I have an 91 NA that just won't hold onto it's alternator belt. I have tried two different belts (a cheapy and then a Goodyear). I've also tightened and retightend it along with liberal use of belt dressing. It's worse when the ambient temperatures are high (85 degrees+). Does Mazda make a belt specifically for the FC? I was told to use a "6-ply belt" by an alternator shop, but no one at the local parts stores seems to know what the hell I'm talking about! The car is stock and I still have my A/P, A/C, and P/S. Any suggestions (other than "just tighten the belt") would be appreciated.

TODD
1991 RX-7
1981 911SC

 

Belt dressing is not a good idea. It can cause more problems. Best to clean the pulleys off with alcohol and install a new belt. Contrary to popular belief, that belt must be tight, with not very much play. Some say you'll knock the bearings out, but I still have the original alternator with 168,000 miles, so crank it down. Because of the location, it's difficult to keep it tight when adjusting, but keep at it.

 

My alt belt jumped off the pulleys and ate it self when I used belt dressing... that wasn't pretty. Also that clutch fan may be locking up for some reasion at a high RPM. If it does that the alternator belt... and for that matter air pump belt will slip around the waterpump pulley. Very seldom will the belts be tight enough to keep that waterpump pulley/clutch fan from slipping with the fan locked up at <4krpm. It wont lock up then unless the clutch fan is screwed, but it can happen.

After removing the clutch fan my powerband went up to about 8.5k, wheres I could hardly ever hit 7.5 due to the clutch fan trying to lock up all teh time.

 

When tightening the belt, I like to get a long screwdriver or something similar, and have a friend pry up on the alternator while you tighten the adjusting bolt. It should have as little as 1/4 inch deflection, or you will see belt slippage from time to time.

-Ben

 

Thanks for all the answers. Can I remove my fan and take a SHORT drive to see if it is indeed locking up @ higher RPM? If not, what is the best way to test the fan clutch?

I had considered that maybe the alternator belt was slipping because of oil or something on the lower pulley, but another pulley dragging would probably cause a similar reaction.

TODD

 

did your car vibrate at high RPM as well?

 

Yes, I get a vibration between 7 & 7.5K RPM. It's not bad, but defintely not there in the lower RPM band.

TODD

 

Todd, I had the same problem after a cheap belt was put on the alternator, it actually flipped over and partially shreaded!

When I had the engine out for a rebuild I replaced all of the belts with Goodyear Gatorbacks, they seem pretty good, I'm at 3000 km's with these and haven't had a problem.

Replacement Products for MAZDA RX-7 - 1991 1.3L 2 Rotor Eng

Part No. Applications Usage Metric Part No. Replace By
V-Belts
15321 V-Belt, Alt 11AV0800
15382 V-Belt, Fan & AP 11AV0955
17380 V-Belt, AC & Idler (w/o Turbo) 13AV0965
17386 V-Belt, AC & Idler (w/Turbo) 13AV0980
17425 V-Belt, PS & Idler 13AV1080


What Goodyear belt did you try?

 

get a dual bell pulley and have 2 belts

 

Thanks again for the info. I haven't had time to look at the car (or the belt #'s), but hopefully I will make time and get to the bottom of it.

If I'm moving, can I operate the car w/o the cooling fan for a short period?

TODD

 

I finally had time to check my alt belt. It is indeed a goodyear gatorback 15321 11AV0800. The belt dresing has left a sticky gunk that is probably becoming slick as it gets hot. I'm going to remove all the belts, clean all the pulleys, and install a new belt. Hopefully, this will solve my problem. It's really becoming a PITA with this 95+ degree weather I've been experiencing in Savannah -- the belt is slipping all the time!

I'll report back after my pulley "tune-up".

TODD

 

i too lazy to read the whole thing but. go get a larger than stock double pulley. they are specifically designed to top slippage @ high rpms. sorry if someone said this already

 

This is really starting to p!ss me off! Today, I removed all the belts. I cleaned each pulley with brake cleaner (first with paper towells, then with Q-tips!). I installed a brand new Goodyear belt for the alternator and re-installed the other new belts. I went for a test drive and I'm getting all the warning lights at 3K RPM+.

