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sometimes-pilot

4afe Valve Timing

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my daughter overheated her Geo (sorry, not a corolla) which has the 4AFE engine, and the cylinder head is too far gone to machine, so I got a used engine, 77,000 mi, out of a salvage yard. good time to replace the timing belt & water pump, so the engine is on my garage floor before installing them.

 

however, when i rolled the crank over to tdc the camshaft TDC timing marks weren't where I thought they're supposed to be...meeting on a horizontal plane ( i think i'm right but am willing to be corrected). if i line up the camshaft TDC timing, the crankshaft timing mark shows 15 degrees after TDC; put anothe way, i believe cam timing is 15 degrees before where it should be.

 

i talked with a mechanic who suggested maybe the belt slipped a tooth, but said performance would be obviously much poorer.

 

so here's my questions: it's a non-interference engine, so i am presuming that valve timing which is off 15 degree will not have the valves & pistons coming together, and therefore that's no consequence.

 

next: is there any possibility that a DPO would have knowingly advanced the valve timing to get some performance advantage.

 

am i correct about the camshaft timing marks should be in horizontal alinement at TDC (looking through the exhaust camshaft hole, the timing mark on the #1 exhaust bearing lines up correctly at this point).

 

TIA,

 

Steve Rineer

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Hello and welcome to the forums. I'm pretty sure it sounds like you got TDC for piston #1 correct - double check and line up the hole of the camshaft timing pulley with the timing mark on the bearing cap. Make sure the crankshaft position key groove is pointing upward. Verify that the piston is at TDC via physical check.

 

There should be two sets of match markes on the pulleys and belt - make sure they line up verically (one set on the crankshaft pulley and one on the camshaft pulley) - should double check that the timing marks from earlier line up (camshaft timing pulley with the timing mark on the bearing cap and timing tab by the crank). I usually turn it a full two revolutions to get it back up to TDC and verify the marks - good way to double check and make sure that nothing shifted.

 

Might be able to find some online photos on the Autozone website - free service, and makes 100% more sense if you have a picture to go along with the explantion. Hope that helps.

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Hello and welcome to the forums. I'm pretty sure it sounds like you got TDC for piston #1 correct - double check and line up the hole of the camshaft timing pulley with the timing mark on the bearing cap. Make sure the crankshaft position key groove is pointing upward. Verify that the piston is at TDC via physical check.

 

There should be two sets of match markes on the pulleys and belt - make sure they line up verically (one set on the crankshaft pulley and one on the camshaft pulley) - should double check that the timing marks from earlier line up (camshaft timing pulley with the timing mark on the bearing cap and timing tab by the crank). I usually turn it a full two revolutions to get it back up to TDC and verify the marks - good way to double check and make sure that nothing shifted.

 

Might be able to find some online photos on the Autozone website - free service, and makes 100% more sense if you have a picture to go along with the explantion. Hope that helps.

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Thanks...

 

the timing belt definitely slipped a tooth at some point. One mistake I made is that 15 degrees of rotation at the crank ends up being only 7-1/2 degrees error where it counts...at the camshaft end, because the camshaft rotates at half the speed of the crank.

 

i slipped a rod down the spark plug hole to make sure the crank TDC timing mark was correct (it was, but i wanted to verify).

 

using a punch through the sprocket hole to the exhaust cam bearing satisfied me that it was off only one tooth, ergo 7-1/2 degrees. i'm not the brightest at this stuff, so tonight i was counting cam sprocket teeth and got 48. 360 degrees divided by 48 = 7-1/2 degrees.

 

7-1/2 degrees of error at the cam gives me a little better feeling that it is unlikely (if it ever was possible) that something got bent inside.

 

thanks for the help...sure wish i knew about this site a while ago.

 

regards,

 

steve rineer

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My factory repair manuals give instructions (and also pictures) on how to set the timing.

You do have to get everything lined up correctly for the timing to work.

I had a car that would not start (could not find anything wrong, relays, fuses, etc.) due to timing belt off.

Changed the belt a tooth or two (or three) and the car started right up.

It also had the 4A-FE 1.6L engine.

Glad to hear that you got it all fixed.

Come back to the forum anytime.

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Guest NELLY CAPE TOWN

HI MY CAROLLA 160I GLE 4AFE ENGINE HAS A TAPPING SOUND COMING FROM THE CAMPS CAN I REPLACE THE SOLID SIMS WITH THE MODERN HYDRAULIC ONES IS IT POSSIBLE OR IS THERE A SPECIFIC HYDRAULIC SIM FOR THE 4AFE PLS REPLY

 

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