Timing belt slippage - how much is too much?
#1
Timing belt slippage - how much is too much?
1996 4-runner, 270K miles on it. Non running. The report from son #4 is that "it just quit." His mechanic claimed probably a broken rod. Daughter #4 is a serious gearhead, so she wants to fix it for the experience. Had the truck towed to the house.
Test #1 - lets see if it cranks. And it does. And nothing is clanking - I think one would hear a broken rod... but the engine is clearly struggling... and I think timing belt.
So, into the engine bay we go, off comes the timing belt cover... Timing belt is not broken and actually looks pretty good. We lined cams up to TDC. Looking at the crank pully, it is a good 5 degrees post TDC.
Is this enough to cause the engine to stop running? I know its a noob question, first time I've even done this, so I'm a noob
Thanks
Test #1 - lets see if it cranks. And it does. And nothing is clanking - I think one would hear a broken rod... but the engine is clearly struggling... and I think timing belt.
So, into the engine bay we go, off comes the timing belt cover... Timing belt is not broken and actually looks pretty good. We lined cams up to TDC. Looking at the crank pully, it is a good 5 degrees post TDC.
Is this enough to cause the engine to stop running? I know its a noob question, first time I've even done this, so I'm a noob
Thanks
#2
Registered User
iTrader: (1)
Any slipping of the timing belt is to much
Have you pulled the codes !!??
I am curious what you will see.
If it stopped along the road it should have tripped something
I would venture it saw a big difference between the crank sensor and cam sensor and shut the fuel off.
Without knowing and being in person it is just a guess.
Have you pulled the codes !!??
I am curious what you will see.
If it stopped along the road it should have tripped something
I would venture it saw a big difference between the crank sensor and cam sensor and shut the fuel off.
Without knowing and being in person it is just a guess.
Last edited by wyoming9; 07-25-2015 at 10:53 AM.
#3
re: codes
never even thought to do it! good idea.
I'm just assuming it jumped a tooth or two. But I would think that if the crank and cams were properly aligned, the should be EXACTLY on TDC, right?
I'm just assuming it jumped a tooth or two. But I would think that if the crank and cams were properly aligned, the should be EXACTLY on TDC, right?
#5
Registered User
Timing belts will not slip without damage to the belt due to the teeth. What may have happened is crank bolt may not have been tightened properly leading to a sheared Woodruff key, allowing the crank pulley to slip a few degrees. Since ignition timing is keyed off the magnets in the sprocket, this could cause the motor not to run, even though crank and cam are still correctly aligned.
Last edited by TheDurk; 07-25-2015 at 11:01 PM.
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