Harmonic Balancer Came Apart

2001 4x4 Tundra, 240K miles. Bought it last month, had it towed home as it wasn't drivable due to the serpentine belt removed to fix a seized pulley and the owner gave up on it. I tore the front of the engine down and did a timing belt replacement, along with a new alternator, new tensioner pulley, new coolant hoses, new radiator, thermostat, etc.

Fired it up and ran beautifully. I have been driving it off and on for the past couple of weeks, maybe have 25-30 miles on it and when I was coming home this afternoon, I heard some squeaking coming from the engine and then I smelled burning rubber. Fortunately I was only a mile or so from home. I shut it down and popped the hood and I was immediately drawn to the crankshaft pulley (harmonic balancer). I noticed that somehow the rubber insert of the pulley had literally walked out of the balancer and the serpentine belt had jumped off the pulley and was now riding on the rubber insert!

If I had of ignored this problem and continued to drive it, I would suspect there would have been a catastrophic failure that would have caused irreparable damage to the engine. I do not at this point know why the balancer failed.

I have ordered a new one and it should be here sometime next week..

This weekend I will tear it down and get it ready for the new balancer. I suspect the balancer is going to be hard to get off due to the present condition it is in. Of course, I will include revenant pictures as I go forward with the repair...

 

Did the Crank Bolt come loose and allow this condition? Its hard to picture a space for the bearing to come apart without a loosened Bolt allowing space between the TB Gear and Pulley Balancer.

 

Wow ! You dodged a bullet there. Never heard a story like this concerning a Toyota product.

 

No, the crank bolt is secure. I don't know the genesis of the failure, yet.

I've never heard of this failure with a harmonic balancer with the 4.7L either. Aware of it happening on other vehicles, just not this one. Will try to get you guys some pictures tomorrow. Right now, have...to...watch...football!

 

Harmonic balancers of this type fail often. Don't know about Toyotas history of the rubber insert working out, but is sure happens a lot to US autos. I had to replace it 3 times on my 1990 Jeep Comanche over the 25 years and 250K miles that I owned it. I caught it twice before it completely failed, but once it did come completely apart while driving. Not a catastrophic issue.

A quick search shows all sorts of the same failure, from big diesels to Nissans, to Chevy, Ford, Chrysler. Pretty common.

 

I’ve recently done a Timing Belt Change with the Aisin Kit. Bought and installed the New Style Accessory Belt Tensioner along with New Fan Bracket Pulley. The old pulley was grindy. The New Tensioner has mega tension compared with the old one. In addition, its pulley is a different size and located askew from the original axis.

Just some observations.

 

I know there is something you're telling me here, but I am not quite following exactly what it is. I too used the Aisin kit and used a new belt tensioner along with a new serpentine belt. The only thing I noticed when I put it back together was the serpentine belt was a little tight - meaning I had to rotate the belt tensioner full stop to get the belt on. There was very little travel left on the tensioner once I released it. Don't know if this was the cause or not...

 

I was making observation. My New Accessory Belt is a Heavy Duty Gates and it went on with no problems of clearance. There was plenty of play in the new tensioner to accept my belt. The tension was very strong, though. Wondering if the new tensioner has created this condition?

 

Not sure. Could have been the wrong belt...

Will know more tomorrow afternoon after church. Saturday is football day, so I'm pretty much glued to the tube for the remainder of the day..

 

Different brand belts that cross-reference to your OEM are often slightly longer or shorter, but only by a few millimeters. Some go on easier than others.

 

Well... here it is...carnage and all...

Before we get to the pictures, some of the visuals are from underneath the vehicle and some are from the top side perspective, so if they look upside down, that is why. The harmonic balancer is toast. A new one was ordered yesterday. Things I encountered during the teardown this morning that have me both surprised and concerned are: the timing cover is toast. Don't know if these are NLA or not, I sure hope this is not the case. The harmonic balancer started to eat into the front of the engine where the crankshaft sensor is. Fortunately, I think it is going to be okay as it was running prior to me shutting it down. I am not sure on this engine but this area may be a portion of the block itself, so I possibly dodged a bullet here. There doesn't seem to be any appreciable debris from the timing cover in the area of the timing belt - at least not that I can see at the moment.

Crankshaft pulley (harmonic balancer bolt) was tight and I had to use a breaker bar to break it loose, but since the inner part of the balancer walked out of the outer rim of said part, the bolt itself must have come loose. I did torque it down during assembly. My torque wrench only goes to 150ft/lbs, so when I achieved that spec I used another 1/2 inch ratchet and tightened it about 10 degrees more - was this the failure mechanism? Don't know...

Also, I found some remnants of "never seize" on the inner race of the crankshaft pulley applied by yours truly. This may have been an idiot move by me to do this, but it still doesn't account for why the pulley separated. So, I'm not sure of the failure mechanism at this juncture. Anybody got an extra timing cover, please let me know!

 

Whoa! Almost tore into the Crank Sensor Bung. You caught it just in time before needing an Oil Pump Assy.

Not sure why this Pulley isn’t a one piece design. @lsaami might have your part.

 

Dang. Whenever mine failed the pulley always moved forward, behind the rubber insert. The inseet would start to work its way out the front, but the outer pulley ring would move forward, too. That was dang near catastrophic for sure!

Maybe depends on how the pulleys are all aligned. All the pulleys are surely out of line with each other, if only by a couple hundredths or thousandths of an inch. But that could determine which direction the outer portion of the balancer moves when it fails. All depends on the machining of the mounting brackets.

 

@empty_lord have you ever seen a thing like this?

 

Rare. But typically happens after someone does a timing belt and holds the pulley with a strap wrench to remove the bolt.
The rubber can also just fail too.

 

I used this tool on the pulley:

Schley (SCH64300) Lexus and Toyota Harmonic Damper Pulley Holding Tool

 

Then likely just failed rubber. Never had one come off like that. Usually it is a belt squeal well before that happens

 

Parts have arrived. Took a little bit of work to get the new timing cover in place, simply because you usually put that on 1st before you put on everything else, but a little patience goes far and I got it in there and buttoned up without having to remove the water pump and the tensioner pulley. Next was the new harmonic balancer and I bought a 50-250ft/lbs torque wrench just so I can verify the crankshaft nut at 181ft/lbs. The torque wrench will come in handy for torquing the nuts on my tractor as well..

While I had it torn down, I went ahead and bought a new fan clutch as I believe the original one was shot. Battery back in place and re-filled the radiator and hooked up the top radiator hose. All is left is to hook up the battery terminals and fire it back up. I don't anticipate any problems but I'm leaving the first start for tomorrow.

 

Very rare indeed. Best of Luck.

 

Starts and runs. Back in business again...