Starter amp draw

[JimDoani]

First, thanks for all the good advice concerning the broken filter head on my A, got everything back together, although it was quite a chore doing it from the top. Anyhow, finally time for the first start. I had pulled the starter earlier in the project, cleaned it up and put new brushes in. The bushings were all good. Checked the field coils for shorts and open circuits, all was good. Its turns the engine over great, until I put plugs in and it had compression. It's pulling about 200 amps trying to crank the engine under compression. Is this high, low, or OK? The battery cables are getting warm, but the starter remains cool. I've checked and cleaned all the connections. BTW, it's a '52 with 12 volt system. Thanks!

 

[John T]

That 200 amps under load doesn't sound unreasonable to me. The starter amps under load depends on, of course, the engines compression, temperature, oil viscosity, battery condition, bearing clearances, voltage drop in cables etc etc so I nor anyone can say from here or even if there what your compression or bearing load etc is.

A newly rebuilt engine even if alls well can be quite a load on a starter until she wears in a bit.

Sounds like you already did the right things, check each and every battery and starter and starter switch and ground connection,,,,,,,have a good charged heavy duty battery,,,,,,,,,,oversized cables if necessary,,,,,, see if she does better if the battery is being jumped. Id pull start her and let things seat and wear in a bit before you started a lot of work.

Sometimes a ground cable connection RIGHT AT THE STARTRER improves performance, especially if the current has to go through some thin wimpy rusty seat box connections. Or at least try grounding on a good clean shiny bolt to the frame versus the seat box frame.

A voltmeter on the starter while cranking can give an indication of excess voltage drop in cables and connections. If the battery voltage is 12.6 (but will drop when cranking) see what the starter voltage is while cranking. If its say 10 to 11 or so volts Im not too concerned but if its like 9 or less Id be thinking about cable or connection problems or a weak battery.

Hard to say over the net or even if there absent some specs and data and voltage readings, however, 200 amps isn't unreasonable

John T

 

[JimDoani]

Thanks John. I don't know why I didn't think to check the voltage drop when cranking. And I will change the ground cable regardless. It looks pretty rough. And I will definitely attach it closer to the starter, I like that idea.

 

[teddy52food]

If your cables are getting warm at 200 amps, I would put bigger ones on.

 

[buickanddeere]

(quoted from post at 14:11:02 07/04/14) First, thanks for all the good advice concerning the broken filter head on my A, got everything back together, although it was quite a chore doing it from the top. Anyhow, finally time for the first start. I had pulled the starter earlier in the project, cleaned it up and put new brushes in. The bushings were all good. Checked the field coils for shorts and open circuits, all was good. Its turns the engine over great, until I put plugs in and it had compression. It's pulling about 200 amps trying to crank the engine under compression. Is this high, low, or OK? The battery cables are getting warm, but the starter remains cool. I've checked and cleaned all the connections. BTW, it's a '52 with 12 volt system. Thanks!

Teddy is on the right track. That starter should be drawing 400+ amps. There is VD between the battery and starter.

 

[JDemaris]

1107942 starter on a late B @ 5 volts draws 65 amps at 6000 RPM no-load and 600 amps when locked up at 3 volts and making 16 lbs. of torque.

1108950 on an A or 60 @ 11.3 volts draws 63 amps at 5500 no-load and 675 amps when locked making 30 lbs. of torque and voltage at 4 volts.
Untitled URL Link

 

[John T]

You're welcome, a ground cable relocation may help. Again, that 200 amps figure certainly isn't too high.

John T

 

[JimDoani]

Thanks for all the help guys. A new ground cable, a known good hot battery, and it came to life!!!
Very happy with the tractor after this first start. No leaks, 30 psi oil pressure, temp running good. Needed very little carb adjustment for the engine to settle into a good idle. Shut it down and the oil pressure bleed down nice and slow, bearings must be in good shape. On restart it hit on the first compression. This one's a keeper!!

 

[John T]

"A new ground cable, a known good hot battery and it came to life!!! "



Yayyyyyyyyyyyyyyyy Congratulations

John T