timing belt on 95 Lexus

[sp53]

Hi anyone, I am working on a timing belt on 95 Lexus/Camry v6 1mz engine. Och! anyway does somebody know if I should compensate for a couple degrees of timing alignment on the crank because when I engaged the hydraulic tensioner on the belt the crank rolls away from TDC about that much.
Steve

 

[jessebogan]

If the amount of movement is a full tooth on the belt, it is off by that much. If less than a tooth, it is likely OK.

 

[sp53]

Ok Jesse my problem is that I set both cams on their marks and put the crank on zero then put the belt on, but when I engage the tensioner the crank mark moves 3/8 of an inch perhaps 10 degrees on the pulley. Should I allow for this movement when I put the belt in place?
Steve

 

[TR3driver]

It's not a "must" one way or the other. But in general it's better to install slightly advanced rather than slightly retarded, because the belt will stretch in operation.

Since I assume the tensioner is pulling the timing retarded, I'd go one tooth advanced.

 

[sp53]

Thanks a lot for your note Randall. When you say not a” must” do you mean that as long as the cams are in harmony at TDC and that if the crank is off a tooth or moved in the assembly process the computer will compensate for the timing? The vehicle is distributor -less ignition.
Steve

 

[DrEntropy]

The computer cannot compensate for a mechanical timing issue. If the crank is off a tooth on tensioning the belt, UN tension it and MOVE the crank so it is a tooth away from TDC before the belt is tensioned again.

You should be able to clip the belt to the trailing cam (closest the tensioner)with something like a clothespin, run the belt to the next cam then to the crank sprocket with enough tension to get it right. The "slack" will (or should be) all at the tensioner leg of the belt then.

 

[DNK]

Sounds like a question for Ben. PM him

 

[Banjo]

Use some vise grips set with just enough tension to hold the belt in place on the cam pulleys(don't mush the belt). then back the crank pulley counterclockwise just enough to get the belt on. there should be a little metal tab that keeps the belt on the crank pulley, then gently turn the crank clockwise again to tension up the belt. at that point your timing marks should all be on and there should only be slack where the tensioner will take it up.
Doc is right. one tooth off, and these motors will not run correctly. You'll either have no bottom end, or no top end, or a never ending check engine light.

 

[sp53]

Thanks you guys so much for the help. I basically did what doc suggested and moved the crank and let it fall back to zero similarly to putting in a distributor. The Haynes book I have was helpful, but perhaps I glossed over that part. I then turned the motor over twice and all the marks came up at zero. Anyways this vehicle is challenging. I am wondering if they lift the engine up and roll it forward to work on the Lexus. I have found an oil leak on the back valve cover and the cover is well hidden. Any ideas?
Steve

 

[Banjo]

the 1MZ-FE is the same engine as in the Avalon, Camry, and Sienna. I've done more than a couple of those belts and water pumps. once you've done a few, they're fairly easy. I've never moved the engine to do the belt. I recommend buying the actual Toyota belt, it comes with paint marks that make for a fool proof install. Or you can make your own paint marks like I sometimes do as long as you mark the old belt before removing.
biggest challenge with the timing belt job on a 1MZ or a 3MZ can be those 2 big long bolts that go from the dog bone mount down to the aluminum engine bracket. if they get seized in that bracket, they can be lots of fun to get out. usually it's the rear one that is stuck. But overall I've found the V6 belt to be easier than the 4 cylinder motors. just the way it's packed in there I guess.

 

[sp53]

Thanks Banjo you answered the questions before I could ask them. Yes I did find those bolts to be a real pain and they are one of the reasons I thought the engine might have to move. They clearly put those in with engine higher than the frame. You are so right if I do this again, I will get the belt from Toyota. The belt I bought had paint marks and I was able to line them up on the cams, but the lower mark had no definite reference point that I could see and that still has me worried. Usually the manufactures are smarter than me. I turned it over by hand and everything seems to be right. I pray that it starts. Thanks again Banjo your skill is much appreciated.
Steve

 

[DrEntropy]

What was sooo <span style="font-style: italic">wrong</span> with CHAINS?!?!

