intake gasket leak

[Billpinsc]

I noticed a smalll lesk in my intake gasket today. Any info about replacing it will be helpful. THANKS

[killian96ss]

What year S10 are you working on? Does it have a 6 cylinder or a 4 cylinder? We need more info in order to help you!

Steve

[HenryJ]

What year and are you still running Dex? I will assume that it is running Dex, and that it is an early model as well as a six cylinder crewcab since it is posted in the stock crewcab forum. The early engines received gaskets that may not be compatible with the OAT based coolant. OAT (Organic Acid Technology) aggressively attacks contaminants converting them chemically and leaving a black residue. Basically it alters the contaminant and neutralizes it. The problem is that it sees the gasket as a contaminant and attacks it. In this process the coolant eats away at the gaskets to the point of leakage.
I have not been able to figure out just when they changed the gasket material. I never have really worried about it since I went green very early.

Here are the procedures. I included the upper manifold replacement, as the regulator is another weak link and when you are in this deep it might be worth considering its replacement.

Intake Manifold Replacement - Upper
Removal Procedure

Important
The upper intake does not have to be removed to remove the lower intake manifold.

1. Disconnect the breather tube at the air cleaner outlet duct.
2. Remove the air cleaner outlet duct retaining wingnut.
3. Disconnect the IAT sensor harness connector.
4. Remove the air cleaner outlet duct from the throttle body.
5. Disconnect the accelerator cable from the throttle body.
6. Remove the accelerator cable from the accelerator control cable bracket.
7. Disconnect the cruise control cable, if equipped from the throttle shaft and the accelerator cable bracket.
8. Disconnect the vacuum hose from the intake manifold for the vacuum tank.
9. Remove the power brake booster vacuum hose.
10. Disconnect the following electrical connectors:
* The A/C compressor clutch
* The A/C compressor cutoff switch , if equipped
* The throttle position (TP) sensor
* The idle air control (IAC) motor
11. Disconnect the following electrical connectors:
* The fuel meter body assembly
* The manifold absolute pressure (MAP) sensor
* The EVAP canister purge solenoid valve
12. Remove the engine wire harness clip from the accelerator cable bracket.
13. Move the engine wiring harness aside.
14. Remove the accelerator cable bracket from the throttle body and the intake manifold.
15. Remove the accelerator and cruise control cable bracket from the throttle body.
Leave the accelerator and cruise control cables on the bracket.
16. Remove the PCV valve hose assembly from the intake manifold and the valve rocker arm cover.
17. Remove the bracket for the engine wiring harness from the intake manifold stud.
18. Remove the fuel lines from the fuel meter body assembly.
19. Remove the EVAP canister purge solenoid valve.
20. Remove the studs for the upper intake manifold.
21. Remove the upper intake manifold.
22. Remove the upper intake manifold gasket from the groove.
23. Discard the gasket.
24. Remove the seal from the fuel meter body assembly.
25. Discard the seal.

Important
Do not immerse the assembled upper intake manifold in cleaning solvent.

26. Clean all sealing surfaces and the inside of the upper intake manifold with a shop towel and cleaning solvent.
27. Inspect the upper intake manifold for the following:
* Cracks or other damage to the exterior
* Cracking or damage to the gasket grooves
* Loose or damaged bolt hole thread inserts
* Damage to the throttle body mounting surface
28. If replacing the upper intake manifold, turn and remove the power brake booster vacuum tube fitting from the upper intake manifold.
29. Remove and discard the seal.
30. If replacing the upper intake manifold, turn and remove the PCV valve cover from the upper intake manifold.
31. Remove and discard the seal.
32. Remove the throttle body if replacing the upper intake manifold.
33. Remove the MAP sensor if replacing the upper intake manifold.

