Calling 348 brothers with engines currently out...

Chaps,

My local indy mechanic is 99.9999% done with my major service (plus lots of other stuff).
We're currently held up because the standard alternator belt for the nippon denso setup doesn't fit.
It's WAY too tight to go on even with the tensioner at the end of it's limit. It's pretty tight even with no tensioner installed, as you can see from the pic !

We've checked all the brackets to make sure they are all "denso" compatible, and they do appear to be.

David at Ricambi has graciously volunteered to get under his mondial t and measure the crank pulley (because there are two types) and I suspected maybe they had a different diameter.

My mechanic and I looked over the problem today and the only thing left I can think of is the pulley on the denso alternator itself.
That's where the brotherhood comes in !

I know a couple of you guys have your engines out right now and probably have easy access to a nippon denso alternator.
What I'm looking for is the diameter of the denso pulley. Not the diameter of the flange that's around it, but the inside diameter where they belt touches the pulley.
The one I have is 57.23 mm in diameter and my last hope is that this is in fact the wrong one.

The original belt had stretched and cracked so much that it actually fitted, but the new belt is impossible. You can't even get the tensioner installed with the belt on. It's that tight. Too tight. We've looked for alternate belts, in fact Daniel has probably sent us 3 or 4 by now. We've also called various belt providers but everything is either smaller or much larger. We need maybe half in inch larger.

This is the last hope before we go fabricating a top bracket to get an extra 10 mm "adjustment" out of it.

Daniel / David at Ricambi have been super helpful on this, but we're all now scratching our heads wondering what on earth is going on.

So, are there any brothers out there with easy access to measure the a nippon denso pulley diameter ?

I'm a brother in dire need and hope someone can help out.



Many thanks

Simon (& Mike the hassled mechanic working on it).
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Don't fab anything.

Just take your belt down to the auto parts store and match is up with one just a little bit bigger. If you are in a real pinch use a 4 rib for the time being until you can find a proper 6 rib belt.

 

Yeah, we've done that.
We went to pep boys and had every single belt out in the store room. They let my mechanic in the back to rummage through.



He's got a lead from Sport Auto in North Carolina that he's following up on tomorrow. Basically a different belt. Those guys say there are actually two types on denso in existence (as far as I can gather) one with a shield and one without. Mike (mechanic) is checking up with Dayco tomorrow but I don't hold out much hope.
I think it's the darn pulley on the alternator, but what do I know, I'm a software engineer and that's hardware.

:-D

 

Simon, here's a pic of mine. I had to use some dividers and my dial calipers to measure the pulley, but here's what mine measures approx:

Outer Flange 64.0mm
Outer Edge of pulley teeth 57.02mm
Inner Edge of pulley teeth 52.95mm

Mine seems to be the same size as yours.

I am replacing both my A/C compressor and alternator belts, and one is quite a bit smaller than the other (don't remember which is which at the moment). But make sure you have the right part number for the Denso alternator and not the older Delco. Not sure if they both have the same no. of ribs on the pulley, but if you have a Delco belt, it may be too small. As long as the alternator and bracket are installed correctly, hard to see how the right belt wouldn't work, unless somebody retrofitted some other Denso to your car that has different bracket dimensions. Good luck getting this worked out.
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Thanks Rick !

They do look like the same dimensions. Darn. That was my best hope.

I do actually have a delco belt too and you're right, that's even shorter. We've tried maybe 30 belts. All either shorter or just too long to tension up.

I have the later, denso brackets. The two types are visibly very different on the parts diagram on Ricambi's site, and match exactly with what's on the car from the "looks" of it. Don't have actual dimensions, but given that they look so different we'd notice.

We also checked the part number on the denso alternator. It's the same as Daniels car, and is the correct part number listed on the parts diagram.

However, Daniels car had the same issue, the belt would not fit. Sport Auto did something to fix it, but said it was related to a different belt, apparently they got a different belt from dayco, but it didn't seem like that today as Daniel got under his 348 and took a look to see what they did. Seemed like his belt was the same as mine, but his bolts holding the brackets looked new and shiny indicating a difference.

It's really very weird. Everything looks right, but the belts are amazingly tight. So tight that you'd only be able to get the tensioner on if you prized in on with knuckle scraping pressure which we think will be too much for the alternator bearings. We know belts loosen pretty quickly from new, but it needs to loosen a lot to be even able to move the tensioner off it's loosest limit.

There are two types of crank pulleys as well. One with lots of holes in it (to lighten it I guess) and one with only two holes in it. I have the one with many holes. David says he'll measure his that has only two holes and we'll see if that's it. I doubt that however, they look like direct replacement parts that are just lighter and in any case my car looks standard with all denso compatible parts (it's a 92)

The only think I can think of is to either make a new top bracket and pull it in as much as possible, which really isn't much before it hits the engine casing.
Or, put a spacer of some description on the top bracket to move it out into the realms of some of the larger belts we have. Probably an inch or less would do it.

Really weird problem.

 

After my last post, I also was thinking about perhaps different crank pulley sizes. Really weird... we'll see if I have the same problem when I reinstall my alternator. My old alternator belt was old and cracked .... maybe this is part of the reason? Here are a couple pics of my setup, in case it's of any help. Perhaps idler pulleys are of different sizes?
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Hey Rick,

your belt looks as bad as mine did. Cracked pretty badly.
Your setup looks identical to mine. I wonder if you could measure the tensioner pulley too ?
Mine is 89.89.

We've got a slightly larger belt coming from Dayco which give us just a little extra room, but not much.
If it works I'll let you know the dayco part number, just in case.

 

SportAuto just put a new belt on my 348 last month.
If you need me to, I'll crawl under it an get the info off of it for you.

I think you can get them locally.

Before that I got one from Ricambi, and it worked too...
it was tight getting it to go on but still had room for the tensioner
pully to work properly.

I also have the original belt laying around if you need the numbers off that.
Let me know.

 

Just measured it Simon, and I measured 90.0mm, so must be the same. Let us all know how you resolve this.

 

Stop the press!!!

I completely forgot about this! Is was on the last page of my alternator rebuild thread, and was posted by GeorgG. Part #144909 for the 90/amp Nippondenso alternator has the larger 770mm belt. The 105/amp alternators have the smaller 760mm belt, updated part number #199830. So maybe you have the belt for the 105 amp instead of the 90amp alternator????? Check to see which belt you ordered.

 

Thanks for the info Ernie !
This is REALLY useful. Sport Auto had mentioned two types of denso alternator too, but I don't think were as specific as you.
Mike (my hassled mechanic) called Dayco on Friday and they also came up with a belt that was 10mm longer, but again, no one knew why.
I wouldn't mind betting that this is the answer !

It's good to know, plus it ads a 3rd choice for alternator belts for 348's. Delco, Denso 90 and Denso 105

I really appreciate all the replies here, it's been a frustrating saga trying to come up with a belt that fits.

I'll let you guys know how we get on with it this week.

 

The longer belt is indeed required for 90A alternators.
We got the belt today (770 mm) direct from Dayco and it fits like a glove.
So definitely 3 types of alternator belt setups to be aware of chaps.

Delco, Denso 90A and Denso 105A, each with differing belts.

I don't have the part number of the belt handy, but I'll likely see it this weekend and will post here to verify with Ernies # number.
I feel great ! My mechanic says we'll be back on the road with the ol' girl next weekend.

I'll do a picture write up of the lows and highs of this 5 month saga when it's done.

 

Sweet.

Gald work out.

 

+1... and thanks for the followup!!

 

Here's the details of the belt we got that fits.
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My engines coming out soon, seems like everyones getting majors right now