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Changing the timing belt on a recently purchased 2003 RX300 with 161K. Decided to change because I didn't know when/if previous owner had done the service, and there was no sticker on the TB cover. I had not noticed any issues while driving.
After removing the upper and lower timing belt covers to get at the belt, I tried to align the crankshaft and camshaft pulleys, but the timing marks don't align!
I took some pictures of the aligning marks.
You can see that the cam pulley marks line up with the timing marks, but the mark on the belt is 2-3 inches away. Same for the rear cam and the crankshaft.
I am perplexed as to cause, and it didn't seem to be creating any driving issues. The Aisin kit instructions states the 1MZ-FE engine is a "FREEWHEELING" engine and therefore "...the possibility of valve-to-piston damage in the event of a timing belt failure may be minimal or very unlikely."I would appreciate any comments / suggestions on re-aligning the marks. Somehow the vehicle was able to compensate so as not to affect drivability.
I would appreciate everyone's thoughts on how to proceed. My thoughts are as follows:
- Adjust with the old belt on so that the crankshafft pulley is on-mark, which means the front and back cams will be off-mark.
- Remove the old timing belt
- Align the front cam and back cams onto their respective marks
- Install the new belt
Postion of the crank with the mark and the cams with the mark should always stay in sync. Just verify that these three are on mark and ignore the markings on the belt. While the cam and the main have 1:2 relationship the belt is long.
As far free-wheeling (non-interfering), the RX has VVT and in certain condition the cam can be advanced enough to interfere.
Incidentally, the marked side of the belt goes over the tensioner pulleys and after a w while of running the markings are rubbed off. So if you have the marks, it means the belt has been replaced not so long ago.
The mark on the crank is definitely off while the two marks are at top-dead center. The only issue with the vehicle is a rattle from under the valve cover on cold start, lasts thirty seconds or so. Otherwise no drivability issues at all.
Crank mark is bit hard to tell and the best way is to mount the pulley, You dont have to bolt it on as the pulley goes on on one position.
For 1:2, the best place would be reading up on 4 stroke engines. Do not spin the crankshaft once you have the belt off. The crankshaft will match the mark on exhaust stroke and on compassion stroke and only the compression TDC is correct.
Got it, 1:2 means one turn of the cam for every two of the crank, so you have to be careful for intake vs. exhaust stroke alignment.
Can you also tell me what to look for when the pulley is mounted? I am not aware of any timing marks on the pulley.
The car ran fine before, so likely the car was in-timing before service. It is most likely that I caused the problem during the tear-down.
When I was trying to get the timing marks to line up initially, I used the nut on the front camshaft pulley. Turning was not smooth, so I'm thinking it's possible that the belt "jumped" a few notches on the crank when I did that.
The main pulley has a mark and one of the plastic t-belt covers (bottom one if my memory serves me right) has 0 and +/- markings. You can temporarily mount the cover and pulley and clearly observe the 0.
One has to be careful, but you remove the spark plugs, then you dont have to fight the compression, but 1-3-5 have poor access. Luckily the compression is not to bad. The tensioner is supposed to take up the slack and you can not jump the belt even with jurkey motion.
I took a video of what happens when the front cam was used to rotate the belt. Pushing from the cam created a bulge in the belt feeding the crank, and the tensioner can't take up the slack from the front. The belt did eventually jump the crank in the last seconds of the video.
As secondary confirmation of the jump, I lined up the cam marks again by pulling on the crankshaft, and now the crank mark is even further to the left than before rotating from the front cam again.
I then did two full rotations of the crankshaft, whereon all the marks fell on their previous spot (confirming normal 2:1 rotation ratio of crank:cam).
No matter what, I'll be checking top-dead-center and valve positions before I put things back together. And I won't be using the cam anymore to move the timing belt!
I normally use the cams and crank to take up slack. Makes it easier to inatall the belt over the teeth, so turn it back a tooth then slip belt on, then move back forward, to tighten. I then use zip ties on cams to keep belt from slipping.
