My undersink RO system leaks at all four tube connections on the manifold. I inspected the fittings and the o rings are fine. I inspected the tubes and I cut off the ends of each piece to make sure that they weren't scuffed. The system is a Culligan ac-30 good water machine.

You didn't post the size of your engine so please pick the appropriate one:

3.8L

1. Relieve the fuel system pressure.
   
2. Drain the cooling system.
   

1. Remove or disconnect the following:
2. Negative battery cable
   

• Supercharger
  
• Thermostat housing
  
• Exhaust Gas Recirculation (EGR) tube at the intake manifold
  
• Engine Control Temperature (ECT) sensor
  
• Intake manifold
  

To install:

1. Install or connect the following:
   
   • Intake manifold with new gaskets. Torque the bolts, working from the center out, to 11 ft. lbs. (15 Nm).
     
   • ECT sensor connector
     
   • EGR tube to the intake manifold
     
   • Thermostat housing
     
   • Supercharger
     
   • Negative battery cable
     
2. Refill and bleed the cooling system.
   
3. Run the engine and check for leaks and proper engine operation.
   

4.6L
4.6L Engine

1. Remove the brake booster hose from the throttle body.
   
2. Remove the fuel pressure regulator vacuum tube from the fuel pressure regulator and the water crossover.
   
3. Remove the PCV fresh air feed tube from the camshaft cover and the throttle body.
   
4. Remove the PCV dirty air tube from the PCV orifice in the right camshaft cover and from the intake manifold.
   
5. Disconnect the fuel injector electrical connectors from the fuel injectors.
   
6. Remove the fuel injector wiring harness.
   
7. Remove the fuel rail bracket nut from the engine lift bracket.
   
8. Remove the fuel rail studs.
   
9. Lift and remove the fuel rail with injectors.
   
10. Loosen the plenum duct clamp in order to remove the intake manifold.
    
11. Remove the intake manifold bolts.
    
12. Remove the intake manifold.
    

To install:

1. Install the intake manifold, fitting the plenum duct over the intake manifold duct.
   
2. Loosely install the intake manifold bolts.
   

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Intake manifold torque sequence-4.6L engine

2. Tighten the intake manifold bolts in sequence. Tighten the intake manifold bolts to 89 inch lbs. (10 Nm).
   
4. Tighten the plenum duct clamp to the intake manifold. Tighten the plenum duct clamp to 24 inch lbs. (2.75 Nm).
   
5. Inspect the fuel injector O-rings. Ensure the fuel injector O-rings are not missing, misaligned or damaged. Replace the O-rings if necessary.
   
6. Lubricate the intake manifold fuel injector bores with light mineral oil (GM P/N 9981704), clean engine oil, or equivalent.
   
7. Install the fuel rail with fuel injectors as an assembly.
   
8. Install the fuel rail studs. Tighten the fuel rail studs to 80 inch lbs. (9 Nm).
   
9. Install the fuel rail bracket nut to the engine lift bracket. Tighten the fuel rail bracket nut to 89 inch lbs. (10 Nm).
   
10. Install the fuel injector wiring harness.
    
11. Connect the fuel injector electrical connectors to the fuel injectors.
    
12. Install the PCV dirty air tube to the PCV orifice in the right camshaft cover and to the intake manifold.
    
13. Install the PCV fresh air feed tube to the camshaft cover and the water crossover.
    
14. Install the fuel pressure regulator vacuum tube to the fuel pressure regulator and the throttle body.
    
15. Install the brake booster hose to the throttle body.
    

It is located inside the condensor tube running to the evaporator.

Here are the removal/installation instructions as per alldata:

TOOLS REQUIRED

J 39400-A Halogen Leak Detector
J 26549-E Orifice Tube Remover

REMOVAL PROCEDURE
-Recover the refrigerant. Refer to Refrigerant Recovery and Recharging.
-Remove the air cleaner assembly.
-Remove the vacuum brake booster.
-Remove the condenser tube.
-Use J 26549-E in order to remove the expansion orifice tube. IMPORTANT: DO NOT use any solvents or chemicals to clean the porous plastic inlet filter of the expansion orifice tube.
-Inspect the expansion orifice tube for the following conditions and clean or replace with a new tube as indicated:
-Broken plastic frame (1); replace the tube.
Inlet filter (3) damaged or plugged with fine gritty material; replace the tube.
Inlet filter (3) coated with metal chips, flakes, or slivers; remove the coating with low pressure shop air ONLY and reuse if the filter is cleaned satisfactorily. Do NOT reuse the O-ring seals (2).

INSTALLATION PROCEDURE

IMPORTANT: Lubricate the new O-ring seals (2) with mineral base 525 viscosity refrigerant oil.
If you reuse the orifice tube, install new O-ring seals (2).
Carefully grasp the edge of the expansion orifice tube (1) without touching the inlet filter (3) and insert the expansion tube into the condenser tube until fully seated.
-Install the condenser tube.
-Install the vacuum brake booster.
-Install the air cleaner assembly.
-Evacuate and recharge the A/C system. Refer to Refrigerant Recovery and Recharging.
-Leak test the fittings of the component using J 39400-A.

3.3L & 3.8L Engines
Firing order: 1-2-3-4-5-6
Distributorless Ignition System
The Driver's Side Front spark plug is the #6 cylinder.