Installation Procedure

1. Install the throttle body, if removed.
2. Install the MAP sensor, if removed.
3. Install the PCV valve cover, if removed, using the following procedure:
1. Install a NEW seal (O-ring) on the PCV valve cover.
2. Lubricate the seal with clean engine oil.
3. Install the PCV valve cover in the upper intake manifold.
4. Turn and lock the PCV valve cover in position.
4. Install the power brake booster vacuum tube fitting, if removed, using the following procedure:
1. Install a NEW seal (O-ring) on the power brake booster vacuum tube fitting.
2. Lubricate the seal with clean engine oil.
3. Install the power brake booster vacuum tube fitting in the upper intake manifold.
4. Turn and lock the power brake booster vacuum tube fitting in position.
5. Install a NEW seal on the fuel meter body assembly.
6. Lubricate the seal with clean engine oil.
7. Install a NEW upper intake manifold to lower intake manifold gasket in the groove of the upper intake manifold.
8. Install the upper intake manifold onto the lower intake manifold.
9. If reusing the fasteners, apply threadlock GM P/N 12345382 or equivalent to the threads of the upper intake manifold attaching bolts.
10. Install the upper intake manifold attaching studs.
1. Tighten the upper intake manifold attaching studs on the first pass to 5 N·m (44 lb in).
2. Tighten the upper intake manifold attaching studs on the final pass to 9 N·m (80 lb in).
11. Install the fuel lines to the fuel meter body assembly.
12. Install the EVAP canister purge solenoid valve.
13. Install the bracket for the engine wiring harness on the lower intake manifold stud.
14. Install the engine wiring harness bracket nut.
Tighten the engine wiring harness bracket nut to 12 N·m (106 lb in).
15. Install the accelerator and cruise control cable bracket to the throttle body.
16. Install the accelerator and cruise control cable bracket nuts.
Tighten the accelerator and cruise control cable bracket nuts to 9 N·m (80 lb in).
17. Install the accelerator control cable bracket to the throttle body and the intake manifold.
Tighten the accelerator control cable bracket studs and nuts to 12 N·m (106 lb in).
18. Connect the PCV valve hose assembly to the intake manifold and the valve rocker arm cover.
19. Position the engine wiring harness.
20. Install the wire harness clip to the accelerator cable bracket.
21. Connect the following electrical connectors:
* The fuel meter body assembly (1)
* The manifold absolute pressure (MAP) sensor (3)
* The EVAP canister purge solenoid valve (2)
22. Connect the following electrical connectors:
* The A/C compressor clutch (1)
* The A/C compressor cutoff switch (5), if equipped
* The throttle position (TP) sensor (2)
* The idle air control (IAC) motor (3)
23. Connect the vacuum hose from the vacuum tank to the intake manifold.
24. Install the power brake booster vacuum hose to the intake manifold.
25. Install the cruise control cable, if equipped to the throttle shaft and the bracket.
26. Install the accelerator cable onto the throttle body.
27. Wrap the cable in between the finger of the hook tab and the pulley wall. Make sure that the cable is fully seated in the pulley groove. The cable must not lie outside of the hook tab.
28. Install the accelerator cable to the accelerator cable control bracket.

Notice
* Handle the MAF sensor carefully.
* Do not drop the MAF sensor in order to prevent damage to the MAF sensor.
* Do not damage the screen located on the air inlet end of the MAF.
* Do not touch the sensing elements.
* Do not allow solvents and lubricants to come in contact with the sensing elements.
* Use a small amount of a soap based solution in order to aid in the installation.

29. Install air cleaner outlet duct to throttle body.
30. Install air cleaner outlet duct to MAF sensor.
Tighten the hose clamp to 4 N·m (32 lb in).
31. Connect the IAT sensor harness connector.
32. Install the air cleaner outlet duct retaining wingnut.
Tighten the wingnut to 2 N·m (18 lb in).
33. Connect the breather tube to the air cleaner outlet duct.
Intake Manifold Replacement Lower

