hvyd Posted May 25, 2015 Report Share Posted May 25, 2015 As title says. I've replaced alternator and water pump. Running Saturn 90 amp alt. Pulleys are clean and spin straight. I'm at a loss. Any help would be great. Even found a slightly wider belt . 1 Quote Link to comment
flatcat19 Posted May 25, 2015 Report Share Posted May 25, 2015 Are they in line with each other? How is the belt breaking? 1 Quote Link to comment
hvyd Posted May 25, 2015 Author Report Share Posted May 25, 2015 They are in line. Been running this setup for a number of years with no issue. The only thing that I can maybe think to do is put battery on a trickle charge and see what happens. Other than that I'm at a loss 1 Quote Link to comment
hvyd Posted May 25, 2015 Author Report Share Posted May 25, 2015 Before I changed any parts was able to witness belt starting to smoke and then hauled but to get home and it broke on the way 1 Quote Link to comment
tr8er Posted May 25, 2015 Report Share Posted May 25, 2015 Your alternator is the problem I would expect. Look again at how in line the pulleys are. It's hard to see, but they can easily be out of line. Hold a straight edge to the face of the crank pulley and see if it sits across the face of the alternator pulley. If it does, well, I've been wrong before. It's worth the one minute re-check though. If it's not that, 1 Quote Link to comment
MicroMachinery Posted May 25, 2015 Report Share Posted May 25, 2015 Which parts did the issue arise after replacing? You say the water pump and alternator.. did you do them both at the same time? 1 Quote Link to comment
datzenmike Posted May 25, 2015 Report Share Posted May 25, 2015 Spin the alt and the pump separately by hand, do they turn easily? Are you sure this is an automobile belt and not a fractional hp electric motor for a clothes dryer? They are different. I've had misaligned pulleys and they will run for along time like that. The edges fray though. Does the belt squeal? 1 Quote Link to comment
Stoffregen Motorsports Posted May 25, 2015 Report Share Posted May 25, 2015 If an auto parts store generic alternator was used, it is a possibility that the pulley has a ding in it, which can easily throw a belt. Check for dings, bends or nicks in all the pulleys, including crank pulley. Misalignment is not as big a problem as it sounds. 2 Quote Link to comment
hvyd Posted May 25, 2015 Author Report Share Posted May 25, 2015 The problem is I've been lending it to my nephew. So, to me out of nowhere this issue arises. Replaced alt and water pump same day. Belt squeals and starts smoking. Then shortly afterward breaks. I've had this setup on for years with no issues until 2 days ago. Water pump felt a bit stiff when spinning it so I replaced it thinking that was the problem. Replaced alternator first because voltage at idle was 12.6 ish and when I spun it there was an audible squeak. Alternator is new not a reman. Water pump is new not a reman. All the belts were for the datsun. Even bought a belt that was slightly wider then what was called for. 1 Quote Link to comment
Stoffregen Motorsports Posted May 25, 2015 Report Share Posted May 25, 2015 Take the belt off and see if you can spin the water pump and alternator by hand. If one of them is getting bound up, this will smoke and throw a belt. High revs can destroy an alternator ( I know from experience) which is why race cars run large diameter alt pulleys. If your nephew is revving the piss out of it, the alternator could be losing it's bearings. New auto parts store generic is still not as good as OEM or custom rebuilt. I have seen "new" alternators with bad bearings and bent pulleys. Or wrong pulleys. Have you checked to see if the pulley on it is the right groove width? 1 Quote Link to comment
hvyd Posted May 25, 2015 Author Report Share Posted May 25, 2015 It's a pulley that has been on the truck for 20 years. I've owned this truck since 1996 so everything done to it has been done by me. Everything spins freely. I did notice the water pump pulley has a slight wobble to it. Nothing horrible. Gonna replace it with another one I have. 1 Quote Link to comment
hvyd Posted May 25, 2015 Author Report Share Posted May 25, 2015 Could a bad cell in the battery cause the alternator to be overworked and throw/break belt? Meaning a cell in battery shorting or grounding internally 1 Quote Link to comment
