Self leveling suspension

have a coolant pressure test done to determine for leaks in the system. have a compression test done to determine head gasket or cracks.. Check radiator cap is holding the set pressure and is opening to admit water back from the reservoir on cooling. Check hose from radiator to reservoir is tight with no cracks in it.

WAIT UNTIL YOUR ENGINE IS COLD,YOUR RADIATOR PRESSURE CAP IS LOCATED ON THE COOLANT OVER FLOW RESERVOIR, THATS WHERE YOU ADD COOLANT WHEN COOLANT LOW,YOU POUR COOLANT IN THE OVER FLOW RESERVOIR UNTIL COOLANT LEVEL REMAIN AT FULL COLD MARK DONT OVER FILL OVER FLOW RESERVOIR, WHEN COOLANT LEVEL STOP DROPPING WHEN ADDING COOLANT AND COOLANT LEVEL STAY AT COLD MARK ON THE RESERVOIR YOU RADIATOR HAS THE CORRECT COOLANT LEVEL IF COOLANT LEVEL KEEP DROPPING CHECK FOR COOLANT LEAKS AROUND RADIATOR AND THE TOP AND BOTTOM RADIATOR HOSES, LOOK FOR COOLANT LEAK AT WATER PUMP GASKET OR SEAL OR LEAK AT WATER PUMP WEEP HOLE IF YES REPLACE WATER PUMP.

Yes it is not that hard to replace.


REMOVE OR DISCONNECT

1. Retainer and electrical connector from fluid level sensor.
2. Drain brake fluid front mister cylinder reservoir.
3. Reservoir hose from master cylinder. Plug hose to prevent fluid loss and contamination.
4. Brake pipes from master cylinder. Plug open pipes to prevent fluid loss and contamination.
5. Two attaching nuts.
6. Master cylinder.
7. Reservoir, if it is to he used on replacement master cylinder.

INSTALL OR CONNECT

1. Reservoir onto master cylinder, as needed.
2. Master cylinder on to power booster.
3. Attaching nuts. Tighten to 27 Nm (20 lb. ft.).
4. Brake pipes. Tighten brake pipe fittings to 15 Nm (11 lb. ft.).
5. Reservoir hose onto master cylinder.
6. Fill master cylinder reservoir to full level mark using only Delco Supreme 11 Brake Fluid, or equivalent DOT 3 brake fluid.
7. Electrical connector to fluid level sensor, secure with retainer.
8. Bleed hydraulic system.
9. Recheck fluid level in reservoir

It sounds like you need a new Radiator cap for the overflow style Radiator. The overflow style has a recovery vent which draws the water back through the radiator neck and into the engine. Low heat levels are also a sign of a water shortage.

Your antifreeze strength needs to be 50/50. This sounds like there is an ice block inside the Radiator or engine. Get the strength of the antifreeze tested.

You could have an internal leak; you need to have the system pressure tested. The overflow tank should drain back into the radiator and it relies on a sealed system to work. If you have a leak, there will be no Vacuum pressure to draw the antifreeze back into the engine.

It could be a head gasket leak, or a leaking heater core, or bad radiator or a bad hose. The pressure test can be done by anyone with a gauge. You could try Autozone or Oreillys for their loaner tools. Ask for a Radiator tester pump. You can also have the cap checked.

Radiator and A/C shops do this test routinely. A real Service station used to do this routinely until they went self-serve.

I hope my solutions give you a few alternatives because a head gasket is a costly repair. I hope you find my solutions very helpful.

This job requires special tools and special training. If you lack either, you risk SERIOUS personal injury. Injury comes VERY EASILY!

You need to address oil levels, proper and legal refrigerant recovery, system evacuation, and recharge.

You were planning to also replace the receiver/dryer, correct? It also needs the oil in it measured and incorporated into the amount of oil (in %) that would need to be added. FAILURE to address these and other issues will guarantee premature system failure and likely compressor damage.

Take this job to a qualified shop.
Sorry

IF self leveling (gas struts) are faulty,when you come to a stop after driving for about 10 mins,the rear will not have risen to level.(still low).then they will need replacements fitted,they are not that expensive,compared to some air suspension types.(just in case im not clear,the rear pumps itself up AFTER moving off/driving and will settle when stopped for awhile after.)

