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View Full Version : Battery Light On...ScanGauge shows 11.4V


mything2
02-05-2014, 06:49 PM
My 2006 T1N (2007 Airstream Interstate) is displaying the battery icon. My ScanGauge2 shows 11.4V while the engine is running and that low voltage was confirmed when my battery died a day later. This engine battery is new and was retested good just to be sure no bad cells. I'm now suspecting the alternator (original). I have 45K on the Sprinter and this battery light appeared a couple of weeks after I replaced the engine battery but I don't think that has anything to do with this charging problem. I'm checking the cables to/from the alternator as well as the ground cable but a quick look didn't uncover anything. Sailquik (Roger) suggested I pull the alternator and take it to a shop and have it bench tested before I jump and replace it. I will do that but I've never tried removing the serpentine belt (I have a replacement) and have some concern with the tensioner and how to "deactivate" prior to my pulling the alternator and eventually reinstalling the new belt and alternator.
I have a VOM but I don't know a lot about testing automotive DC systems and would appreciate any and all suggestions/recommendations on further testing as well as thebest way to relieve the tensioner to get the belt off.
Thanks
Dan

gtholden
02-06-2014, 03:06 AM
I had a similar issue on my 2005 this past year. I didn't have the battery light come on, but the van died a few times when the scangauge hit 11.5v. I did all kinds of checks with wiring, searching for grounds etc. but ended up at the advice of the forum and my mechanic to replace with a new alternator. I went with the 200amp and now I get 14.1v on crank up and then around 13.8 until the battery is fully charged. I couldn't be happier even though the 200amp was really pricey. I bought it from europarts and switched it out myself. I don't consider myself a mechanic, but have okay mechanical reasoning ability. I took my time and it took me about a half day to make sure everything was done properly. The alternator swap was pretty easy, but the belt and turbo resonator took some time. If you search the forum you will find great write-ups on the belt, resonator and alternator swaps. Good luck. My recommendation would be to go with the 200amp bosch. It is well worth the money.

Aqua Puttana
02-06-2014, 03:12 AM
... as well as thebest way to relieve the tensioner to get the belt off.
Thanks
Dan
I believe that the belt tensioner was discussed in this thread. vic


http://sprinter-source.com/forum/showthread.php?t=18432

surlyoldbill
02-06-2014, 03:22 AM
Check ebay and amazon for replacement Bosch alternator, I think mine was less than $150.

cahaak
02-06-2014, 12:44 PM
You can release the tensioner from the top or bottom of the engine. If you are by yourself, it works better to relase from the bottom while removing or replacing the belt. If you have a helper, they can release the tension from the top and that allows you to work with the belt under the engine. The tensioner is fairly easy to get to with a socket with the correct extension length on it.

Chris

lindenengineering
02-06-2014, 01:12 PM
My 2006 T1N (2007 Airstream Interstate) is displaying the battery icon. My ScanGauge2 shows 11.4V while the engine is running and that low voltage was confirmed when my battery died a day later. This engine battery is new and was retested good just to be sure no bad cells. I'm now suspecting the alternator (original). I have 45K on the Sprinter and this battery light appeared a couple of weeks after I replaced the engine battery but I don't think that has anything to do with this charging problem. I'm checking the cables to/from the alternator as well as the ground cable but a quick look didn't uncover anything. Sailquik (Roger) suggested I pull the alternator and take it to a shop and have it bench tested before I jump and replace it. I will do that but I've never tried removing the serpentine belt (I have a replacement) and have some concern with the tensioner and how to "deactivate" prior to my pulling the alternator and eventually reinstalling the new belt and alternator.
I have a VOM but I don't know a lot about testing automotive DC systems and would appreciate any and all suggestions/recommendations on further testing as well as thebest way to relieve the tensioner to get the belt off.
Thanks
Dan

Dan
Roger is right!
I often send out a suspect alternator out for a bech test--one good unit was condemned for bad charging only to discover the pulley was slipping on the clutch; nothing more!

The other is mag chloride getting inside the alternator. A good clean up on the diode pack connectors and I have found many can be brought back to life!
Dennis

surlyoldbill
02-06-2014, 02:44 PM
You can release the tensioner from the top or bottom of the engine. If you are by yourself, it works better to relase from the bottom while removing or replacing the belt. If you have a helper, they can release the tension from the top and that allows you to work with the belt under the engine. The tensioner is fairly easy to get to with a socket with the correct extension length on it.

Chris

I put a piece of pipe over the handle of my socket wrench, and used a tie-down to hold that end while I took off the belt. I have a lot of tricks for working alone, because I'm too surly :smirk:

Also, it's not much more expensive, and less labor, to just replace the entire alternator instead of the clutch pulley. One sign of a failing clutch pulley is a "chirp" of the belt when you turn the engine off.

MercedesGenIn
02-06-2014, 04:26 PM
My suggestion would be to take a look here:

With the relative low miles on the vehicle I would suspect more likely the alternator sprag clutch than the alternator itself. This is a one directional mechanical clutch pulley that allows drive in one direction only. Its a common fail throughout most of the complete Mercedes model ranges and can fail in several ways. The internal clutch collapses and the pulley falls off, or its clutch begins to free-wheel when it should not. The purpose of this clutch is to remove any tensional issues with the serpentine belt should the engine revs (crank rotation) fall quicker than the alternator under load. Well worth a check before removing the alternator or suspecting more complex things.

A quick check is to flip off the front plastic cap to the pulley on the alternator: if there are any red rust deposits in here, the sprag clutch is most likely worn and must be replaced. You will need a 'special' tool kit, but it can be replaced in situ without removing the alternator. This inspection in my view should form part of a regular service routine, as to lose the pulley whilst driving is at best a 'no-fix' at the side of the road!

All the best.

Steve

skydiver007
02-07-2014, 02:17 AM
I had a similar issue on my 2005 this past year. I didn't have the battery light come on, but the van died a few times when the scangauge hit 11.5v. I did all kinds of checks with wiring, searching for grounds etc. but ended up at the advice of the forum and my mechanic to replace with a new alternator. I went with the 200amp and now I get 14.1v on crank up and then around 13.8 until the battery is fully charged. I couldn't be happier even though the 200amp was really pricey. I bought it from europarts and switched it out myself. I don't consider myself a mechanic, but have okay mechanical reasoning ability. I took my time and it took me about a half day to make sure everything was done properly. The alternator swap was pretty easy, but the belt and turbo resonator took some time. If you search the forum you will find great write-ups on the belt, resonator and alternator swaps. Good luck. My recommendation would be to go with the 200amp bosch. It is well worth the money.

Very glad to hear that it worked out for you. Never did hear back if the new alternator solved your issue. Sounds like it did. :thumbup: