1989 W250 overcharging

[Make It Work]

Hi everyone!



I have a 1989 W250 with an A727 trans. Its old iron but it gets the job done and I've owned it a long time. 2 batteries ago I got amazing service life out of it. The battery after that only lasted a short time. I noticed a sulpher smell when stopped and thought nothing of it at first but when I touched the battery cable, I noticed it was hot. They battery soon failed.



Now I have a new battery and took a voltage reading. It was charging at about 18 volts! I did some online searching and found I am not alone with this problem. Here is what I have done so far:



1) Ran a 6ga wire from the negative terminal of the battery to the firewall on the same screw that mounts to the voltage regulator.



2) Installed a parallel jumper wire from the blue wire between the regulator and alternator to cure the slight voltage drop I was reading.



3) Installed a heavy duty relay with 10GA wire straight from the positive of the battery to the blue wire of the regulator. I have to use a separate toggle switch for the relay or it backfeeds power keeping the engine running even if the key is turned off. I'g guessing I would need a diode somewhere to be able to make the relay go on & off with the ignition key.



4) I can turn the charging system on or off from the cab by a tglle switch I installed between the green wire leading from the regulator to the alternator. If the volt meter (I had to install) shows the voltage getting too high, I simply shut off the charging system.



The battery now charges between 14. 6 and 15 volts. I still think thats a bit high. I tried another voltage regulator but that didn't make any difference. It was a cheapo aftermarket regulator as is the one that came with my used truck. Any suggestions before I try to retrofit an entirely different alternator? I've read rumors that maybe an OEM or Napa regulator might work better but I hate to invest to find out it doesn't really help. Thanks for any insight.



Other than that, its been a heck of a reliable truck. I've always put a dab of outboard 2-stroke oil in the fuel (about 3/4 oz per gallon) and have never had any (VE) pump issues (knock on wood).



The turn signals stopped working but a few squirts of carb cleaner into the column switch fixed that right up.



The steering is a bit sloppy but I'm used to it.



I hate the gearing with a slippy converter & no overdrive but its hard to complain too much with such a great engine under the hood. Does a great job of pulling my boat.

 

[Wayne M.]

Welcome aboard!
I had a '92 and it had a voltmeter. Does the '89 have one too? When you realized it was kicking out 18V, what did the dash say? If the dash gauge (If you have) reads normal, My quick answer is the same as a similar problem with classic Mopars, you may have a wiring problem at or near the bulkhead. where exactly did you get the 18V reading?

Ya, mine had the 518 trans and I'll never forget the first time I drove a manual truck and was able to actually use the grunt from that engine instead of having it slip away in the converter. Regarding the steering, I found the borgeson steering shaft a good investment.

 

[JLEONARD]

15 volts is perfect. That's what it should be at an idle with everything turned off.

 

[Bob Beauchaine]

Welcome aboard - it's always good to see new blood.



I installed a volt meter due to the alternator failing and my truck ran for about 3 weeks before the batteries died. I've got the volt meter on a SPDT switch (on-off-on) so I can read battery with the engine running or not running. This little problem cost me 2 batteries - I have a dual battery setup - and alternator and finally a starter. My voltage reads between 14. 0 and 14. 5 while running. I have run this setup for about 2 years with no problems.



Bob

 

[ENafziger]

The 14. 6 volts sounds right. FWIW, the last black series voltage regulators that I ordered from Summit Racing were genuine Mopar made in the USA. I'd recommend ordering one of those and at least keeping it in the glovebox in case...

Welcome!

--Eric

 

[Joseph Donnelly]

I agree on getting a good regulator. Sometimes with good tie rods, the steering is sloppy either because the overcenter adjustment (stud and nut) on the steering box top cover needs to be tightened just a little bit. Also, the sintered metal "shoes" in the coupling between the box and the steering shaft going into the cab are worn out. They are cheap and can make a juge difference.

 

[DVolk]

Ive read that there is some alternator shops that can turn them into a self regulating unit

 

[HHhuntitall]

Self regulate, or contact MysteryMan here on TDR. He has a limited supply of the old 50amp design voltage regulators... .

 

[Make It Work]

Thanks for the suggestions! I made a YouTube video to show whats going on with the voltage. I will delete the video in a week or so.

(Note: broken video link removed by admin)

 

[Wayne M.]

