BY5260

I'm trying to install the new timing belt and I'm confused with the proper marks for lining this up. I stopped at my Lexus dealer and the mechanic told me that I definitely have an "Interference Engine". I know there's been some confusion about this engine being interference. That worries me as I've turned the camshafts numerous times in an attempt to line them up and look for marks.

I've listed some pictures for reference. I appreciate any help that you may be able to provide. Picture #1 shows what engine I have.

This is on a 2005 ES330. The second picture shows the front/left cam. You can clearly see the red mark on the timing cover #3 and on the sprocket. I could line-up these marks but it is somewhat difficult to get them exactly aligned as the sprocket seems spring loaded and it wants to stop at certain spots. When I align these marks it's between these spots so it takes a little work to hold it proper.

The third picture shows the crankshaft with the gear installed. You can clearly see the yellowish mark on this gear (about 7:00). I thought this was the only mark on that gear until I removed the bracket that holds the gear. I then saw a red mark and even green marks on it. In it's current position (red at about 5:00), those marks are not visible when the bracket is installed. You'll also see the red mark on the engine (at about 11:00) I've also taken 2 other photos of the gear showing the yellowish, red and green marks better.

The next picture shows a mirror image of the back/right cam. You'll see a red mark on the plastic electrical line that runs along this area (hard to see but it's there). I don't believe this is a factory mark but may have been placed here by previous mechanic that changed the timing belt. The next photo is mirrored and shows the sprocket mark that is about 2:00 (the mirrored image makes it look like it's at about 11:00) In this photo, you can also see the mark that has been placed on the electrical wiring. This mark would about the 11:00 area. I don't really see any additional marks on this cam except the red one described below in next sentence.

The final picture shows a non-mirror image of the back/right cam. You can see a slight red mark on the timing cover #3. I'm not sure the source of that mark.

My new timing belt has lines on it indicating "where" it should line up on the gears/sprockets. Here's where I need some help. The back/right sprocket is the most difficult to determine the proper alignment. I'm thinking if I can get the belt properly positioned on the crankshaft and the front/left cam, it should be easier to line up the back/right with the red mark on the sprocket. Does this sound reasonable?

So, should I rotate the crankshaft so the red mark on the gear aligns with the red mark on the engine (or the yellowish or green)? I don't believe the crankshaft has moved since I removed the old belt. Is it difficult to rotate? Should I rotate it only one direction? (obviously it would be easier to rotate it clockwise with the bolt installed).

After rotating the crankshaft (if that's the recommendation), do I then line up the red marks on the front/left cam? Because there may be a lack of marks on the back/right cam, I could line-up the belt mark with the red mark on the sprocket. Does any of this make sense? I'm just looking for the proper way to get things set up for a successful finish to an interesting project.

I appreciate all of your help and welcome any comments you may have.

LeX2K

This vid shows you pretty much all you need to know.

azneastsid

Not sure what damage could have occurred.
For Future reference, I would have aligned the markings before removing the belt and marked the timing belt with white out at each pulley. Then transfer the same markings to the new timing belt with the correct distance from each marking.
That way its fool proof when replacing the belt.

BY5260

You are exactly right. I should have marked everything before I pulled that belt off. When I looked at it originally, I saw marks on it and figured it would be an easy replacement based on what I saw. I've also watched that video probably 10 times. I've also watched other videos on the subject.

I was hoping that someone would be able to look at that photo and tell me if it was safe to rotate the crankshaft so red on the gear lines up with red on the engine. I believe, but not certain, that's how it's supposed to be and then the yellowing mark on that gear would indicate where the line on the timing belt should line up. I don't want to start turning the crankshaft and then learn later, because it's an interference engine, that I shouldn't of turned it with the camshaft in the position it is currently. If I knew it was safe to turn the crankshaft, I'd then rotate the front/left camshaft so the red marks lined up. I'd then only be able to determine where the rear/right camshaft needed to be placed by the marks on the new belt.

I believe this would get me all back in business. At least I'd dare attempt to start it after I placed the timing belt. Any thoughts?

LeX2K

You are way way over thinking things, follow the instructions in the video! Does the replacement belt have marks on it? If so rotate the cams and crank where they need to be and install the belt. There is no valve collision issues to worry about and even if there was turning the engine by hand would not cause any damage.

Forget about the colour of the marks the machined marks on the cams are what you will be using.

azneastsid

I think hes worried because its an interference engine.
But anyways, i think you should be fine if you can rotate it as long there isn't any resistance. If there is, the piston may be hitting the valve.

