# Alternator failure and mileage? **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [May 11, 2025, 5:49pm UTC](https://community.cartalk.com/t/alternator-failure-and-mileage/200220 "2025-05-11T17:49:08Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![bing](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/bing/32/4619_2.png) [@bing](https://community.cartalk.com/u/bing)\ **Post date:** [May 19, 2025, 7:23am UTC](https://community.cartalk.com/t/alternator-failure-and-mileage/200220/42 "2025-05-19T07:23:40Z")
I’ve only ordered new from rock so rhere was no core return. I bought Napa with life warranty and after replacing twice just bought a new delco. On the way to a funeral in South Dakota and had to swap the dang thing in the parking lot so I just buy new now. The rebuilts can be junk. ---
**Author:** ![VOLVO-V70](https://avatars.discourse-cdn.com/v4/letter/v/8e8cbc/32.png) [@VOLVO-V70](https://community.cartalk.com/u/VOLVO-V70)\ **Post date:** [May 19, 2025, 12:57pm UTC](https://community.cartalk.com/t/alternator-failure-and-mileage/200220/43 "2025-05-19T12:57:21Z")
> [@sciconf](#): > > Anyone know who pays for shipping the core? You will pay for the shipping of the core but their order page does have shipping labels with lower rates . Of course you could have called Rock Auto and asked them that question . ---
**Author:** ![jtsanders](https://avatars.discourse-cdn.com/v4/letter/j/c2a13f/32.png) [@jtsanders](https://community.cartalk.com/u/jtsanders)\ **Post date:** [May 19, 2025, 1:29pm UTC](https://community.cartalk.com/t/alternator-failure-and-mileage/200220/44 "2025-05-19T13:29:55Z")
Another way to determine shipping costs is to put the item in your basket then go to checkout. The shipping costs should be shown in the bill before you have to enter your credit card info. ---
**Author:** ![davesmopar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/davesmopar/32/41750_2.png) [@davesmopar](https://community.cartalk.com/u/davesmopar)\ **Post date:** [May 19, 2025, 1:52pm UTC](https://community.cartalk.com/t/alternator-failure-and-mileage/200220/45 "2025-05-19T13:52:28Z")
> [@sciconf](#): > > Since then no issues - I also tightened the belt. Then just leave it alone, keep an eye on it as normal, but sometimes electronics just simple glitch for a lack of better terms… It’s been what, 8 days at least?.. ---
**Author:** ![sciconf](https://avatars.discourse-cdn.com/v4/letter/s/919ad9/32.png) [@sciconf](https://community.cartalk.com/u/sciconf)\ **Post date:** [May 19, 2025, 3:36pm UTC](https://community.cartalk.com/t/alternator-failure-and-mileage/200220/46 "2025-05-19T15:36:04Z")
> [@VOLVO-V70](#): > > … . Of course you could have called Rock Auto and asked them that question . Invalid response showing inexperience. ---
**Author:** ![Jerome-Silverman](https://avatars.discourse-cdn.com/v4/letter/j/71e660/32.png) [@Jerome-Silverman](https://community.cartalk.com/u/Jerome-Silverman)\ **Post date:** [May 19, 2025, 5:27pm UTC](https://community.cartalk.com/t/alternator-failure-and-mileage/200220/47 "2025-05-19T17:27:41Z")
Sometimes a relay contact sticks, keeping something energized that should be off when the engine is not running . Difficult to find it is intermittent. ---
**Author:** ![JoeTro](https://avatars.discourse-cdn.com/v4/letter/j/13edae/32.png) [@JoeTro](https://community.cartalk.com/u/JoeTro)\ **Post date:** [May 20, 2025, 7:24pm UTC](https://community.cartalk.com/t/alternator-failure-and-mileage/200220/48 "2025-05-20T19:24:39Z")
I would recommend that if your alternator is a difficult R&R, don’t risk doing it twice by ordering a cheap REMAN. Get a brand-name unit and pay the extra money. ---
