Brickers:

model: 1985 745t

Wondering about the recommended belt deflection method in my Haynes manual. The instructions state that the alternator and power steering belts should have a deflection of 5-10mm and the ac should have 1-2mm.

First off, is this correct? I tightened the alt. and ac to this spec, but they seem REALLY tight... I just don't want to kill my alternator or anything.

Second, is this spec for new belts? Does it anticipate the expansion/stretching of belts over time, or should you tighten the belts as they stretch to keep them within this spec?

The reason for these second questions is that I recently replaced the alt. and ac belts as I stated before, and tensioned them to spec. However, I did not replace the ps belt as I didn't see an easy way to get it off and didn't have time to deal with it. I have now noticed that the ps belt has at least double the deflection recommended (at least 10-15mm if not more), and want to know if I should try and tighten it up a little. The belt looks solid (no cracking or signs of wear), and I'd like to try and keep it on until the spring if possible.

On a sidenote, how does one retension the ps belt or get it off? I didn't look to closely or pull the underpanel when I did the other belts, and I can;t see any positive tensioning device or other simple means of loosening the ps pump to get the belt out. I imagine you have to go in from underneath (since its basically under the engine), but would welcome any advice.

Thanks,
Rick

rt: sounds a lotta too-tight on them-thar belts, amigo. I use the old thumb-in-the-center-of-the-belt deflecting method, looking for about a 1/2 inch-or-so. I would also suggest checking the tension after a few days of driving, like 2 or 3 times the 1st week, and maybe weekly after that, just to make sure that all is well. Hell, I check 'em every time I open the hood. As far as 'looking OK' on that one belt, "looks aren't everything," "looks can be deceiving," and other platitudes spring to mind. Many-a belt has shwed its true dying nature upon removal and closer inspection. I have always subscribed to the theory of 'replace one, replace 'em all.' That way you KNOW that they were all done; and Hey! you're down there anyway, why not? I did all of that 2 summers ago, when one belt broke. Don't remember about the degree of inconvenience/difficulty with the P/S belt, but seem to recall having to loosen the bracket nut/bolt on the alternator anyway. Somebody is bound to chime in the correct/helpful info on that one. Good Luck, amigo.--PD.

It's a little tight to get to the PS belt tensioner adjustment, but not that bad. It is MUCH easier if you have the engine fan taken off (4 bolts). I mean, MUCH easier. Either that or the turbo hoses. Either way you'll save yourself a lot of trouble. It's locked by a 13mm (or 12, can't remember offhand) on the front sidee, and the adjuster faces the right side of the car and can be accessed a couple of ways. Use extensions or whatever you need to get in there, but it really isn't that hard.

You can reach up from below, but that's not that easy because you have to go over the PS pulley to get there.

My philosophy on belts is to run them as LOOSE as possible without sacrificing their job which is to drive the accessory. That means, if the alternator will run well without squealing or losing it's capacity because of a sliding belt, then it's good enough. I tension the AC belt on 700s pretty tight, but the compressor bearings are more likely to handle the increased pressure. Also the belt is much heavier duty, and is meant to drive a heavier accessory. The PS belt is also the water pump belt, so it has to be tensioned appropriately, but not overtightened. That's not a good belt to be slipping, but if you overdo it, the water pump bearings will get ratty faster than normal.

The alternator belt should deflect maybe 1/2 inch in the middle. But again, enough to drive the alternator under full electronic load in temperature extremes when belts often slip.

I retighten belts after a few days of driving (for me 200 miles or so). If you retighten once, you should be able to get away without doing it again.
--
Chris Herbst, near Chicago, IL. 93 940, 91 240, 90 240, 88 740, 87 240

Is there any sign or indication of a belt that is too tight? Is that 1/2" with firm pressure to the middle of the longest run of the belt? Is it normal if the alternator moves a little on the bushing when you push down?

Yes, the p/s belt is pretty well buried down under the block/hoses. The reason I didn't replace the p/s belt (or go to the trouble of doing it) was because I had spent 2 HOURS getting the damned alternator remounted after inserting new bushings. SUCH an annoying job, the bushings wouldn't line up and I kept hitting the metal center bracket with the mounting rod... argh.

-Rick