LeX2K

Well if he's not willing to rotate the engine then he'll never get it back together. There could be resistance when rotating the crank due to compression depending on the position of the cams. I personally do not think the 3MZ is an interference engine going by experience.

ES300NZ

I'm not 100% sure on this, my my understanding is that toyota vvti engines are ONLY an interference engine when the VVTI is operating.

everything else was adequately covered by knowable members above, so I have of nothing of valve to add, I would only be repeating others correct advice.

LeX2K

VVTi on the 3MZ varies cam phasing not valve lift so this does not affect the interference aspect (if any) of the engine.

BY5260

I appreciate all the help and comments. I'm trying to be careful not to ruin this engine. I guess I'm really worried because my local dealer shop told me this engine is an interference engine. You seem knowledgeable about this so I'm going to line up the marks and try to start it. I guess the worst that can happen is a non-start and then the need to fix the tensioner and try again with different belt placement.

LeX2K

By hand rotate the engine 5-6 revolutions to make sure it turns smoothly before attempting to start. What brand of timing belt do you have?

ES300NZ

if the timing marks are correctly lined up it won't do damage to the engine. if i recall correctly, you need to make sure the slack is on the tensioners side before you release it or it will pull itself out of time. If that happens, undo the tensioners bolts, pull it all apart, and reset the timing. Then compress the tensioner carefully in a vice until the pin slides back into place. I had to do this like 3 or 4 times until I worked out the method.

BY5260

After reading the advice here and doing other internet research I decided I had little choice left, so I decided to put it together and see if it would start.

I'd been putting a plan together in my mind. It seemed reasonable and it made sense to me but I had that deep worry about the interference aspect of this engine. Here was my thoughts; The crankshaft position likely hadn't changed since I prematurely removed the timing belt. So I started the belt replacement there. I wasn't so concerned about getting it at TDC (top dead center) as I could find no engine mark on the back/right camshaft. After aligning the proper belt mark with the yellowish dot on the crankshaft gear, I then went to the back/right camshaft. I aligned the lines on the timing belt with the red mark on the camshaft sprocket. I had to rotate the sprocket to get it to properly align but I finally got it. I then finished at the front/left camshaft sprocket. I worked to place the timing belt mark with the red mark on the sprocket. This required a lot of work to get the slack out of the belt. I should mention that I'd placed clamps on the belt to keep it in place on the crankshaft and back/right camshaft.

The belt was fairly tight but there was obviously some slack in it. I tried to keep that slack in front of the belt tensioner (removing and installing the belt tensioner on this motor was about the toughest part of the project). With things now aligned, I pulled the tensioner pin. I had high anxiety but I was committed.

I got in the car and turned the key. The battery had discharged enough that it wouldn't turn the engine very far. I turned the key off and got back to look at my marks to see if they were still aligned. The picture below shows the front/left camshaft. Without thinking to much, I immediately thought the belt must of slipped during the failed start up. I grabbed the tools to start the removal of the belt tensioner so I could now go to Plan B. Plan B was to get everything to TDC. I hesitated for a minute and decided to put the battery charger on it. I wanted to give it a good turn to see just "where" the belt marks would go with some good cranks. After a few minutes of charging, I got back in the car and turned the key. MUCH TO MY SURPRISE THE ENGINE IMMEDIATELY STARTED! I started and ran perfectly. I really believe it was more smooth than it had been prior to starting this process. I let it run a couple of minutes (without antifreeze) and turned it off. The timing belt lines were all over the place in regards to marks on the crankshaft and camshafts. It didn't make sense to me but I was sure happy. I started it again a few times after adding antifreeze and it runs real smooth.

So I don't know if there's something to my thoughts of lining things up like I did or MAYBE I JUST GOT SUPER LUCKY. Either way, the car is running.

Thanks to each of you for your comments and suggestions. You're welcome to give me your thoughts about my success here.

speedkar9

There's no harm turning a 3MZ engine cam forward or backward by 1/4 turn.
When I was changing my ES330's timing belt the cam slipped forward and made a metallic "clunk". Sure that may have been my valves hitting the piston, but it was not violent enough to cause any damage.

Major damage from interfering valves occurs when the timing belt fails at high RPM.

ES300NZ

the timing belt, timing marks will move away from the timing marks on the cam wheel and crank wheel once the engine runs, they are for installation only.