It Should be pretty tight, except the leg where the tensioner will be installed. Which when you install it and pull pin it will take out that slack. Then turn engine over a few times, make sure cams/crank still line up.
As far free-wheeling (non-interfering), the RX has VVT and in certain condition the cam can be advanced enough to interfere. Salim
This topic was discussed on another forum a few months ago. I made this same assertion and was challenged so I started doing a little research. Can not remember which forum now, but a couple old timers who appeared to be experts on this issue said under no circumstances, with or without VVTi, is the 1MZFE interference. They were frustrated that this myth would not die. They had torn the engine down, made measurements, etc, etc. For me it is a non-issue because I do not push the TB, usually changing it well before it is due. I do not know the truth here, but I do not think we can say for sure that the 1MZFE engine with VVTi is interference under any condition.
This is where the marks on the belt come to rescue. Start by rear (next to the fire wall) cam on the mark and the belt on the mark. One trick is to put a zip-tie to lock the belt to the cam. Drape the belt over the front cam making sure the cam aligns with the mark and the belt mark is on the spot too [techs generally do not use the marks on the belt and they ensure there is no slack. You can turn the front cam a bit to create slack, but the belt should be taunt between the two cams and both the cams must be at the mark(s). Finally the crank must be at TDC mark and there should be no slack between the front cam and the crank. All slack should be on the tensioner side and only pull the pin after making sure there is no slack between cams and the front cam -to-crank and all three members are on their mark.
Remember to clip the zip tie if you have used it before hand cracking the crankshaft 2 turns to very there is no interference and timing remains good.
This topic was discussed on another forum a few months ago. I made this same assertion and was challenged so I started doing a little research. Can not remember which forum now, but a couple old timers who appeared to be experts on this issue said under no circumstances, with or without VVTi, is the 1MZFE interference. They were frustrated that this myth would not die. They had torn the engine down, made measurements, etc, etc. For me it is a non-issue because I do not push the TB, usually changing it well before it is due. I do not know the truth here, but I do not think we can say for sure that the 1MZFE engine with VVTi is interference under any condition.
Art: I know the V8 vvti is interfering. The non vvti V8 [old LS/SC] are not. When it comes to RX there are posts that claim interfering/non-interfering. I use weasel words to protect members. At the same time, I too am strong proponent of 90k (max 110k) replacement of of the T belt as the rollers and tensioner needs to be examined. My other thought is how many timing belt services would an owner save by putting off the replacement.
Art: I know the V8 vvti is interfering. The non vvti V8 [old LS/SC] are not. When it comes to RX there are posts that claim interfering/non-interfering. I use weasel words to protect members. At the same time, I too am strong proponent of 90k (max 110k) replacement of of the T belt as the rollers and tensioner needs to be examined. My other thought is how many timing belt services would an owner save by putting off the replacement.
Salim
Agree, V8 is totally different animal. Also agree that interference or not should not be a factor. Who wants to be traveling at high speed on busy interstate and have TB fail? Your engine may not be damaged but you may be killed or kill someone else.
The post-op on my timing belt work is all positive.
Turns out the old hydraulic tensioner was quite weak, such that the plunger could be depressed a few millimeters just with finger pressure. That must be how the timing belt was able to jump the belt when turning from the front cam - mentioned above. The tensioner wasn't doing it's job.
Even better, in this previous thread, I was trying to diagnose an engine noise/clacking that developed not long after we had purchased the car.
Well, replacing the tensioner (plus TB, pulleys, etc etc) actually fixed that problem too.
I heard a plasticky ratling sounds on your second (warm) idle in the 2016 post. I have that problem and it clears up when I change the timing belts and tensioner/pulleys. But it keeps coming back after about 10-12k miles. Only solution is to change the timing belt and tensioner/pulleys again. All Toyota parts.
07-20-17, 09:50 AM
Old Timing Belt Not aligned!
