Engine/Transmission (1994 - 1998) Alternator - charging ?

[SteveAnsley]

Ok, maybe this is normal - just seems a bit different.

This moring it seemed like the voltmeter was slow to come up, caused the check engine light to stay on a second or two longer.



Under load the voltmeter is reading a half needle above 14 volts; I don't remeber what it read before, but thought it might have been more.

With the motor off it reads 12 volts - start the motor and the gauge 'slowly' climbs to 14 volts (about the same speed the oil pressure gauge rises)



All else seems fine.

Is this normal?

Am I remembering things differently?

Is this a 'sign' of potential alternator trouble?

Time for a beer and shut-up?

 

[Signal73]

Maybe it is just taking longer to make up for the draw the grid heaters are taking out of the battery?



My alternator is making a burning smell the first thing in the morning I think its about to go toes up because the grids are drawing now that its getting colder.



Where yours ends up is the same place mine does FWIW...

 

[CumminsPower98]

Mine just recently got to the point it didn't start charging at all at a cold idle. I could rev it up and then it would come up slowly and then be ok throughout the day. I had replaced the brushes before this and it worked for a while. I replaced it and now it comes right up and the brushes were not worn out this time. I think I probably weakened it last year when I ran the batteries down at a truck stop sitting for the weekend and had to jump it and then drive away letting the alternator take the load. Maybe the rectifier was giving up, not sure. I got 312k miles out of it so I can't complain.



Mine always reads over 14 but it depends on temperature as to how far over. The colder the higher and it does take a few seconds to come up there at a cold start with grids running so yours is probably fine.

 

[San Felipe Bob]

Check the brushes

Mine did the same thing.

It finally quit charging 800 miles from home.

I drove all the way home without any help from the alternator.

Thanks to my dual Odyessy 1700's.



Turned out the brushes were toasted.

Autozone had the Alernator , however I did have to use my pully.

Good thing I had an Air impact wrench for the pully swap.



SFB

 

[J Shocik]

Steve, I had to replace my alternator 2 yrs. ago. When I started it & let it idle, the gauge would read about 10 volts. Running the motor to 1200-1500 rpm the gauge would read normal. I went to Autozone & replaced the alternator (lifetime warranty). Problem solved. If you go this route, make sure you get an alternator that pushes 136 amps. Their books show the Dodge CTD's taking a 120 amp. & that is wrong.

 

[SteveAnsley]

Thanks for the responses.



The volt meter is showing 14 @ idle and while cruising.

Seems Ok, I just don't remember how fast the needle rose to 14 in the past.

It was just that one morning that it caught my eye being noticeably slow - slow enough to cause CEL to come on.



Can the autozones, etc. test the amperage output w/ the alternator in the truck?

I'm not against replacing if it's showing signs of going south, 135 k on the clock.

Making a road trip from DFW to Little Rock for Thanksgiving.



Edit:

Is a 14 volt reading on the gauge correct while at idle and/or cruise?

Should it be higher?

 

[firemanmarc]

My 1997 takes a 120 amp alternator, not a 137 amp. This I know as I blew the 120 amp fuse the other day and put on about 60 miles running around trying to find one... . Certainly sounds like you need a new alternator. Mine was $150 at Napa... GOod luck, Marc

 

[CumminsPower98]

My option list from dealer via VIN code shows mine should be a 136 amp yet the Carquest books show only a 120 amp for my year. The books showed 136 amp starting in '99 so I had them order one but the connections were different for the 24 valve. What gives? Also what Larry B sells new is a 120 amp. How does one get the 136 amp? If I had the money I would go with one of those 200+ amp ones I have seen talked about on here. I too had to change the pulley, they had some little tiny 3 groove deal on there.

 

[J Shocik]

I bought my truck brand new in '97, and according to the window sticker (yes, I kept it) the diesel engine option shows as part of that group a 136 amp alternator w/ 750 amp battery. I could be wrong, but I believe this pertains to all CTD's (at least the '97's).



As for getting the 136 amp alt. at the auto part store, I just asked for it. I had the parts clerk show me the 120 & the 136 side-by side. There was no difference. But, I too, had to change the pully.



I believe all auto parts stores books & computers show the CTD's taking a 120 amp alt as this is the standard equipment for the standard truck (gas motor). My window sticker shows as standard equipment a 600 amp battery w/ a 117 amp alt. I believe when some computer geek configured the auto parts stores computer files, he didn't take into account the 136 amp option. Some of the 5. 9L V-8's take the 136 as an option, so the books show it.

 

[JPittinger]

Its not hard to pull the brushes off the backside. You can check them to see if they're still contacting; if they're short you can lengthen the slot they ride in till you find replacements. Mine stopped charging and I found brushes at a local starter rebuilder. I think LarryB has them too, but not sure. Wayyyy cheaper than a new one (<$10).

-JJ

 

[firemanmarc]

Would I assume if my 97 was to have a 136amp alternator then the fuse protecting it would be 136amp instead of 120amp. When I blew the fuse last week changing my thermostat(nevermind how I did it) I went to my local dealer and they showed a 120amp fuse for my vin number. I would love also to put a 136amp one on, but would I not blow the fuse if it is still only 120amp... Thanks, Marc

 

[J Shocik]

To tell you the truth Marc, I don't know. I would guess the voltage regulator would somehow take care of that. Plus figure the added power needed to cycle the grid heaters in the winter. I'm just relaying the information on the window sticker of my '97.

 

[DonTX]

Just this evening I was looking thru my fancy dealer brochure handout (courtesy of ebay) for my 97, looking for alternator size. It plainly states that ALL CTD models came with the 136 amp alternator in 1997.

 

[Nate]

I'm having problems with my alternator as well...



I checked it today with my multimeter and with the truck parked for the past 3 days, my batteries were showing 12. 23 volts.



I fired it up, and it was showing ~12. 23v and would drop down to ~11. 45v when the grid heater kicked on. I also checked at the output side of the alternator, and it showed the same.



Does this sound like my alternator is crapping out? I know normally a good system should be showing ~13. 8v

 

[J Shocik]

When you first start the truck, the grid heaters will cycle a few times, drawing plenty of juice from the alt. that's why you see it "waving" at you, you know, going between 10 & 14 volts on the voltage gague. Batteries sitting for 3 days showing over 12 volts appear to be good, a load test will tell you that. By my experience, the alt. will slowly die, as compared to GM alts, which just die like light bulbs. Hope this helps.

 

[CumminsPower98]

That's a bummer that I got a 120 amp, I wish I would have tried harder to get a 136 amp. I guess I needed to have them look up a gasser one or something. Oh well, maybe next time I will feel like spending well over $350 or something insane and get one of those 200+ amp ones.