ISC Valve R&R and cleaning

[Doctor J]

Notes:
The polymer made components on the older cars are brittle due to the exposure to the engine heat and/or aging process. Caution must be used during the service.
Tools and materials

• 10 mm and 12 mm sockets, 3/8 drive
• 8 inch long extension and ratchet handle
• Flat and Phillips screwdrivers
• Vise grips or impact driver with ½ lb hammer and Phillips bit
• Small flat screwdriver, or pick tool (to release the wire locks and to scribe)
• Nail puller
• Bent nose pliers
• ¼ inch nut driver
• Cotton swabs
• Carburetor cleaner or 2:1 xylene / acetone mix
• 2 Hose clamps
• SAE30R7 5/16 ID hose 1 foot long
• WD40 or equivalent
• RTV sealant
• TB and ISC valve gaskets (can be reused)

Process:
1.Remove air intake tube
2.Disengage accelerator cable from throttle body (TB)
3.Unbolt TV cable bracket from TB and disengage cable from TB (this step will preserve the TV adjustment necessary for transmission operation) and pivot it away
4.unplug TP sensor and ISC valve connectors
5.Pull off the PCV hose
6.Push the vacuum hoses on the top of TB of their fittings
7.Remove 4 bolts and separate the throttle body from the intake plenum; the throttle body to plenum gasket usually stays intact and sticks to the throttle body in many cases; at this step the TB is still attached to the engine by 2 coolant hoses and one air bypass hose.
8.Using bent-nose pliers squeeze the coolant hose clamps and move them 2 inches down the hose; release the clamps
9.Pull the hoses off the fittings (inserting the nail puller as a wedge between the hose and ISC valve may help to break it loose) be sure to catch some coolant which will escape
10.Reach down under the plenum and pull the air bypass hose from the metal vacuum line; this hose will be replaced by 5/16 “ID SAE30R7 hose
11.Place TB with ISC valve attached on the work bench; remove air bypass hosethe
12.Remove Dashpot (91 model only) and 4 TB to ISC valve screws using vise grips or impact driver and hammer
13.On the throttle body clean the vacuum ports and PCV orifice as necessary;
14.Inspect the TB to ISC valve gasket
15.Inspect the ISC valve shutter; if is covered by sludge, clean it up using solvent and cotton swab, if claiming cannot restore normal operation clean the bearing
16.SCRIBE bimetal spring cover to ISC valve alignment mark then remove 3 screws with Phillips screwdriver. DO NOT remove the CENTER screw!!
17.Remove spring cover assembly with gasket and white nylon washer that covers the bearing.
18.Note the valve rotor to bimetal coil drive slot position (10.30)

19.Clean the gum around the bearing and lubricate it with few drops of ATF or turbine oil
20.Rotate the shaft couple turns; if this is not restoring valve operation, replace the ISC
21.Assemble the bimetal coil making sure that marks are aligned and rotor is in 10.30 position
22.Clean the coolant hose fittings remove corrosion and paint them as necessary (87 model only, newer are stainless)
23.Apply thin layer of RTV around the coolant passage and attach ISC valve to TB using four screws
24. Measure air bypass hose and cut the same length of SAE30R7 hose lubricate the fitting and slide hose on it; discard the old hose.
25.Install TB assembly in the reverse order; use worm clamps on the coolant hoses instead of OEM clamps.