Signs of a weak starter motor

[TwoUpTourer]

My VZ has a good battery, a big bugger, at 640CCA, and yet the crank is difficult to turn over, so my thoughts are drifting from it being a weak battery to perhaps something, anything else. No matter the weather, the battery I have doesn't ultimately fail, I just have to try a few times before the crank will actually spin more than a quarter turn.
So can a starter motor be weak?
If so, what aspect of it causes that weakness? Earthing? Dry solder contacts etc?
Wreckers nearby have ones for $55, so it's not a fortune to try one to rule it out as a cause, but personally I'm unaware that they had a state somewhere between working and dead.

 

[vc commodore]

Could be the starter...Could be the battery cable at the starter or earth cable from the battery...It also could be the loom connected to the starter, or maybe the battery is actually on the way out.

Only way to determine the problem is, first check the battery is fine by getting it load tested....Check all the wiring to the starter is fine....And finally check the battery terminals are tight and clean and the battery earth is earthed to a clean earth point

 

[RossK]

^ Check this.
we had slow starter and intermittant no crank - I replaced battery and starter to no avail in our VZ.
Checked the voltage on the starter lead and solenoid trigger wire and found variable voltage and resistance.
Replaced both and has been great since. Spins over much faster and starts quickly.
The cables wrap around the front of the sump and up around very close to the exhaust mainifold. The cables heat age and break down, causing increased resistance, less Volts to the starter.

 

[TwoUpTourer]

^ Check this.
we had slow starter and intermittant no crank - I replaced battery and starter to no avail in our VZ.
Checked the voltage on the starter lead and solenoid trigger wire and found variable voltage and resistance.
Replaced both and has been great since. Spins over much faster and starts quickly.
The cables wrap around the front of the sump and up around very close to the exhaust mainifold. The cables heat age and break down, causing increased resistance, less Volts to the starter.

An interesting lead. So what voltage should I be seeing at two points?
And am I right in saying that cable replacement alone was sufficient? I'm confident the battery is not the problem, as I replaced it and got the same result, so some connectivity issue is probably correct.

 

[wannaeatyourbrains]

Yeah, I am interested in this issue. My starter motor is slow to turn over when it is hot. It is a pain in the bum. Starter and battery are surely fine.

I have changed the positive lead from the battery.

The solenoid wire is only going to stop the solenoid engaging after you turn the key to start, right? The delayed cranking comes after the solenoid has engaged. So I guess not that.

I already cleaned the earth points for the negative lead. The negative cable can crap itself, huh? Anyone know what the resistance in that should be?

Anyone got any other clues?

I don't have a heat shield, and hot here is bloody hot. Could that simply be the problem?

Anyway, you inspire me to mend it. I am going to have a crack at that now.

 

[vc commodore]

I don't know what the resistance is for the negative cable, but the way I test is by feel....Next time your car is hot, get someone to crank it and touch the earth cable and feel if it is hot....You only need to touch it for a second to know...

Barring that being the issue, the next step is the starter itself....

So yep, try the earth cable first...Cheapest and easiest one to try

 

[Pollushon]

Yes starter motors can go weak before they die. Honestly it's not something I'd go second hand with should it prove to be the culprit. How has this come about? Out of the blue or over time?

 

[wannaeatyourbrains]

Yeah it is hot as! Noticed that ages ago. That's not right, huh?

I been putting up with this for so long. I will change it. Thanks.

 

[vc commodore]

Yeah it is hot as! Noticed that ages ago. That's not right, huh?

I been putting up with this for so long. I will change it. Thanks.

Earth being hot definately not normal....When you change it, please let us know the end result...

 

[wannaeatyourbrains]

Mate, you will know soon. No mucking around here.

I just went scavenging the desert for some cable. Found these old buses today.

Turns out buses have sick V8s. Would love to salvage them. Nothing rots here, they would start up easy. Put one in a boat. They will all be buried under the new highway soon. Such a pity. Says something 350 on them.

Jesus under the buses was all these holes as big as your fist. I had to lie among them to rip some cable out.

Do you think it would come out quickly either? Bloody metal cable ties, had to bend them back and forth a million times to break them. Stressing all the while scorpions or giant spiders were going to swarm out and drag me into their lair, to be torn to bits and eaten in the darkness. Tonnes of crap in my eyes.

Anyway, success. Some real nice battery cable. I will change it over and see if this resolves the issue.