My 1965 D7E had the direct electric start conversion done sometime in its life. It has this alternator installed: A closer image in the next post.
This number is the only number on the alternator, but it is on the pulley. The entire charging system was "disabled" at the very least. It started fine when I got the dozer, but today, it suffered from low batteries and had to be jumped to start. I don't have electricity at the site, so charging the batteries overnight each night is not an option. I need to get the charging system back operational, so I am trying to get this alt checked out - an impossible task without a "proper" model number. Also, did the conversion to direct start use the original charging system, or did it have to be upgraded? Wires have been cut all over the place, so is there a schematic of the charging system available? I know... I am asking for a lot, but I need to get Bertha up and charging again.
Looks like possibly a Delco 12SI, should be some numbers stamped into the frame, might have to use a wire brush to find them
I forgot to mention that it is a 24V system (aren't they all?).
12SI came in 12V and 24V, again, if you can find them, there should be some numbers stamped into the frame that would give more specific model info
Style identification Catalog Unfortunately, only 12v numbers.
Delco 12SI in twelve o'clock position.
Front of 12SI showing black thermoplastic fan.
I just wire brushed the entire outside of the alt. I still can't see any more numbers. Any hint as to where to look?
That's not unusual to find no numbers, Delco alternators have been "cloned" by aftermarket suppliers for years, they don't stamp numbers on aftermarket parts. Drat!
But this one IS a Delco alt. A clone would be alike in everything EXCEPT the Delco-Remy logo on the face. To do that would be a trademark infringement, an action that Delco would most likely defend in court.
Sure looks like a 12si to me. But, don’t get wrapped around the axle about it. You could go with another 12si or a 15si or even a 10si. It’s not rocket science or an impossible task. It’s like 1960’s technology and the most simplistic alternator ever built with the largest aftermarket support. You can go on the Amazon and purchase any part you need to fix it.
And you are absolutely correct. That 12SI is an odd one anyway, obsolete now with Delco, but the 10SI, there's a gazillion of them out there. https://www.amazon.com/REPLACEMENT-...hvlocphy=&hvtargid=pla-4583451676701166&psc=1
For testing purposes, hook spade terminals 1 and 2 to battery B+ terminal on the alternator and run a wire to the battery positive terminal. If it charges when running, then you just have to figure out how to wire one to the ignition switch, and one to the wiring harness for a voltage sense, or just leave it hooked to B+, it will work fine there as long as you don't use a lot of electricity and the main alternator wire is big enough. You can try to test it on a bench with a socket driving the pulley, but it sometimes takes a high RPM drill, like a drywall screw gun to get enough RPM to charge.
I wouldn't think it would be hard for an auto electric shop to test and/or repair it. If it's beyond repair they could provide a replacement too.
Use a 24si. Standard on Cat machines of that era.
I STR D7E's of that era only came with a Delco Remy generator, not alternator. I'd guess, at some time in the past, the generator or regulator pooped itself, so a common alternator was bolted on, and the regulator and the unnecessary generator wiring got the heave-ho. The D7E came with a 12V electrical system for pony start - direct electric was 24V. But a single wire 24SI as Check Break says is the simple solution today, as so much early electrical stuff is now totally obsolete.
Okay, someone found numbers on this thing. I read them as: 1105183 66A SM 9 12VNEG Here's a photo of the numbers: Am I correct in reading this as a 12V negative ground, 66 AMP output alternator? If so, could this have ever worked?
Yes, 12V Negative, 66A output, and the 1105183 is the Delco Remy P/No. Not sure on the other numbers, I see 5M 9. This setup could only have charged one 12V battery in a 24V setup - or perhaps your system is actually 12V direct electric? Delco Remy made heavy duty starters in 12V. I converted my '72 Mack F785 Maxidyne from air start to 12V Delco Remy electric around 1980 - it worked just fine for me, although the climate where I live is mild "Mediterranean"climate, hot Summers and mild Winters, similar to Southern CA. We don't get freezing temperatures very often, only rarely for a short time (2-4 hrs) on cold Winter mornings.
Not on a 24V system, unless someone changed the rectifier. I suggested the 10SI in 24V because the 10SI is still fairly common and I think it will mount to the existing 12SI mounting, 24SI might require modifying the mounting
Some maybe minor but possibly major points I would make is who did the conversion and did they also modify a 12 volt alternator to be a 24 volt? Not sure what would need to be changed but it could be that someone swapped some parts but never changed the number on the casting. Or someone who worked on old trucks like say B model Macks could have had it set up with a series parallel switch to charge off the 12 volt alternator but supply 24 volts to the starter. And while I'm going off the deep end trying to think of what might have been done, are you sure the 12 volt batteries are wired up in series and not parallel?
I looked again and you are correct. It is "5M 9". This gal is definitely a 24V start - it has 2 12V batteries in series. I did notice on the starting solenoid that "12V" was stamped on it. There is no tap at 12V from the batteries, so it must be getting 24V. Also, on this engine, is airflow supposed to be OUT the radiator front (this one is)? There are a lot of leaves on the engine side of the radiator and nothing on the outside. Walking around the front of this gal gets you a blast of hot air from the radiator. I haven't checked the fan geometry to see what direction the fan SHOULD be turning. Right now, I am up to my *** in mud, so little things are going to have to wait. On this regulator, I'm going to assume that it is working correctly and rig up a harness to energize the coils and put alligator clips on the ends and charge each battery separately (20 min on one, 20 min on the other, repeat as necessary). I'll order a proper regulator once back at home base. Thanks to everyone for bearing with me.
That's definitely a weird electrical setup. When you say "starting solenoid", are you referring to the magnetic switch solenoid? - or the solenoid on the starter that pulls the pinion into engagement with the flywheel ring gear? The fan is normally a "blower fan" - the air goes from the engine bay out the front. You can acquire "sucker" fans (or reversible fans) that can pull the air the other way. These are not common, they are usually only used in extremely cold conditions when the operator is looking for some warmth! The engine bay is normally covered in this case, so the warm air goes back over the operator compartment. It's important the radiator core is washed out regularly. A small fire-fighting pump with a 3/4" hose and nozzle is handy for this, you don't need high pressure, just a modest volume and pressure of water. I use a 100-200 gallon tank with the fire-fighting pump, and throw in a cupful of laundry powder to assist in removing oily deposits in the radiator core. If you operate in dry conditions where the tracks can throw up trash such as stubble, sand, and other debris, this can be sucked in by the fan and build up in the radiator core - and even sandblast the core. As a result, if these conditions exist in your operation, you're best advised to source a set of perforated screens for the sides of the engine bay. These screens stop that debris from getting to the fan and the radiator core.
Could someone have hooked up the batteries wrong? There's a lot of unknowns. I know you can use a 6 volt starter with 12 volts if the engine is in good shape and starts easily but not sure about 24 volts on a 12 volt starter or 12 volts on a 24 volt starter. I think the latter would have slow cranking speed. Try to find some markings on the starter and then get a suitable alternator to charge the batteries. An alternator should be cheaper than a starter.
Agree on the 6 volt starter in a 12 volt system, my old Farmall has been working like that for decades! Maybe post a couple pictures showing the wiring and someone might see something there.