bad intake manifold gasket?

[fordkiller91]

What year and model number?

[mattjones]

the year is in my sig... 1999 and its a 1500 z71 all other mods are also listed in sig.

[bt02chevy]

Yes, it is a very good chance you have a bad intake gasket. I speak from experience when i say, its best to go to the dealer and
get GM intake gaskets. The sets you get at an auto parts store sometimes wont fix the problem... lol ask me how i know. they should be black and green in color. GM p/n 89060413.

Also be sure to replace the knock sensor wire harness when you do the sensors.

yes all of this could hurt your mileage as well.

And yes, there were 2 designs from GM. a orange set, and a new improved green set. Make sure you get the green ones. Also when replacing the
knock sensors, i like to put some RTV sealant around the boot above the sensor where they sit in the valley. keeps a little more moisture out
of them that way.

Good luck and feel free to ask any questions if you have any!!

[98silverbullet]

BT02CHEY hit the nail on the head.

btw check your fuel pressure before you change the gaskets.

[mattjones]

thanks guys! and ill defiantly be doing the rtv trick to avoid having to redo work lol from the homework i have done it seems like if i dont disconnect the coolant line running to the TB i wont have to worry about a mess with coolant is this correct? i feel like this is such a simple question but i like to know what im expecting before i do this people say it only takes 2-3 hours depending on how many cold ones you're knocking back is this about right?

[kerrige]

I bet less than 2 hours if you go quick. I have done it before, but until 90mins is within reach.

[bt02chevy]

Yes, thats exactly right.
I bypass that throttle body coolant line on all of mine, just to make it easier everytime i pull the throttle body off.
I dont believe there is any performance benefit from that, and i live in Texas, so i dont need it to warm anything up. I just
bypass it to be able to remove the throttle body alot quicker.

[98silverbullet]

thanks guys! and ill defiantly be doing the rtv trick to avoid having to redo work lol from the homework i have done it seems like if i dont disconnect the coolant line running to the TB i wont have to worry about a mess with coolant is this correct? i feel like this is such a simple question but i like to know what im expecting before i do this people say it only takes 2-3 hours depending on how many cold ones you're knocking back is this about right?

After time a bit over a hour is possible. Its a easy job.