need help: slow cranking, alt wire hot

[jerry]

well, after 2 weeks of inactivity, it started up after a few cranks, but was generally uneventful. i let it warm up for a bit then turned it off. about an hour or so later i noticed that it was significantly slower in cranking, but was able to get it to turn over.

parked it for the evening and unfortunately, can not get it started today. it is very slow in cranking. the dummy alternator light does NOT come on.

the battery measures 12.58V and goes to 10.5V while cranking. it returns to 12.5V after cranking.

the noticed that the 3-prone plug wire from the alternator is getting hot after cranking.

i drove it last night and revved it up quite a bit thinking i have a charging issue but i'm starting to think my starter is going bad.

btw, can't seem to get it started to pull the 3-prong plug while running as was suggested in another post to troubleshoot.

is a new starter motor in my immediate future?? ideas??

[c.d.iesel]

starter motor ?

no.....

not till you've inspected all the wiring incl.

ground connections first - as per other thread on the same subject

voltage when reving at 3500 rpm? = __________ (much more that battery voltage) 13+ volts

alternator history ?

[jerry]

the grounds appear clean and unencumbered as far as i can see. the mystery area for me right now is the wire bundle from the regulator to the alternator. it's in its original rubbery/gooey sleeve and i'm just about ready to cut it open for a look.

this car was so well behaved prior to this. no prior warning. i've got a spare starter lying around, so for the amount of time it'll take to swap out, i can chance it.

[cj]

Did you check/clean your battery terminals? What kind of condition are your cables in?

Cris

[jerry]

Did you check/clean your battery terminals? What kind of condition are your cables in?

Cris

they're spotless... cables are vintage, but appear intact. suppose i could verify with a continuity check. i should expect 0 ohms if i measure resistance from one end to the other, right? i'm not the most electrically literate wrench.

[Chris_B]

From what you say, you have a voltmeter. What reading do you see when the motor is running? Should be somewhere north of +14V at the battery, if your charging system and battery are OK. The alternator plays no part in starting the motor (at that moment). Just how hot is that alt wire, and which wire is hot?

Sounds like you have dragging starter, which you could test with a clamp-on ammeter. Also, to eliminate the possibility of a bad battery, you could have it load tested.

[Guest Anonymous]

the noticed that the 3-prone plug wire from the alternator is getting hot after cranking.

If that section of harness is getting hot it means current is trying to ground through it instead of through the ground strap, as that is the next easiest path back to ground from the block to the chassis. I would just replace the ground strap now. If you let it go, you can melt that whole section of the harness and fry your alternator and regulator. Trust me, I've fixed that mess before...

BTW, you'll probably never get a significant resistance reading with a multi-meter at each end of the ground strap no matter how rough it is.

[ingraham]

A better way to measure the ground cable resistance is to measure the voltage end to end during cranking. It should be about one-half volt.

[jerry]

If that section of harness is getting hot it means current is trying to ground through it instead of through the ground strap, as that is the next easiest path back to ground from the block to the chassis. I would just replace the ground strap now. If you let it go, you can melt that whole section of the harness and fry your alternator and regulator. Trust me, I've fixed that mess before...

that makes the most sense. are you referring to the small ground between the alternator and timing cover, or the ground strap from the battery (-) to engine block? will look into that tomorrow. gave it a rest today to work on my Malaga project for the first time in months.

[Guest Anonymous]

The big strap that goes between the block and the battery and has the small strap connecting to the inner fender. Most likely, that one is not doing a good job of letting current from the starter back to ground (- on the battery) and the current is finding an alternate route through the little brown ground wire in the 3-pin alternator harness.

Basically, your starter is trying to pull more amps than what it can ground through the existing wiring, so the wiring is heating up and the starter is slowing down.

[jerry]

thank you very much for the information. i'm on my way to replace both wire cables off the battery as a 2nd pair of eyes described them as poor condition, despite my opinion to the contrary. i'm learning all the time...

will update as to my results when they occur.

hopefully, this lesson will implant into my brain for future reference.

[Marty]

If you have the stock rod type of throttle linkage a down and dirty way to check the condition of you ground circuit is to lightly touch the throttle return spring, be careful it might be hot enough to burn, if its hot the linkage is trying to work as part or all of the ground circuit. This think this should also work on cable linkage but I haven't had the chance to try it.

[jerry]

Guilty as charged...

turned out the problem was simply a poor positive battery cable. replaced it with new and the starter spun like new.

only problem, was that in my haste i replaced the starter with an older unit lying around. damn if the teeth were slightly worn enough to grind on my flywheel. argghhh......

soooo..... got to spend some quality time in the drizzling rainy cold reinstalling my perfectly good original starter.

you haven't experienced the Zen of 02 Wrenching until you've installed then removed an older, big-assed 02 starter in such tight quarters.

bonus points for installing the uppermost bolt if you have a water-cooled choke fitting attached to the engine block.

henceforth, i will replace any old big-assed starter with the smaller bosch units currently available. they even have more clearance to use a socket with on the mounting flange.