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Trying To Set Timing


jtbel
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On my 97 LS400, I had the cam pulley marks aligned with the marks at the cam rear plates. And, the crankshaft pulley mark at "0". Then I turned the crank 50 degrees clockwise. I removed old belt and installed new one. I put the bottom belt mark with the circle indention on the crank pulley, then aligned the left and right cam pulley marks with the belt marks. The problem is when I rotate the crank twice, the cam pulleys are only aligned with the rear plates, when the crank mark is on the most left notch (just left of the "10")instead of the "0". I checked it twice. Is this right or what did I do wrong? Thanks

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I was just looking at that. When turning the crank 50 degrees clockwise, my cams also turn, just like is shown. Then I install the belt like shown on the crank, then align the left and right cams with the marks on the belt, just like shown. At this point the crank pulley is still 50 degrees right from "0". So then I rotate twice, and the cams align with the rear plates, but the crank mark is at the 3rd mark before "0" (just left of the "10"). If I put crank mark at "0", then the cams will be right of the rear plate marks. I did it exactly as shown, the only thing I can think of is maybe the marks on wrong on the belt.

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Thanks for the great looking pic. By the way that you had the cam pulleys aligned with the rear plates and the belt marks, I would have to assume that you did not rotate the crank 50 degrees from "0". Am I right? Because if you had, the cam pulleys would have been about 25 degrees to the right of the rear plate marks. I'm also assuming that the pic was taken before you rotated the crank twice to check timing. Because I think after you rotate twice, the belt marks no longer align with the cam pulleys. Please let me know if you did or did not rotate the crank 50 degrees from "0", so that I may try that, because right now I am rotating it the 50 degrees (as the manual states), and it does not line up. Thanks

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no, we did not rotate the crank..... and we have replaced 5 TB jobs for family members and all ran /runs great, without rotating( we didnt know you were supposed to do it).... and now we know you dont have too. 3 LS400 & 2 LX470.

we just aligned the marks, removed the old belt - done our work- put the new belt on, never turned the cams or crank...

post-5365-0-01156500-1315482799_thumb.jp

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That 50 degrees is in there to allow for extra clearance between pistons and valves in case one (or both) the cams should 'snap-roll'(due to spring tension) a bit when you remove or reposition the belt. You probably could get by without rotating to 50 ATDC like Billy said.

Now, when aligning the new belt, you can go two routes. You can use the markings on the belt to align the crank to the cams or you can forget the belt marking and just make sure that when the crank is at 0 TDC, the cams align to the plates. But in any case, you are right to be concerned. Something is wrong. Do not even attempt to start that engine until both cams line up perfectly with the plates and the crank is @ 0 TDC and this after you have rotated the crank multiple times. Of course you know the cams only align every other crank revolution. But they should be in perfect sync.

Review this photo set of my 98 LS400 timing belt install and see if it provides any help ->

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Thanks a bunch guys! No, I'm not starting anything until everything aligns. That's probably true that if you don't rotate the 50 degrees, then you don't need markings on the belt at all. As long as the crank is at "0", and the cam pulleys align with the rear plates. I guess at this point, I will just put the crank at "0", take off the belt, then align the cam pulleys with the rear plates. I will use some wire to hold the cams in place, just to be safe until the belt is back on. I still can't understand how it is supposed to line up after rotating it 50 degrees, because it obviously did'nt work in my case.

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I still can't understand how it is supposed to line up after rotating it 50 degrees, because it obviously did'nt work in my case.

You probably are only off by a single tooth to cause the anomaly you see. Close but no cigar. The reason it all works @50 degrees is because you use the markings on the belt to get things aligned. First the CR on the crank dot, then the cams. I suppose it is possible(though doubtful) that you got a mis-marked belt. Is it OEM or aftermarket?

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Well guys I got it to work! Wow, what a difference! It drives like a brand new car. I'm pretty positive that the belt markings were off. If I were to do it again, I would'nt bother turning the crank 50 degrees. As long as you use some chicken wire going through the back of the cams to hold them steady, until you have the belt on. I would have to say that doing the timing belt seemed like it was a bit easier than changing the starter. Anyway, I had previously changed the plugs, wires, rotors, caps, and radiator, so it really drives like new. The symptoms I had were a code for the driver's cam sensor that kept coming back, would not start from cold without giving it gas, pinging during acceleration, and a miss at highway speed. I did'nt know if a new timing belt would fix it, but it was really cracked and shiny already, so I was planning to do it anyway. Either it jumped a tooth out of time, or the belt was stretching too much. Anyway, it was a very good result. Thanks especially to Paul for sending me the online manual.

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Well guys I got it to work! Wow, what a difference! It drives like a brand new car. I'm pretty positive that the belt markings were off. If I were to do it again, I would'nt bother turning the crank 50 degrees. As long as you use some chicken wire going through the back of the cams to hold them steady, until you have the belt on. I would have to say that doing the timing belt seemed like it was a bit easier than changing the starter. Anyway, I had previously changed the plugs, wires, rotors, caps, and radiator, so it really drives like new. The symptoms I had were a code for the driver's cam sensor that kept coming back, would not start from cold without giving it gas, pinging during acceleration, and a miss at highway speed. I did'nt know if a new timing belt would fix it, but it was really cracked and shiny already, so I was planning to do it anyway. Either it jumped a tooth out of time, or the belt was stretching too much. Anyway, it was a very good result. Thanks especially to Paul for sending me the online manual.

Well, congrats jtbel. Glad to hear you got things sorted out. You deserve a beer. :cheers:

So, how many miles were on the old belt and how did you finally resolve the issue? Did you just ignore the belt markings and put the belt on with crank at TDC and cams aligned to backplate?

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Well, the car has about 160,000 miles, and the belt had a bunch of small cracks and was very shiny, so I would assume that it was the original belt because going by the "every 90,000 mile" table, I doubt it would look that bad if it was the second belt. And yes, I installed the belt just as you described.

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