Urgent! Timing belt install/line-up question!!
05-26-14, 07:31 AM
#46
Well thanks for finding my tutorial "humorous to the extreme". That's why I took the time and pains to publish it...for your amusement.
Here's the deal. You can use the marks on the belt to get the initial alignment set. I know the OEM belts are plainly marked and if you align the belt marks with the marks on the cam pulleys and crank, you should have perfect timing. However, the REAL proof of correct timing is not in the belt markings but rather the metal stamping in the pulleys and engine. Those marks are permanent and are the ONLY ones you should ultimately use to decide if your timing is correct. I just got done with replacing a 92 LS400 belt and the timing was dead on with the stampings after initially using the belt markings to install the belt with the tensioner installed (though pin not yet pulled). After pulling the tensioner pin, we rotated the crank 720 degrees and verified that the stamped marks were exactly on. Engine ran perfectly.
I do not know why you are sounding some kind of alarm that all of this is now somehow incorrect.
Here's the deal. You can use the marks on the belt to get the initial alignment set. I know the OEM belts are plainly marked and if you align the belt marks with the marks on the cam pulleys and crank, you should have perfect timing. However, the REAL proof of correct timing is not in the belt markings but rather the metal stamping in the pulleys and engine. Those marks are permanent and are the ONLY ones you should ultimately use to decide if your timing is correct. I just got done with replacing a 92 LS400 belt and the timing was dead on with the stampings after initially using the belt markings to install the belt with the tensioner installed (though pin not yet pulled). After pulling the tensioner pin, we rotated the crank 720 degrees and verified that the stamped marks were exactly on. Engine ran perfectly.
I do not know why you are sounding some kind of alarm that all of this is now somehow incorrect.
06-20-14, 10:12 AM
#47
No guys, that's really not it.
And I apologize for the "extreme" comment Randal. Your tut is very much one of the best on the net, it obviously wasn't created for my amusement - I shouldn't have belittled it.
Because you said you just did a 1992 LS and it worked - possibly this points to some special circumstance?
All I can speak to is that each of the independent shop mechanics, Lexus dealership mechanics, and private people who have done this job that I've asked in person - have all said exactly the same thing: "Advance the crank by one tooth - or do the job over again."
Again: If you follow the factory shop manual instructions which tell you to line up the belt's white marks with the crank and cams when set to TDC (crank) and aligned to the metal marks on the black shields (cams)... and then you release the hydraulic tensioner, Bam, that's it. The cams will rotate counter clockwise out of perfect timing. If you start the car, there is very little power, it shudders under throttle, and if you leave the motor running, within a few minutes you'll have a glowing passenger side (USDM models - obviously right hand drive would be "drivers" side in this case) cat and exhaust manifold.
This actually looks very much like what happens when you loose one side or the other's coil pack (glowing manifolds and cats) - but in this case it's due to not setting the belt off by one tooth on the crank.
I know - it sounds completely wacky - but that's why all the "alarm".
If you lived in my area (Tampa FL), I invite you to my spot to see for yourself. It's a comfortable working space (all things considered) and I'll supply the tools, beers and food
And I apologize for the "extreme" comment Randal. Your tut is very much one of the best on the net, it obviously wasn't created for my amusement - I shouldn't have belittled it.
Because you said you just did a 1992 LS and it worked - possibly this points to some special circumstance?
All I can speak to is that each of the independent shop mechanics, Lexus dealership mechanics, and private people who have done this job that I've asked in person - have all said exactly the same thing: "Advance the crank by one tooth - or do the job over again."
Again: If you follow the factory shop manual instructions which tell you to line up the belt's white marks with the crank and cams when set to TDC (crank) and aligned to the metal marks on the black shields (cams)... and then you release the hydraulic tensioner, Bam, that's it. The cams will rotate counter clockwise out of perfect timing. If you start the car, there is very little power, it shudders under throttle, and if you leave the motor running, within a few minutes you'll have a glowing passenger side (USDM models - obviously right hand drive would be "drivers" side in this case) cat and exhaust manifold.
This actually looks very much like what happens when you loose one side or the other's coil pack (glowing manifolds and cats) - but in this case it's due to not setting the belt off by one tooth on the crank.
I know - it sounds completely wacky - but that's why all the "alarm".
If you lived in my area (Tampa FL), I invite you to my spot to see for yourself. It's a comfortable working space (all things considered) and I'll supply the tools, beers and food
Last edited by CLRH2O; 06-20-14 at 10:24 AM.
06-23-14, 06:05 PM
#48
Well, all I know is that of the three Lexus engines that I have done thus far, I have never had to advance the crank by one tooth to compensate for the tensioner. I get the belt marks lined up perfectly, pull the tensioner pin and then rotate the crank two revs and recheck the permanent engine marks. They have aligned perfectly and confirm the initial belt markings. The engines have then all run flawlessly as well. Maybe it is different for others, but I have had no issues with the FSM procedure.
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