Toyota corolla 160i with 3zzfe engine exhaust cam timing gear key way breaking

Timing marks are often not on the engine but on plastic covers

Might check for restricted exhaust--bad converter. Any codes set?

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If its the 1.6litre 4afe. Turn the crankshaft to TDC, ie. Tiny slit on the crank pulley should be straight underneath the 0deg mark. The cams, intake cam is driven off the exhaust cam by means of two gears. Installation marks. They have 4 holes in front of the gears. Front being closest to timing belt. Upon installation one hole in each gear should face upwards and the other holes should face each other between the gears. On the exhaust cam pulley there is a hole drilled through it, ie. timing mark. It should face up. Directly inline with the grove in the first cam cap. If you have 1.6litre 4age engine. Between cam gears and cylinder head there should be a plate. groves in cam gears should face the groves in the the plate.

run fault codes to find which sensors have not been installed correctly or are defective. Possible cam/crank position sensor faulty. It is very easy to miss a connection or incorrectly put a connection together.

You need to have the alarm module scanned by the dealer.

Dual overhead cams?

With engine Crankshaft on TDC and cam timing set correctly this is the position where No. 1 cylinder is firing at the start of the power stroke. At this point No. 4 cylinder is also at TDC but is just at the end of the exhaust stroke and starting the intake stroke so the exhaust valve will be almost finished closing and the inlet valve will just be starting to open. This is referred to as the inlet and exhaust valves rocking.

sounds like you had an oil feed problem to the head and the camshaft seized ,could have been low on oil ?? not sure i think it might have a keyway on cam but cant remember if its part of the cam casting or a woodruff key .if it was part of the camshaft casting then this would account for damage but to break the bolt as well then i would look further ,to be totally honest without the engine in front of me i cannot diagnose what caused the failure .

j__quin: 4-AC engine I believe we are both referring to.
Your cam gear can only fit one way and if you look at the cam gear, you will notice that there is a small hole in the gear close to the center, somewhat in between two of the large holes.
Position that small hole at the 12:00 PM and look through the hole.
You should be able to see a timing mark through the hole on the head. The mark should be dead center.
At the bottom, the crank woodruff key will be at 12:00 PM.
Also on the back side of the timing gear on the crank closest to the block, is a notch "V" which you line up with a dot on the block.
You should see the two line up with the key in the 12:00 PM position.
Put the belt on, when you set the tension, a good way to check it, is to find the longest span between the tensioner and the gear.
Take your fore finger and thumb and try to twist the belt. It shouldn't twist more than 45 degrees.
Good luck.