1995 E-250 voltage spikes!!! Please help
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From: Southeast Kansas
1995 E-250 voltage spikes!!! Please help
I noticed a spike a few weeks ago after replacing alt 2 weeks prior. Yesterday was driving and looked down to see very low voltage so I went to Orielly's, had them check battery and alternator. I was told the alternator was bad so replaced it at store. First alternator off tested on bench-good. He exchanged it and tested that one (before installation)-good. I installed the new alt the van still not charging, spent all night tracing wires and looking for bad connections. I found a fusable link by battery had split so I replaced it-started charging. Great - Till I started heading out of town to go home! The van started spiking way up to 18 volts, so today spent most of the day checking grounds and connections. The grounds were replaced a month ago. Battery is six months old and has never had a problem, but switched it out just to see if it fixed the spiking issue. It seemed to make it worse, it would stay at 18 volts, so installed first again Still spiking when revved up.
Fleet Owner
Joined: Aug 2010
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From: Reynoldsburg, Ohio
Sounds like the alternators are defective from the rebuilder---voltage regulators not functioning properly.
I'd suggest a new, not rebuilt alternator with lifetime guarantee from NAPA---about $180 IIRC. If that's not feasible maybe return the existing part to O'Reilly's for a cash refund and go to a completely different parts outlet. Its highly possilble they have a bad batch of alternators so unless you want to keep changing parts weekly this might be your best bet. If not you'll need a new battery as well.
Of course if that battery is over 4 years old and has suffered these over volt conditions it might be time for it to go as well. NAPA has a great 75 month battery with extended length full replacement guarantee, not that pro-rated crap from day one. I've used them in at least 8 vehicles and have not had a problem in over 7 years.
HTH
I'd suggest a new, not rebuilt alternator with lifetime guarantee from NAPA---about $180 IIRC. If that's not feasible maybe return the existing part to O'Reilly's for a cash refund and go to a completely different parts outlet. Its highly possilble they have a bad batch of alternators so unless you want to keep changing parts weekly this might be your best bet. If not you'll need a new battery as well.
Of course if that battery is over 4 years old and has suffered these over volt conditions it might be time for it to go as well. NAPA has a great 75 month battery with extended length full replacement guarantee, not that pro-rated crap from day one. I've used them in at least 8 vehicles and have not had a problem in over 7 years.
HTH
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From: Southeast Kansas
I am thinking the same about a bad batch. I am going to try and see if I can get a refund from them and just buy a brand new one somewhere else. Will see how it does then, will let you know.
Cross-Country
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Is voltage regulator built in alternator or is it a separate unit? A bad regulator can cause 18 volt spikes. A bad regulator gave me 18 volt spikes and fried my computer, blew some fuses and burned out some bulbs.
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From: Southeast Kansas
Van seems to be fine now! Part store did not have another alt so I asked them if they had the old one still there. Sure enough they did and since I noticed the shorted fusible link the other night after replacing the old alt with a new one, so I asked for it back. Just to see if there were any differences I re-installed it and have not had any spikes or low voltage signs. I guess when the fusible link had the short it just wouldn't let the van charge. The bad luck was getting a bad alternator thinking mine was bad. Thanks everyone for your help. Will let you know in a few days how it does.
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From: Southeast Kansas
I am going to Ford tomorrow to order a higher amp alt for the van and found out today that it would be cheaper to go with the higher amp than the lover amp, just in case mine shoots crap - I will have a replacement!
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Fleet Owner
Joined: Aug 2010
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From: Reynoldsburg, Ohio
Its always ironic how the higher amp alts are cheaper---must make more of them?
I should have advised you to put a volt meter across the battery terminal of the alt and to a known good ground---should have seen no more than 14.7 volts if I recall correctly. At idle it will be no less than 11 or 12 volts---if so the alt is good.
With the fusible link you changed it or simply reused the one you suspected as being blown?
What I like about the 5.4l motor is how easy the alts are to change--three bolts, a few connectors and replace the serpentine belt and off ya go! Once had to change mine on a 15 degree day---took me 1:15 from start to finish which included going to NAPA for new one. Since I bought a new alt there was no core needed so I've kept the bad one---might have it rebuilt one day or give it away if someone needed a core.
I should have advised you to put a volt meter across the battery terminal of the alt and to a known good ground---should have seen no more than 14.7 volts if I recall correctly. At idle it will be no less than 11 or 12 volts---if so the alt is good.
With the fusible link you changed it or simply reused the one you suspected as being blown?
What I like about the 5.4l motor is how easy the alts are to change--three bolts, a few connectors and replace the serpentine belt and off ya go! Once had to change mine on a 15 degree day---took me 1:15 from start to finish which included going to NAPA for new one. Since I bought a new alt there was no core needed so I've kept the bad one---might have it rebuilt one day or give it away if someone needed a core.
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From: Southeast Kansas
I looked at the Chilton's book I have for our vans and it kinda showed how to go about testing it, so I did. The newer alt would spike to 18-19 volts when half throttle. I tested the base voltage and did a running test, but once you gave it throttle it jumped! I installed the older alt and haven't had a problem since. The fusible link I found and replaced after installing the new alt. I guess that was the only problem I had with the old alt not charging (fusible link). I have drove the van about 150 miles and not a spike to be seen or even any movement from needle! Once I installed the old alt again I tested the voltage and it was at 14.3 even when stepping on throttle. Thanks for the help and advice!
Post Fiend
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Spike is most likely caused by a bad signal from the sense wire that tells the alternator what voltage is at the battery.
You got a corroded wire / bad contacts / or the bad fusible link.
Sometimes, the only sure way is to install a brand new sense wire, and also, replace the alternator pigtail, where the break most often happens.
You got a corroded wire / bad contacts / or the bad fusible link.
Sometimes, the only sure way is to install a brand new sense wire, and also, replace the alternator pigtail, where the break most often happens.
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