Loud startup, drive belt not moving (1 Viewer)

[richinsd]

Hoping that someone can help me. My '03 (190K miles) is having problems.

The symptoms are:

a.) a very loud noise on startup. Like 747 loud. The noise lasted 5-10 seconds and then subsides,
b.) the fan doesn't spin, and I couldn't turn the steering wheel at first, but then as noise goes away, the fan begins to turn and steering comes back.
c.) when I jumped out to look at the engine, the serpentine belt doesn't appear to be moving at all during the noisy period.

So I assume the crankshaft pulley is just slipping along the grooved part of the belt? Can a failure (or impending failure) in one of the other pulleys cause this to happen? Any ideas on how to sleuth it out? Fan spins freely when cold so i think the clutch is ok.

If I take off the belt, is there a way that you can tell if any of the pulleys might be causing it to freeze in the beginning?

TIA

 

[FxFormat]

Check your tensioner, if it's not applying pressure to the belt it'll just slip and not spin the pulleys

 

[OwnerCS]

Check your tensioner, if it's not applying pressure to the belt it'll just slip and not spin the pulleys

^^^^ Hopefully this is only a belt tensioner problem.

I haven't personally witnessed this on a 4.7L yet, but on other Toyota and crankshaft pulleys (usually 1995 or older models) with this design.

There is a rubber crankshaft damper ring where I have experienced separation. The inner part of the crankshaft pulley spins without turning the outer pulley ring. It will make a squealing noise until the rubber damper heats up and gives some bite.

This is a picture from a 1998-2007 Landcruiser crankshaft pulley to show the rubber damper.

Outer ring after separating from the rubber damper. This is one of mine that separated.

This is a separated harmonic balancer from a Tundra 4.7L. If you detect the harmonic balancer is separating, do fix it as fast as you can.

 

[richinsd]

^^^^^Thank you for these replies.

On the damper separating possibility, are you saying that the visible part crank pulley would not be moving until the damper heated up?

 

[OwnerCS]

^^^^^Thank you for these replies.

On the damper separating possibility, are you saying that the visible part crank pulley would not be moving until the damper heated up?

That's how it happened to me in the early days. Very soon the pulley completely separated and started rubbing against the timing belt cover.

If I suspected it was happening to me, I would pull the splash pan so I could inspect from underneath to shine a light on the crankshaft pulley to see if the crankshaft part was spinning faster than the outer pulley ring. Its usually easily identified with a visual inspection.

I'm forgetting that I drive a vehicle that is now 23 years old and will soon be eligible for this to happen.

I usually look for cracks in the rubber damper part to see if the rubber is breaking down to get in front of a failure. I need to do this for mine.

 

[cruiserdan]

Also check all the pulleys to see if any of them are locked-up. A locked pulley would put an extra strain on the crank pulley which could shock a weak one enough to break the damper ring.

 

[richinsd]

Well I got a photo of the crank pulley.

I also got a video, but I can't figure out how to post it. But the it doesn't look like there is any damage to it...at least from this angle.

Not sure if this is relevant, but here is the tensioner pulley. Believe it was changed at the first timing belt service (about due for another).

I guess next step is to release the belt and twist pulleys? What does a failing bearing feel like?

 

[94SRUNNER]

Well I got a photo of the crank pulley.


View attachment 2895745

I also got a video, but I can't figure out how to post it. But the it doesn't look like there is any damage to it...at least from this angle.

Not sure if this is relevant, but here is the tensioner pulley. Believe it was changed at the first timing belt service (about due for another).

View attachment 2895770


View attachment 2895772

I guess next step is to release the belt and twist pulleys? What does a failing bearing feel like?

Yes. Pull the belt and check all of the pulleys.

 

[Bisho]

I had a bad alternator that I literally could not turn by hand. Your 747 loud Could be your crankshaft spinning against the belt until it starts moving.

 

[awesomeissquid]

On the tensioner there are some alignment marks to identify if it is within tension spec or if it needs to be replaced.

 

[OwnerCS]

I would release the belt and turn pulleys by hand. They should turn freely. You'll know when one isn't spinning correctly.

I do see some wear on the back of the belt. It may be scrubbing and wearing against the fan bracket pulley that is not turning freely.

Before my fan bracket bearing started to seize up, the belt rubbing against the fan pulley made a whining moan when it was cold. It was not a typical belt squeal.

 

[richinsd]

^^^^^^very timely reply. i realized that wasn't the tensioner pulley that i posted earlier.

after I did correctly locate the tensioner pulley, i can't get it to twist CCS and release any pressure on the belt. the bolt just twists counterclockwise. i've probably stripped it by now. i did see some marks that looked like alignments on the tensioner.


here is a pic with flash (and glare)

here is a pic without flash (much more readable)

 

[OwnerCS]

Here's a post for reading the tensioner tick marks. Something just looks wrong with the tensioner position and the fact that it will not let you spring it counterclockwise.