Wow. There's a lot going on under that hood! In my post #2, I asked about the voltmeter, I should have specified original equipment. That truck has an ammeter, meaning it has the classic Chrysler voltage regulator system circa 1970. I'd like to know what the ammeter is doing while all that was going on, and if it still works. AFAIK, the ammeter is a critical part of the entire electrical system. If that is open or inop, it can cause trouble like that.
Also, regarding the steering coupler, you can change the sintered shoes, but if the coupling itself is worn, it won't be a good repair.

 

[Make It Work]

The ammeter has been inoperable as long as I've owned the truck (over 10 years).

This is definitely a no-frills truck. Not even vents for air conditioning.

 

[Wayne M.]

The ammeter has been inoperable as long as I've owned the truck (over 10 years).

This is definitely a no-frills truck. Not even vents for air conditioning.

Indeed, Dodge trucks were lower frills than most others. Starting right about that time, they finally started getting with the program, and the '94's things got cushy. But I had a '81 D350 Royal, which was top trim, and it had NO power options- not even A/C. It had a cool bucket & console interior though.

Back to the charging issue, how long has it been cooking batteries (2 batteries ago)? I don't know if the cummins option in '89 changed anything, and with that big alternator, but with the Chrysler charging system like that, there should be 2 field poles in the alternator, and 2 wires on the regulator (used to be dark blue) and they should be connected, with a splice to key on voltage. Always a good system IMHO, as long as the regulator was good and grounded. Any issue would be a no charge situation. Overcharging usually pointed to a wiring problem.

 

[Make It Work]

Agreed, back in the day when the Cummins was the only direct injection game in town, they called the shots and the dealers laughed at me when I mentioned things like extended cabs. The answer I got was: "Dodge sells every Cummins pickup they make - there's no need for them to change anything. " I finally found this one used and it was a compromise to get the auto trans, a mistake I would never repeat. I have been driving sticks since I was a teenager. If this truck is ever totalled or stolen, it will be replaced with a stick and preferably a 12 valve. In California, pre 1998 diesels are currently exempt from the state's smog check program. This truck is not my daily driver. It is my boat puller and workhorse. It gets the job done and is very reliable. I can leave it at the boat launch ramp overnight and not worry about it getting scratched or door dings.

The first replacement battery was a Delco group 31 that I bought as a blem from the battery shop for $30. It lasted 7 years! I would still smell that sulphur smell sometimes which, of course, was electrolyte being burned off by the overcharging. The alternator tach would sometimes stop then start working again, and the diesel wait light would randomly come on while driving. The dash illumination light would randomly alternate from super bright to dim. These was the symptoms of the problem.

My last battery was a generic branded group 31 that lasted 2 1/2 years. Now, the battery I have now is a bit smaller than the 31's I've been using but the warranty is much better. The 31's were 1 year and thats it since its considered a commercial battery. There's plenty of cranking amps in this battery I have now and the engine starts every time within 2 seconds of turning the key no matter what the outside temp. I disconnected the manifold heater since its just not needed and was going haywire.

My last resort would be to replace the alternator with a self regulated Delcotron I have sitting in the garage. I might have to do some fabricating but it would certainly be easier to get the one there now working right. Should I bypass the ammeter?

 

[HHhuntitall]

If you do a search here on TDR, there is a thread on how to self regulate your alternator... it may be in the second gen threads, but it's the same alternator... .

 

[Wayne M.]

HH are you sure about the alternator? My '92 had a nippo and the field was controlled by the PCM. It also had a voltmeter in place of a ammeter.

Make no mistake, if my '92 was a club, I probably would have converted to a 5 speed and I'd likely still have it today. Circumstances and being blown away in amazment by my sig truck made instant gratification the choice. The 5 or even 6 speed conversion is an option for you. Please note that you already have a 12valve engine. The differences are that it's not intercooled, and the injector pump is different.
It's ok to leave the ammeter, as long as its not open. I don't think it is because the whole truck seems to be working. Some people eliminate it by making a small metal plate to join the lugs in the back, like a shunt.
It sounds to me that you have some underlying wiring issues. IMHO, the truck is worth the effort to straighten out.

 

[EDankievitch]

Your Alt voltage reg is bad. It's located right above the turbo silver box. I use to have a few in my 89 just for that reason ether they fail in over charge or no charge. They don't seem to like the heat if you re locate it away from the turbo I've been told they will last longer. The part use to cost about $35. well that's what the last one cost me... ... . Long ago...

 

[HHhuntitall]

I think I might know a little about trucks like yours.....

Here's what the two alternators look like from 89 to 2002, typically. In 89 and 99-2000, there were two alternators available, the Bosch/Dodge (with two pole wire plug) or the Nippodenso (two studs)... . (then the Bosch '03+, but I'm not going there) The Bosch can be used in place of the Denso, just put lugs on the two wires. . they're non-polar, so they can go either way... .

