Crankshaft Pulley


#1

I have a 1998 Toyota 4Runner SR5 w/3.0 2-wheel drive automatic. Timing belt was changed @ 100k. No real problems. It’s been a good vehicle. Then, @ 198k I had the time timing belt replace again. After approximately 2k miles I heard a tapping noise. It sounded like a deisel. The shop that did the belt change said it sounded like a lifter. Later on they said the key which holds the crank pulley on the shaft had been ground up. They’d never seen such before. Also, said I was really lucky the crank is okay – I’ve not seen it yet but I’m going to look at it before pulley is replaced – Anyway, they wouldn’t say what the pulley would cost, but a new one wasn’t much more than one off a junker. My question is: Did they botch the pulley while doing the belt job by not reinstalling something correctly?


#2

Very odd. They say it was ground up when they disassembled it the 2nd time, it was ok the first time I assume?.
I cannot see how the key woudl get ground up.
How did they remove the end nut. One method is to hold the pully and rotate the nut, there is a tool you can bolt onto the pulley on my Toy truck, yours may be similar. Now if osne one were to let that tool in place and then crank the engine you are in danger of shearing the key, just like you do when you hit a kerbstone with the bhade of your lawnmower and shear the key in it.

Another shade tree method of getting the nut off is attach a large socket and “T” handle. Then activate the starter and the the nut may come loose when the handle hits the ground. Assuming the engine rotation CW as you face it.

another possibility is they did not completely tighten the pully on reassembly, so it was sliding up and down the shaft, wearing out the key in the process, and wearing the slot in the pulley also.

Maybe someone forgot an end washer, so the bolt bottomed out in the crank, so it was tight, but the pully was still loose and tree to float. Engine vibration woudl do the rest over a long period.


#3

When they put the crankshaft pulley on, after the timing belt change, they didn’t get the crankshaft pulley bolt torqued correctly. Their mistake. They should be replacing the crankshaft pulley at no additional charge to you. They know it.


#4

something doesn’t sound right.

it would be unnecessary to even remove the crank pulley.

however, the timing belt tensioners may not haver been tightened or secured properly; or the idler pulley (s) may not have been replaced.

more info.

as HK says, the shop knows something is amiss, you need to hold their feet to the fire to get this returned to good condition.


#5

On these V6 engines with timing belts, removing the crank pully is a must to get at the lower belt pulley.


#6

I’ll betcha that the “wrenches” forgot the thick, flat washer between the bolt head and the face of the pulley. It is also critical to tighten that bolt to the torque specs. as per manufacturer’s or Chilton/Haynes specs. It sure sounds like the crank pulley slid back and forth on the crank shaft thus stripping out the key. I would certainly check the condition of the keyway on both the end of the crank and the inside of the pulley with an “eagle eye”. Make absolutely sure that when the new key is installed that it takes about a half a grunt, probably two thumbs worth of pressure, to get that key back in. Anything looser and you’re peeing up a rope against the wind. Ensure that they use a brand-new key. I highly suggest a new pulley. Why take a chance with the wrecking yard possibly dropping something in the dirt or on a rock? Make absolutely sure that the flat washer is installed. It is critical to space the retaining bolt by using that thick washer to accommodate proper torque of the bolt/crankshaft. Replace the belt tensioner with ‘new’, also.
Do you think that they’ll install parts bought by you? You can realize savings by just buying your own parts. Just buy the highest quality that you can though on parts like this, most are about the same quality. If the parts stores tell you that the pulley is a “Dealer item”, check other auto parts places. If you don’t have any luck that way, then consider a junk yard replacement. Like the carpentry mantra of ‘measure twice, cut once’, check all parts twice and install once.


#7

Thank you all so much for your helpful replies. Here’s the latest - I went today to the shop and looked at the crank pulley key myself. It’s boogered up at the very end of it. It appears the key was never properly seated in its place. Shop guy said he called Toyota and they said it was a design flaw and a very common problem. My reply was: Well, it’s run for 200k without this problem. He just shrugged his shoulders. I stated that it improperly reassembled. I know it, and you know it too. He said no. I don’t know about the flat washer between the bolt head and the face of the pulley, nor the torque they used. I looked at the crankshaft and it looks fine. But anyone with eyes can see the crank pulley is shiny just barely in side the key groove, and the key is not ground up; it’s twisted off at the very end tip of it. Is this stuff about “a common problem” bull or not? Thanks for all of y’all’s help – BigDan


#8

I doubt that it’s a common problem. Most Woodruff key and keyway problems are caused by failure to seat the key all the way, failure to tighten a bolt, etc.

What I would be concerned with here the most is just how tight a new key fits the keyway in the crankshaft. The key MUST fit tight. If the new key can be installed with the fingers only then odds are that it’s not going to last over the long haul and the next time could be catastrophic; as in new crankshaft.

If this is an alleged chronic problem then ALLDATA does not show a Technical Service Bulletin being issued about it. Maybe you should call Toyota and if they verify it’s not a problem then go back and present that info to the shop.


#9

I don’t think you need a new pulley, just a new key. I do think this is their fault though, I really sounds like someone forgot to torque down the crank nut. Let me add though that if the new key does not fit into the crank pulley groove very snugly, then the pulley will have to be replaced. The knocking sound you heard was the pulley rocking back and forth against the key.

Note: the key is made of softer material than either the crankshaft or the pulley so if it fails, it doesn’t damage either of them, theoretically anyway.


#10

I wanted anyone that’s been interested to know what I’ve found out. The mechanic admitted that he DID NOT use a torque wrench. Moreover, when asked how much torque he used he couldn’t say, so his reply was he thought about 65 ft/lbs. He didn’t even look up the factory specs to see what was called for. In the end he said he used a Snap-On portable impact wrench and it was plenty tight when he finished with it. We disagreed with each other. I got upset. He stands on his version that his work is beyond reproach. I’ll bet he used the rate manual to figure out how to pass the savings on to me, but didn’t think he needed the benefit of the shop manual to perform the job.
Thanks for all the input. Naturally, I’m screwed as usual. BigDan


#11

Thank you for keeping us informed. Wished we could be of more help.
The 65 ft. lbs. is not inherently bad and the truth be known, 65 should hold it fine.

In theory, hammering it down with an impact wrench should provide enough grunt to hold it. The problem here could be one of 2 things:

  1. Maybe the air compressor was down a bit at the moment he was tightening this and the torque being applied by that impact wrench was not enough.
  2. It’s possible the air tank was up and he hammered it too aggressively, leading to pulled threads. In this case it’s anyone’s guess what the real torque is. It could be 20 ft. lbs. or…

If his work was beyond reproach then he would have had the torque wrench out of its case and used that instead of a pneumatic hammer.
It would be interesting to examine the keyway and crankshaft bolt threads but without vehicle in hand anything I’ve posted here is pretty much theory only.

If it had been 20k miles or something since the belt was changed I would give the mechanic the benefit of the doubt. At the current vehicle mileage of around 200k and only 2k miles having passed since the work was done then this could very well point to improper tightening of the crank bolt.
No suggestions as to what to do about it though.


#12

My impact wrench worked just fine on the last timing belt job I had. No need to hold the crank with any such tool. Had to use a holding tool when I re-installed. I don’t use the impact tool on re-installs.


#13

Yes, sir, thank you for your reply. His air compressor was stolen lately and he’s got a really small one for airing up tires. I menioned to him about the small compressor and he said he used a battery powered wrench, Snap-On brand. Again, sir, thank you.