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Crank Bolt - Did I #&%@ Up?


AZ Mike
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1999 Lexus LS400 - interference engine - in attempting to loosen crank bolt, the pulley moved in CCW direction. I am thinking that this is a bad thing. Is it?

Mike:

Was the timing belt still in place on the crank pulley and cam pullies? If yes, then there shouldn't be any problem. Provided the belt was on, then the crank and the cams rotated in synchronization.

If the belt wasn't on, then yes, you could have done some serious damage. All it takes is just a little kiss of the top of a piston to hit a valve and bend it. It doesn't take much bending of a valve to lose all compression in a cylinder. One side of the valve raised 3 to 5 thousandth's of an inch and goodbye compression. I'd also suggest that you use cam locks anytime the belt is off. Install the locks prior to removing the belt.

There is an opening in the bellhousing to insert a bar through a hole in the flywheel to keep the crank from turning when you remove or re-install the crank bolt. Find it and use it. The torque on the crank bolt is something in the neighborhood of 180 foot pounds of torque.

Good luck and let us know how things progress.

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Whew! Timing belt is still on!! I was sweating bullets thinking that I had f'd up.

Can I loosen that nut with a socket driver with jack handle over driver (my poor man's breaker bar)? Or do I need to find a friend with an air driver?

What are cam locks? I get the idea that they prevent the pulleys from moving, but I have not heard of them before. Is that a loaner tool, or something I should go out and buy?

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Whew! Timing belt is still on!! I was sweating bullets thinking that I had f'd up.

Can I loosen that nut with a socket driver with jack handle over driver (my poor man's breaker bar)? Or do I need to find a friend with an air driver?

What are cam locks? I get the idea that they prevent the pulleys from moving, but I have not heard of them before. Is that a loaner tool, or something I should go out and buy?

Hi Mike:

I don't want to assume too much, but if you were trying to break the bolt loose with the timing belt still on (which is how you should do it), then no, you couldn't damage anything....... AS LONG AS THE CRANK AND BOTH CAMS TURNED IN SYNCHRONIZATION because the timing belt was still in place. Sorry.......

Cam locks are devices that clamp onto the back of the cam sprockets and keep them from moving when the belt is off. The lifters will cause the respective cam to find it's natural point of least spring pressure. That will probably not coincide with the alignment marks on the block (Crank) and heads (Cams). If the springs/lifters shift the cam while the belt is off....kiss, kiss $$$$. A lot of people will say you don't need the locks., I'm not one of them. Unfortunately, locks are not real common & they may be hard to find.

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Very interesting, Threadcutter. Thank you for bringing up the cam lock issue. I don't believe I have ever heard

mention of it in the T-belt replacement write-ups.

There was mention of cam locks by sapper_daddy in an earlier thread: http://us.lexusownersclub.com/forums/index...\&st=0

Is this somewhat the tool to which you are referring ---> http://www.shamanshop.net/store/proddetail...9195.0/file.htm

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Whew! Timing belt is still on!! I was sweating bullets thinking that I had f'd up.

Can I loosen that nut with a socket driver with jack handle over driver (my poor man's breaker bar)? Or do I need to find a friend with an air driver?

What are cam locks? I get the idea that they prevent the pulleys from moving, but I have not heard of them before. Is that a loaner tool, or something I should go out and buy?

Hi Mike:

I don't want to assume too much, but if you were trying to break the bolt loose with the timing belt still on (which is how you should do it), then no, you couldn't damage anything....... AS LONG AS THE CRANK AND BOTH CAMS TURNED IN SYNCHRONIZATION because the timing belt was still in place. Sorry.......

Cam locks are devices that clamp onto the back of the cam sprockets and keep them from moving when the belt is off. The lifters will cause the respective cam to find it's natural point of least spring pressure. That will probably not coincide with the alignment marks on the block (Crank) and heads (Cams). If the springs/lifters shift the cam while the belt is off....kiss, kiss $$$$. A lot of people will say you don't need the locks., I'm not one of them. Unfortunately, locks are not real common & they may be hard to find.

as long as you were turning by hand, then even if the belt wasnt on, its likely that you didnt damage anything. These engines have Iron valves. Very hard to bend by hand. If you were using an impact, air or otherwise, the outcome would be different.

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Very interesting, Threadcutter. Thank you for bringing up the cam lock issue. I don't believe I have ever heard

mention of it in the T-belt replacement write-ups.

There was mention of cam locks by sapper_daddy in an earlier thread: http://us.lexusownersclub.com/forums/index...\&st=0

Is this somewhat the tool to which you are referring ---> http://www.shamanshop.net/store/proddetail...9195.0/file.htm

landar;

Or, something like this.......same, but less;

http://www.sjdiscounttools.com/lis36880.html

Or like this...........different, but more;

eBay SIR Tools

The clearance behind the cam sprockets is tight. It might be that there is a cam lock tool that is specific to your motor as opposed to a generic, one size fits all tool. But for $28.00, it's worth a shot to see if it fits properly.

As I said earlier, if either cam is positioned in such a way that any of the cam lobes are pushed off center by the valve springs, when the cam goes (moves) it does so with a lot of force and it happens so fast, you won't see it.

If you wanted to risk it, you could try to rotate either cam sprocket by hand with the timing belt removed. There is enough force from all of the valve springs that the sprocket would chew up your hand. I wouldn't recommend trying it, you'd probably end up with at least one bent valve. It is the force from the valve springs that will cause the damage.

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Threadcutter...you've got me to thinking about this subject of holding the cam. Wondering about the following:

1) It seems that there might be some cam locations that would be much less likely to snap-rotate than others. For instance, TDC+x.