datzenmike Posted May 25, 2015 Report Share Posted May 25, 2015 No. Stop lending it to your nephew. 4 Quote Link to comment
hvyd Posted May 25, 2015 Author Report Share Posted May 25, 2015 Lol. Thanx Mike. OK, I've kinda narrowed it down to a huge draw on the alternator. While all wiring g is attached to alternator can here very audible wheering sound. When unplug negative on battery sound becomes less, unplug Harness to side of alternator it goes away completely. By doing that no more output on alt. I think what's happening is alt is becoming overworked getting hot and seizing causing belt to break. Have also changed batteries just for my own sanity. 1 Quote Link to comment
MicroMachinery Posted May 25, 2015 Report Share Posted May 25, 2015 No. Stop lending it to your nephew. Wisdom. 1 Quote Link to comment
hvyd Posted May 25, 2015 Author Report Share Posted May 25, 2015 That it is. Just trying to give the kid a hand up. 1 Quote Link to comment
Stoffregen Motorsports Posted May 25, 2015 Report Share Posted May 25, 2015 I doubt a bad battery can cause this. I would say the wobble in the H2O pump pulley is more likely the culprit. Do you have access to a battery load tester? If you think it needs a battery, why don't you replace it? Wait, you say the pulley's been on the truck for 20 years? But then you say the alternator is new. Did you use the old alternator pulley when you installed the new alternator? 1 Quote Link to comment
datzenmike Posted May 25, 2015 Report Share Posted May 25, 2015 The 620 output is only 39 or less amps.... on a good day. At 14 volts that's under 550 watts. There is 746 watts in one horse power so assuming some losses you have (maybe) one hp on that belt, not near enough to break it. Something is wrong with that alternator, maybe the bearing. 1 Quote Link to comment
kelowg Posted May 26, 2015 Report Share Posted May 26, 2015 belt is not tight enough! also recommend using cogged style belt. Charge battery overnight, so When u start it alt doesnt see much of a load. if belt squeals its loose. My belt makes noise at startup if i run batt down with stereo.(saturn alt also) 1 Quote Link to comment
dr.feltersnatch Posted May 26, 2015 Report Share Posted May 26, 2015 Do you drive on gravel roads much? 1 Quote Link to comment
hvyd Posted May 26, 2015 Author Report Share Posted May 26, 2015 Under load alt is noisy like a load on it. Had battery tested load checked fine. 12.7 volts no load. Any rate battery is fine, even tried another battery that is new same situation. Saturn alt has a serpentine style pulley, I've put my belt pulley on it. Changed water pump pulley. Some how it's either a bad alt that I replaced alt on truck with or out of the blue my truck has developed an electrical issue causing an over draw on alt when running. Unplug battery load lessons on alt but it still is putting out 14.6v at output lug on alt. Unplug Harness and load sound goes away no more power output. Negative off battery,unplug Harness truck dies. Somewhere there is something in the truck that just developed and is overwhelming alt making it drag hard on belt over a few miles it smokes belt and snap. 1 Quote Link to comment
hvyd Posted May 26, 2015 Author Report Share Posted May 26, 2015 No gravel roads. Belt isn't loose. Gonna have to start unplugging things until I find a culprit I guess. This truck has been in my family since the dealer's lot and harness is unmolested. 1 Quote Link to comment
Stoffregen Motorsports Posted May 26, 2015 Report Share Posted May 26, 2015 I still think it's a bad alternator. Good luck. 1 Quote Link to comment
banzai510(hainz) Posted May 26, 2015 Report Share Posted May 26, 2015 should NOT take the cables off while running I think its a alternator myself. or chinese belts have you tryed a Battery drin test? if batter dont go bad then dont need the test. alt hard to spin ???????????? grounds good and clean(batt cable end for ground) 1 Quote Link to comment
kelowg Posted May 27, 2015 Report Share Posted May 27, 2015 Tighten the belt a little more. Bet u it stops. U have double the work load on that belt and pulley vs oem alt. Take more bit on Belt/pulley to produce the higher current 1 Quote Link to comment
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