Crank Pulley/Harmonic Balancer Issue - How bad is it?

[ntk]

Hey all,

So here's the back story:
I daily drive a 99' 100 series in Colorado. I was driving up to Denver (70ish miles) for an interview last Friday, when I noticed a noise from the engine bay that was a bit concerning after I pulled off the interstate. It sounded like a rubbing with an intermittent knocking. I went about my business, did the interview, and checked it out in the parking lot afterward. The crank pulley was wobbling a good bit and it was making the noises that I heard. I really wasn't sure if it was a big issue at the time, because I hadn't done any research on the subject. I needed to get home (another 70ish miles) and decided it would be okay to drive (maybe not?) as it seemed to drive just fine.

I made it all the way home without issue, but when I made the last turn into my neighborhood, I lost power steering, the battery light came on, and the serpentine belt had fallen off. I immediately parked it in the driveway and haven't moved it since. I'm in college and currently live in an apartment and don't have the tools or space to dig into it myself right now, so I'm planning to take it in to a shop this week.

The reason I'm posting is to get an idea of how big of a deal this is going to be, and to see if anyone else has had something similar happen. I've only got 175k on it, and the previous owner had it maintained by the dealer for its entire life until I bought it about 10k ago. Any thoughts on if this is going to be as simple as tightening the bolt for the crank pulley, a new crank pulley, or an engine rebuild? Any help is appreciated!

 

[2001LC]

Can you get a picture of the crank pulley. I suspected it's not the crank pulley but one of the other bearings that has failed. i.e fan bracket, idler pulley/bearing or tensioner pulley/bearing, etc.

For the crank pulley (harmonic balancer) to fail, is near impossible. But If crank bolt was not torque on, it could come loose. Crank pulley could then be moving in and out on end of crank.

Vane pump (power steering pump) not shown

 

[ton504]

I've seen the harmonic balancer(crank pulley) separate on a few lexus models. Not common but it does happen. Not sure what causes it but I can only assume it's from people using a chain wrench on the harmonic balancer.

Lets see some pics so we can confirm the pulley. Hopefully the damage to the front cover/components are minimal where you can just replace it with a good harmonic balancer.

 

[ntk]

Thanks for all the helpful info. I'm about 80% sure it was the fan bracket/pulley that was the one wobbling. I'm going to have it towed to a shop this week to get it taken care of. I did a small bit of research on what goes into replacing the fan bracket... my timing belt is going to need changing in 10k or so, would it make sense to have this done at the same time? Is there anything else that would be wise to service while that is being done? Thanks again for the help.

 

[gatormark91]

Yes, do the timing belt at the same time. Replacing the fan bracket is about 75% of the same work as the timing belt

 

[2001LC]

Good idea to go ahead an do T-belt job. Good home work on your part as it will save $ in long run..

I like to do both Timing-belt idler pulleys, tensioner and water pump as they fail much sooner then belt itself. Many do cam and crank seal also, I don't unless leaking.

This is a the VVti engine, so cam sprockets (VVT actuators) look different then non VVT.

If serpentine (drive belt) belt tensioner is weak replace it also, it comes with the tensioner pulley. Same goes for idler pulley, but that one is easy anytime.

If spark plugs, ignition coil boots (coils if you have the coin), thermostat, heater tees, coolant flush and PCV value and hoses haven't been replace this is a good time also. This aligns all with T-belt timing (90K miles or 7 year). But these are not part of T-belt labor.

 

[2001LC]

I've seen the harmonic balancer(crank pulley) separate on a few lexus models. Not common but it does happen. Not sure what causes it but I can only assume it's from people using a chain wrench on the harmonic balancer.

Lets see some pics so we can confirm the pulley. Hopefully the damage to the front cover/components are minimal where you can just replace it with a good harmonic balancer.

I'm guilty.

I learned to use chain wrench from the most senior Lexus mechanic in the state of CO. I went to him for solution after destroying my HB holding tool while trying to break the crank bolt loose. This was on a Lexus IS300 (straight six), which is known to be one of the toughest crank bolt around. We had that IS300 for another 50K miles without issue. Fact is chain wrench is most common tool for holding the HB/pulley.

I use a piece of drive belt over the HB/pulley to protect belt grooves, but most don't. I've lost count of how many HB I've seen chain wrench marks on the belt groves. But I've never seen a bad HB on a 100 series, for that matter on any engine I've worked on.

But hey I can see why you'd assume that, it could happen I suppose.

 

[nissanh]

There is a rubber damper strip built into the crank pulley. When that wears out, usually not common, the crank pully wobbles and could touch the T-belt cover.

 

[ntk]

Got it into my mechanic today, and the consensus was that the fan bracket bearing had seized. He's gonna go ahead and do the timing belt, water pump, and coolant flush as well. Thank you all for the help!