Pulling vacuum on intake to test for leaks?

O

outlander

NAXJA Forum User

Location

Columbus,Ohio

• Feb 20, 2016

• #1

I suspect i have a very slight intake manifold gasket leak but before i pull the manifold to replace gasket i want to be sure.

My idea is to plug the vacuum niples on the intake,block off the throttle body,remove the rockers so all intake valves will be closed at the same time and pull a vacuum on the manifold.

Sound plan?

 

old_man

NAXJA Forum User

Location

Loveland, Colorado

• Feb 20, 2016

• #2

No. Sorry, there will always be at least one intake valve open.

 

O

Overland

NAXJA Forum User

Location

The Chihuahuan Desert

• Feb 20, 2016

• #3

Just spray around the manifolds with carb cleaner while it's running. You'll find the leaks.

 

O

outlander

NAXJA Forum User

Location

Columbus,Ohio

• Feb 23, 2016

• #4

I did that....no change in idle.

Old man;
I have to disagree with you....with rockers unbolted all valves are closed.(im sure you already know that so i assume you missed it in the original post)

 

O

outlander

NAXJA Forum User

Location

Columbus,Ohio

• Feb 23, 2016

• #5

Im shelfing the idea for now...if its leaking its very minor.(i can hear it sounds like someone inhaling on a harmonica on a real low note)

Will retorque manifold bolts after another heat cycle.

 

M

md21722

NAXJA Forum User

Location

TN

• Feb 23, 2016

• #6

Spraying with carb cleaner or using propane around the intake ports, injectors etc is a better way to isolate vacuum leaks.

 

old_man

NAXJA Forum User

Location

Loveland, Colorado

• Feb 23, 2016

• #7

outlander said:

Old man;
I have to disagree with you....with rockers unbolted all valves are closed.(im sure you already know that so i assume you missed it in the original post)

Click to expand...

You are right, I missed that. But all that messy work :nono:

 

R

Raine883

NAXJA Forum User

Location

East Texas

• Feb 29, 2016

• #8

I've always used the ol cigarette in a bottle trick to find vacuum leaks