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Wondering if there is a certain sequence for tightening accessory belts. Just completed new poly bushings. When I tighten the alternator belts, the front belt snugs up tight way before the back belt( belt nearest the firewall). When I get the back belt tight, the front belt is then too tight. Any thoughts on what I might be doing wrong? Thanks.
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Okay, I just had a little fun with trigonometry, and I'm partly retracting what I wrote previously.
I was previously somewhat dubious about these possibilities:
1) that the alternator was mounted too far forward or back;
2) that the alternator wasn't aligned (i.e., parallel to the block).
I'm no longer merely dubious of the above.
After further consideration, the problem with (1) was that it would necessarily produce the problem you described because the belts would still be parallel to each other (unless you somehow screwed up the mounting of the water pump pulley) and have the same tension if they have the same length.
And my problem with (2) was far more fun. I found (by calculations and graphing) that for one of the two (very closely spaced) belt slots to be so differently spaced from the water pump and crankshaft (harmonic balancer) pulleys to noticeably affect belt tension, the alternator must be skewed (pivoting on its front mount) out of parallel to the block about 15 degrees or more (something impossible that the mounts wouldn't allow).
So you can forget about the above possibilities, and (with due credit to Sir Arthur Conan Doyle) after eliminating all the impossibilities, I'm going out on a limb and declaring, with almost "carved in stone" certainty, that you have two belts of different length (which isn't as "improbable" as Sir Arthur might have intended).
As I wrote in the first message, swap them and then seen which is tighter.
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Ken, I'm no Sir Arthur, but I submit the "difference" between the lengths of the matched set or otherwise is insignificant compared to the variation caused by change in axial alignment (parallel shafts) which occurs when you tighten the belts against the give of the accessory bushings. IOW, you'll swap the belts (not inconsiderable effort) and puzzle over the result.
My thoughts are oil-soaked accessory bushings, belts baked, worn thin and bottoming, and a glazed alternator pulley. The already marginal two-belt three-point 240 alternator configuration outgrew its engineering as alternator capacities since 1975. They got it right in the 740, but ...
--
Art Benstein near Baltimore
If electricity comes from electrons, does that mean that morality comes from morons?
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I, too, would first think of soft/degraded bushings allowing for twist, but the O.P. reported that this was immediately following installation of all new poly bushings.
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You're right. And I have no experience with the poly bushings -- only what I've read about them here, and the disparity in durometer among the different suppliers of them. Also, I understand why the poly bushings are popular, and why the next step, solid aluminum fillers, are available to 240 owners. I can infer the OP knows something about that by choosing poly.
My experience is, if you start from a point where the belts are loose, and the alt shaft divergent from parallel, you can tighten the belt through parallel and beyond it, making the the two belts look like different sizes in a much greater amount than you'd expect to find even in two runs of the same part no. not matched. Yes, I tried the flipping inside to outside to learn this, using a new "matched set." The "long" belt is always on the inside once it is tight. That's where the trig comes in.
--
Art Benstein near Baltimore
A hangover is the wrath of grapes.
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To All, I switched the belts putting the front belt to the rear and the rear belt to the front. This time the rear belt tightened before the front. At that point, I just kept turning the adjustment screw until the two were somewhat close in tension. The rear belt is still just somewhat tighter than the front but, I guess I will have to be satisfied for now. The bushings were installed correctly and everything seems to be lined up with no distortions and as I said in my initial post, the belts were purchased as a set from IPDUSA. Thanks though to all of you for your input. Ya'll are a great support group.
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posted by
someone claiming to be oldduke
on
Fri Apr 25 06:01 CST 2014 [ RELATED]
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now wait a minute art ben- as a sage without peer, you have given me a conundrum wrapped in an anomaly. you say who wants a 740? have thought for a while now the late 240 like the slantsix dodge was just about the ultimate in available auto engineering and the 740 at least its equal and better in some ways. example- word here is the worst job on the otherwise easy to repair 240 , is the hellacious r and r of the blower motor. but it was corrected, redesigned and made easy to do on the 740. please correct me if i am misinformed. thanks tons oldduke
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I said what??? ;)
--
Art Benstein near Baltimore
A Freudian slip is when you say one thing but mean your mother.
