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Fan belt broke... Where are the tensioners so I can get the belts off? (72 240z)

574 Views 4 Replies 3 Participants Last post by  corrado33
So my Dad passed his 72 240Z down to me since he can't really work on it any more. It's been sitting in our garage for a while, so I got it out, did all the necessary things to start up an old car that's been stored for a while, and I took it for a test drive.

The belt was squeaking initially, but as I was driving down the road, about a mile from home, it just stopped.

I though to myself, "Well, this could be a good thing (problem fixed itself), or a bad thing (belt broke)."

So of course not a quarter mile later I pulled off because the car was overheating. I got it home by driving a tiny bit at a time, then letting it cool down.

And now I need to replace the belt. OF COURSE it's the closest one to the engine so I have to remove the other two belts first to get this one on, but I have NO idea where the tensioners are. I know for the belt that broke, the alt moves, right? Then there's a big belt in front that has a small pulley up in the upper right (if you're looking at it straight on). Is that the one I need to loosen? Then there's the second belt that goes toward the driver's side of the car (didn't look at what it goes to). I'm assuming whatever it goes to moves cause it's the only other thing the belt touches.

Also, when I bought the belts, they had two for this car that were VERY similar in length, one is slightly longer. I'm sure I could get both to fit, so which one is it?

So, any help?
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"You'll be the first to know!" Belts are a personal thing. It's not that massive of an engine NOT to see any 2-1/2" tensioners. (12mm and 14mm will be your friends.) Alternator adjusts INWARD for loose. - Norm K.
Yeah I figured it out. These engines are ridiculously easy to work on. (I'm used to 90-present cars). The idler pulley was the tensioner for the big belt. There was only two bolts on it. One took the pulley off and one rotated the assembly to loosten the belt.

Well, I did have a datsun 70-79 repair manual too, so that kinda helped. (Told me it was a tensioner, and how tight to make the belts)

The other two belts were easy, the alt moved in and (I'm guessing) the compressor moved in. I had to move a hose out of the way to get to the bolt for the alt though. That was annoying. Almost done now though, just putting the fan back on. Why is there a little spacer plate inside the pulley? It's impossible to get the pulley, plate, and fan all lined up at the same time, and you can't pass the entire assembly down there.

Currently I'm waiting for some very weak glue to dry so it'll hold the plate and pulley together long enough for me to put them on.
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You need to be paying CLOSE attention when you start the engine.Something caused that belt to break.
Arubabill said:
You need to be paying CLOSE attention when you start the engine.Something caused that belt to break.
Already started. Already driven. No squealing either. It was a very old belt, even when I took it off it was all dryrotted to heck. I replaced the other oldish belt too when I was in there. The big belt was already replaced recently.
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