73-87chevytrucks.com
73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Chevygold on November 28, 2022, 05:20:21 am
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Can anyone explain why my truck is shredding the alternator belt with painful regularity? Standard 350 set up with the alternator on the passenger side, first indication is belt squeeling then silence and no charge!
I've polished the pulleys with fine emery in case they were rough after standing for a while but no joy, these belts are difficult to obtain in UK as they are a section not commonly used over here.
I think it's the original alternator so not a hugely uprated one which overloads the drive.
Starting to get frustrated as I can't go any distance before the belt fails, latest ones were mile maker by Continental so guessing they should be reasonable quality?
Thanks
Graham
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Forgot to say I checked alignment and the pulleys are in line.
Graham
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Year make model and pics of your setup would be helpful. What part # belt are you using?
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Sorry Vile '76 C10 Cheyenne SBC 383 alternator on Passenger side, belt CONTINENTAL 15445MK Mileage Maker I'll try to post a picture in the morning.
Graham
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Strange...
Is that the same brand you've used with painful frequency?
Could be a bad production run if so.
Change brands maybe?
You're not over tightening are you? I'm sure there is a inflection gauge that will give you the range somewhere...
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Belt you are running is for Fan, Alternator And Air Pump; Automatic Transmission; Without Air Conditioning
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Per VZ, a very common belt for many years.
You need to look for other factors: over tightening, loose tightening, oil saturation, bad run on manufacturing, mice, rust, oh wait...
Maybe a warped or splitting wheel surface?
Pics would be great!!!
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Hi All, here's some photos. Like I said pulleys all in good condition, polished with fine emery just to be sure, no splits or wobbles
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You can see how worn the belt is by how deep in the pulley it is, looking at the fan it looks like a 12SI so it has been upgraded, I'm running an electric fan so that's a bit less load on the belt, alternator spins freely with the belt off without any rumbles from the bearings, belt tension tight enough not to slip and scream but not so tight it kills the water pump!
The alternator belt on my '70 Corvette has been on since I got it over 5 years ago without any issues so I know they can last longer.
Are there alternative pulley sizes available? thinking a slightly larger one would help with more area for the belt to grip on.
You can see all the rubber dust from this belt all over the front of the engine.
Thanks
Graham
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I would like to see a good picture of the alternator pully groove with the belt off. I suspect that the groove could bee worn. In fact check all pulleys for wear. Should be a V with no step wear.
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Hi Mike, I'll have a look but I'm pretty sure that's not the case, the pulley has no step that I could feel and a new belt sits properly in the V, the belt that is on there in the pictures has gone from 12mm wide to 7-8mm so sits low in the V probably bottomed out in the bottom of the V so has no chance of driving the alternator properly.
Thanks
Graham
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7448 V-Belt is what you want.
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I'm curious, how many belts run between the water pump pulley and crank pulley?
Adjust the belt tension by hooking the alternator fan with your fingers and rotating it using all of your hand and wrist strength. The belt is properly adjusted when the alternator pulley no longer slips. This is the best method of tensioning v-belt-driven alternators/generators on virtually any automotive/truck application.
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Now that I look at your pictures again, it looks like the Power steering belt is only going around the water pump and not the crank pulley. If that is the case I believe that it is causing the alternator belt to carry to much load and causing the belt to slip.
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Only one belt connecting the W/P pulley to the crank certainly is of some concern since that single belt wraps only about 1/4 of the W/P pulley. If you add an upgraded alternator with greater output into the mix(?) belt load increases even more, potentially overwhelming a single belt in spite of the fact that the fan has been eliminated. So the failures may actually pivot around both the belt dimensions (length, width, angle) and the belt routing configuration.
Properly fitted belts should ride up to about 1 mm proud of the pulley grooves. When all is said and done, fitting the engine with the correct, properly tensioned, and appropriately routed belts likely will remedy the cyclic failures you've experienced.