The manufacturer may know about this issue and be able to advise about a "safe" location to park the cam.

2) This would be more work, however back the rockers off and relieve the spring pressure on the loaded valves. Would require

pulling the valve covers and then later readjusting the tappets but that's a small price compared to damaged valves.

Just buy the cam lock, right?! :rolleyes:

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Threadcutter...you've got me to thinking about this subject of holding the cam. Wondering about the following:

1) It seems that there might be some cam locations that would be much less likely to snap-rotate than others. For instance, TDC+x.

The manufacturer may know about this issue and be able to advise about a "safe" location to park the cam.

2) This would be more work, however back the rockers off and relieve the spring pressure on the loaded valves. Would require

pulling the valve covers and then later readjusting the tappets but that's a small price compared to damaged valves.

Just buy the cam lock, right?! :rolleyes:

landar;

As far as I'm concerned, you're absolutely correct. One small thing though............Just exactly where is the "magic spot"? I don't know...........Makes it tough to, and potentially expensive to guess.

What I would suggest is get a set of locks that appears to come the closest to what you actually need. Before you remove the belt, put the locks in place and make sure everything is solidly staying put.

If you are satisfied the locks will hold everything solid, remove the locks, back out all spark plugs to remove compression, turn the whole works with a large ratchet on the crank bolt so the index marks on the crank and cam sprockets line up with their respective index marks on the heads and block. By backing out the plugs, you will not be fighting cylinder compression, only valve spring pressure. Re-install the locks , pop the belt off, replace the tensioner, pop the new belt on, double check for proper orientation/alignment/index marks and assuming it's all correct, remove the locks & you're done......no worries. Oh yeah, there is that little detail of putting everything else back together........Yechh.......

There is someone that lurks around here that might be willing/able to recommend a good set of locks. He lives on Vancouver Island (I'm very jealous.....) and besides being a bit cantankerous, he does quality work and I think he's the kind of person that would religiously use Cam locks. Maybe if he reads this post, he will chime in & tell us what he uses. I sometimes think if the engineers at Lexus were smart (they do pretty well in that department) they would have designed the cam sprockets with holes through them that would line up with threaded holes in the block. That way, you could line up the holes, put bolts through the holes in the sprockets, into threaded holes in the block & now you've got the whole works locked off. Simple & easy. My '95 didn't have it, but newer LS's might.

Oh, and BTW, the marks on the new belt will only line up with the index marks on the crank & cam sprockets AND motor index marks ONCE every number of belt teeth +1 revolution. If the belt has 72 teeth (A GUESS!, I don't remember how many there are), then all index marks will only line up 72 + 1, or every 73 revolutions. Don't go looking for everything to line up every 2nd, 3rd or 4th revolution. Won't happen.......been there, done that too.....

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Ok, this is going to sound like pure f'ing insanity, but i swear to god it's true..

When i bought my 01 is300 with 105k on her, i decided that she was going to get the 100k service. so i bought the tune up supplies and a timing belt and tensioner. then i took the car up to my buddy's shop and we went to work. he told me from the get-go that there was going to be one thing i didn't like when it came time to take off the crank pulley. i nodded and smiled. 'sure, sure. i know sometimes you've got to do some ugly stuff to get the job done.'

so we pull the thing apart, and he gets the front covers off and he's ready to take off the crank pulley. he puts a wrench on the crank pulley, and lowers the car just far enough that the wrench is almost touching the ground. then he tells me to get in the car. then he tells me to turn the key. this is where i start to get nervous. 'um, what?'. 'yeah, just give it a little bump.' so against my better judgement, i give it a little bump. the car damn near jumped off the lift! my buddy's laughing his !Removed! off cuz i'm cursing a blue streak, but i *BLEEP* you not, that crank pulley came loose!

he then tells me that this is the only way to get the pulley loose without having to remove the radiatior to get clearance for an impact gun. we put everything back together; haven't had a problem with her!

except for that damn headlight ballast.. but that's another story!

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I have used the starter alot of times. it is very ease "pipe on breaker bar" . But the way I look at it is U have to tighten it buy holding the flywheel might as well take it off that way. starter still works and crank bearings have no flat spot on them. it was a honda TSB that a read and got me to stop using the starter. do what u want. torque wrenches make it nice for the next guy toooooooooooooooooooooo

http://www.torqueinlesstime.com/

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Ok, this is going to sound like pure f'ing insanity, but i swear to god it's true..

When i bought my 01 is300 with 105k on her, i decided that she was going to get the 100k service. so i bought the tune up supplies and a timing belt and tensioner. then i took the car up to my buddy's shop and we went to work. he told me from the get-go that there was going to be one thing i didn't like when it came time to take off the crank pulley. i nodded and smiled. 'sure, sure. i know sometimes you've got to do some ugly stuff to get the job done.'

so we pull the thing apart, and he gets the front covers off and he's ready to take off the crank pulley. he puts a wrench on the crank pulley, and lowers the car just far enough that the wrench is almost touching the ground. then he tells me to get in the car. then he tells me to turn the key. this is where i start to get nervous. 'um, what?'. 'yeah, just give it a little bump.' so against my better judgement, i give it a little bump. the car damn near jumped off the lift! my buddy's laughing his !Removed! off cuz i'm cursing a blue streak, but i *BLEEP* you not, that crank pulley came loose!

he then tells me that this is the only way to get the pulley loose without having to remove the radiatior to get clearance for an impact gun. we put everything back together; haven't had a problem with her!

except for that damn headlight ballast.. but that's another story!

Yep, kinda makes you pucker up all over, doesn't it?................but it does work. It's just nasty though. Three fingers of Johnny Walker Black ahead of time helps a bit.

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