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posted by
someone claiming to be oldduke
on
Fri Apr 25 18:56 CST 2014 [ RELATED]
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sorry art- i misquoted you from somewhere. will do better next time. cut me two slices of humble pie. apologies oldduke
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It looks like an old Buick.
Dan
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I already read a couple of the first responses. I don't believe that the alignment of the alternator to the crankshaft pulley (and don't forget the water pump pulley, which I assume you remembered to snugly mount, being part of this "triad" as well) could be SO out of line to cause this problem without your seeing this as very obvious, unless ...
... you actually installed the new poly bushing incorrectly, viz. the shoulders of one or the other of the bushings are reversed, or something like that, so that the alternator is too far forward or back, thus making the belts skewed. But even so, you should be able to see the misalignment easily -- and I think you would have noticed if this was the case.
On the other hand, if the alternator was just skewed out (i.e., not parallel to the engine block), I don't think it would cause such a difference that you would notice distinctive belt tightness. Just think of the trigonometry -- how far out of line (degrees) must the alternator be to cause such a difference in pulley position between two adjacent "slots" on the pulley? This, in fact, would be something that only would cause unequal belt wear over many miles, a very subtle difference in belt tension, something you couldn't measure easily and certainly wouldn't observe as substantially as you're reporting here.
I think it's MUCH more likely that, simply, your two belts aren't quite the same length. These belts are supposed to be sold in manufacturer's matched pairs, wrapped together as a set!
If you just bought two individual belts of the same (supposed) size or part no., it's likely that permissible manufacturing tolerances are the real culprit.
To test this, reverse the belts -- i.e., put the front belt in the rear, and the rear belt in the front. Then see which one is looser or tighter.
Then report back to us. Good luck.
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Thanks everybody for your quick responses. I will try the belt swap between the front and back belts. I did purchase them as a set along with the power steering belt and the a/c belt all from IPDUSA. They are Continental belts. I will let you know how it goes and if I discover a mistake on my part.
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Hi Sjam,
They have two different sizes. What year is your car?
104517 - V Belt - Alternator/Water Pump 10 x 925mm
101745 - V Belt - Alternator/Water Pump 10 x 920mm
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You never mentioned the model year of your car, but for both of my '93 240s, the original belts (I recorded their numbers many years ago) were
9.5W 918L, Volvo p/n 973537-4.
Note that it's a 9.5 mm width, not the 10.0 mm width that the other guy offered. Maybe he's got an older model year. On my old '84, the correct size was 10.0 mm wide, as in 10W 925L, and the original p/n was 966965-6, later superceded by 977260-9.
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It sounds like the alternator may be out of alignment with the harmonic balancer? Look from above and see if the alternator pulley and the harmonic balancer are lined up with each other,
Maybe the accessory bushings were not installed in correct alignment.
Dan
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I agree, the alignment is first up in the list here. This must have been understood to some degree for someone to cough up the bucks for poly, anticipating a less resilient mount.
Were the alternator housing bolt holes OK? Egged out where the long bolt passes through?
Another thought is belt thickness. I recall a post last year or so, where someone recognized the 9.5 and even 10mm belts were quickly bottoming in the pulley. The top of the belt was sunk into the pulley. I think the belt grip and power transmission occurs mostly at the upper sides of the V, at least that would be the point where mechanical advantage is highest.
I think most of us have been buying Conti belts (as matched sets) but I'm not saying genuine Volvo is necessarily better in this respect.
--
Art Benstein near Baltimore
I used to work in a blanket factory, but it folded.
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The problem is most likely as Dan has described but one other possibility is that the belts are slightly different in length. At one time you could buy aftermarket belts for 240 alternators in matched sets--that is--from the manufacturer they are matched for equal length. Nowadays they seem to only come as individual belts. I don't know about Volvo belts lately. -- Dave
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Dave
I have been buying matched sets of Continental belts for years.
Dan
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Ahhh--then that's the answer--when I was doing more auto repair not too many years ago I dealt with a wholesale/mail order company with their office located on Long Island and a warehouse in PA and they carried Continental brand. Anything I ordered could be had in a day--two at most. They've changed their catalog and stock - not for the better - and I've lately used an independent store and sometimes chains. -- Dave
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Dave
I have always been able to get them from FCP Groton or eEurparts.
Dan
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