Replacing Water By-Pass In Pipe O-Rings and Manifold Removal - The Acura Legend & Acura RL Forum
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Old 07-03-04, 01:09 AM   #1 (permalink)
Join Date: Mar 2002
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Replacing Water By-Pass In Pipe O-Rings and Manifold Removal

In order to replace the two O-rings of the Water By-Pass In Pipe (vertical tube under the Throttle Body - Connects Thermostat Base to the Water Passage) the Manifold must be removed.

Remove Engine Splash Shield
Remove Strut Bar
Remove Air Cleaner Assy
Unbolt Emission Control Box
Relieve Fuel Pressure
Drain Radiator Coolant
Remove Radiator Hose From Thermostat
Disconnect Vacuum lines from Air Boost Valve, EGR, Control Diaphrams, and Front of Engine
Remove the LT side Vacuum Line Pipe
Disconnect harness from Throttle Body
Disconnect hoses attached to Throttle Body
Remove Throttle Body
Unbolt Thermostat Base
Unbolt Fast Idle Valve
Unbolt Bracket between Fast Idle and Air Suction Valve
Unbolt Air Suction Valve
Remove EGR Valve
Remove The Front and Back Coil Packs from LT side
Disconnect Brake Booster Line
Unbolt Temp Sensor attached to Water Passage
Unbolt EGR Pipe connected to Manifold
Remove PCV and its line
Remove Elbow on Manifold
Remove Wire Loom Bracket RT front of Engine
Remove Fuel Injector Connectors by using a pick and prying the silver U shaped retaining wire from the connector. The U has two sm "hooks" which must be pulled out in order for the connector to release from the fuel injector body.
Unbolt Injector Harness from Heads and position out of way of Manifold
Unbolt RT Cam Cover to allow harness to be moved out of the way.
Unhook control cable from Heater Control
Unbolt Heater Control from firewall and push it and hoses down.
Unbolt fuel line from fuel rail
Unbolt Intake Manifold Bolts
Unbolt Water Passage Bolts
Grab both fuel rails and lift off Manifold.
Remove Water By-Pass In pipe from Manifold.
Remove old Intake Gaskets

Install new O-Ring to Water Passage (top of block: connects to Thermostat Base
Install new O-rings to Water By-Pass In Pipe.
Install Pipe back into Manifold
Clean Intake Gasket surface and Head surfaces
Install new Intake Gaskets
Install new hoses to Fast Idle Valve
Install new O-ring/Gasket/Filter to Fast Idle Valve
(will need pick, drift to remove filter and a socket to drive the new one in)
Carefully position new Fast Idle Hoses to match the old. I gave an additional 1/8 inch to each hose by not pushing them onto the nipples to the extend of the old)
Remove EGR Pipe from Manifold
Clean EGR Pipe and Manifold Orifice
Install new gasket
Install EGR Pipe nuts only to be even with stud. Need to have it swing to clear the EGR base and allow new EGR gasket
Place Manifold back onto engine.
In order: Reinstall Fast Idle Valve and Bracket, then Air Suction Valve. (I used OEM tension hose clamps on the new hoses)
Tighten nuts of the EGR Pipe to Manifold
Reinstall Brake Booster Hose
Install New Fuel Line Sealing Washers

The rest is the opposite of the removal. The only really tricky bit is to "dry fit" the manifold and the Fast Idle Valve to make sure you have enough hose length. The other is tightening the EGR Pipe nuts. The 1/4 drive with sm extension and 10 mm will do it.

Draw diagrams, make description lists of what vacuum line goes where.

Put fasteners from each component unbolted/removed into Zip Lock bags and label.

Parts needed are associated with the Manifold, Air Suction Valve, Air Boost Valve, Manifold Elbow, The By-Pass In pipe (order a new pipe as well), Thermostat and Throttle Body

Cost for Gaskets, Sealing Washers, O-Rings, New By-Pass In Pipe, and Fast Idle Hoses was $183. A suggestion would be to call AOA and inform of the repair you intend to perform and let them send all the required gaskets, o-rings, seals and parts.

You might want to replace the heater hoses and control when the Intake Manifold is off. Add $86, less if you use stainless clamps instead of OEM spring clamps.

Add $22 for 2 gallons of OEM coolant.


Phillips Screwdriver
Flat-blade Screwdriver 8" and the smallest you have.
10 mm regular and deep 1/4 drive socket
10 mm regular and deep 3/8 drive socket
Extensions: 1" - 6" for 1/4 and 3/8 drive
11 mm 1/4 drive socket
12 mm 1/4 and 3/8 drive socket
Set of picks
10 mm, 11 mm, 12 mm, and 17 mm combination wrenches
8" pliers and needle-nose pliers
Torque Wrench capable of 10+ lb-ft.

Should be able to do this in about 4 hrs. More if you add heater hoses.

Last edited by LPB; 07-03-04 at 01:27 AM.
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Old 07-03-04, 02:54 AM   #2 (permalink)
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Wow, sounds like a tedious job. Props for taking the initiative to do it yourself, and thanks for the step-by-step procedure.
Did you take any pics along the way?
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Old 07-05-04, 02:52 AM   #3 (permalink)
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Originally Posted by smth_hckr
Wow, sounds like a tedious job. Props for taking the initiative to do it yourself, and thanks for the step-by-step procedure.
Did you take any pics along the way?
Sorry, no photos. Besides, they would not provide any salient information. The most important info needed is what needs to be removed/disconnected/replaced, and thus what components/parts will require new gaskets, o-rings, clamps, or replacement hoses.
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Old 07-23-04, 05:07 PM   #4 (permalink)
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I am new at legends so can you please tell me why the o-ring said in the thread need to be replace? And what is the indication that the o-ring is bad. Thank you!
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Old 10-23-05, 10:35 PM   #5 (permalink)
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When going back together with new gaskets, should they be put on dry or with some sort of sealant? Also, what about sealant on o-ringed gaskets like the water pump? I like using Hylamar which doesn't harden, but seals good.

I appreciate the detailed list because this is exactly what I need to do. I was hoping to get by without pulling the intake by raising the water passage enough, but no luck... Thanks! Pat
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