1) The alternator is rebuilt. I had it checked by an autoparts store and it is putting out 14.7+ volts.

2) I still have my A/P, so a dual pulley is not possible.

I think something else is locking up and causing the belt to slip. Could the waterpump be locking up? It's not making any noise or weeping. Could the fan clutch locking up cause the alternator belt to slip?

Can anyone point me in the right direction with this problem?

TODD

 

How are you setting belt tension???

Too tight will waste belts... too loose will slip

 

I have about 1/2" deflection on all my belts. I have the alternator belt tighter than I would normally set a belt, but I've never had belts slip like this car. I had a GTI 16V in the eighties that reved to 7200 RPM -- w/o slipping a belt. Is it possible I have the belt too tight, creating friction and heat -- causing it to slip?

TODD

 

BUMP in the road.

 

you keep ignoring people saying dual belt pully why is this? do you have your air pump still??? Also you may just want to get another fan clutch to see if this is the cause, you can usually pic them up for around 10 bucks on ebay. Also what you may want to do is run with only the alternater belt on and see if it happens however if it doesn't put each belt on one at a time and see if it is the a/c or p/s pullies that are locking up.

 

I stated on "page 1" that I still have my air pump (to control my ports and VDI). My engine is largely stock. I could understand if the belt was slipping @ 7k RPM+, but 3K? If the factory deemed it necessary to have dual pulleys to avoid slippage, they would have installed them. I'm trying to find a solution w/o ripping out my air pump, installing a dual pulley, and having to electronically control my 5th and 6th ports / VDI. I will try the alternator belt by itself and add the other belts. That sounds like a logical move.

 

OK, I removed all the belts and cleaned the pulleys with rubbing alcohol. I then installed a new belt and tightened it to spec. I drove the car around the block with nothing but an alternator belt and it still slipped! The only other thing it could be is the waterpump. The car does not overheat, but I have a slight crack in my radiator.

Could the waterpump be jamming up? Is this common? It does not weap or have any bearing noises.

I don't understand how an alternator could cause enough resistence for a new, tightened belt to slip

 

Are you using new Mazda/Mitsubishi belts or???

 

i had a problem with my alternator getting loose after hard driving. i swapoed out the bolt (partially cuz i snapped it ) re adjusted my ground wire . and pulled up (by hand) on the alternator and tighten pretty tight on the bolt and the belt is fairly snug, i havent had a problem. but my question to you is. is there alot of belt residue inside the engine bay? could it be possible one of your pulleys (mainly your alt pully) that is semi off center or something causing it to not line up perfectly with the crank pully??

 

Are you sure that it is the belt slipping? The water pump was going on my TII, it sounded just like a belt slipping. Replaced the water pump and fixed the problem. It sounded worse when the car got hot, but it also sqealed at low rpm's.

Steve

P.S Maybe it was a belt sliping now that i think about it. I guess the bearings were going in the water pump causing the belt to slip.

 

I am using a goodyear gatorback belt. I've considered a Mazda belt, but I didn't know they were available. I must be clear when I say that I've tried all the obvious fixes. I ran the car with only one belt turning the alternator/waterpump and it still slipped. The waterpump is showing no sign of being defective -- no weeping, overheating, or bearing noise. My climate is very hot right now (avg. temp 95 degrees F.). Could heat be to blame?

I appreciate all the advice, but nothing has helped this situation. I am very mechanically inclined and this is not a simple "just tighten the belt" issue. The car is almost undriveable.

TODD

 

Hey, What condition are the pulleys in? There is a distinct possibility that one or more pulleys are worn to the point where the belt bottoms out in them. The only gripping surfaces are the sides, so if the belts are bottoming out that could cause the problem.

 

One or more of the pulleys or the waterpump is (I think?!) to blame. When I examine the the alt. pullley, there are distinct rubbing marks (on the sides) where the belt is rubbing. With the amount of tension I have on the alt. belt, it should not have the ability to slip unless there is grease on the pulley or the pulley itself is not presenting a good surface on which to grip. When I tighten the belt, it seems to "bend in" towards the middle of the pulley, only making good contact on the sides.

Can someone list the measurements (diameter, width between front and back of pulley and inner height, in inches) of the alternator pulley for comparison?

Thank you