plenum question
#1
01-23-2015, 10:41 AM
Join Date: Mar 2009
Location: Mt Airy NC
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plenum question
Hopefully in a month or so i will be getting a 94-01 truck. I looked at the 1st page about the plenum and will finish looking at them. My question(s) are is there any way i can look at it and see if been replaced without taking the intake off? If i drive a truck up and good size hill and the gasket is good it should have no problems going up the hill. If bad gasket then would have problems going up the hill? Besides doing a rebuild is this the most expensive repair on the motor? Any info will be helpful and thanks
#2
01-23-2015, 10:53 AM
It says it right there on the first page. You dont have to remove the intake.
How to check the plenum:
Get a good flashlight and, if possible, a dentist mirror. Remove airhat assembly. Open throttle plates and, using the flashlight and mirror, try to get a 360* view of the bottom of the intake manifold. If there is a considerable amount of oil pooling in there, either the plenum is gone, or the pcv is bad. Pcv would spew less oil than plenum.
For a more thorough inspection, remove the throttle body and perform the same check; it will be easier to get a good view with the TB off. Note that you will need a NEW tb gasket for re-installation if you go this route (~ $4).
Magnet-on-a-stick test:
This test is to determine if your plenum has already been replaced (by previous owner). You will need a telescopic magnet (available at most tools/parts suppliers). Remove airhat assembly. Open the throttle plates and probe the bottom of the manifold with the magnet. If it sticks on the bottom, the plenum plate is OEM, if not, it has been replaced with an aluminum plate (which means it has already been fixed).
Whether this is the most expensive repair depends on what else is wrong. Not expensive at all if you are just replacing the plenum plate and gasket. This info is readily available by searching.
How to check the plenum:
Get a good flashlight and, if possible, a dentist mirror. Remove airhat assembly. Open throttle plates and, using the flashlight and mirror, try to get a 360* view of the bottom of the intake manifold. If there is a considerable amount of oil pooling in there, either the plenum is gone, or the pcv is bad. Pcv would spew less oil than plenum.
For a more thorough inspection, remove the throttle body and perform the same check; it will be easier to get a good view with the TB off. Note that you will need a NEW tb gasket for re-installation if you go this route (~ $4).
Magnet-on-a-stick test:
This test is to determine if your plenum has already been replaced (by previous owner). You will need a telescopic magnet (available at most tools/parts suppliers). Remove airhat assembly. Open the throttle plates and probe the bottom of the manifold with the magnet. If it sticks on the bottom, the plenum plate is OEM, if not, it has been replaced with an aluminum plate (which means it has already been fixed).
Whether this is the most expensive repair depends on what else is wrong. Not expensive at all if you are just replacing the plenum plate and gasket. This info is readily available by searching.
Last edited by jkeaton; 01-23-2015 at 10:55 AM.