Removal Procedure

1. Disconnect the battery negative cable.
2. Remove the air cleaner outlet duct from the throttle body.
3. Remove the air cleaner assembly.
4. Drain the cooling system.
5. Remove the radiator inlet hose at the water outlet.
6. Remove the heater hose from the intake manifold.
7. Remove the water pump inlet hose form the intake manifold.
8. Disconnect the accelerator control cable from the throttle shaft and the accelerator cable bracket.
9. Disconnect the cruise control cable, if equipped from the throttle shaft and the accelerator cable bracket.
10. Remove the accelerator cable bracket from the throttle body and the intake manifold.
11. Remove the accelerator and the cruise control cable bracket from the throttle bracket.
Leave the accelerator and cruise control cables and the wiring harness on the bracket.
12. Remove the following electrical connectors:
* The fuel meter body assembly
* The EVAP canister purge solenoid valve
* The idle air control (IAC) motor
* The throttle position (TP) sensor
* The A/C compressor high pressure switch, if equipped
* The A/C clutch switch, if equipped
* The exhaust gas recirculation (EGR) valve
* The engine coolant temperature (ECT) sensor
* The ignition coil
* The ignition control module (ICM)
13. Remove the engine wiring harness from the retainers.
14. Move the engine wiring harness aside.
15. Remove the distributor.
16. Remove the exhaust gas recirculation (EGR) valve inlet pipe from the intake and exhaust manifold.
17. Disconnect the fuel supply and return pipes at the rear of the intake manifold.
18. Disconnect the vacuum hose from the intake manifold, if equipped with A/C.
19. Disconnect the vacuum brake booster hose
20. Disconnect the PCV hose assembly from the intake manifold and the valve rocker arm cover.
21. Remove the EVAP canister purge solenoid valve.
22. Perform the following in order to remove the left front bolt for the intake manifold:
1. Remove the drive belt.
2. Loosen the nut for the power steering pump rear bracket at the side of the engine.
3. Remove the secondary air injection (AIR) reactor pipe bracket nut from the power steering pump rear bracket front stud, if equipped.
4. Remove the nut for the power steering pump rear bracket at the front of the engine.
5. Remove the bolts and the nut for the power steering pump mounting bracket.
6. Leave the A/C compressor, if equipped, and the power steering pump on the power steering pump mounting bracket.
7. Slide the power steering pump bracket forward to access the bolt at the front of the intake manifold.
23. Remove the lower intake manifold.
24. Clean all sealing surfaces.

Installation Procedure

1. Install the lower intake manifold.
Notice
Proper lower intake manifold fastener tightening sequence and torque is critical. Always follow the tightening sequence, and torque the intake manifold bolts using the 3 step method. Failing to do so may distort the crankshaft bearing bore alignment and cause damage to the crankshaft bearings.


Tighten lower intake manifold bolts first pass to 27 in lb, second pass 106 in lb, final pass 11 lb ft.

2. Position the power steering pump mounting bracket.
3. Loosely install the power steering pump mounting bracket bolts and nuts.
4. Install the nut for the power steering pump rear bracket at the front of the engine.
Tighten the power steering pump mounting bracket bolts and the power steering pump rear bracket nuts to 41 N·m (30 lb ft).
5. Install the AIR reactor pipe bracket nut to the power steering pump rear bracket front stud, if equipped.
Tighten the AIR reactor pipe bracket nut to 41 N·m (30 lb ft).
6. Install the drive belt.
7. Install the EVAP canister purge solenoid valve.
8. Connect the vacuum brake booster hose.
9. Connect the vacuum hose to the intake manifold, if equipped with A/C.
10. Install the PCV hose assembly to the intake manifold and the valve rocker arm cover.
11. Install the fuel supply and return pipes to the rear of the intake manifold.
12. Install the exhaust gas recirculation (EGR) valve inlet pipe to the intake manifold and the exhaust manifold.
1. Tighten the EGR valve inlet pipe intake manifold nut to 25 N·m (18 lb ft).
2. Tighten the EGR valve inlet pipe exhaust manifold nut to 30 N·m (22 lb ft).
3. Tighten the EGR valve inlet pipe clamp bolt to 25 N·m (18 lb ft).

Important
In order to install the distributor for the correct engine timing, position the engine to number one cylinder top dead center.