CYLINDER HEAD REMOVAL

2.5L Engines

1. Before servicing the vehicle, refer to the Precautions Section.
   
2. Drain cooling system and engine oil.
   
3. Relieve the fuel system pressure.
   
4. Remove or disconnect the following:
   
   • Negative battery cable
     
   • Upper radiator hose and heater hose
     
   • Right side fuse/relay box and move aside
     
   • Engine undercover
     
   • Resonator and air cleaner case
     
   • Engine top cover
     
   • All electrical and vacuum lines at the head
     
   • Fuse hose quick connector at fuel tube side
     
   • Engine harness and power steering hose bracket
     
   • Timing chain
     
   • Drive belt tensioner
     
   • Camshafts
     
   • Spark plugs
     
   • Exhaust manifold
     
5. Support the engine from above and below with a suitable jack and hoist.
   
6. Remove or disconnect the following:
   
   • Power steering pump and reservoir and wire aside
     
   • Auxiliary drive belts
     
   • A/C compressor and wire aside
     
   • Upper sway bar links
     
   • Front and rear engine mount through bolts
     
   • Lower ball joints
     
   • 2 steering gear housing mounting bolts
     
   • Front suspension member bolts and front suspension member
     
7. Loosen the cylinder head bolts in the sequence shown and remove the cylinder head.
   

Removing the front suspension member—Altima


Cylinder head bolt removal sequence—2.5L engine–Altima and Sentra


Cylinder head bolt tightening sequence—2.5L engine–Altima and Sentra

To install:

1. Clean the gasket surfaces.
   
2. Using new head gaskets, install the cylinder heads.
   NOTE If possible, replacement of the head bolts is suggested.
   
   
3. If replacement of the head bolts is not possible, perform the following bolt measurement:
   
   • Measure the diameter of the head bolt 0.43 in. (11mm) from the bottom of the bolt.
     
   • Measure the diameter of the head bolt 2.17 in. (55mm) from the bottom of the bolt.
     
   • Whenever the size difference between the 2 measurements exceeds 0.0091 in. (0.23mm) the head bolts must be replaced.
     
4. Apply clean engine oil to the bolt threads and seating surfaces and tighten the cylinder head bolts in sequence as follows:
   
   • Step 1: 72 ft. lbs. (98 Nm).
     
   • Step 2: Loosen all the bolts completely.
     
   • Step 2: 29 ft. lbs. (33 Nm).
     
   • Step 4: Plus 75–80 degrees clockwise.
     
   • Step 5: Plus 75–80 degrees clockwise.
     
5. Install the front suspension member and tighten the bolts to the specifications shown in the illustration.
   
6. Install or connect the following:
   
   • 2 steering gear housing mounting bolts
     
   • Lower ball joints
     
   • Front and rear engine mount through bolts
     
   • Upper sway bar links
     
   • A/C compressor
     
   • Auxiliary drive belts
     
   • Power steering pump and reservoir
     
   • Exhaust manifold
     
   • Spark plugs
     
   • Camshafts
     
   • Drive belt tensioner
     
   • Timing chain
     
   • Engine harness and power steering hose bracket
     
   • Fuse hose quick connector at fuel tube side
     
   • All electrical and vacuum lines at the head
     
   • Engine top cover
     
   • Resonator and air cleaner case
     
   • Engine undercover
     
   • Right side fuse/relay box and move aside
     
   • Upper radiator hose and heater hose
     
   • Negative battery cable
     
7. Fill the cooling system and engine oil
   
8. Start the vehicle, check for leaks and repair if necessary.
   

freon level is low . One of those 2 ports u see will be the one u want. It will be the smaller of the 2 as the refill hose will only lock onto the correct fitting.

It is normal for some cycling of the compressor as the ride heights change and the compressor vents and fills air springs. Info:

Air Compressor
The air compressor:

• Is not interchangeable with the rear air suspension (RAS) air compressor.
• Consists of the compressor and vent solenoid; neither are replaceable as individual items.
• Is a single cylinder electric motor driven unit that provides pressurized air as required.
• Is powered by a solid state relay, which is controlled by the air suspension control module.
• Passes pressurized air through the compressor air drier that contains silica gel (a drying agent). Moisture is then removed from the compressor air drier when vented air passes out of the system during vent operation.
• The drier may be replaced separately.
• The drier has dual ports and is not interchangeable with the RAS drier.

