Timing belt replacement instructions

The Owners Manual calls for replacement of timing belt at 90,000 miles. It is at 90,000 miles and I intend to keep the car another 30,000 miles. Is this replacement necessary and if I don't what are my risks?

I changed timing belt/water pump. I did not remove the cam sprockets for this job. Last belt/pump change at 112,000 (by dealer, pre-purchase).
Prior to starting, there was a substantial noise coming from the vicinity of the water pump and accessories, and I could not diagnose the source of the noise. Due to the mileage, I decided to do the belt/pump change and figured I'd come across the source of the noise in the course of the job.

After removing the accessory belts, I started the engine as a check to see if the noise was still present, to check if it was an accessory. The noise was still present.

After removing the pulley's and tensioner and water pump, none of them appear to have failed enough to make the noise reported above, but who knows, at high speed one of them could have been the culprit.

After belt install, I rotated crank by hand 2 times to check for interference. Tried with starter, no start. I did not keep trying.

When I re-inspected crank and cam timing marks again, I discovered that the rear cam had moved counter-clockwise (relative to facing the engine) from when I took the old belt off, so the belt was initially installed out of time. To be more specific, the crank and front cam were in proper alignment, the rear cam was off counter clockwise 60-80*) I have subsequently learned that that cam was not in a resting "unsprung" position in the aligned TDC state. [Neither of the two video tutorials I consulted mentioned this, but I have since watched others that warned about it]

I disassembled, re-set the tensioner, then re-installed the belt with both cam sprockets in proper alignment with the crankshaft. Again, I turned crank times by hand. Then I tried to start the car, and still no start.

- I have verified spark at the front left plug.
- Ground straps did not need to be removed.
- I have made sure there is no crud where the crank sensor is.
- I smell fuel, that's the extent of my fuel check.
- There are no fault codes in my reader.

The engine turns over with the starter normally, nothing seems odd. Hand turning still encounters compression.
It does not even hint of wanting to start.

I realize it is possible I bent one of more valves on the rear cylinder bank with the initial install. I don't think so because I did a hand crank 2x with no resistance (except compression). However, I assume that even if one bank has valve-train issues, the car should still try to start, and if there where issues, it would show up in other symptoms.
Q1: Is this a correct assumption?

Q2: What diagnostics can I do to track down to figure out what's preventing the car from starting?

Thanks for the reply Roy.

I don't have a compression tester (at least not the one that reaches down into the plug hole on the Highlander), and I think the intake manifold and throttle body would have to be removed to test the rear cylinder bank on the Highlander (V6). Isn't that an awful lot of labor for a starting diagnostic, with all due respect? Even if compression is compromised on one bank, I think the ignition should try to start the engine. I had asked the question above to see if that can be confirmed.

Is there an ignition and/or fuel diagnostic test you could recommend?

Ah ha. I've never used it to scan live data, but turns out it does, and I can select which parameters.
I don't know what the advance numbers should be, but it looks like the fuel system has OL. I was thinking that was no power, but just read that it means open loop. Inconclusive to me.

What do you think?

If the timing belt breaks in the 3 litre V6 does any engine part damage result?

Sorry about that. First picture was with key at ignition, second pic was while cranking the starter.

I can't say I can hear the fuel pump, but I don't know what to listen for.
What would it sound like? I assume this would be prior to cranking?

I hear a click from the rear when the key turns to ignition position. There is about 1-1.5s between the key turn and the click.

So I asked what it would sound like and you didn’t say. Whining or whirring? I thought maybe the click was the pump going off, but there’s no electric motor sound that I can hear. I’m going to have my wife turn the key while l listen at the back.

2001 Toyota Highlander, V6 3Liter, I am changing the timing belt & water pump as part of a major service. Following the manuals instructions step by step I removed everything in the way and had access to the belt.

The crank shaft mark was on "O", both cam shaft marks were lined up with the marks on the their heads.

The instructions then said to rotate the crankshaft counter clockwise 60 degrees, then release the tensioner pulley, and remove the belt in a set sequence.

When I removed the belt from the cam shaft on the front of the motor, it spun about 30 degrees.

First instinct was to put all parts in box, have car taken to garage - let them
fix it !

I have done 5 or 6 timing belts before, but never had anything move when I removed the timing belt before.

Still willing to try and do this myself if I can do so without ruining motor.

If I go ahead and install the new water pump, without disturbing any of the shafts, then move each shaft back to its timing mark, install the new belt, then rotate the motor numerous times - as long as each time the crankshaft mark is on "O", both cam shafts line up with their marks, then:

1. Best case, all is well, car will run as designed.

2. "Worst" case, car will not run - BUT neither of the heads will be smashing valves on pistons because the marks mean that at TDC the valve will always be in an ok position relevant to their pistons.

I appreciate any advice to get me successfully out of this situation !