13. Remove the spark plug for number one cylinder.
14. Rotate the crankshaft until number one cylinder is in the compression stroke.
15. Align the two reference marks on the crankshaft balancer (1) and (4) with the two alignment marks (2) and (3) on the front cover.
16. Install the spark plug.
17. Install the distributor.
18. Position the engine wiring harness.
19. Install the engine wiring harness in the retainers.
20. Install the following electrical connectors:
* The fuel meter body assembly
* The EVAP canister purge solenoid valve
* The idle air control (IAC) motor
* The throttle position (TP) sensor
* The A/C compressor high pressure switch, if equipped.
* The A/C compressor clutch switch, if equipped.
* The exhaust gas recirculation (EGR) valve
* The engine coolant temperature (ECT) sensor
* The ignition coil
* The ignition control module (ICM)
21. Install the accelerator cable and cruise control bracket to the throttle body.
Tighten the accelerator cable and cruise control bracket nuts to 9 N·m (80 lb in).
22. Install the accelerator cable bracket to the intake manifold and the throttle body.
Tighten the accelerator cable bracket studs and nuts to 12 N·m (106 lb in).
23. Install the accelerator control cable to the bracket and the throttle shaft.
24. Install the cruise control cable, if equipped to the bracket and the throttle shaft.
25. Install the water pump inlet hose to the intake manifold.
26. Install the heater hose to the intake manifold.
27. Install the radiator inlet hose to the water outlet.
28. Fill the cooling system.
29. Install the air cleaner assembly.
30. Install the air cleaner outlet duct to the throttle body.
31. Connect the battery negative cable.

[Billpinsc]

Thanks i have a 2001 CC . I've only had the truck about 4 months.the Dex that was in it was the original i'm sure. About 3 weeks ago i removed the Dex. that stuff was nasty, I had to flush system and remove the resevoir and clean it as well (the resevoir was full of brown sludge) I went back with prestone green. Right now the leak is very small, but I know it will get worse so i'll let you know how the replacement goes.

[killian96ss]

Wow, that sounds like a lot of work for just replacing an intake gasket. I'm sure some of those steps are unnecessary.

Steve

[killian96ss]

Billpinsc, what kind of mileage does your CC have? I would really like to know why GM is still using Dex-Crap when it has been proven to cause so many problems.

Steve

[Billpinsc]

Steve the crew has 95,000. All those steps scared me to, but i guess it is better to safe.

[HenryJ]

Wow, that sounds like a lot of work for just replacing an intake gasket. I'm sure some of those steps are unnecessary.

You probably take some steps for granted.
It is a fair representation of what needs to be done. The picture of the bolt tightening sequence is not there, but we can find a way to include that should someone actually decide to undertake this project.

There are quite a few that do take on projects like this, but usually those have a book, or get one before diving in. This forum can be of assistance , but is not really a good substitute for a manual that you can put your greasy fingers on when you need it.

[Billpinsc]

Is there a particullar manuel i sould get.

[HenryJ]

How involved in repairs do you intend to get?
I like Haynes manuals for a specifications quick check. Torques and sequences are easy to find. Chilton's will work to , but frustrates me when trying to find anything.

The best is the factory manual. Helm Publishing (Helminc.com?) is the source. There are a couple very good threads on this subject.

[killian96ss]

Sometimes when you jump into a big project it is a good idea to label hoses, put parts into labeled bags and take pictures to use as a reference when putting it all back together. It may seem like a lot of extra work, but when you go to reassemble everything the whole process will go a lot smoother.

One of my friends just did a top end rebuild on the V-6 in his 4 Runner and if he didn't label everything and take pictures it would have taken him forever to put it all back together.

Steve

[Billpinsc]

I'll take a look at the factory, but i will proberly go with the Haynes

[Billpinsc]

I just checked Helmnic.com. Now i'm sure it will be Haynes the Helms price was a little too much for me!

[F9K9]

Wow, that sounds like a lot of work for just replacing an intake gasket. I'm sure some of those steps are unnecessary.

Steve

I remember the same manual requiring that the front fenders being removed to take off the ZR5 flares. A few sheet metal screws accessed fron the wheel well was all that was holding them on

[HenryJ]

I'll take a look at the factory, but i will proberly go with the Haynes

Open it up and make sure it has the information that YOU are seeking before you buy. Some places have a few different brands of manuals to look at. Where Haynes might be my preference, someone else may do better with Chiltons, or another publisher.
Open it up and see if the directions make sense, clear pictures or diagrams, etc.