Cranks slow with the key, fast at the relay

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open the relay and polish the breaker contacts with 400 or higher grid. Ohm resistans shoul be lower than 0.5 ohm!
You can measure the voltage drop at the starter relais. Should be less than 0.5V. Voltmeter to connector Bat relais and Starter out at relais. I bet yours read around 2V! Parallel voltage measuring is the fastest way to diagnose. Voltmeter Batterie plus to starter connector should be as low as possible 1- 0.5V or less. Same ground from battery to engine/starter ground.
Bad connectors create always excessive heat.
 
It does seem like there is a voltage drop (resistance).
The only question is where.
recheck using the internal resistance (voltage drop) method described above.

You should also check the ammeter during a normal start (with key). Should just be a small current flowing to ignition.

Kern Dog said:
I saw the voltage regulator was smoking.
Click to expand...
This makes me suspect something wrong in the 'ignition" circuit.
Is the regulator "seeing" battery voltage when the car is running?
Is the battery seeing the same voltage as the alternator is running at? Especially when the battery is recharging, but also when lights or other loads are on?

If not, the VR might have been full fielding for extended periods of time.
Use the handheld voltmeter and the dash ammeter together to figure out what's going on.
 
this is what was described above.

1739722243373.png


It must be done while cranking. Cranking puts a load on the contacts and if there is resistance it will raise the voltage reading above the 0.5V or so.


Think of it this way...

lets say you have a wire with 15 strands and you measure resistance of that wire with an ohm meter (no load) you would get 0 Ohms (best case, or what ever your meter reads when its leads are touching)

now take the same wire and cut all but 1 of the 15 strands and measure resistance your meter will read the same as in the first measurement.

The wire with all its strands can handle (just a numbers for illustration) 15 Amps, the wire with only 1 strand left can handle 1 amp.

If you try to power that 15 amp load with a wire only able to handle 1 amp the wire will heat up and resistance will be increased and voltage will be decreased so the voltage drop of the wire will be 11 volts and you only have 1 volt to power the load

In starter motor world 12-13V would be great, 10-11 is typical, 8-9 is marginal, 6-7 probably will result in the dreaded click of death. so you can see how 2 volts lost can make or brake the starter system.






AGAIN this is assuming there is not some other system in the car drawing a load while cranking... lights, electric fans, high watt amplifier, shorted field cir in the alternator, other high current draws.
 
If your gonna relpace the relay & I agree you should, try to find a new old stock one, the new chinesium ones suck....
 
open the relay, clean and polish the points. measure the points diode for function and replace if necessary. i did this on many customer relays from Bosch, they still run. I hate plastic or repro ****...
 
I appreciate the suggestions.
For some of the testing and diagnosing, I'd probably need to watch someone else do it first to help me understand it.
Some stuff is easy for me, some stuff might as well be in Chinese for how hard it is for me to understand.
 
Dana67,
You are missing the point. Without the screwdriver shorting out the relay contacts that energise the sol, the starter cranks slowly. The starter can only crank slowly, fast, or inbetween if the starter relay is energised. So the relay is operating but the internal contact points are likely pitted over years of use, from the high sol current. The pitting is causing a voltage drop from the high resistance of the contacts, which in turn reduces the current to the sol & it's ability to make pull in the sol armature disk that bridges the starter terminals. Bridging the relay contacts with the s'driver gives the sol a little more current, enough for the armature to pull in the armature disk more firmly & provide full current to the motor. The sol contacts are copper which wear away with usage & make poor/no contact. The dreaded 'click'. I build up the contacts with silver solder & that restores starter operation.
 
Bewy said:
You are missing the point
Click to expand...
No I got the point that the screwdriver bypasses the relay that was my point. It seemed that you were suggesting that the screwdriver was bypassing the ignition switch and the bulkhead connectors only.

Either way... We are on the same page
 
I had this exact same problem a month or so ago and it was my timing that was too advanced.
 
Yeah, that is correct.
I swapped in another relay and it cranks just as fast by the key as it does by crossing the terminals on the relay.
New ones are around $30 from the auto parts stores, which sparked the memory of a member here mentioning the process of disassembling them to clean the contacts.
I have maybe 15-18 of these in the shed in all stages of condition. I could try taking them apart and cleaning them up.
 
Kern Dog said:
Yeah, that is correct.
I swapped in another relay and it cranks just as fast by the key as it does by crossing the terminals on the relay.
New ones are around $30 from the auto parts stores, which sparked the memory of a member here mentioning the process of disassembling them to clean the contacts.
I have maybe 15-18 of these in the shed in all stages of condition. I could try taking them apart and cleaning them up.
Click to expand...
Ok, so you found the issue was indeed the relay. I wouldda never thought that. :rolleyes:
 
It did seem possible that the wiring was to blame since it cranked fine at the relay. It just didn't occur to me that crossing the terminals of the relay essentially took it out of the equation.
 
Kern Dog said:
It did seem possible that the wiring was to blame since it cranked fine at the relay. It just didn't occur to me that crossing the terminals of the relay essentially took it out of the equation.
Click to expand...
Yeah I think some dipshit in post #3 said somethin about the relay. lol
 
Since electrical matters are way near the bottom of my skillset, stuff like this gets by me. I figured that the relay either worked or it didn't. The thought of corrosion and resistance didn't even enter my mind.
 
Kern Dog said:
Since electrical matters are way near the bottom of my skillset, stuff like this gets by me. I figured that the relay either worked or it didn't. The thought of corrosion and resistance didn't even enter my mind.
Click to expand...
Well don't feel bad. Usually, the only way I remedy electrical problems is to guess. lol

Most of the time, I'm a good guesser.
 
I don't beat myself up over it. We all have our strong points and areas where we need help.
I'm thankful for this forum and helpful members.

01 bowing.gif
 
Kern Dog said:
I do have the terminal with the brown wire grounded since when I patched this car together, I didn't have the wiring that went to the neutral safety switch/backup lights.
I'll try running 12 volts to the yellow wire/terminal.

View attachment 1716366343
Click to expand...


I know this doesn’t make any difference,,,,but is that yellow wire almost broken at the terminal in the plug ?
When I enlarged the picture it looks very suspicious .

Tommy
 
I am not sure.
The car starts fine now so I suspect that it must have enough strands in the wire to still work.
 
Last edited:
Bewy said:
The problem is in the relay. In post #1, the s'driver is essentially shorting out the contacts inside the relay. Note that even with the contacts bridged, the current is still flows through the SAME wiring & connectors. So if it spins fast with the relay terminals bridged, then it cannot be these items causing the problem. The relay contacts maybe burnt from arcing or worn way. You can buy a 150 amp relay which comes as a black cube, only sligthly bigger than the popular Bosch 30 amp relay. This is what I use for the starter relay. 150 amps is waaaaaay more than the solenoid draws but it means the surface area of the contacts is greater, resulting in less arcing/wear.

View attachment 1716366369
Click to expand...
Mark this day. I agree with Bewy.
 

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