Had my car repaired.They replaced valve covers, gaskets, plugs, filters, manifold intake and front axles. Now my engine light goes on and I was diagnosed PO325 and PO400 by Auto Zone. Help. Should I take it back to where it was serviced?

I'm sorry, but I can't provide visual images or diagrams. However, I can describe the general order of gaskets in a 1999 Dodge Durango engine from the top going down:

1. Valve Cover Gaskets: These gaskets are located on top of the cylinder heads and seal the valve covers. They help prevent oil leaks from the top of the engine.
2. Intake Manifold Gasket: The intake manifold gasket seals the connection between the intake manifold and the cylinder heads. It helps maintain proper air-fuel mixture and prevents vacuum leaks.
3. Throttle Body Gasket: If equipped, the throttle body gasket seals the connection between the throttle body and the intake manifold. It ensures proper airflow into the engine.
4. Exhaust Manifold Gaskets: These gaskets are located between the exhaust manifold and the cylinder heads. They seal the exhaust gases and prevent leaks.
5. Head Gaskets: The head gaskets are situated between the cylinder heads and the engine block. They seal the combustion chambers and coolant passages.
6. Oil Pan Gasket: The oil pan gasket is located at the bottom of the engine and seals the oil pan to the engine block. It prevents oil leaks from the oil pan.
7. Front and Rear Main Seals: These seals are located at the front and rear of the engine crankshaft. They prevent oil leaks where the crankshaft exits the engine block.
8. Timing Cover Gasket: If equipped, the timing cover gasket seals the timing chain or belt cover to the engine block. It helps protect the timing components and prevents oil leaks.

If it is a 6 cylinder engine you will probably need to remove the intake manifold to replace the rear valve cover gasket. If that's the case the intake manifold also has two hidden screws in the rear against the firewall as well as an EGR exhaust line that must be removed before the intake manifold will come off. I highly recommend you buy a haynes repair manual for your make/model and a flexible mirror-on-a-stick to use for dis-assembly. The spark plugs can be removed after the valve covers are removed (if the valve cover is leaking you will likely have oil pooled around the plugs anyway).

Dear Sir,
Here is the oil leaking Problem Identifying Technique

Engine oil leaks from the valve cover gasket are common.

The intake manifold plenum gasket may leak and cause increased oil consumption/burning and a spark knock during acceleration; the gasket should be replaced.

External oil leaks from valve cover gaskets, intake gaskets (front or rear), and the rear crankshaft (rear main) seal area are common. The rear main seal is an unlikely source. Normally, the bearing cap mating surfaces (as well as the sealing surface between the oil pan and bearing cap) are the source for the leaks.

Engine oil leaks at the distributor can be misdiagnosed as leaks from theintake manifold seal, oil pan gasket, or rear crankshaft (rear main) seal. A revised distributor is available if oil is found inside the distributor.

If the oil filter casing shows signs of distortion from excessive oil pressure, theoil pump should be replaced.

Often misdiagnosed as a leaking oil filter gasket, the oil filter adapter can seep from between the adapter and engine block.

Carbon buildup on the top of the piston is common. As the buildup increases with mileage and over time, symptoms may vary from light ticking, to ticking/hammering, to hammering/knocking noises. Fuel injector cleaner often solves the problem.

I think it helps to analyse u r Problem

Find out if this air valve is considered an Emissions part. I would say it is not, but it depends on the effect on the emissions. If it is a covered part, the Emissions devices are Federally mandated to last a longer period of time and miles than the rest of the car.

The air valve is usually a different component than a throttle valve. The air valve is a part inside the air intake which changes the flow of air underneath the intake manifold. The throttle valve is a big flap on the top of the intake manifold which moves directly with the gas footpedal. The air valve operates automatically to change the air passages beneath the intake. The throttle valve changes the air opening from the air filter and is manually controlled by the footpeadal.

You might ask them if the engine has manifold "runners" and if it does, then that could be the problem. Ford had several problems with these runners. Also, I can't say if your design is a sandwich manifold, but the sandwich intake manifold had a gasket in the middle to join top and bottom and over time the gasket dissolved making a leak.

I would get a second opinion for this repair.

Not easy but doable. I would mark anything you aren't familiar with to get it back together right. Please let me know if you have any questions, and thanks for using FixYa.


