Changed the thermostat and upper and lower intake gaskets, seal for fuel line feed, and had enging and coolant flushed, it's still overheating and makes something of a squealing sound... Don't know what else it could be...
Yeah squealing would probably be a bad water pump bearing. Also when it starts to overheat do you hear sort of a "popping" or thumping noise from the radiator? If so then your radiator is clogged, but since you just had it flushed it probably isn't. More than likely your waterpump. I know what you're going through. GM's cooling systems aren't that great.
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Yes there are cooling system hoses under the intake, here are instructions to remove the intake.
Remove the Intake Manifold
1Drain the cooling system and relieve the pressure in the fuel system. Disconnect the negative battery cable, the air intake duct, the IAC valve connectors, the throttle position sensor and switch connectors, and the EGR solenoid valve.
2Pull the EVAP canister vacuum and purge hoses, the vacuum hoses from the EVAP, the brake cylinder, pressure regulator and EGR tube. Tag and disconnect the spark plug wires. Remove the distributor cap.
3. Take out the three left bank injector connectors, the thermal transmitter, the ground harness, breather pipe and the upper manifold. Disconnect the fuel feed and return lines and plug them with golf tees to prevent fuel spillage.
4Locate the right injector harness connectors and disconnect them as well as the fuel rail and injectors. Remove the coolant temperature switch harness connector and the water hose from the thermostat.
5Loose the bolts on the lower manifold in sequence. Remove the bolts and left the intake manifold from the engine. Remove the gasket and discard it.
6Clean the mating surfaces by scraping the old gasket material and carbon deposits. Clean the surfaces with solvent and inspect them for damage.
Install the Intake Manifold
7Put a new gasket in place and install the lower intake manifold to the engine. Tighten the bolts in sequence as follows: first pass-35 inch pounds; second pass-78 inch pounds and third pass 70 to 84 inch pounds.
8Connect the ECT sensor connector, the fuel supply manifold and the right bank injector connectors. Connect the fuel lines and then install the upper intake manifold. Put the breather pipe in position.
9Install the intake manifold ground cable, the thermal transmitter, the left bank injector connectors and the distributor. Reconnect the spark plug wires.
10Continue reconnecting all the components, reversing the order in which they were removed. Connect the negative battery cable to the terminal. Refill the cooling system with the appropriate coolant.
11Start the engine. Check for fuel or vacuum leaks.
Disconnect the negative battery cable. Place a clean drain pan under the radiator, open the drain **** and drain the cooling system.
Remove the air cleaner assembly and the fuel injector sight shield.
Disconnect the cables from the throttle body and mount bracket.
Remove the coolant recovery reservoir.
Remove the inner fender electrical cover on the right side.
Remove the right rear crossover pipe heat shield.
Disconnect the fuel lines from the fuel rail and from the cable bracket.
Remove the alternator and brace.
Remove the throttle body cable mounting bracket with the vacuum lines and disconnect the vacuum lines.
Tag and detach the electrical connections at the throttle body and both banks of fuel injectors.
Disconnect the vacuum hoses from the canister purge solenoid valve and transaxle module and intake connection.
Unbolt the power steering pump and move forward. DO NOT disconnect the fluid lines.
Tag and disconnect the spark plug wires position lay aside.
Disconnect the coolant bypass hose from the intake manifold.
Remove the solenoid valve mounting bracket and power steering support brace from the intake manifold.
Disconnect the heater pipes from the intake and front cover.
Remove the alternator support brace from the intake.
Disconnect the upper radiator hose from the housing.
Remove the thermostat housing and thermostat from the intake.
Detach the electrical connector from the temperature sensor and sensor switch.
Unfasten the intake manifold bolts, then remove the manifold as an assembly. Remove and discard the gaskets.
If separating the upper manifold from the lower, proceed as follows:
Remove the fuel rail and fuel injectors.
Detach the coolant sensor switch.
Remove the manifold end cap cover.
Remove the upper intake manifold and throttle body assembly from the lower manifold. Remove and discard the gaskets.
Thoroughly clean all gasket mating surfaces.
