Written by kawamatt2
Well after 100,000 miles and seeing some wierd antifreeze like build-up on the inside of my oil fill tube i figured it was about time to replace the notoriously leak prone vortec 350 intake gaskets. To start with, this has been by far the most involved piece of maintenance i have done to this truck. I had never done anything this involved either. So basically short of what little info i could find on the internet i was flying blind. I will add though that my father helped me out through the whole process and he has worked on an engine or two.
So, to begin. As i have found through some interweb research intake gasket failure is a common problem for the 88'-98' style chevy 350. Characteristics of a leaky intake gasket are usually a milky oil, falling coolant level, white smoke, or in my case a redish build-up inside the oil fill tube. To replace the intake gaskets the concensus is to use Felpro gasket set MS98000T. This set comes with the two instake gaskets, upper intake plenum gasket, throttle body gasket, fuel injector assembly gasket, fuel line o-rings where they attach to the manifold, valve cover gasket, and what i think was a distributor gasket. There may have been other parts included but i can't recall because i probably didn't use them. I purchased my gasket set from rockauto.com and it was about $65 shipped. While i had it apart i decided to go ahead and replace the thermostat, cap, rotor, and radiator cap. So once you have all this you are ready to tackle this job.
First off, don't get too overwhelmed with the mess of wires that greet you after you pop the hood.
What i chose to do first was to take off the upper and lower fan shrouds and drain the radiator. Have a couple of buckets or one big one handy because the **** will drain from two or three different spots in front the drivers tire.
Next, take off the air filter assembly and tube to the throttle body.
Go ahead and remove the upper radiator hose and the thermo and thermo elbow. I also unscrewed the egr tube at this point.
That done, i chose to unbolt the throttle and cruise cables. There is a bracket on the a/c compressor and the upper intake.
Now you can start to unplug all the sensors and stuff related to the intake. It would probably be a good idea to take pictures of each connector and where it came from but i'm fairly certain no two connectors will interchange. I only took so many pics to help remember the routing of all the wires.
It is at this point that i would like to address the issue that seems to be so common with the heater hose quick disconnect. Below is a picture of the quick disconnect fitting.
As you can see there is a plastic liner inside the metal fitting. This plastic degrades over time and pulling out the hose often times shatters or in some way degrades it to the point that it will leak upon re-assembly. The problem lies in the removal of the fitting from the intake. The fitting has what looks like either thread lock or sealant on its threads into the intake and is notorious for breaking the threads off inside the intake requiring the user to drill out the remaining fitting and retapping to .5" pipe tap. I foolishly rushed the tear down process before thinking of my options and went ahead and pulled the hose out of the fitting. I had the choice when re-assembling to try and put the hose back in the fitting hoping it wouldn't leak and try and remove the fitting from the intake. I was almost positive that i would break the fitting and this wasn't an option. My truck is my only means of transportation and it had to be able to get me 400 miles back from my parents house to where i live 2 days later. SO, with all that said, if i were to do this again in the same situation where i couldn't afford any down-time for broken parts other than what is required for intake replacement i would leave the fitting in the intake and cut the hose about a foot back from the intake.
Once the hose is cut you can remove the intake leaving the quick disconnect and section of hose still attached. When re-assembling i would use one of these to reconnect the section of cut hose.
I actually already had this intalled in that hose but as i said earlier i rushed dis-assembly and never even thought to remove the hose from one of the ends and leave the quick disconnect alone as opposed to removing the quick disconnect from the intake. So this is my recommendation for dealing with the GM quick disconnect.
Now moving on, i went ahead and unplugged the three plugs from the a/c compressor and unbolted it. You can then just lay it back onto the passenger side inner fender like so.
At this point i marked the plug wires and removed them from the cap and removed the cap from the distibutor.
I then continued to unplug wiring harness **** from the intake and remove the brackets that hold the wiring harness up off the intake. I also remove this ground wire from the front of the block on the passenger side so i could get a little more slack in the harness for when i would need to tie it up out of the way.
Go ahead and unplug the big connector for the fuel injector pod and protect it somehow. I used a ziplock back to put the connector in and stuffed a rag down into the pod. You can also disconnect the fuel line at the back of the intake. (Note: It helps to get up in the bay and sit on the core support to reach some things.)