IGNITION COIL REMOVAL & INSTALLATION
3.0L Engine

1. Remove the wiper arms
2. Remove the left and right side air inlet grilles
3. Remove the wiper motor.
4. Detach the power brake booster vacuum connection from the intake plenum.
5. Disconnect the spark plug wiring harness from the ignition coil.
6. Detach the electrical connection from the ignition coil.
7. Remove the bolts from the ignition coil, and remove the coil.

To install:

1. Installation is the reversal of the removal procedure.
2. Tighten the coil bolts to 71 inch lbs. 8 (Nm).
3. Tighten the power brake booster vacuum connection until snug.

valve cover removal & installation3.0L Engine
RIGHT

1. Disconnect the negative battery cable.
2. Remove the intake plenum and the intake manifold.
3. Remove the spark plug boots from the spark plugs, and then the wires from the routing retainers. Make sure they are tagged for proper installation.
4. Remove the rocker arm cover-to-cylinder screws, the cover, and the gasket/seals. Discard the seals.

NOTE Ensure all eight sealing O-rings are accounted for. They may stick to the camshaft bearing caps or fall into the oil return journals in the cylinder head.

Fig. The location of the valve cover O-rings is shown here

Fig. The valve cover sealant application points
To install:

1. Install new valve cover seals. Lightly coat the new seals, including O-rings, with engine oil prior to installation. The oil application will assist in holding the O-ring seals to the valve cover.
2. Apply a thin coat of silicone sealer at the front and back of the seals.
3. Install the valve cover to the cylinder head, and tighten the bolts to 71 inch lbs. (8 Nm).
4. Route the spark plug wires into the retainers, and install the plug boots to the spark plugs.
5. Replace the intake manifold and the intake plenum.
6. Connect the negative battery cable.

LEFT

1. Disconnect the negative battery cable.
2. Remove the intake plenum and the intake manifold.
3. Remove the spark plug boots from the spark plugs, and then the wires from the routing retainers. Make sure they are tagged for proper installation.
4. Remove the oil filler spout.
   1. Unlock the tab.
   2. Twist counterclockwise.
   
   
5. Remove the rocker arm cover-to-cylinder screws, the cover, and the gasket/seals. Discard the seals.

NOTE Ensure all eight sealing O-rings are accounted for. They may stick to the camshaft bearing caps or fall into the oil return journals in the cylinder head.
To install:

1. Install new valve cover seals. Lightly coat the new seals, including O-rings, with engine oil prior to installation. The oil application will assist in holding the O-ring seals to the valve cover.
2. Apply a thin coat of silicone sealer at the front and back of the seals.
3. Install the valve cover to the cylinder head, and tighten the bolts to 71 inch lbs. (8 Nm).
4. Install the oil filler spout.
   1. Insert the spout and twist clockwise.
   2. Ensure the locking tab seats on the valve cover bolt head.
   
   
5. Route the spark plug wires into the retainers, and install the plug boots to the spark plugs.
6. Replace the intake manifold and the intake plenum.
7. Connect the negative battery cable.

INTAKE MANIFOLD REMOVAL & INSTALLATION

3.0L Engine
This vehicle uses a sequential multiport fuel injected engine. Fuel injector connectors must be positioned onto their appropriate fuel injector or engine performance and exhaust emissions may be seriously affected. Fuel injector connectors are numbered to match their cylinders.

1. Remove the intake plenum.
2. Properly relieve the fuel system pressure.
3. Remove the fuel supply and fuel return hose from the fuel rail.
4. Fuel injector electrical harness connector.
5. Remove the intake manifold bolts and the intake manifold.

NOTE Mask off the ports to the intake manifold spacer. If foreign objects enter the engine, severe damage may result.
Clean the intake manifold sealing surfaces with a non-abrasive tool or solvent.
Do not damage machined aluminum surfaces or improper sealing may occur.

Fig. Location of the guide pins for the intake plenum-3.0L engine

Fig. Intake plenum-to-intake manifold mounting

Fig. The intake manifold bolt locations
To install:

1. Remove the masking from the intake ports.
2. Install the intake manifold, and tighten the intake bolts to 15 ft. lbs. (20 Nm), rotating the tightening sequence.
3. Reconnect the fuel injector electrical harness connector.
4. Couple the fuel supply and fuel return hose,. Tighten the connection to 11 ft. lbs. (15 Nm).