If replacing the upper manifold, proceed as follows:
Apply a 1⁄16 in. bead of Loctite® Instant Gasket Eliminator 51845 or equivalent to the lower manifold mating surface. Make sure to circle all bolt holes.
Carefully lower the upper manifold and throttle body assembly onto the lower manifold.
Tighten the upper manifold retaining bolts to 19 ft. lbs. (26 Nm).
Install the manifold end cap cover and the coolant sensor switch.
Install the fuel injectors and rail to the manifold assembly.
Clean the mating surfaces and install the intake manifold gaskets and seals. Apply sealer to the ends of the of the intake manifold seals.
Position the intake manifold and apply a suitable thread lock compound to the bolt threads. Tighten the retaining bolts to 88 inch lbs. (10 Nm), twice, in the sequence shown in the accompanying figure.
Attach the electrical connector to the temperature sensor and sensor switch.
Install the thermostat housing and thermostat with a new gasket.
Connect the alternator support brace to the intake.
Install the solenoid valve mounting bracket and power steering support brace to the intake manifold.
Connect the heater pipes to the intake and front cover.
Attach the coolant bypass hose to the intake manifold.
Install the power steering pump support bracket and tighten to 37 ft. lbs. (50 Nm).
Install the spark plug wires on both sides.
Install the belt tensioner pulley and tighten to 33 ft. lbs. (45 Nm).
Install the power steering pump.
Connect the vacuum hoses to the canister purge solenoid valve and transaxle module and intake connection.
Attach the electrical connections at the throttle body and both banks of fuel injectors.
Install the alternator and brace.
Connect the throttle body cable mounting bracket with the vacuum lines.
Install the right rear crossover pipe heat shield.
Install the cables to the throttle body.
Connect the fuel lines to the fuel rail and mount bracket.
Install the inner fender electrical cover on the right side.
Install the coolant recovery reservoir and upper radiator hose. Fill the cooling system.
Install the air cleaner assembly and the fuel injector sight shield.
Ha, you tried to fool me with the bit about a 3.5 L motor--I could find that one...here is the complete procedure from AutoZone.com:
Clean the gasket mounting surfaces. Be sure to inspect the manifold for warpage and/or cracks. If necessary, replace it.
Position the gaskets on the cylinder head with the port blocking plates to the rear and the This Side Up stamps facing upward. Then apply a 3 / 16 in. (5mm) bead of RTV sealant on the front and rear of the engine block at the block-to-manifold mating surface. Extend the bead 1 / 2 in. (13mm) up each cylinder head to seal and retain the gaskets.
Install the lower intake manifold. Tighten the bolts in sequence and in 3 steps, as follows:
Step 1: 26 inch lbs. (3 Nm).
Step 2: 106 inch lbs. (12 Nm).
Step 3: 133 inch. lbs. (15 Nm).
Install or connect the following:
Power steering pumpAlternator bracket bolt near the thermostat housingWiring harness to the lower manifold components, including the injector, EGR valve and ECT sensorAir conditioning compressor bracket-to-the lower intake manifold pencil braces
Install transmission oil dipstick tube, if necessary.
Fuel supply and return lines to the rear of the lower intake
Temporarily reattach the negative battery cable, then pressurize the fuel system (by cycling the ignition without starting the engine) and check for leaks.
Disconnect the negative battery cable.
Install or connect the following:
Heater hose to the lower intakeUpper radiator hose to the thermostat housingDistributor assembly and engage the wiringIgnition coilConnect vacuum hoses to the upper and lower intake manifold.New upper intake manifold gasket, making sure the green sealing lines are facing upwardUpper intake manifoldManifold retainers. Tighten them to 88 inch lbs. (10 Nm) using two passes.Purge solenoid and bracketBrake booster vacuum hose at the upper intake manifoldPCV hose to the rear of the upper intake manifoldVacuum hoses to both the front and rear of the manifold assemblyThrottle bodyThrottle linkage to the upper intakeWiring to the upper intake components including the TP sensor, IAC motor, MAP sensor and the fuel meterEngine coverAir intake assembly
If the manifold was replaced, install or connect the following:
Vacuum source manifold.
