End-all Be-all plenum thread
Legend
Joined: Jun 2009
Posts: 8,025
Likes: 72
From: orangeville ontario
this just popped up on another forum and i thought it was some good plenum info. how to test if your plenum is blown
Yes there is a way to test. TSB instructs you to use a vacuum gauge on pcv breather line. A normal engine has positive crankcase pressure or blow by and will build pressure in the crankcase, which reads on the gauge. If it builds positive pressure at all, stop the test, it passed. If you don't stop the test by 3 or 4psi you will probably blow out the dipstick, oil pan gasket, or valve cover gasket.
An intake plenum leak will create a suction on the crankcase, and it will show up as vacuum.
The shadytree method is to just look for oil down the throttlebody. That works somewhat in "theory", but ends up causing owners to pull an intake they didn't necessarily need to. Often regular blowby pcv oil pools are confused for valley pan.
It is justifiable to pull it anyways if the heavy duty valley pan is to be installed, but not worth it if the crappy stock style gasket is replaced and tin cover reused. The cover itself is often the problem.
An intake plenum leak will create a suction on the crankcase, and it will show up as vacuum.
The shadytree method is to just look for oil down the throttlebody. That works somewhat in "theory", but ends up causing owners to pull an intake they didn't necessarily need to. Often regular blowby pcv oil pools are confused for valley pan.
It is justifiable to pull it anyways if the heavy duty valley pan is to be installed, but not worth it if the crappy stock style gasket is replaced and tin cover reused. The cover itself is often the problem.
Captain
Joined: Jun 2012
Posts: 683
Likes: 1
From: East Coast
yeah so they hold them in position..was wondering how that worked out...as for the rtv, does it go under the cross over gasket ends?
Captain
Joined: Jun 2012
Posts: 683
Likes: 1
From: East Coast
Just got back from the auto part store. Read the back of the package and it states 24hrs for full cure. I ordered mine online and they put the shipping sticker on the back of the rtv package (that's why I didn't know..fyi)...but thanks...I guess I'm going to hit the four corners BEFORE I put the cross overs on...
Record Breaker
Joined: Feb 2009
Posts: 1,140
Likes: 3
From: Fredericksburg, VA
you could always do both sides...that wont hurt it any. btw, got my intake manifold today, and the reason i ordered this one from ebay is because........it doesnt have a divider! bwahahaha! call me a lazy bastard, but i dont have to do THAT mod now lol
EDIT: got one question. theres a metal bracket with three bolts in the lifter valley that looks like its holding down the lifter sleeves? just wondering if its safe to take that off so i can clean under it, and if it is, what the torque of those 3 bolts are. thanks!
EDIT: got one question. theres a metal bracket with three bolts in the lifter valley that looks like its holding down the lifter sleeves? just wondering if its safe to take that off so i can clean under it, and if it is, what the torque of those 3 bolts are. thanks!
Captain
Joined: Jun 2012
Posts: 683
Likes: 1
From: East Coast
you could always do both sides...that wont hurt it any. btw, got my intake manifold today, and the reason i ordered this one from ebay is because........it doesnt have a divider! bwahahaha! call me a lazy bastard, but i dont have to do THAT mod now lol
EDIT: got one question. theres a metal bracket with three bolts in the lifter valley that looks like its holding down the lifter sleeves? just wondering if its safe to take that off so i can clean under it, and if it is, what the torque of those 3 bolts are. thanks!
EDIT: got one question. theres a metal bracket with three bolts in the lifter valley that looks like its holding down the lifter sleeves? just wondering if its safe to take that off so i can clean under it, and if it is, what the torque of those 3 bolts are. thanks!
Record Breaker
Joined: Feb 2009
Posts: 1,140
Likes: 3
From: Fredericksburg, VA
yep thats the one i'm talking about lol. has 3 bolts holding it in the valley. if its not a good idea to take it out, then i wont. i'm just being a picky, i like my stuff clean and i can see that its still got gunk under there that i can't get at with the vacuum lol
Captain
Joined: Jun 2012
Posts: 683
Likes: 1
From: East Coast
TIP: Since you should remove your throttle body when doing the plenum job, ya mine as well do it right. Use 'throttle body/carb' cleaner' (remember some tb have a special factory coating which can be damaged if you use something else to clean it. Protect the sensors! Get a handful of q-tips and go to town. Remove & carefully clean the IAC..If you can afford it, replace it ($35-45) I spent $2.50 on the can of cleaner..
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