild the one that is in the truck. i wish you guys lived closer so i could pay ya'll back for all the help. thanks a ton

[datzenmike]

you running a PCV on the crank to the intake manifold???????

you know the hose the comes from the block to the lower part of the inatke under the carb. This can suck some of it up!!!!!!!!!!

 

Usually you have more pressure at idel then when going faster it will start sucking IN.

 

maybe you have worn rings!!!!!!Blowby

 

Isn't it the other way 'round Hainz? At idle the manifold vacuum is highest and the PCV easily collects any blow by, but as you rev under load, vacuum drops and if blow by is severe enough flow reverses out the breather on the valve cover?

 

As for blow by a severely damaged exhaust guide could let exhaust pressure up into the valve cover area yet you would still have good compression and not burn any oil. It's a stretch I know, Occam's razor... the simplest thing is probably the right thing.

[banzai510(hainz)]

Mike Im pretty sure

at idle it blows out at the crankcase(my sidedraft equip cars) with open vent

 

when I rev it up it starts to suck in(this is the air)

 

 

I dont know what the PCV is doing can only assume the pressure pos/neg is pulling it from whatever has the greast pull.

 

so if you have both the TOP valve cover vent routed to the carb(to get sucked in)

and have the lower crankcase vent to lower intake PCV hosed hooked up I think you got it covered.

 

in this link youll see a white 90 deg fitting . this will rout to the valve cover vent from the aircleaner.

 

You still might have excessive BLOWBY this what Im tell ing just helps from hidding the smell. If you ck later and lots of oil in carb then I say you need to ix the main proplem.

[datzenmike]

The open end attaches to the PCV valve on the intake.

 

 

http://i138.photobucket.com/albums/q251/datzenmike/L16PCVhosetoblocknonsmog.jpg[/img]"]

 

The open end should go here.

 

http://i138.photobucket.com/albums/q251/datzenmike/PCVtubevalve-1.jpg[/img]"]

[Cruzn620]

just an update, i hooked up all my vacuum lines today, and i think i have my PCV hose routed the right way. Mike, on that lower pic, on my truck, there are two spigots side by side. i have my PCV hose routed to the OUTSIDE (nearest to the fender) spigot, and then the other spigot blocked off. is this right or do i need to reverse that? i'm going to give her another whirl tomorrow if it warms up a bit. do you guys have any clue why my truck spins really fast when im trying to start it then "wham!" stops like a piston is stuck or something? it usually does that twice before it will hit and run. THANK YOU!!!!