Well after 100,000 miles and seeing some wierd antifreeze like build-up on the inside of my oil fill tube i figured it was about time to replace the notoriously leak prone vortec 350 intake gaskets. To start with, this has been by far the most involved piece of maintenance i have done to this truck. I had never done anything this involved either. So basically short of what little info i could find on the internet i was flying blind. I will add though that my father helped me out through the whole process and he has worked on an engine or two.
So, to begin. As i have found through some interweb research intake gasket failure is a common problem for the 88'-98' style chevy 350. Characteristics of a leaky intake gasket are usually a milky oil, falling coolant level, white smoke, or in my case a redish build-up inside the oil fill tube. To replace the intake gaskets the concensus is to use Felpro gasket set MS98000T. This set comes with the two instake gaskets, upper intake plenum gasket, throttle body gasket, fuel injector assembly gasket, fuel line o-rings where they attach to the manifold, valve cover gasket, and what i think was a distributor gasket. There may have been other parts included but i can't recall because i probably didn't use them. I purchased my gasket set from rockauto.com and it was about $65 shipped. While i had it apart i decided to go ahead and replace the thermostat, cap, rotor, and radiator cap. So once you have all this you are ready to tackle this job.
First off, don't get too overwhelmed with the mess of wires that greet you after you pop the hood.
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What i chose to do first was to take off the upper and lower fan shrouds and drain the radiator. Have a couple of buckets or one big one handy because the **** will drain from two or three different spots in front the drivers tire.
Next, take off the air filter assembly and tube to the throttle body.
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach
Go ahead and remove the upper radiator hose and the thermo and thermo elbow. I also unscrewed the egr tube at this point.
That done, i chose to unbolt the throttle and cruise cables. There is a bracket on the a/c compressor and the upper intake.
You must be registered for see images attach
Now you can start to unplug all the sensors and stuff related to the intake. It would probably be a good idea to take pictures of each connector and where it came from but i'm fairly certain no two connectors will interchange. I only took so many pics to help remember the routing of all the wires.
You must be registered for see images attach
You must be registered for see images attach
It is at this point that i would like to address the issue that seems to be so common with the heater hose quick disconnect. Below is a picture of the quick disconnect fitting.
You must be registered for see images attach
As you can see there is a plastic liner inside the metal fitting. This plastic degrades over time and pulling out the hose often times shatters or in some way degrades it to the point that it will leak upon re-assembly. The problem lies in the removal of the fitting from the intake. The fitting has what looks like either thread lock or sealant on its threads into the intake and is notorious for breaking the threads off inside the intake requiring the user to drill out the remaining fitting and retapping to .5" pipe tap. I foolishly rushed the tear down process before thinking of my options and went ahead and pulled the hose out of the fitting. I had the choice when re-assembling to try and put the hose back in the fitting hoping it wouldn't leak and try and remove the fitting from the intake. I was almost positive that i would break the fitting and this wasn't an option. My truck is my only means of transportation and it had to be able to get me 400 miles back from my parents house to where i live 2 days later. SO, with all that said, if i were to do this again in the same situation where i couldn't afford any down-time for broken parts other than what is required for intake replacement i would leave the fitting in the intake and cut the hose about a foot back from the intake.
Once the hose is cut you can remove the intake leaving the quick disconnect and section of hose still attached. When re-assembling i would use one of these to reconnect the section of cut hose.
You must be registered for see images
I actually already had this intalled in that hose but as i said earlier i rushed dis-assembly and never even thought to remove the hose from one of the ends and leave the quick disconnect alone as opposed to removing the quick disconnect from the intake. So this is my recommendation for dealing with the GM quick disconnect.
Now moving on, i went ahead and unplugged the three plugs from the a/c compressor and unbolted it. You can then just lay it back onto the passenger side inner fender like so.
You must be registered for see images attach
You must be registered for see images attach
At this point i marked the plug wires and removed them from the cap and removed the cap from the distibutor.
You must be registered for see images attach
I then continued to unplug wiring harness **** from the intake and remove the brackets that hold the wiring harness up off the intake. I also remove this ground wire from the front of the block on the passenger side so i could get a little more slack in the harness for when i would need to tie it up out of the way.
You must be registered for see images attach
Go ahead and unplug the big connector for the fuel injector pod and protect it somehow. I used a ziplock back to put the connector in and stuffed a rag down into the pod. You can also disconnect the fuel line at the back of the intake. (Note: It helps to get up in the bay and sit on the core support to reach some things.)
You must be registered for see images attach
You must be registered for see images attach
You must be registered for see images attach