 

[jessebogan]

Chains never need fixen'. Can't have that now can we??? When I get made King of the World, any car that has a sideways engine will be required to have DUPLEX timing chains. (See Stag, or newish Jag V8s for why not to use bicycle chains in an engine...) I just did the belt and waterpump in an 02 Volvo. They seem to go out of their way to make the whole belt job mopre complicated than it needs to be. My hands still hurt.

 

[Banjo]

As far as Toyota goes, Belts are out. All their new engines have chains.
Ancient Toyota Secret. If a Toyota motor has a belt, it is a non-interference engine. Meaning that the valves don't contact the pistons if the belt breaks. Chain motors are interference. It's cheaper for a manufacturer to produce an engine with a belt, but tighter emissions controls, and the widespread use of variable valve timing has necessitated the use of chains.
You got your wish Jesse.
Steve. There are two marks on the crank pulley, one is a small notch between two of the crank sensor teeth on the rear flange of the pulley. at TDC it's at about 11 o'clock and lines up with the arrow on the engine, The other is on the front face of the pulley. it is a shallow circle on the end of one of the pulley teeth. It's not very easy to see, and it sits about 5 o'clock with the pulley at TDC. That mark is the one that lines up with the mark on the belt. I usually highlight it with a paint pen to make it easy to see. same with the notches on the cam pulleys

 

[DrEntropy]

If I had a sense of humor I'd laugh. The Lotus engines I've run for decades have had single row chains... now I'm concerned about chain ~QUALITY~!!!

...where's my local *'merican* bicycle shop?!?!

 

[sp53]

Now I am a little freaked out because I am going to go and try and start that engine this morning. I kinda feel like your picture Banjo. I saw that mark on the pulley face and lined it up with the mark on the belt thinking that was what it was for, but it advanced the timing too much when I put the plastic cover on. Anyways perhaps I did not orientate the belt on the cams right and that mark might move to a different spot. I did move the belt around by hand and it came back to zero with the cams on their marks???????
Steve

 

[jessebogan]

Just think Reynold Doc. Besides Chapman was a wizard with the simplificate and add lightness thing. He would have used half width chains if he coulda found any. And since they live with Diesela, and an Alfa or two, they know better than to let the side down by something as uncouth as failing...

 

[Banjo]

Steve, if you rolled it over and the marks all lined up again, you should be good. Those are the important marks. Even if it's off, you won't do any damage. Worst case is you'll have to go back in and fix it.
I actually get the belt on, roll it over to check, then start the engine for a moment before I put it all back together. then if I need to reset the belt, I'm still right there.
There's no reason you can't start and run the engine with the belt shields off.

 

[sp53]

Well Banjo it started right up, BUT the right front cam sprocket is rubbing on the back of the top cover making some serious smoke. When I removed the water pump, the book I had (Haynes) maintained that the back of the upper cover should be removed. They said all cover parts need to be removed. Well that means both cam sprockets would have to come off along with most of the top half of the engine. I just removed the right one and prized the cover out just a fuzz to get the pump off. I really do not think I bent the cover but something is wrong, and if someone told me this story the first thing I would think is they bent the cover. Perhaps the sprocket in on backwards or there was a small spacer between the cam and the sprocket? I do not know but something is too tight. At first I thought the little 10m bolts that hold the cover on were hitting, so I tried to tighten them up, they have that rubber grommet, and they did move some. However, one broke off. It has been awhile since I broke a bolt. It is just the outside ring of the cam sprocket that is hitting. Anyways have you ever had that that sprocket off? How do you get the water pump out from behind the cover?
Steve

 

[Banjo]

I remove the two studs that go through the pump and bracket,undo the two bolts in the middle of the shield, put my prybar behind it and pry the shield out just far enough to weasel the pump out. Always gotta check when puttin it back in that I didn't tweak it. now, the pulleys, the rear one has the flange on the outside, but the front one only has the flange on the side nearest the motor. Make sure you have the pulley on right, and make sure the shield didn't get tweaked.