Let's get some other members to chime in on this.

[PIC/VIDEO]: Serpentine belt tensioner markings. What does this mean? Squeak noise

I've got the FSM and I've searched here, but maybe it's right under my nose and I'm not seeing it. I'm getting a minor low-volume, high-pitched "wheeeeee" sound from what I assume is the V-belt, only on a cold start. It goes away within 30 seconds and never comes back. I just had the TB done a...

forum.ih8mud.com

 

[richinsd]

Thanks for the link to the other thread.

The pic of the tensioner was taken after I had tried to unsuccessfully release the belt (when the bolt was just turning CCW) so I can't with 100% certainty say that those readings are similar to when I had heard the noise. the belt "feels" tighter now after the CCW tensioner bolt twisting .... but that is simply my opinion. i have no measurements.

Is there a trick to "unsticking" the tensioner when the CCW bolt twisting doesn't work?

 

[Bisho]

Based on Craig’s diagram, your belt is too short. How long has it been on? Are you sure it’s routed correctly?

I happened to check mine, and it’s between the B area and the A.

 

[richinsd]

Thanks for all of the comments/suggestions.

The serpentine belt has been on since last TB replacement at ~105K. Believe it was 2013?? I'm going to guess it was the right belt. The shop I had do it is a Toyota indy shop and does an awful lot of LCs around here. Like I mentioned above, the belt feels tighter than it was before I started the attempt at CCW tension release. I'm wondering if I somehow increase the tension??

Seems like it may be time to cut the belt and replace the tensioner assembly? I did not know it was rated to 175K (I think that was mentioned in the thread in post #13). apparently the fan bracket is as well? I'm going to have to find a 100 series FSM I guess.

 

[richinsd]

Follow up from yesterday.

So I actually yanked on the belt this morning and the tensioner pulley did in fact move. But I still couldn't get it to twist with the socket wrench to release enough to slip the belt off. However if you pull hard enough, you can generate enough tension to slip the belt off of the idler pulley. A bit of wrangling after that and the belt was free.

Switching the socket wrench to clockwise, I removed the bolt from the tensioner pulley. Plenty of fine dust/filings

this is zoomed in so the resolution isn't that great, but there is plenty of debris in there.

but the tensioner pulley is now off......and it's completely locked up. I'm going to assume (hope) it was that way before I stripped the bolt. All other pulleys seem in good shape....although the idler has a little movement in it...and it spins quite easily which apparently is not a great sign according to several of the other threads here about replacing idler/tensioner pulleys (it's supposed to spin but be a little tight?).

 

[richinsd]

Went underneath to see what I could find. This is the tensioner assembly (the tensioner pulley has been removed). The silver threaded hole is where the bolt for the tensioner pulley goes. Lo and behold, there is a crack in the bolt hole. It's very possible I caused that when I was cranking CCW to release the belt, but in any event, I'm pretty sure that's the reason that the tensioner wouldn't release. The actual tensioner spring seems fine.

So ordering a new tensioner assembly from Toyota.

Getting this one off and the new one on should be interesting. More wrenching than I've done in the past.

Thank you all for the helpful posts and suggestions.

 

[OwnerCS]

Went underneath to see what I could find. This is the tensioner assembly (the tensioner pulley has been removed). The silver threaded hole is where the bolt for the tensioner pulley goes. Lo and behold, there is a crack in the bolt hole. It's very possible I caused that when I was cranking CCW to release the belt, but in any event, I'm pretty sure that's the reason that the tensioner wouldn't release. The actual tensioner spring seems fine.

View attachment 2896856

So ordering a new tensioner assembly from Toyota.

Getting this one off and the new one on should be interesting. More wrenching than I've done in the past.

Thank you all for the helpful posts and suggestions.

Good job! You've got it.

 

[Mike NXP]

Went underneath to see what I could find. This is the tensioner assembly (the tensioner pulley has been removed). The silver threaded hole is where the bolt for the tensioner pulley goes. Lo and behold, there is a crack in the bolt hole. It's very possible I caused that when I was cranking CCW to release the belt, but in any event, I'm pretty sure that's the reason that the tensioner wouldn't release. The actual tensioner spring seems fine.

View attachment 2896856

So ordering a new tensioner assembly from Toyota.

Getting this one off and the new one on should be interesting. More wrenching than I've done in the past.

Thank you all for the helpful posts and suggestions.

Same issue happened with mine a while back in regards to the bolt hole cracking. I went to swap out a pulley for maintenance and ended up swapping the entire tensioner. Either way it is good to get the tensioner replaced and get this job out of the way.

Procedure to swap it out isn't all that bad, no special talents needed just slow and steady. The power steering and alternator get moved out of the way. I just kept my power steering lines and pulley attached and just hung it off to the side with a bungee. The vacuum lines that attached to power steering were brittle and the piece they mount to broke and I had to replace that. The plastic clips on alternator are fragile and may break as well.