Timing belt or other engine failure?

Commenting on if belt was installed correctly or not: tooth count is probably the most guaranteed way to set it properly. I had an experience with old Subaru where prior owner set teeth by marks and made one off, it was an easy fix and an immediate jump up in vehicle resale value :slight_smile:
IMHO, at this point the question if belt is correctly installed is settled.

I would say this area is very likely the most interesting to explore.

From what I’ve read, Sienna of this year would engage fuel pump via relay before start, then right after engine transition above the threshold RPMs will switch over to the circuit controlled by the oil pressure sensor.
So, my first idea would be to back-probe the wire feeding the fuel pump and see if pump stays energized after start.
The same can be accomplished by testing the fuel pressure in the engine bay.
Not sure what of these two methods would be more troublesome to OP.

Another note I found on this generation of Sienna is that upon transitioning to the oil pressure controlled fuel pump circuit, power goes through the big resistor installed somewhere in front bumper area, and apparently it is a part failing often. I would not explore this until fuel delivery is a definite suspect by testing pressure or pump power line.

Regarding the crankshaft sensor testing: tachometer responds in a normal way during the start attempt showing about 1500 RPM. Is this a conclusive indication that the sensor works OK?

To each his own

I go by the marks, I don’t count the teeth

If you feel more comfortable concentrating on tooth count, versus looking at the marks, that’s fine

But I can tell you with absolutely certainty . . . I’ve never counted teeth. I’ve always gone by the marks, double-checked my work, then spun the engine twice by hand, and everything was still correct. I’m thinking maybe that guy with the Subaru was less meticulous in double-checking his work . . . ? I wasn’t there. It’s just a thought. No offense intended to anybody, in case that guy happens to be your friend.

Now if we’re talking about a chain setup, with colored links . . . yes, I will make sure they are properly lined up with the appropriate markings

I can’t speak specifically for the Sienna, but generally speaking, when the oil pressure sensor/switch is in the picture, so to speak, it’s used as a backup, in case the fuel pump relay isn’t functioning.

From what you say, apparently Toyota does things a little differently, versus the domestics. But their vehicles are generally reliable, so it seems to make no difference

Not my friend, some prior owner of my first Subaru I happen to buy for $3K and later sell for $5K :slight_smile:

Of course I was watching marks, but since it was not convincingly pointing to stamps on the engine, I started teeth counting, found my eyes did not fail me and it was one tooth off on one side.

Counting was really easy: I was making a mark with Sharpie on every tenth tooth, so I was not afraid to miscount, I was leaving evenly-spaced lines as I was coming along… the belt on opposite design engine is really long one.

It was a little bit funny why I even went there: at idle car would make slight bounce left-right, so I’ve checked compression and it was good on left side and 10% down on right side, so I suspected belt installation issue.

In my case, I enhanced the factory marks with white chalk. It sure made a big difference

Old 2.2 liter Subaru engine used to have marks done in a way where it was impossible to tell if they point to the tooth or between teeth. They were placed far from the sprocket and made by the stamp not in the center of the plate, so I was not confident at all in it as a marker.

So I watched the video and you definitely have it timed correctly or it wouldn’t run that smooth for the first few seconds. Something is grinding right before it dies. Are you absolutely sure all the sprockets including the water pump, oil pump, idler, crank and camshaft turn freely? Did you spin them all by hand before installing the belt. Sometimes there is a reason the belts break other than wear, like a pulley seizing

deleted :cat:

I spoke to a friend of Nikolayh who is helping him to bring this Sienna together now.
They managed to get it started and going apparently, it was a main air flow hose between the air filter fox and throttle plat unit.
Once they’ve got it reattached, engine is running.
I hope he will post more details, as I’m only carrying a second-hand news.

Problem solved: air intake hose jumped off opening up a huge leak. It could had happened just before the belt failure in the cold weather triggering the rupture.
The system didn’t let me post this earlier (limited number of posts per day)
Thanks everyone for useful suggestions!


Glad to hear it was something easily repaired!


Summary and the lessons learned (for anyone who is not interested to read through the whole thread):

  1. Aftermarket parts could be of a very low quality: the timing belt has cracks at EVERY tooth after 60K miles.
  2. In such poor shape, the timing belt fracture could be triggered /masked by some other (even minor) engine failure.
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You don’t need to do that. Get a can of ether starting fluid at the auto parts store. Start the engine and as it starts, begin spraying the fluid into the air intake. If the engine keeps running, the problem is indeed that the fuel supply has been cut off.

There are times when there is no substitute for a fuel pressure gauge

And while ether, starting fluid, etc. can lead you in a certain direction, it can also lead you astray, or show you what you WANT to see

Here’s a good example . . .

A few years ago, a van came into the shop for a no-start

Yeah, it started after I gave it a blast of ether

however, it didn’t just run for a few seconds

It KEPT running, without additional ether. If fuel has been entirely cut off, an engine will only run so long on ether, not 30 minutes, for example

So . . . I DID hook up that fuel pressure gauge

Turns out the fuel pump was turning on, but the pressure was a little lower than specs. Low enough that the engine wouldn’t start without additional help (ether), but enough so that it would STAY running

No offense, but your theory might lead you to believe that “fuel supply has been cut off” . . . that was certainly not the case

In my case, it was simply an aging fuel pump that was on the way out. No problems with “unauthorized start”, bad key or anything along those lines.

In fact . . . the fuel pressure while running was good enough, so that there weren’t even any lean codes

Another example . . .

A colleague had started diagnosing a no-start, but he wasn’t allowed to complete the diagnosis

He claimed it briefly ran on ether. I wasn’t there to witness it

He thought it needed a fuel pump . . . I quickly dispelled that idea. Fuel pressure was within specs. Pump energized each and every time. No problems at all in that regard

No spark

turned out it needed a pcm

Very good points. I agree with all of them.

The last time I used starting fluid appeared to be a case of the immobilizer, as was suggested in this case. That’s what led to my suggestion.

In fact, I subsequently got out my oscilloscope and showed ('94 Buick) that the 50 Hz square wave was present to the PCM, and it did in fact turn out that the PCM was bad.

Given that the OP did not sound technically expert, I figured that it wasn’t likely that he had a fuel pressure gauge or knew how to use one. Thus my suggestion to start with the ether test.



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