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When the power steering pump was driven from the crank via the water pump the belt fouled the bottom hose connection on the block damaging the belt, I think this is due to the short waterpump?
I think it should have a long water pump as when the fan was fitted it was back from the shroud on the radiator but this is how it came to me.
I could shim the alternator and water pump pulleys forward a little but that would put them out of line with the crank pulley, another way around it would be to go serpentine but that's big bucks I think?
Vile, how does a 7448 belt differ from what I have?
Thanks all
Graham
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I think VZ said it earlier! Appears you are not using a V belt and that is what you need. The alternator is wrong for your engine as it does not have the V belt pulley as the rest of the engine has (from the pics).
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Yeah I have to say pics aren't that helpful, low res. If you got your camera closer I could understand more of whats going on.
Having said that, and I could be wrong, the power steering pump should have a belt that is solo to the crank.
BTW, what is that big hose going toward the manifold from the left (passenger) side?
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Alternator V belt is CONTINENTAL 15445MK Mileage Maker as already stated, the one in the picture is badly worn which is why it is sitting so low in the groove.
I didn't try a belt from the crank pulley for the power steering pump, will have to have a look and see if that is possible.
Thinking back it seems my troubles started after taking the power steering pump drive from the water pump.
Hose is the bottom radiator hose to block which is where the belt was fouling on the original set up.
Graham
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The pump has a tension-er on the right side. Look for a cool tool from bd to tighten it 8)
I think you got a bad run on belts or it's a crappy brand. Did you look up VZ's recommendation?
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I haven't found a belt routing diagram specific to your 1976 C10 SBC. Nonetheless, after studying the 1976 factory parts books, I believe JohnnyPopper is correct that the P/S pump should be driven directly from the crank pulley using a 7/16" wide v-belt. A 15/32" wide v-belt is specified by the factory to wrap around the alternator, fan and crank pulleys. Be sure to use the correct width belts for the greatest bite in the pulley grooves and acceptable durability. Heavy-duty v-belts should outperform the economy-grade Mileage Marker belt in your pics. Adjust the belts as previously described or use a gauge.
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These are images of the correct era pulley belt setup with non-AC truck.
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Thanks for everyones help with this one, it was after the mention of the power steering pump drive from the crank that I remembered I'd changed that belt after I found it was rubbing on the bottom hose. In the meantime I had changed both radiator hoses as they were passed their best, I have now fitted the 15445 belt round the crank pulley, power steering pump pulley and water pump pulley and its clear of the bottom hose so all good there.
The alternator now has an AX43 belt round the crank and water pump pulleys, this is a little too wide but I'll run it for now and see how it settles in, hopefully we got to the bottom of the problem and this will help others with belt issues!
Thanks again
Graham
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Nothing like a dirty SBC, great pics.
So Graham, did you say the belt your running on the alternator is too wide? (couldn't tell from original pics )
That might be your problem, it's being drug into the v of the pulleys.
Notice how the belts are snug in the pics VZ sent? That's what you want.
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The belt I fitted today on the alternator is an AX43 which is 43" length and 1/2" wide so stands a little proud of the pulley but it'll do for now, water pump pulley is double groove so it has double belt drive so if either alternator or PS pump belt fails I still have drive to the water pump!
Thanks for the pictures Vile, all back to how it was and with the new hoses the belt clears fine, the old hoses must have swollen with age causing the belt to foul.
Thanks again
Graham
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The 1/2" belt is only 1/32" wider than the factory 15/32" width specification. If you look carefully at the cross-section of a v-belt the angled walls have a short vertical truncation of the sidewalls at the outer diameter of the belt. When a new belt is slightly proud of its groove (~1 mm), the sidewalls of the belt still effectively make full contact with the pulley groove for maximum bite. So there should be no worry about that.
Graham, please keep us apprised of the outcome after it accumulates some mileage. Hopefully, the issue is resolved.
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Yes BD that's what I figured, will let you know how it goes after a few miles.
Graham