Timing Belt Idler Pulley question

The saga of replacing my water pump continues. Finally swapped out the water pump, and now am putting everything back together. For those of you who have not ever considered replacing your water pump - it is a rather time consuming endeavor on the Miata - remove the cam shaft cover, accessory belts, timing belt, etc...

Anyhow, putting it all back together now. After torquing the timing belt idler pulley to the specified torque - should the idler pulley spin or be locked down tight? In other words, do I need to buy a new timing belt idler pulley?

kc

Reply to
bam2chan
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It should definitely spin after torquing. I don't know if you need to buy a new one or not, but if it doesn't spin freely, loosen it and fix what ever is hanging it up.

Reply to
Natman

I may be missing something here, but I remember torquing the idler pulley after having the replacement timing belt in place. That being the case, how is the idler pulley gonna spin freely if it applying tension to the timing belt? As I say, maybe my brain is suffering from frostbite, but...

Pete

Reply to
Pete

The tension pulley is definitely torqued after replacing the timing belt. I could not find anything that said when to torque down the idler pulley. My other thought was that while I could not spin the pulley, that the timing belt could. For sure - the pulley was not turning (by hand) when I took the timing belt off - so - what does that mean? That is the million dollar question.

I am going to try and clean up the surface of the pulley (by the head of the bolt) in case anything is causing friction, and potentially just tighten to the min torque and see how that does. This project has already taken longer than I had hoped - true I had to leave town for a week - but two weekends later - still no car.

Any other ideas?

kc

Reply to
bam2chan

A seized pulley gets replaced. They typically last long enough that they only need replacement at every other timing belt change. But at 114k, when my water pump started leaking, the bearings in both pulleys were dry and on their last legs.

Reply to
Lanny Chambers

From your first post: " After torquing the timing belt idler pulley to the specified torque - should the idler pulley spin or be locked down tight? "

From this I assumed that the pullet turned freely *before* you tightened it down. If you can't turn the pulley by hand, then it has siezed and will need to be replaced.

Reply to
Natman

torquing the timing

But, if the pulley is spinning - then it is spinning metal on metal, vs. the tension pulley which spins freely and does not touch the metal behind it. As for the idler pulley, I don't know how it could have ever spun freely - the bolt head presses against the pulley - what would sieze? Are we sure it should spin freely?

Reply to
bam2chan

Are we sure it should spin freely?

If it doesn't, you will be replacing the new timing belt very shortly, as well as getting a new idler pulley. If tightening the mounting bolt causes it to not turn freely, something is wrong.

When we replacet the timing belt on my 99, both pulleys felt a bit rough, so they were replaced. They did turn freely.

After torquing the timing

Reply to
Chuck

Both pulleys contain sealed ball bearings. Eventually, the grease migrates out past the seal, and shortly thereafter the dry bearing will seize. A seized pulley will destroy the belt in short order.

The goal is to change them just before this occurs. :-)

Reply to
Lanny Chambers

The idler pulley has a center mounting piece about 1.25 inches in diameter. Outside of the center is the inner race of the bearing that remains stationary. The brown seal and the outer race of the bearing turn with the pulley.

Yes the pulley HAS TO TURN. No question about it.

The bolt should touch the center mount AND NOTHING ELSE. Judging by the mark on my old pulley the washer under the bolt was about 5/8" in diameter. If yours is so large that it touches anything else, you are using the wrong bolt / washer. Or possible you are trying to install the pulley upside down. The pulley shoud be installed with the projection in the center TOWARD the engine block.

Reply to
Natman

mounting piece about 1.25 inches in

I am installing it correctly - and to be on the safe side - I called Mazda. They informed me that the idler pulley does NOT turn. The tension pulley does turn.

Reply to
bam2chan

He also may have mounted it on backwards and it is clamped up tight against the waterpump housing !

Bruce Bing '03 LS

Reply to
BRUCE HASKIN

It should NEVER spin freely ! If it spins when you hold the center and move the outer part, throw it in the trash! You should be able to turn it and have some drag. If you can spin it like a bike wheel, the next thing you can expect is the idler will come out thru the front cover some time when you are turning up the wick and hit 7,000 RPM. I have seen two cars come in after that came about. Very ugly !!!

"If it spins with very little effort, it is shot !"

Bruce Bing '03 LS

Reply to
BRUCE HASKIN

Your "Mazda Dealer" is as full of shit as a Christmas Goose !!!

The "Idler pully" is just that ! "AN IDLER" It is a bearing and the out side surface rotates ! It does not just sit there an let the belt slide past it !

Tell your "Dealer", to stick to selling cars and not fixing them, cause he does not understand how things work on cars !

Bruce Bing '03 LS

Reply to
BRUCE HASKIN

OK - good clarification. It does move with difficulty, and as I asked originally - it does not turn easily by hand, but I assume the timing belt does move it as required. My question still remains - if it is turning - is it not turning metal against metal (back of the pulley against the water pump)? So I am assuming then I am good to go for now.

Reply to
bam2chan

center mounting piece about 1.25 inches in

If you want to believe that the idler pulley stands still and that the belt slides over it at 7,000 RPM, you go right ahead. It's not true, of course, but you seem to be far more interested arguing than getting your car to work.

I give up.

Reply to
Natman

center mounting piece about 1.25 inches in

still and that the

I am not arguing - but I am getting several different answers.

  1. It does spin freely
  2. It does not spin freely
  3. It should not spin
  4. and on and on!!
Reply to
bam2chan

He does however understand how things work on people who should be bringing their cars into his service department instead of being provided consulting for free.

Leon :)

Reply to
Leon van Dommelen

But if it "does move *with difficulty*", as the OP stated in another post, then the bearings are shot also.

Leon

Reply to
Leon van Dommelen

OK fair enough. This is a difference in semantics about what "spin freely" means. Let me try to resolve it.

1) The pulley HAS to be free to turn when it is installed. That's why Mazda put a bearing in it! If you start the car with the idler unable to turn your belt will quickly destroy itself in a cloud of blue smoke.

There is no room for intellegent discussion of this point, any more than whether or not your engine really needs oil or "It's only flat on the bottom", do tires really need air?

THE PULLEY *MUST* BE ABLE TO TURN!

2) The pulley should turn smoothly with no trace of roughness.

3) You should be able to feel the resistance of the grease that is packed inside. If it spins freely for several revolutions like a roller skate wheel, then the grease is gone and it needs to be replaced.

Best bet: just buy two new pulleys.

Reply to
Natman

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