Hi all,

Issue:

I noticed my water pump pulley was wobbling today while idling. The wobble goes away with a higher, steady state rpm, but returns when in idle. I've noticed that the coolant is pretty low too, so my research indicates that it might be a water pump issue.

When I took the belt off and moved the the water pump pulley, it had a slight (~1-3mm)"wiggle" to it. Defining my positive x axis as going from the driver's seat through the front of the car, this wiggle was in the x direction. I noticed that the idler pulley had the same wiggle in the same direction.

I think the idler pulley spun smoothly despite this slight wobble. I think the water pump pulley spun smoothly also, but this was hard to tell due to the fact that the pulley had rusted to the water pump, so I couldn't get the pulley out to only test the pump.

Video evidence:

https://www.youtube.com/watch?v=JHg7cK47onU

https://www.youtube.com/watch?v=R5lZ15Anxcw

https://www.youtube.com/watch?v=UDRilWyJ_1g
(Quieter video in my garage)

https://www.youtube.com/watch?v=Tsw6TMjvj48
(Video of "wiggle" in idler pulley)

Info to consider:

2001 S2000.

I just changed my spark plugs and did a compression test. The results were 1 - 222 psi, 2 - 222 psi, 3 - 224 psi, 4 - 219 psi. So, nothing out of the ordinary.

Engine has ~100k mi on it. Unknown time when the valve's were adjusted or serpentine belt changed (got it used from my cousin and I've solely been repairing it due to his negligence). I will be changing the serpentine belt ASAP because I noticed it was worn, although not terrible. I am trying to diagnose if I need to change other pulleys and parts at the same time.

Questions:

What do you think?

There seems to be a tiny bit of a clicking sound in the third video. Does anybody else hear that? Could it be the valves or is that a normal? It's not loud so I don't think it's the TCT. Thoughts?

Thanks!

 

Water pump needs investigating, that defo isn't right. Take the belt off and check the play in the pulley, it may just be that the pulley isn't bolted on correctly, I think it is extremely rare for a water pump to fail though.
Your idler pulley seems ok to me, mine was like that so I replaced it and the new one was about the same, because that is the pulley thay obviously provides the tension etc there has to be some play in it as it 's always moving, hope this makes sense.

 

Thanks for the reply tozerman.

What you said makes sense. I took the bolts off the water pump pulley and tried to take the pulley off to re-install it...but I couldn't because the connection with the water pump was so rusted on that it wouldn't budge. Any special suggestions (outside of the normal wire brush, WD-40, and force) to get the rusted connection to become free? It did spin rather smoothly though, so your suggestion of changing the belt might work.I did noticed that the belt was starting to crack in some places and was very easy to put on, so it might be too loose.

I will change the belt to the Goodyear Gator belt, reassess the situation, and post the results.

 

leave the belt alone, you need to find a way of removing the pump pulley, even if it means removing the pump from the block and sorting it out on a bench.

 

I changed the belt because it was cracked and old. Like I expected, the wobble didn't change. I agree that I have to get the rusted pulley off of the pump. So...I'll try my best to get if off!

When I took the pulley bolts off, they were REALLY tight. I had to put a lot of torque to get them off...a lot more than 10 lbf-ft. So it makes me think it's one of two things:

1. The pump doesn't rotate freely, which means the bearing is bad and I have to replace the pump (or the bearing).
2. The pump rotates freely, but the pulley is deformed from overly tightened bolts. In which case I just need to replace the pulley.

Thoughts?

 

Have just watched your videos again closely and if I were a betting man I would say the pulley is deformed (not sure how that could happen) either way as the pulley is seized on you may as well remove the pump and I bet that you will find the problem, 100%.

 

I believe they make puller tools specifically for getting stuck pulleys off their shafts. I think you can rent them at Autozone, etc. for free. This keeps you from having to drain the coolant and remove the water pump.

 

CoolGuy094, thanks for the information. I've already ordered a new water pump, so I will not be using the tool to diagnose my current pump. I will, however, use this tool in the future if my new water pump gives me trouble.

tozerman, I thought that was it too, but I got in contact with a S2000 owner from the UK who was having the same problem and he said that the problem for him was the pump, not the pulley. I saw his video on Facebook and his posting on s2ki and my problem looks exactly like his. He told me that the problem was the internal pump and not the shape of the pulley, so...I preemptively ordered a water pump.

I'll update this thread when the water pump (a used on with 40k miles on it, put with a detachable pulley) comes in. Thanks for all the help!

 

I have no experience failed water pumps, but if I see a pulley wobble like that, I imagine that the bearing the shaft is on is shot and the pump needs replacement. After you pull it, put them side by side for comparison.

 

Ok, so I changed the water pump and pulley over the weekend. It was definitely the water pump bearing. When I pulled the water pump out I was able to hear a very faint squeaking that I couldn't hear while it was in the car.

I couldn't, for the life of me, get the seized pulley off the water pump to do further analysis. But, the replacement went well and now there is no wobble. Thanks for the input!