Idler Pulley Flange Nut

I'm dealing with the exact same issue now. Thank you for tracking down this info. Just curious, since your last post have you been able to find the original nut anywhere?

Thanks again.

 

Too bad I did NOT find out that you need this sooner. I will be away from my shop for the next three months, but I do have a supply of J.I.S. 10.9 grade M10x1.25 flange nuts with 14mm hex heads.

I had to order them from an overseas supplier in 100 quantity.

 

Thanks Shu for the information. I have also just had to deal with this issue for my 2005 prius. Unfortunately the nut would not come off and I ended up destroying it with cold chisels (not easy - there is limited access). I also damaged the thread of the bolt, and had to find a replacement. One thing I noticed is that the replacement bolt and nut was coloured bronze (same as in Hobbits 100k maintenance picture), while the original was coloured silver (or grey). So a different metal? I was wondering if 2005 pri might be more susceptible to this problem if a different metal was used?

cheers,
Dean

 

I would love to order a couple just to have in case mine breaks off

 

I have them in ISO grade 10, but I'm not allowed to sell them, here. What is the length of the bolt? I might be able to get it, too.

The bolts are NOT bronze. They are ISO Grade 10.9 medium carbon steel. The yellow plating is zinc chromate. The plating was standard with Japanese and other imported cars until the early part of this century.

Chromates were soon banned as a carcinogen. The manufacturers, including Toyota switched to a standard zinc plating.

Hope this helps.

 

For those owners who had trouble removing this nut, I was wondering what tools you used:

1. Brand name of 14 mm socket used
2. 12 point or 6 point
3. Any other comments about this. For example, if you used a tool other than a 14 mm socket.

Thanks.

 

The closest SAE equivalent to 14mm id SAE 9/16 inch. It works, too.

The J.I.S. or Japan Industrial Standard is different form the original DIN or Deutsche Industrie Norm Standard used in Europe.

J.I.S specifies small hex heads.

There are two Taiwanese companies that hold about 90% of the after market on these fasteners. Their bolts are marked with "WT" or "JH" on their heads to meet with the marking requirements of the original US Department of Commerce standard to deter counterfeiting of fasteners.

 

My friend with a 2007 just did this repair a couple weeks back, he said that nut was very hard to remove. He mentioned there was loctite from the factory on the nut. This guy works on cars all the time so for him to notice it being difficult, there must be something that's out of the ordinary.

 

Well, the tightening torque on the nut is only 30 ft.-lb. The purpose of my question above is to see whether the use of inappropriate tools is part of the problem. I believe that a quality six-point, 14 mm socket and a cheater bar with extension is sufficient to gracefully remove the nut and allow its reuse.

I've done the Prius serpentine belt replacement 3x now; once on the 2001 and twice on the 2004. There was no Loctite used on the idler pulley nut, on either of those two vehicles.

I haven't done this on the 2007 yet because my daughter has taken over that car, the odometer reading is not yet at the point where this needs to be done and I don't see the car (or her for that matter) that much since they reside 500 miles away...

 

The 2007 had 70,000 miles on it with a leaking water pump. That was the reason to mess with that nut. I couldn't believe it when he told me but he's not a rookie in repairs so there must be something to it.

 

I had the same issue; the idler nut is frozen on there as are the water pump pulley bolts. You need some good sockets and patience to get those off.

 

IMHO, the Snap-On Flank Drive sockets and wrenches perform better that any other socket/wrench.
I've had bolt heads rounded by common sockets, and the Snap-On was usually able to remove them.

 

No disagreement that there is a reason Snap-On can command a premium price in the professional mechanic marketplace.

However, for DIYers who are not generating income with their tools, I would say that Craftsman and the various brands sold by Home Depot/Lowes work very well.

If the DIYer can avoid buying/using the very cheapest tools sold by places like Harbor Freight, I think that person can succeed in the DIY maintenance discussed here, without paying amounts for tools which threaten to deplete his children's college fund.

It really helps to have the correct tool for the job, for example, using only 6-point sockets of the correct size when any reasonable amount of torque has to be exerted.

 

I'd like to add that I avoid using 12 point sockets unless the bolt head is 12 point.

 

One of my favorite pastimes or hobbies is the study of OEM and after-market fasteners.

I have quite an extensive collection and am always acquiring more.

I just like the proper fasteners. A lot of purist would KILL to get the correct fasteners for their vintage cars.

 

Thats interesting Rude person's. Then the replacement bolt and nut I got from the wreckers must have
come from a Prius 2005 or earlier that still used zinc chromate bolts and nuts (there seems to be a mix
among other nuts on my car). The Yaris has the same engine, but an alternator in place of the idler
pulley - so not sure whether the replacements could have come from a Yaris.

I would recommend not damaging the bolt! the bolt is not standard - it has another thread through the
head where the tension adjustment bolt goes - to get a replacement through a toyota dealer was over
$AUS100 and ex Japan (have to buy the whole idler pulley assembly). I was lucky to find one at
the wreckers (still had to pay for the pulley, but only $AUS30). Its got an '8' written on the head. No WT or
JH that I could see.

Patrick Wong: You might have a good point. I used a 12 point 14mm socket from a cheap tool set bought
from K-mart (perhaps an Australian version of a Wal-mart type store), and a cheater bar - which seemed
to work until I realised I was stripping the nut rather than turning it. However, this set of sockets has
never given me trouble before. The belt was changed at 202k kms (~126k miles?), so at the time I was
wondering whether it was the factory belt, or whether it had been replaced before and the nut over tightened.
Maybe I was too ready to blame someone else for my problem!

JC91006: I didn't notice any loctite on the nut, but not sure what to look for. I used WD40 and then
something supposedly more powerful on it - but it wouldn't move. Even after cracking the nut, it
wouldn't move.

cheers,
Dean

 

Dean,

Do you have a photo or drawing of the exact specifications.

I am a machinist and can make almost anything. I used to make replacement parts for the old 190 diesel engines used on the Mercedes models of the 1960's. I have the capability of drilling an tapping even 10.9 grade hardened steel bolts.

Maybe, this will help someone here.

Rude person's

 

Hi Rude person's,

Thats really nice of you, although I hope no one else ever has to replace this bolt. Here
are some pictures of the damaged bolt. I don't have any technical drawings, its about 55mm long.
Hobbit also has a picture of the whole idler pulley assembly at:
100K maint - 2
(scroll down almost to the bottom).



cheers,
Dean

 

Dean,

Instead of a specially made bolt, a block of steel or other material can be made that's drilled at 90 degree angles. This is a common adjustment method used for pulley adjustment over the years on many cars. What is the threading size on the cross drilled head?

On the alternative, if there is space, the bolt can be threaded from the back into a lathe turned and threaded sleeve with a square head for the piece that needs to be cross drilled and threaded.

These are just a few methods of making workable replacement parts.

It helps to have a machine shop and extensive tooling available.

Rude person's