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More fun on the Frankenmotor.

lizrad999 · 2026-05-17 12:55

All right gents (and Ladies), after squirrel'ing to another project for a couple months I have resumed throwing copious amounts of time at the Frankenmotor. The engine is completely together and ready to start. When I bought this thing, I was told it was 24Vdc, and it had two batteries installed. (If you want to call it that) It cranked, started, and ran at that time. Since then, everywhere I looked says the OEM was a 12Vdc starter and alternator. #1. Can someone please confirm this thing is in fact 12Vdc please? One battery will not turn it over well. Thinking the starter might be the wrong one for this machine, I managed to pull it off last night. (I could strangle whomever put the starter bolt up against the frame so close....) Oil began leaking out of the starter mounting hole, so I removed a little 1/8" plug from the bottom of the bell housing and got a fairly steady flow of oil. (about two to three quarts) In searching with google, I have found several sources that say the bell housing typically has oil in it by design "wet bell housing", but that it is a sign of leaking torque converter or rear main seals......those are conflicting statements?!?!? #2. Is there or is there not supposed to be oil in the bell housing? I think there is not. Engine and Serial number below.

Replies18
  1. #1Simon C2026-05-17 19:36

    Is this on a Cat Dozer as was not mentioned. How many hours on the unit. Does the starter have any 12V versus 24V on it. How about the alternator, what is stamped on it. Simon C

  2. #2CRC CAT D5K22026-05-17 21:20

    I have just chucked you S/N into Web sis. A Cat D3B correct? The parts book a type one starter and type 2 starter. Both 12 volt. Hope this is of some help.

  3. #3Welder Dave2026-05-17 23:05

    D3B is definitely 12 volt. Is it a Delco Remy or a Nippon Denso starter. Some people changed the ND starter to a Delco for ease of service and parts. I wonder if someone put a 24 volt replacement starter on it? Not sure on a D3B but 931B loader version uses a huge 8D battery and it cranks over pretty easy. I think the battery acts as extra counterweight.

  4. #4lizrad9992026-05-18 21:17

    It is indeed a D3B Caterpillar. 12Vdc is all I can find as well.... With regards to markings on the alternator OR starter, there are zero stickers, stamped numbers, info plates, anything. Just a sanity check with the experts. I have already swapped the alternator and I KNOW it is now 12Vdc. The Starter is not terribly old looking. THe bottom end appeared to have been media blasted, and everything is fairly clean. But when I tried to start it with one battery, it wasn't happening. Now I have to decide if I drop this starter at the rebuild shop and make sure (assuming they can tell between 12 and 24Vdc) or bite the bullet and buy an aftermarket one. $400+. Any takers on the oil in the bell housing question? By oil I mean like 2-3 quarts. Again, sanity check. I suspect there is NOT supposed to be, but in the event I am wrong, I'd hate to pull the motor/transmission to fix a "non-issue".

  5. #5Nige2026-05-18 21:31

    According to the electrical schematic it is a 12v system. Are the two (I assume 12v) batteries that are installed in it right now connected in series or in parallel.

  6. #6John Strange2026-05-18 22:07

    https://777parts.com/caterpillar/53/m1828/SEBP12500173.html Seems to indicate a single battery, but it's a big battery, when I look up the cat part # it looks like a massive battery though, but doesn't give any specs on it.

  7. #7lizrad9992026-05-18 22:24

    They were in series.

  8. #8Old Magnet2026-05-18 22:52

    Originally used a BCI# 8D 12v battery 1500 CCA weighs 130 lbs.

  9. #9Nige2026-05-18 22:58

    Were they 12v or 6v batteries.? Got photos.?

  10. #10Simon C2026-05-18 23:22

    Sounds like someone got something wrong, if there is 12 volts in series. Agree with Nige, need to see battery Box picture. Simon C

  11. #11lizrad9992026-05-19 00:46

    There is no question in my mind they were both (two different size and brand) automotive 12Vdc batteries. The machine is old enough that it has been monkeyed with previously, probably many times in its life. The battery cover is completely missing, there is NO red wire anywhere (I could only identify the positive by following it to the starter) and there was a 2' battery cable with two ends on it. Hence the "in series" comment. I have long since removed the batteries and disposed of them since they were no good. At this point I am confident it is supposed to be a 12Vdc system, and that is what I am putting back in it. Using the BCI No. 8D 12Vdc battery.​ Whether I can recover some expense getting this questionable starter converted or confirmed to 12Vdc is the only remaining concern regarding the power. Thanks for the help everyone! Now, about that oil in the bell housing.....

  12. #12Welder Dave2026-05-19 02:27

    8D in a 931B loader version.

  13. #13Welder Dave2026-05-19 02:28

    See what happens with a known good battery. Also check the grounds. An 8D battery lasts a very long time if it only has to start a 65 H.P. engine, assuming the engine is in good tune. Just a bugger to manhandle! As far as the oil I'm not sure but it is a wet starter so some oil is expected. I think it's supposed to get picked up by a scavenge pump. Someone more knowledgeable would know.

  14. #14John Strange2026-05-19 23:49

    lol that's a massive battery.. 130+ lbs, have fun with that

  15. #15Welder Dave2026-05-20 00:55

    Some 8D's are even heavier. I had one that was probably 145-150lbs. Even the place I exchanged it for a recoditioned battery said it was extra heavy. Of course it was the one that was the hardest to get out because it was dead with the Cat on a trailer with the backhoe. The back panel had a lip that wouldn't let the battery come out. I had to take the entire seat frame out which was beatch itself.

  16. #16oarwhat2026-05-20 06:55

    An 8D battery for a little D3 . That's nuts.

  17. #17Welder Dave2026-05-20 12:35

    It could be because the D3B and 931B are the same at the back so why make separate battery boxes. Easy way to add more counterweight. I think some have put a 4D in instead.

  18. #18Slowvojockey2026-05-20 17:38

    If it starts up without much cranking, I have replaced a few 4D’s with group 31’s on a 1 to 1 basis as the cranking amps and cca’s are basically the same, it’s just the reserve capacity that’s different. Group 31’s are about 1/4 the price and 1/2 the weight of a 4D here.