Problem changing timing belt 2.6L 4ZE1 engine

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Problem changing timing belt 2.6L 4ZE1 engine

Postby mcthorogood » Fri Jun 18, 2010 7:10 pm

I recently replaced the timing belt in my newly acquired 1988 Trooper II with an automatic transmission. To loosen the crankshaft pulley bolt, I used a breaker bar with wood blocks and cranked the starter. To hold the crankshaft pulley while torquing the crankshaft bolt, I used an 8" chain wrench and a leather belt to protect the crankshaft pulley.

Everything was fine until I tried to set the ignition timing 12 degrees BTDC. After fiddling for several days, I finally determined that the timing mark on the crankshaft pulley was not in the correct position.

The part of the pulley that is keyed onto the crankshaft is a harmonic balancer. The balancer is made of three parts; an inner flange keyed to the crankshaft, an outer ring which functions as a pulley, and a rubber ring that separates them. The balancer dampens torsional vibration of the crankshaft. While torquing the crankshaft pulley bolt the harmonic balancer must have slipped.

To make a new timing mark on the crankshaft pulley I removed the top timing belt cover, rotated the engine to the timing mark on the camshaft, and etched a new TDC mark with a Dremel on the crankshaft pulley that lines up with 0 degrees BTDC on the engine block.

Since the balancer only dampens torsional vibration, the angular relation between the inner and outer parts should make no difference. I'll have to check that the balancer doesn't slip anymore, by periodically checking the ignition timing against the new TDC mark. Next time I replace the timing belt, I'll have to replace the harmonic balancer.
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Postby shooter » Fri Jun 18, 2010 7:27 pm

All you needed to do was get the crank timing pully aligned with its match mark, same with cam pulley, and rotor button pointing to #4 terminal (inside of distributor) on the #4 cylinnder compression stroke TDC. You were correct though to make the new mark on the balancer.
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Postby squatch » Fri Jun 18, 2010 9:34 pm

Sounds like you got it. The slipped damper is common and not a problem as the engine is internally balanced.
For the belt set this mark on the crank.
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This mark on the cam. (my pic has a double mark but you get the idea).
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Then check the damper against those. If it's off mark it at the right hand tdc mark. When all the above are on the engine is at TDC for #4 cylinder.
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Like shooter said just mark or eyeball the dist to inside button for #4 in the cap with the rotor. You can use the timing light on #1 or 4 because they go up and down together but fire 180 degrees off from one another. Pulley mark works for either. You can also time these old jewels by ear like in the old days. Advance until it pings climbing hills and retard till it doesn't.
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Postby caveman » Sat Jun 19, 2010 10:44 pm

Your absolutely right. It doesn't matter that the harmonic balancer spins over time. It only causes problems when you need to set the ignition timing and or when you need the extra rpm from it to spin the water pump or the A/C compressor on a hot day. In the future you can buy a new one but don't count on those being around for very much longer. I've chosen to replace mine, some of the other planet members have as well. We're one step ahead of you bud :lurk:
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Postby onetouch » Sun Jun 20, 2010 5:05 am

Yeah, the balancer had slipped on the 89 and I just took the old school approach and advanced the timing too much, picked a nice steep hill, (not a problem in this neighborhood) and just ran it up the hill a few times, backing the timing off a little at a time until the pinging just stopped.

Ran it up to top dead center using the old finger in the spark plug hole method, and made my new mark.

Later on broke down and bought a new one from St. Charles, (wasn't cheap) put it on and checked it with a light and it was barely a half a degree out.

Kinda wish I'd saved my money on that one. :roll:

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Postby caveman » Sun Jun 20, 2010 3:37 pm

I hear you there, not many people have the ear to set the timing like you did thats what I call experience. :D
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