Positive Crankcase Ventilation (PCV) valve.
Manifold Absolute Pressure (MAP) sensor.
Throttle body assembly.
Upper-to-lower intake manifold carrier gasket to the upper intake manifold.
Carefully place the upper intake manifold onto the lower intake manifold. Ensure that the alignment pins in the upper intake manifold align with the holes in the lower intake manifold.
NOTE: Apply thread lock compound, to the bolt threads before assembly.
Install or connect the following:
Upper intake manifold. Tighten the upper intake manifold bolts in sequence to 89 in lbs (10 Nm)
Accelerator and the cruise control cables with the bracket to the throttle body.
EVAP purge solenoid vacuum line to the throttle body.
Connect the electrical connectors to the following:
Mass Air Flow (MAF) sensor
Manifold Absolute Pressure (MAP) sensor
Idle Air Control (IAC) valve
Throttle Position (T/P) sensor
EVAP purge solenoid
Install or connect the following:
Throttle body upper support bracket bolt. Tighten the bolt to 89 in lbs (10 Nm)
EGR valve wiring harness heat shield, nut and the bolt. Tighten the nut and the bolt to 89 in lbs (10 Nm)
Drain radiator. Remove upper rad hose from thermostat housing. Disconnect air intake hose from throttle body. Remove throttle body from upper intake manifold, disconnecting the 2 rubber hoses to the heater line. You may also need to disconnect the fuel line. Remove the exhaust crossover heat shield and loosen the crossover pipe from both exhaust manifolds but don't remove crossover completely. You should have access to the 2 thermostat housing bolts, remove upper bolt but just loosen the lower one about a half inch. Pull the housing out and up from the intake manifold to access the thermostat. Clean the mating surfaces with a gasket remover. replace thermostat, apply a light coating of rtv sealant to both sides of the new gasket. Replace thermostat housing with the gasket to the intake manifold. Apply some rtv to the bolt threads before reattaching housing. Tighten bolts snugly but do not over tighten. Tighten exhaust crossover and reattach the heat shield. Install throttle body attaching the 2 little hoses at the bottom, its a good time to replace these hoses and clamps. Depending on the condition of the throttle body gasket you may need to replace it also. Reconnect the fuel line (if disconnected) Reconnect air intake hose to throttle body. Reattach the upper rad hose to housing. Fill rad with coolant 50/50 mix with water (make sure to use the same type antifreeze that is in the system, they say you can mix green with red but I wouldn't recommend) Leave rad cap off start the car and let it warm up until you can see the coolant circulating and ad coolant as necessary until full. Now there is going to be some air in the system that you need to bleed out. There are 2 bleeders on this system, 1 is on the top of the thermostat housing, and the other is on the metal heater line on top of the water pump (the one that goes across the front of the engine and around under the throttle body that the two little hoses attach to) Bleed the one on the housing first (its the lower one) open it until fluid comes out then tighten it. Then move to the 1 on the heater line(above water pump) loosen it until fluid comes out the re-tighten. Fill recovery tank to fill line replace the rad cap and take it for a ride, watching the temp gage closely. If the temp goes higher than normal than there is probably more air in the system. you'll have to bleed it again.
This is a very labor intensive procedure and I do recommend buying or checking a service manual out from your local library. I've done these in the past and to be honest I just have the dealer do it now. A system flush and thermostat replacement was around $230 the last time I had it done, but it comes with a warranty. And you wont have to rent or buy a fuel line disconnect tool if you end up having to disconnect it. These are the hardest thermostats I've ever replaced.
the manifold gasket must be shot on the manifold. usually when the gasket goes bad it puts oil into the coolant, as far as the guage not working. it must be the thermostat is bad, it probably went bad because of the manifold gasket. I have a 3.1 and the gasket went bad, so I changed it and the thermostat at the time I had it torn down. check to see if the coolant has oil in it. the best thing to do is go to any auto parts store and buy a haynes manual for your specific vehicle, this is based on a complete teardown of vehicle, the book will describe the procedure to change manifold gasket. but if you change the gasket do not forget to replace thermostat and coolant when done. best of luck Toolman,