The vent solenoid:

• Allows air to escape from the system during venting actions.
• Is part of the air compressor cylinder head.
• Shares a common electrical connector with the air compressor motor.
• Is enclosed in the cylinder head casting, which forms an integral valve housing that allows the valve tip to enter the pressurized side of the system.
• Has an O-ring seal that prevents air leakage past the valve tip.
• Opens when the air suspension control module determines lowering is required.
• Provides an escape route for pressurized air when system pressures exceed safe operating levels.
• Has a 1792 kPa (260 psi) internal relief valve.
• Is installed with the air compressor as a unit.

Compressor Relay
A solid state relay is used in the air suspension system for compressor control. The relay incorporates a custom power metal oxide semi-conductor field effect transistor (MOSFET) and ceramic hybrid circuitry. The relay switches high current loads in response to low power signals and is controlled by the logic of the air suspension control module.
The compressor solid state relay is energized by the air suspension control module to have high current flow from the battery to the compressor motor.
Control Module
NOTE: The 4WAS control module is also used for the RAS system. The internal processor recognizes external circuitry to determine if it is installed in a 4WAS or a RAS system.
NOTE: The air suspension control module is calibrated with information from the air suspension height sensors. A new or swapped air suspension control module requires the ride height adjustment calibration process to be performed.
A microcontroller-based electronic air suspension control module controls the air compressor motor (through a solid state relay) and all system solenoids. The air suspension control module also provides power to front and rear height sensors. The air suspension control module controls vehicle height adjustments by monitoring the two height sensors, vehicle speed, a steering sensor, acceleration input, the door ajar signal, transfer case signals and the brake pedal position (BPP) switch. The air suspension control module also conducts all fail-safe and diagnostic strategies and contains self-test and communication software for testing the vehicle and related components.
The air suspension control module is interchangeable between the RAS and 4WAS system.
The air suspension control module monitors and controls the system through a 32-pin two-way connector. The air suspension control module is keyed so that it cannot be plugged into an incorrect harness. There are two sides of the harness connection to the air suspension control module. Each is uniquely colored and keyed to prevent reversing the connections.

Pressure Relief Valve
The pressure relief valve (PRV) protects the rear air suspension components by venting the system to a specific pressure in the case of a system malfunction. The system will decrease the pressure to an acceptable level to maintain vehicle height. In the normal operation mode with normal system pressure, the PRV is constantly closed and does not have any effect on the system performance or function. The PRV is replaceable without any air lines.

1. If the concern remains after the inspection, use New Generation STAR (NGS) Tester connected to the data link connector (DLC) to retrieve continuous diagnostic trouble codes (DTCs) and to execute On-Demand Self-Test diagnostics for the air suspension control module.
   • If the On-Demand Self-Test is passed and no DTCs are retrieved, go to the Symptom Chart to continue diagnostics.
   • If DTCs are retrieved, go to Air Suspension Control Module Diagnostic Trouble Code (DTC) Index in this section.
   • If the air suspension control module cannot be accessed by NGS Tester, go to Pinpoint Test A.

Self-Test
Verify that the following conditions are met before running the On-Demand Self-Test.

• All doors, liftgate, and liftgate glass must be closed.
• The transmission is in PARK.
• The BPP switch is not pressed during the test and the parking brake is not set.
• The accelerator pedal is not pressed during the test.
• The vehicle is not in 4L mode.

1. Fulfill the pre-conditions.

1. Install a battery charger for the On-Demand Self-Test to prevent battery drain.

1. Run the air suspension On-Demand Self-Test.

1. Record all listed DTCs.

1. Retrieve stored DTCs.

1. Troubleshoot any On-Demand Self-Test DTCs first.

1. Retest and clear DTCs after repairs.

top rear most line comes from the pressure regulator, rear side outlet at angle line goes to oil cooler then to fluid reservoir. Smallest of all three lines is a pressure line that goes to the rear self leveling system.