NOTE Counterhold the connections to prevent damage to the fuel rail.

1. Install the intake plenum.
2. Connect the negative battery cable.

2.6L Engine

1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
2. Drain the cooling system.
3. Relieve the fuel system pressure.
4. Remove or disconnect the following:
   • Negative battery cable
   • Hood
   • Accessory drive belts
   • Accelerator cable
   • Positive Crankcase Ventilation (PCV) valve and hose
   • Air intake duct
   • Fuel pressure regulator vacuum line
   • Canister hose
   • Brake booster vacuum line
   • Engine wiring harness connectors at right wheel housing
   • Ground cable connector at the intake manifold, starter and firewall
   • Heated Oxygen (HO2S) sensor connector
   • Alternator wiring connectors
   • Oil pressure switch connector
   • Starter motor harness connectors
   • Ignition coil connector
   • Spark plug wires
   • Distributor
   • Exhaust front pipe
   • Exhaust Gas Recirculation (EGR) gas temperature sensor connector
   • Air pump
   • EGR pipe
   • Heat shield
   • Exhaust manifold
   • Throttle Position (TP) switch connector
   • Cooling fan
   • Water pump pulley
   • Power steering pump
   • Intake manifold
   • Crankshaft pulley
   • Front cover
   • Timing belt. Refer to the Timing Belt unit repair section.
   • Valve cover
   • Rocker arms
   • Camshaft
   • Cylinder head

Cylinder head bolt loosening sequence - 2.6L engine

1. To install:
2. NOTE: Refer to Section 1 of this manual for the cylinder head torque sequence illustration. The illustration is located after the Torque Specification Chart.
3. NOTE: Lubricate the cylinder head bolts with clean engine oil for assembly.
4. Install the cylinder head with a new gasket. Tighten the bolts in sequence as follows:
5. Step 1: 58 ft. lbs. (75 Nm)
6. Step 2: 72 ft. lbs. (98 Nm)

1. Install or connect the following:
2. Camshaft

• Rocker arms
• Valve cover
• Timing belt
• Front cover
• Crankshaft pulley. Tighten the bolt to 87 ft. lbs. (128 Nm).
• Intake manifold
• Power steering pump
• Water pump pulley
• Cooling fan
• TP switch connector
• Exhaust manifold
• Heat shield
• EGR pipe
• Air pump
• EGR gas temperature sensor connector
• Exhaust front pipe
• Distributor
• Spark plug wires
• Ignition coil connector
• Starter motor harness connectors
• Oil pressure switch connector
• Alternator wiring connectors
• HO2S sensor connector
• Ground cable connector at the intake manifold, starter and firewall
• Engine wiring harness connectors at right wheel housing
• Brake booster vacuum line
• Canister hose
• Fuel pressure regulator vacuum line
• Air intake duct
• PCV valve and hose
• Accelerator cable
• Accessory drive belts
• Hood
• Negative battery cable

1. Fill the cooling system.
2. Start the engine and check for leaks.

the thermostat its located in water out hose near to a/c compressor, to change valve cover, front of engine remove the plastic cover with lexus logo using hex 5mm key 2 bolts , unplug 3 spark plug wires ,loose all 10mm bolts on valve cover , to rear engine valve cover remove before the manifold intake and all components , air filter duct , etc.

sounds like an intake manifold gasket leak.

v6 or 4 cylinder?

SECTION 303-01A: Engine - 2.0L 1999 Cougar Workshop Manual
IN-VEHICLE REPAIR Valve Cover Removal

1. Disconnect the oil feed sensor electrical connector.

1. Disconnect the crankcase ventilation tube.

1. Remove the appearance cover.
   1. Position the throttle cable out of the way, and the speed control cable (if equipped).
   1. Remove the eight bolts.
   1. Remove the appearance cover.

1. Remove the spark plug wires.

1. Detach the upper part of the engine front cover out of the way.
   1. Remove the four bolts.
   1. Position the front cover to one side.

1. Remove the valve cover.
   1. Position the throttle cable to one side, and the speed control cable (if equipped).
   1. Remove the nine bolts.
   1. Remove the valve cover

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