1997 LS400 Timing belt possibly skipped teeth
01-21-14, 11:09 AM
#16
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Ok, you got me again….
I should have said that I checked the cam marks when the crankshaft pulley was on the 0º timing mark. I believe that is when all marks should align.
However, I went back and checked the cam gear marks at TDC as determined by using a screwdriver in the number 1 cylinder (front, driver's side). I found that 0º is not TDC. TDC is after the 0º timing mark on the crank (is this correct?)
At TDC determined by the screwdriver, the RH cam gear mark is 3 teeth before the backplate mark, and the LH cam gear is correct.
I did the screwdriver test this morning before heading to work, so it was a quick test, but I am kinda trippin' on the 0º not being TDC. Is this possible or is it user error??
I should have said that I checked the cam marks when the crankshaft pulley was on the 0º timing mark. I believe that is when all marks should align.
However, I went back and checked the cam gear marks at TDC as determined by using a screwdriver in the number 1 cylinder (front, driver's side). I found that 0º is not TDC. TDC is after the 0º timing mark on the crank (is this correct?)
At TDC determined by the screwdriver, the RH cam gear mark is 3 teeth before the backplate mark, and the LH cam gear is correct.
I did the screwdriver test this morning before heading to work, so it was a quick test, but I am kinda trippin' on the 0º not being TDC. Is this possible or is it user error??
01-21-14, 11:10 AM
#17
Driver School Candidate
timing belt marks
Bob,
I'm replacing timing belt and water pump right now on 96 LS400. My timing belt kit came with instructions that are helpful for this procedure. Especially for aligning the crankshaft and camshaft gears for the timing. You have to be very careful on this and very specific for the year of your lexus.
In addition to the instructions I received with my timing belt kit, I have used several online guides to help me with this installation. You might want to check these out. http://www.lextreme.com/timing.htm
http://www.lextreme.com/timing2.html
The second link is extremely helpful for making sure you use the correct marks on your crank and cam gears to align your timing. One more thing that was very helpful to me was the fact that someone had marked the timing marks on my cam gears with white out so that I can easily spot them. Two more links that show the process of setting timing before removal of timing belt and upon install of timing belt:
https://www.clublexus.com/forums/att...7&d=1265665165
https://www.clublexus.com/forums/att...6&d=1265665165
Someone please double check me on these because they are for my 96 and I'm not positive that his 97 is exactly the same procedure and timing marks. My year does have interference engine.
I'm replacing timing belt and water pump right now on 96 LS400. My timing belt kit came with instructions that are helpful for this procedure. Especially for aligning the crankshaft and camshaft gears for the timing. You have to be very careful on this and very specific for the year of your lexus.
In addition to the instructions I received with my timing belt kit, I have used several online guides to help me with this installation. You might want to check these out. http://www.lextreme.com/timing.htm
http://www.lextreme.com/timing2.html
The second link is extremely helpful for making sure you use the correct marks on your crank and cam gears to align your timing. One more thing that was very helpful to me was the fact that someone had marked the timing marks on my cam gears with white out so that I can easily spot them. Two more links that show the process of setting timing before removal of timing belt and upon install of timing belt:
https://www.clublexus.com/forums/att...7&d=1265665165
https://www.clublexus.com/forums/att...6&d=1265665165
Someone please double check me on these because they are for my 96 and I'm not positive that his 97 is exactly the same procedure and timing marks. My year does have interference engine.
01-21-14, 11:17 AM
#18
Driver School Candidate
Tdc
The cam shaft marks will only align on every other rotation of the cranks shaft. So, if you are at 0 with the crank shaft, you might be on the wrong rotation. Rotate crankshaft clockwise until you reach 0 again and see if the cams marks align.
If you read the two documents that I just posted on the previous post I think you will figure it out.
If you read the two documents that I just posted on the previous post I think you will figure it out.
01-21-14, 10:29 PM
#19
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Thanks for the links. They have some good info.
I am waiting for the parts to do the job.
I am checking the cam marks for each rotation, and the case I discuss above is on the correct stroke (unless the cams are waaay off due to the TB slipping).
I placed a screwdriver in the #1 cylinder (front, drivers side) then slowly turned the crank clockwise until it stopped moving up.
LScowboy, is this correct? Am I doing something wrong?
I have some pictures to show the mis-alignment:
----
I am waiting for the parts to do the job.
I am checking the cam marks for each rotation, and the case I discuss above is on the correct stroke (unless the cams are waaay off due to the TB slipping).
I placed a screwdriver in the #1 cylinder (front, drivers side) then slowly turned the crank clockwise until it stopped moving up.
LScowboy, is this correct? Am I doing something wrong?