**Author:** ![sciconf](https://avatars.discourse-cdn.com/v4/letter/s/919ad9/32.png) [@sciconf](https://community.cartalk.com/u/sciconf)\ **Post date:** [June 7, 2025, 10:51pm UTC](https://community.cartalk.com/t/alternator-failure-and-mileage/200220/49 "2025-06-07T22:51:05Z")
> [@TheWonderful90s](#): > > A battery test. > > Maybe the brushes are worn out on the alternator. It happened again after 27days! No car wash this time. Battery measured 12.56v - when cranking it went down to 11.23v and wouldn’t start. When I jump started, it just started - drove it home fine! Since I posted this, I did not replace any related parts. Thoughts on parts that might be causing it? If it were alternator, sparks, I will do it myself. ---
**Author:** ![bing](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/bing/32/4619_2.png) [@bing](https://community.cartalk.com/u/bing)\ **Post date:** [June 8, 2025, 12:28am UTC](https://community.cartalk.com/t/alternator-failure-and-mileage/200220/50 "2025-06-08T00:28:09Z")
I thought we had mentioned th3 current sensor. Attaches to the pos battery post and senses what to tell the alternator or something like that. ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [June 8, 2025, 12:51am UTC](https://community.cartalk.com/t/alternator-failure-and-mileage/200220/51 "2025-06-08T00:51:05Z")
> [@bing](#): > > Attaches to the pos battery post [https://www.samarins.com/glossary/battery-sensor.html](https://www.samarins.com/glossary/battery-sensor.html) Tester ---
**Author:** ![Nevada\_545](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nevada_545/32/41232_2.png) [@Nevada\_545](https://community.cartalk.com/u/Nevada_545)\ **Post date:** [June 8, 2025, 5:40am UTC](https://community.cartalk.com/t/alternator-failure-and-mileage/200220/52 "2025-06-08T05:40:26Z")
> [@sciconf](#): > > Battery measured 12.56v - when cranking it went down to 11.23v and wouldn’t start. If the engine is cranking but will not start, the first suspicion would be insufficient fuel pressure. How long did you crank the engine before giving up on starting the engine? ---
**Author:** ![sciconf](https://avatars.discourse-cdn.com/v4/letter/s/919ad9/32.png) [@sciconf](https://community.cartalk.com/u/sciconf)\ **Post date:** [June 8, 2025, 1:58pm UTC](https://community.cartalk.com/t/alternator-failure-and-mileage/200220/53 "2025-06-08T13:58:38Z")
> [@Nevada\_545](#): > > If the engine is cranking but will not start, the first suspicion would be insufficient fuel pressure. How long did you crank the engine before giving up on starting the engine? Did not persist for a long time. Maybe 30secs. Did not pump the gas pedal either. **What are you getting at?** - fuel pump or fuel injectors? Car gives 35mpg though. How to troubleshoot? em, I used to chage the FFilters on Honda but this one does not have a serviceable FFilter. ---
**Author:** ![sciconf](https://avatars.discourse-cdn.com/v4/letter/s/919ad9/32.png) [@sciconf](https://community.cartalk.com/u/sciconf)\ **Post date:** [June 9, 2025, 1:07am UTC](https://community.cartalk.com/t/alternator-failure-and-mileage/200220/54 "2025-06-09T01:07:20Z")
Could this lose Spark Plug might have caused the issue? It was **totally lose that I just picked it up**. Does the coil need replacement? ![CoilSpark](https://global.discourse-cdn.com/cartalk/original/3X/7/b/7bfb0200832854a85b33cd0d7148b4541ead6299.jpeg) ![Spark1](https://global.discourse-cdn.com/cartalk/original/3X/c/4/c434f4bc1bba88880ebe51d61f935e76bc33308f.jpeg) ---
**Author:** ![db4690](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/db4690/32/2583_2.png) [@db4690](https://community.cartalk.com/u/db4690)\ **Post date:** [June 9, 2025, 1:34am UTC](https://community.cartalk.com/t/alternator-failure-and-mileage/200220/55 "2025-06-09T01:34:00Z")
imo, the coil is not the cause, but rather a symptom of the problem perhaps you’ve got a leaking spark plug tube seal and that’s why that particular coil boot appears different ---
