signs of bad intake manifold gaskets

[etlsport]

just curious, i dont think ive seen this mentioned anywhere else, was using seafoam in the VX today to help cure an idle issue ive been having (when coming to a stop the vx tends to stutter, rpms drop momentarily then come back)

i noticed under the engine cover just above the fuel rail on both sides there are carbon buildups at that joint that look like they are coming from inside the engine.. but i dont have surging idle or most of the other symptoms, just that momentary drop in RPMs

i should probably take some photos but has anyone seen these buildups before?

it makes sense that it would the the intake manifold gaskets since to my knowledge they have never been replaced and im at 83k miles

[WormGod]

You can always zap those areas with some carb cleaner and see if it revs. If so, I am surprised you didnt throw a 171 before you actually had visible signs. :confused:

[etlsport]

ill try the carb cleaner at work tomorrow.. heres a pic of the area in question.. you can see where i rubbed my thumb, it came right off... but is that where the intake manifold gasket is? are those buildups an indication of a leak?

http://www.vehicross.info/gallery/data/500/medium/intake_manifold_004.jpg (http://www.vehicross.info/gallery/showphoto.php?photo=14929)

[Ldub]

ill try the carb cleaner at work tomorrow.. heres a pic of the area in question.. you can see where i rubbed my thumb, it came right off... but is that where the intake manifold gasket is? are those buildups an indication of a leak?

http://www.vehicross.info/gallery/data/500/medium/intake_manifold_004.jpg (http://www.vehicross.info/gallery/showphoto.php?photo=14929)

The area indicated is where the top & bottom halves of the "common chamber", or intake plenum seal together. (or not)

The intake gaskets are located at the very bottom of the common chamber, between the intake & the heads.

Check out some of the pics & descriptions in Wormgods S/C tutorial for clarification...:_wrench:

You can clearly see the intake ports in the heads in the first pic, this is where the intake gaskets reside.

http://www.vehicross.info/forums/showthread.php?t=11035&highlight=supercharger+101

[WormGod]

Ya, there are actually 3 gaskets that accompany the manifold. 2 lower and 1 full for the area you mention. I HIGHLY doubt that gasket has any issues. Just clean it off and go about your way. That buildup is gonna happen and isn't carbon, but a mixture of every single gunk and grime that engines accumulate, heh. You'll be aight. ;)

If it was the 2 lower, well, I would say that might be worth looking into. Those are a problem for ALL of us.

[WILLY]

I actually had a high pitch whistling and the rpms would go up and down and the motor would die when changing gears,so I replaced both upper and lower gaskets and it was fixed.

[blacksambo]

I actually had a high pitch whistling and the rpms would go up and down and the motor would die when changing gears,so I replaced both upper and lower gaskets and it was fixed.


Sounds like the good old 171 code. The original gaskets were torqued to 18lbs. Five pounds too much. They are made of brittle plastic and crack letting too much air in to the intake area. I know it's a pain but change the devils. Your idle will immediately behave properly.

[pbkid]

while we are talking about this part of the motor...:naughty:

you experienced guys-
im throwing a knock sensor code, ive had multiple people look at it to try to find the sensor...the consensus seems to be that it is under the intake manifold. did you guys find this sensor? is their any way to get to it without taking 1/2 of my VX apart???

[etlsport]

good to know, im just tryin to figure out this thing with my idle.. its not bad, never stalled or anything just kinda strange... it got better after seafoam and a tank full of fuel system treatment.. thinking spark plugs are next since mine have almost 84k on them anyway

[Y33TREKker]

while we are talking about this part of the motor...:naughty:

you experienced guys-
im throwing a knock sensor code, ive had multiple people look at it to try to find the sensor...the consensus seems to be that it is under the intake manifold. did you guys find this sensor? is their any way to get to it without taking 1/2 of my VX apart???
Unfortunately, your concensus is correct. It's under the common chamber of the intake mainfold.

[AndyC]

I have mine scheduled to go in for that same problem on Wednesday. My lower gasket is visibly cracked and I had the whistling too so I temporarily used gasket silicon to block the leaks.
I've waited to long to get it fixed but since it's under warranty I figured I'd better get it done soon.

Andy


Danbury Isuzu did the warranty work -

Fixed and covered by my original powertrain warranty - No charge :) Seems like everything is good.