I have some pictures to show the mis-alignment:
----
01-22-14, 05:58 AM
#20
Lexus Champion
sorry, for some reason, your posts from yesterday are just now showing up, maybe there is a server issue on Club Lexus!
anyways, finding the top of the stroke with a pencil or whatever is just the first check, you have to insure you are on the compression stroke, rather than the exhaust stroke - I normally do this by testing cylinder #1 for ability to hold pressure (if it were on exhaust stroke, the exhaust valve would be wide open)
a few more points:
● always turn crank clockwise, never counter-clockwise - if you miss your mark, go two more full revolutions and try again, do not back-up
● confirm TDC via rotor position of driver's side rotor as well
● confirm that crank pulley is tight as a rock, a worn keyway and therefore loose pulley will create havoc in your measurements (and in how the car runs)
and to answer your earlier question:
● TDC always falls at the 0 degree mark (every other rotation), if crank pulley is installed correctly and not worn
more important points:
● it is much easier to feel what is going on in the engine, and turn it smoothly, with plugs out!
● learn the 50 degree technique when setting cams, so they don't try to move on you
anyways, finding the top of the stroke with a pencil or whatever is just the first check, you have to insure you are on the compression stroke, rather than the exhaust stroke - I normally do this by testing cylinder #1 for ability to hold pressure (if it were on exhaust stroke, the exhaust valve would be wide open)
a few more points:
● always turn crank clockwise, never counter-clockwise - if you miss your mark, go two more full revolutions and try again, do not back-up
● confirm TDC via rotor position of driver's side rotor as well
● confirm that crank pulley is tight as a rock, a worn keyway and therefore loose pulley will create havoc in your measurements (and in how the car runs)
and to answer your earlier question:
● TDC always falls at the 0 degree mark (every other rotation), if crank pulley is installed correctly and not worn
more important points:
● it is much easier to feel what is going on in the engine, and turn it smoothly, with plugs out!
● learn the 50 degree technique when setting cams, so they don't try to move on you
Last edited by LScowboyLS; 01-22-14 at 06:03 AM.
01-22-14, 06:14 AM
#21
Lexus Champion
a couple of other things, the marks on the belt are just a convenience, the don't actually matter, what matters are 6 marks that have to align:
● crank pulley mark to 0 mark
● driver's cam pulley mark to cam pulley backing plate mark
● passenger's cam pulley mark to cam pulley backing plate mark
this video, done by an amateur, is a very good job on the timing belt by
● crank pulley mark to 0 mark
● driver's cam pulley mark to cam pulley backing plate mark
● passenger's cam pulley mark to cam pulley backing plate mark
this video, done by an amateur, is a very good job on the timing belt by
01-25-14, 11:30 PM
#22
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Discovered why 0º is not TDC
I am still waiting for the parts, but I pulled off the Harmonic balancer, and found a problem. It was installed incorrectly by the guy I bought the car from.
The reason why the 0º timing mark is not TDC for the number 1 piston is because the guy installed the pulley without lining-up the woodruff key with the keyway in the pulley. He pressed the pulley onto the key at about 40º clockwise from the correct position.
So taking this into account, the LH cam is correct at TDC, and the RH cam is off by 3 teeth.
Pictures:
The reason why the 0º timing mark is not TDC for the number 1 piston is because the guy installed the pulley without lining-up the woodruff key with the keyway in the pulley. He pressed the pulley onto the key at about 40º clockwise from the correct position.
So taking this into account, the LH cam is correct at TDC, and the RH cam is off by 3 teeth.
Pictures:
01-26-14, 09:19 AM
#24
You have to try and mess up installing the harmonic balancer!! It slips right on when you have it lined up properly! That must have been a ton of work to put it on like that. Everyone makes mistakes but that is just amazing.
01-26-14, 10:13 AM
#26
Lexus Champion
we are seeing a lot of this lately! - I think I am going to start recommending that folks pull their crank pulley and inspect whenever things get weird.
I am still in shock that there are mechanics out their dumb enough to move a woodruff key location, they are beyond retarded!
by the way, I would replace the $1 key for sure and you can probably clean up the keyway in that crank damper pulley with a dental pick, just make sure that with the new key and cleaned keyway, that when the pulley is reinstalled that it fits rock solid with no play or wobble, or else you will have to replace the $212 pulley from a good online Lexus dealership
I am still in shock that there are mechanics out their dumb enough to move a woodruff key location, they are beyond retarded!
by the way, I would replace the $1 key for sure and you can probably clean up the keyway in that crank damper pulley with a dental pick, just make sure that with the new key and cleaned keyway, that when the pulley is reinstalled that it fits rock solid with no play or wobble, or else you will have to replace the $212 pulley from a good online Lexus dealership
Last edited by LScowboyLS; 01-26-14 at 10:25 AM.
01-26-14, 04:01 PM
#27
Never underestimate, I guess. I never would've 'thunk' some mechanic would not feel the pulley key falling into place before tightening that crank bolt but...they did. Absolutely stunning. Good find dcrobria. Now, hopefully there are no 'kissed' valves. You probably will want to do a complete timing belt/water pump rebuild.
01-26-14, 08:54 PM
#30
Lexus Champion
I am not sure it was an accident, I think it could have been some Beavis who couldn't seem to get the timing marks to properly align, so he decided to "move that dang slot that is in the wrong place" and make it in a place that gets everything to line up - lol