Diagnostic Flow Chart Procedures
(1) CYCLE VTC ACTUATORS:
Disconnect the VTC Solenoids on both heads. (Refer to illustration for connector locations.)
Connect CONSULT to vehicle's DDL connector and access ECCS "ACTIVE TEST", "Valve Timing Solenoid Test".
Start engine and while noise is occurring, touch "ON" at the bottom of CONSULT's screen.
Connect the VTC Solenoids one at a time, checking to see how the noise changes when the solenoid is connected. Also note which head is affected.
NOTE:
To ensure accurate results, CONSULT is recommended for diagnosing this incident. If CONSULT is not available, raise the engine speed to 2000-2500 RPM and unplug the VTC Solenoids while the noise is occurring. The noise should not be present when the solenoids are connected and may occur when disconnected.
Pay specific attention and record the results of the noise test. Does the noise change, stop or remain constant?
(2) TIMING CHAIN TENSIONER MOVEMENT CHECK:
Remove the valve cover and timing chain cover on the head with noise. Remove the spark plugs and the Brown fusible link to disable the ECCS system. (Refer to illustration for fusible link location.)
Crank the engine and watch the operation of the timing chain tensioner. The tensioner should stay tight against the timing chain as soon as the engine builds oil pressure as indicated by the low oil pressure indicator lamp on the instrument panel going out.
(3) VTC OIL GALLEY DEBRIS CHECK:
Remove the incident cylinder head valve cover. Loosen retaining bolts and remove the number one camshaft bearing cap (closest to the sprocket). Inspect the bearing cap, camshaft and cylinder head oil passage for any evidence of foreign material or debris.
Use a pipe cleaner to reach into the oil return hole under the first intake cam journal. Push the pipe cleaner into the oil supply hole as far as it will go and then pull it out. Examine the pipe cleaner for any metal chips, foreign material or debris.
NOTE:
Refer to illustration for specific location of oil return hole.
Remove # 1 bearing cap from the INTAKE CAMSHAFT on incident cylinder head for access to oil return hole.
NOTE:
Incident noise is affected only by debris currently within the INTAKE CAMSHAFT oil return passage on the # 1 journal.
If any metal debris or foreign material is found in the oil return passage, or the camshaft bearing cap, go to cylinder head oil galley cleaning procedure. PROCEDURE (4)
If no metal debris is found, reinstall the cam shaft and replace the VTC Sprocket.
(4) CYLINDER HEAD OIL GALLEY CLEANING PROCEDURE:
A) Set engine on TDC of compression stroke for # 1 cylinder. Remove both cylinder heads. Remove both intake camshafts.
NOTE:
Review the camshaft timing procedure prior to disassembly to eliminate difficulty during the reassembly procedure (refer to NTB93-126).
B) Locate the oil jets for the VTC oil supply and the timing chain tensioner. (Refer to illustrations.) Use a suitable drill (approx. 1/8") to slightly enlarge the hole in the jet and install a slide hammer type "dent puller" into the orifice*. Remove the jets using a series of light blows. Mark the position of the tensioner oil jet on the left (front) head. This will ensure its location is not confused with the location of the VTC oil passage blind plug.
C) Note:
If the steel VTC oil jet is difficult to remove, use an electric heat gun to heat the area of the cylinder head around the jet to approximately 125 degrees F.
D) Locate the three, 6 mm blind plugs on the front (left) head and one, 6 mm blind plug on the rear (right) head. (Refer to illustrations.)
E) Use a suitable die grinder to carefully remove the staking from around the edges of the plugs. Do not remove any more material than is necessary to relieve the staking. Mark the center of each plug with a center punch. With a suitable small drill bit (approximately 1/8"), drill a hole through the plug. Install a slide hammer type "dent puller" into the plug. Remove the plug using a series of light blows*.
Caution:
When drilling the plugs and jets, be sure to drill on center to avoid damaging the cylinder head. Do not attempt to remove the jets or plugs without using a slide hammer.
F) Use a spray solvent and brush (Brush Set --Mr. Gasket p/n 1211 or equivalent) to clean the passages. Blow all debris from the passages with compressed air. All debris must be removed from the passages, paying particular attention to the blind ends of the drilled passages, and the points that the two drilled passages intersect.
G) Thoroughly dry the passages. Remove all traces of oil from the ends of the oil passages where the blind plugs are installed.
H) Place a small amount of sealant (Loctite # 640 or equivalent) on a cotton swab ("Q" Tip, or equivalent) and dab the end of the oil galley for the blind plug. Drive the plug into position using a suitable pin punch. Plugs are tapered -- pay attention to their direction (chamfered end goes in first). After installation, stake the edges of the new plugs with a center punch. On the left (front) head, be careful not to switch the position of the tensioner oil jet and the VTC oil passage blind plug.
I) Install the new oil jets into the appropriate passage. Do not use sealant on any of the oil jets. The steel jet is for the VTC passage in the deck surface of the cylinder head and the aluminum jet is for the chain tensioner. The tensioner jet is tapered, with the chamfered end facing the head.
J) Reinstall the cylinder heads on the engine using new gaskets.
(5) RECHECK ENGINE FOR NOISE:
Using information gathered during the PRELIMINARY PROCEDURE, verify if original incident noise is still present in either one or both cylinder heads.
Repeat procedure [1] (Cycling of VTC Actuator Solenoids) to confirm incident noise is no longer produced by either cylinder head. This test MUST be performed under the operating conditions that caused the original noise.
If incident noise continues to occur, determine if noise continues without change when VTC is cycled or if incident noise changes or is reduced when VTC is cycled. Refer to Diagnostic Flow Chart for additional repair procedures.
(6) TIMING CHAIN TENSIONER DEBRIS CHECK:
Remove timing chain tensioner from the incident cylinder head(s).
Examine the oil feed hole in the tensioner and the oil jet in the cylinder head behind the tensioner for any metal chips or filings (see photos).
If any metal debris is found in the supply passage, go to Cylinder Head Oil Galley Cleaning Procedure (4).
NOTE:
Always wear appropriate skin and eye protection while performing these procedures.