 

[HHhuntitall]

Lots of info here... . https://www.turbodieselregister.com...y&highlight=single+wire+alternator+conversion

By the way, the alternator above on the right is off a '98 12v... look familiar? The alternators work the same way, either the PCM controls them, '91. 5+, or they are externally regulated, 91. 5 down to..... what? 1963?

Also, after speaking to a former Chrylser engineer, he pointed out that current offerings for the voltage regulators are only rated to about 10amps... . you need three times that to run the larger alternator used on the diesel... . Hence the bouncing guage and short work life... .

 

[HHhuntitall]

https://www.turbodieselregister.com...nent-easy-fix&highlight=alternator+conversion

https://www.turbodieselregister.com...Voltage-Regulator&highlight=alternator wiring

 

[mysteryman]

voltage too high

There are a few things that can be causing your problem. 1) A bad field winding in the alt.. The winding may have a short to ground. 2) your field wiring has a short to ground. 3) You voltage regulator is malfunctioning.. Your truck uses an external regulator (89-91). The trucks used a 7.5 amp regulator. The cars used a 4 amp. No one makes the 7.5 amp regulator anymore. The 4 amp regulators will blow one after another.. The intake grid heaters are really hard on regulators !!!! Many if not most of the 1989 model year trucks used Bosch alt's. THEY WERE JUNK !!! They blew rectifiers all the time. They were replaced with the Nippondenso 120 amp alt's by late 1990. They were pretty good. It's not uncommon to see them go 250 K with out servicing. I have a few hundred NEW Nippondenso alts that I just bought over the summer. I also had some 7.5 amp regulators made. Mine actually have a VOLTAGE ADJUSTMENT screw on them. It can be adjusted from 10.5 v up 19 volts . If you run deep cycle marine batteries you will need to set it at about 13.5 to 13.9 v max . Modern automotive batteries other than marine deep cycle require a slightly higher setting... I also use my regulators as an add on for later model trucks that have the regulator in the main computer malfunction (92 up). I disconnect the field wiring from the main computer . Then splice in the regulator plug that matches my regulator. The place to put my regulator is clearly marked on the fire wall by Chrysler. I have a few cases of the regulators left.. I will make a video of the conversion if enough people are interested. Anyone that needs these parts are welcome to contact me
off list. PM/email or call... Good luck

Hi everyone!



I have a 1989 W250 with an A727 trans. Its old iron but it gets the job done and I've owned it a long time. 2 batteries ago I got amazing service life out of it. The battery after that only lasted a short time. I noticed a sulpher smell when stopped and thought nothing of it at first but when I touched the battery cable, I noticed it was hot. They battery soon failed.



Now I have a new battery and took a voltage reading. It was charging at about 18 volts! I did some online searching and found I am not alone with this problem. Here is what I have done so far:



1) Ran a 6ga wire from the negative terminal of the battery to the firewall on the same screw that mounts to the voltage regulator.



2) Installed a parallel jumper wire from the blue wire between the regulator and alternator to cure the slight voltage drop I was reading.



3) Installed a heavy duty relay with 10GA wire straight from the positive of the battery to the blue wire of the regulator. I have to use a separate toggle switch for the relay or it backfeeds power keeping the engine running even if the key is turned off. I'g guessing I would need a diode somewhere to be able to make the relay go on & off with the ignition key.



4) I can turn the charging system on or off from the cab by a tglle switch I installed between the green wire leading from the regulator to the alternator. If the volt meter (I had to install) shows the voltage getting too high, I simply shut off the charging system.



The battery now charges between 14. 6 and 15 volts. I still think thats a bit high. I tried another voltage regulator but that didn't make any difference. It was a cheapo aftermarket regulator as is the one that came with my used truck. Any suggestions before I try to retrofit an entirely different alternator? I've read rumors that maybe an OEM or Napa regulator might work better but I hate to invest to find out it doesn't really help. Thanks for any insight.



Other than that, its been a heck of a reliable truck. I've always put a dab of outboard 2-stroke oil in the fuel (about 3/4 oz per gallon) and have never had any (VE) pump issues (knock on wood).



The turn signals stopped working but a few squirts of carb cleaner into the column switch fixed that right up.



The steering is a bit sloppy but I'm used to it.



I hate the gearing with a slippy converter & no overdrive but its hard to complain too much with such a great engine under the hood. Does a great job of pulling my boat.