Too much pressure in holding tank will not cause leaks in the RO unit. All too much pressure in tank will do is cause low or no product water in RO tank. Older Culligan RO systems (H8, H83, H5) had fittings that used metal locking washers and these can cut the RO line after the RO has been moved around while changing filters. Newer styles (AC30, Water Tower) use quick connect fittings and the RO line may work loose after filter changes and system being moved around under sink.
Turn the incoming water off to RO, turn the water off on RO tank, open the RO faucet to relieve pressure and pull the line off feeding the RO tank, inspect (you may want to cut off a small portion of the line at the filter) check the o-ring and re-install.
RJ

Any introduction of unmetered air (basically a leak) after the MAF sensor in the air ducting will cause the engine to run lean. You need to check very thoroughly and methodically every tube that connects with the inlet manifold plenum for signs of leaks like cracks and loose joints. Take your time inspecting everything in detail, be quite rough and don't be afraid to twist them around to look at the underside - the leak can be so small that it hard to believe that it is the cause. Also check that the evaporative purge valve is closed when revs are low and the engine is cold. A quick method is to pinch each tube closed in turn for about 10 seconds and listen for any change in engine performance. Check the tube that leads to the brake servo unit for tight fitting seals. If all tubes look good, spray WD40 or carrb choke cleaner around where the the Injectors fit into the manifold and also around the manifold gasket where meets the engine block. A leak may be revealed as a rise in revs as the spray is sucked in an temporarily enriches the air fuel mix. If no leaks are found then check the fuel pressure regulator for correct function.

Right-Hand
Removal

1. Remove spark plug heat shield (12A406).
   

1. Remove distributor to spark plug wires (12286) using Spark Plug Wire Remover T74P-6666-A.
   
1. Disconnect muffler inlet pipe.
   
1. If equipped with secondary air injection, disconnect the secondary air injection check valve tube (9B480).
   
1. Remove attaching bolts and right exhaust manifold (9430).
   
1. Inspect joint faces for signs fo exhaust leaks, cracks or any defect that would make exhaust manifold unfit for use
   

Left-Hand Removal






1. Remove oil level indicator tube (6754).

1. Remove spark plug heat shield.
   

1. Remove distributor to spark plug wires using Spark Plug Wire Remover T74P-6666-A.
   

1. Disconnect EGR valve to exhaust manifold tube (9D477). If equipped with air injection, disconnect the secondary air injection check valve tube.
   

1. Disconnect muffler inlet pipe.
   

1. Remove attaching bolts and exhaust manifold (9431).
   

1. Inspect joint faces for signs of exhaust leaks, cracks or any defect that would make the exhaust manifold unfit for use.
   

Installation

1. Clean mating surfaces of right exhaust manifold or left exhaust manifold and cylinder head (6049). Clean mounting flange of right exhaust manifold or left exhaust manifold and inlet pipe(s). Clean mounting surface for air injection tube or right exhaust manifold. Apply light film of Premium Long-Life Grease XG-1-C or -K or equivalent meeting Ford specification ESA-M1C75-B to right exhaust manifold or left exhaust manifold.
   

1. Position right exhaust manifold or left exhaust manifold on cylinder head. Install attaching bolts and washers, starting at fourth bolt hole from front of each right exhaust manifold or left exhaust manifold. Tighten bolts to 34-47 Nm (25-35 lb-ft), working from center right to both ends.
   
1. Position inlet pipes to right exhaust manifold or left exhaust manifold. Install attaching nuts and tighten to 34-47 Nm (25-35 lb-ft).
   
1. Position the secondary air injection check valve tube and the secondary air injection tube gasket (9C435) at rear of right-hand exhaust manifold. Install attaching bolts and tighten to 19-25 Nm (14-18 lb-ft).
   
1. Attach the secondary air injection manifold tube (9B449) to left-hand exhaust manifold fitting (located under EGR tube). Tighten nut to 30-40 Nm (22-30 lb-ft).
   
1. Attach the secondary air injection check valve tube to rear of right-hand cylinder head. Tighten bolts to 75-85 Nm (56-62 lb-ft).
   
1. Connect EGR valve to exhaust manifold tube to left exhaust manifold, if removed. Tighten nut to 53-72 Nm (39-53 lb-ft).
   
1. Install spark plug heat shield and distributor to spark plug wires.
   
1. Install oil level indicator tube to left exhaust manifold, if removed. Tighten nut to 13-24 Nm (10-18 lb-ft).
   
2. Start engine (6007) and check for exhaust leaks.
   

Hope this helps you...WF †

Hi, The fitting either needs tightened or changed. Is this a brass or plastic fitting?
If the supply line is still ok and not brittle, you can go to your local hardware store and get the new fitting parts. If it is brass, be sure and get the brass insert that goes inside the tubing as well as the compression ring.
Please let me know if I can assist you further.

Vic

I had this with a Kitchenaid Superba and wanted to get rid of the filter holder assembly entirely as I have an undersink unit which serves the fridge. I removed the plastic line (nut) at the back of the fridge (which led to the filter holder at the front) where the flexible copper tubing inserted (this was a 3/8' compression fitting-plastic) and also the returning line (1/4" copper compression nut on a plastic line) at the manifold (again in the back of the fridge) where it gets split between the water line and the ice line. I then just connected the 1/4" flexible copper directly to the manifold (1/4" nut, compression sleeve, male-male connector) using a pre-made 1/4" flexible compression line. Sounds complicated but after seeing how the water routes it was fairly quick work.

is there an internal float that is stuck allowing overflow?