**Author:** ![Nevada\_545](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/nevada_545/32/41232_2.png) [@Nevada\_545](https://community.cartalk.com/u/Nevada_545)\ **Post date:** [June 9, 2025, 1:56am UTC](https://community.cartalk.com/t/alternator-failure-and-mileage/200220/56 "2025-06-09T01:56:19Z")
> [@sciconf](#): > > Does the coil need replacement? I would replace that coil, the loose spark plug might shorten the life of the coil however you did not indicate a misfire problem. One cylinder misfiring normally will not prevent the engine from starting but your engine starting technique is unknown: > [@sciconf](#): > > Did not persist for a long time. > Maybe 30secs. Did you crank the engine one time for 30 second without pause? Or 6 start attempts for 5 seconds each? Or 30 start attempts for 1 second each? Some people crank the engine so briefly before releasing the key and an engine may not start if there is a weak fuel delivery problem. ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [June 9, 2025, 2:13am UTC](https://community.cartalk.com/t/alternator-failure-and-mileage/200220/57 "2025-06-09T02:13:03Z")
I wouldn’t replace the coils. I’d just replace the boots. ![image](https://global.discourse-cdn.com/cartalk/original/3X/1/4/149ec12f16d0566d68bd5c72b1725e15d3bce58c.jpeg) When they get old they don’t grip the spark plug very well and that’s why you replace them. Tester ---
**Author:** ![sciconf](https://avatars.discourse-cdn.com/v4/letter/s/919ad9/32.png) [@sciconf](https://community.cartalk.com/u/sciconf)\ **Post date:** [June 9, 2025, 3:45am UTC](https://community.cartalk.com/t/alternator-failure-and-mileage/200220/58 "2025-06-09T03:45:31Z")
> [@Tester](#): > > I wouldn’t replace the coils. I’d just replace the boots. Brilliant if the coil is still conducting. Yes as you pointed out, the boot was loose on the Plug. I was unaware that the boot can be replaced! Rock Auto price for a single Coil is not cheap! @Nevada_545 - there has **never been a misfire**. Also, I might have held it to crank for 15secs actually but multiple times with no luck - gas pedal was never pressed at all. ---
**Author:** ![sciconf](https://avatars.discourse-cdn.com/v4/letter/s/919ad9/32.png) [@sciconf](https://community.cartalk.com/u/sciconf)\ **Post date:** [June 9, 2025, 3:53am UTC](https://community.cartalk.com/t/alternator-failure-and-mileage/200220/59 "2025-06-09T03:53:35Z")
> [@Tester](#): > > I wouldn’t replace the coils. I’d just replace the boots. You mean the one that is carbon-ed, not all 4? Denso only sell 4 pcs together. Does it matter which brand, STANDARD MOTOR PRODUCTS or NGK: > **[More Information for STANDARD MOTOR PRODUCTS SPP166E](https://www.rockauto.com/en/moreinfo.php?pk=5414391&cc=1442416&pt=10150)** > **[More Information for NGK 59015](https://www.rockauto.com/en/moreinfo.php?pk=7166220&cc=1442416&pt=10150)** ---
**Author:** ![jtsanders](https://avatars.discourse-cdn.com/v4/letter/j/c2a13f/32.png) [@jtsanders](https://community.cartalk.com/u/jtsanders)\ **Post date:** [June 9, 2025, 12:42pm UTC](https://community.cartalk.com/t/alternator-failure-and-mileage/200220/60 "2025-06-09T12:42:28Z")
While only one shows visual effects of aging, they are all likely hardened and will show the same blackening as the blacked coil. I’d replace all of the coil boots. The price isn’t that much different. I’d go with the OEM Denso. ---
**Author:** ![sciconf](https://avatars.discourse-cdn.com/v4/letter/s/919ad9/32.png) [@sciconf](https://community.cartalk.com/u/sciconf)\ **Post date:** [June 9, 2025, 3:55pm UTC](https://community.cartalk.com/t/alternator-failure-and-mileage/200220/61 "2025-06-09T15:55:30Z")
> [@jtsanders](#): > > While only one shows visual effects of aging, they are all likely hardened and will show the same blackening as the blacked coil. I’d replace all of the coil boots. > > The price isn’t that much different. I’d go with the OEM Denso. Thank you - will be ordering Denso today [Previous page](https://community.cartalk.com/t/alternator-failure-and-mileage/200220.md?page=2) [Next page](https://community.cartalk.com/t/alternator-failure-and-mileage/200220.md?page=4)