3.0L V6 timing belt replacement

[fdryer]

As the title implies, I too had my turn at bat attempting timing belt replacement (108k miles) two weeks ago. Water pump and three idler pulleys replaced too. Rather than repeat what's already well written from other members contributing valuable snapshots and workarounds to buying the tool set for locking camshafts and crankshaft in place, I elected to use vise grips as a suitable substitute. I don't remember if the belt was slack but the 1-2 vice grip let go without camshafts rotating. I quickly vice gripped the two camshafts again as I proceeded with belt replacement. This may have set me up for a fall.

Never replacing a timing chain or belt, I'm familiar with the basics of mechanical timing, not the fine points. Upon startup after several manual engine rotations to ensure valves didn't meet pistons, the engine roared to life. Unfortunately, the high idle masked a problem. Once the engine warmed up, there was a distinct rough idle and then the check engine light turned on. P0300 general misfire. One ignition coil was replaced earlier this year. Was it possible for the other one to die? No specific cylinder misfire as before. I let the engine run this way as I considered all the possibilities for about two weeks. Tried injector cleaner and wondered if I damaged the cam position sensor when maneuvering the cam sensor assembly in front of the camshaft cover. A rubber vent hose from the evap solenoid damaged? Many things were considered and last was mistiming. One tooth off from cylinder #1 was the reason. No matter how I looked over initial camshafts meeting the four timing marks and bottom crankshaft mark, everything seemed fine. My bad as I retimed the engine yesterday. Took about 8hrs to carefully examine everything before deciding on moving the #1 camshaft one tooth cw. The camshaft rotated out of time but not enough to throw timing completely off. All I did to correct this was manually move the camshaft into position and use the timing belt to hold it in place. #2 camshaft was locked, a la vise grip, to prevent it from rotating. Most of the time spent was analyzing timing, considering the what ifs when a loose camshaft rotates on it own, setting up timing again then carefully realigning #1 camshaft timing mark to the cam housing notch. After resetting #1 camshaft with some idler pulleys loose to allow belt slack, I tightened all three idler pulleys to take out slack, manually rotated the engine thru several rotations to have timing match up, reset idler pulleys and then noticed discrepancies as the right side belt (of the crankshaft pulley) seemed to go very slack at certain crankshaft positions. Nothing in the service manuals mentions this as I went back and forth with the lower idler and spring loaded idler. Several engine rotations were needed to determine a balance between too tight and just enough for belt tension, even adjusting the spring loaded tensioner several times. Apparently each bank of valves have their way of increasing and decreasing belt tension as the engine is rotated, affecting overall belt tensioning. Struggling thru this until satisfied with more engine rotations, I finally finished and reassembled everything. It was midnight and wash up to rest and eat, rest up for the next day to test. Success. I do not fault using vice grips or the large fender washers with long bolts and nuts to lock camshafts in place. I'm the fault in assessing final timing marks that wasn't obvious the first time. Fortunately for me, one tooth off only resulted in a lumpy idle with no apparent damage of valves meeting pistons (idle after retiming is as smooth as when I bought the car with 12k miles). Acceleration seems no different. I didn't remove spark plugs and worked thru strong cylinder compressions. Hopefully, I didn't do damage unless someone more familiar than me will tell me otherwise.

To wrap up this saga, I have the water pump and three idler pulleys for anyone wanting to rebuild them - replacing bearings will renew these for lower cost but the bearings must be sourced, a bench press needed along with anything else to rebuild them. All I ask is the cost for shipping (UPS or postal, whichever is cheaper). The parts will sit on my bench until someone asks for them or they get tossed. The idler pulleys look near new with nearly zero wear of their black oxide surfaces. No discernible wear on any bearings but they all have 108k miles on them so replacing bearings is the wise thing to.

I went on a local drive after idling to full warm up in my garage to listen to the smooth idle. I left the check engine light on without resetting it. I made two stops, reset the oil change light (replaced oil filter when the OCI light turned on - only 4k miles on M1 oil and have used extended oil change intervals with the next oil change when the OCI light turns on). The cel didn't reset yet and I expect it to reset within the next few engine runs. The only error code is P0300. Any and all critiques accepted.

[lrbraner]

Glad your replacement was a success.
After replacing the timing belt and components on my 2002 L300 using the OTC tool kit (which I bought used on ebay for $50) I believe not using the tool kit increases the chance of small errors in timing. The tool kit has a metal plate that fits in the I.D. of the cam sprocket sets (i.e. 1-2 and 3-4) and has the timing marks engraved in it. Much more precise than using the marks on the back of the timing cover.
Due to the fact that both the idler pulleys are eccentric on the early 3.0, it is very easy to change the relationship between cams 1-2 and 3-4.
Timing can be off either way between the 2 sets of cams.
This was changed on later 3.0's to only the idler between the crankshaft and cams 3-4 was eccentric.
Also I question the ability to precisely find TDC with out above tool or removing the spark plug.
The tool has a part that bolts to the crank and locates against the water pump hub to locate TDC and keep it from moving while tightening the belt.
Just my opinion.

[fdryer]

My fault was not seeing camshaft #1 off one tooth. My only excuse? Poor eyesight and the hoses in the way to seeing a straight ahead view of the cam notch aligned to the rear cam shaft cover notch. .

As to ensuring the crankshaft is aligned for piston #1 at top dead center, the crankshaft hub groove on its face set at 6 o' clock aligned to the engine block notch at 6 o' clock meets tdc setup.

[fdryer]

As mentioned previously, I let the on board diagnostics determine when and on the the fifth driving cycle the OBD II system reset the check engine light.