Tuning Starter trouble

[Mike1alike]

Here it goes...
My battery was low, so I’ve put it on charger. After that, it’s been tested and is in mint condition. Voltage after recharge: 12.8 V
After doing some testing, I’ve discovered that the voltage dropped a lot wile starting the engine, 10.23 V. Some power loss there... I’ve suspected the culprit to be the brushes inside starter. Bought a new set of brushes (with holders/plate) and got down the starter. The brushes inside looked very good, but as long as I’ve got the new ones, I replaced them, put the new ones in. The starter armatures caught my attention though, the rotor collecting blades were worn off. The next day I’ve bought new starter armatures and replaced that too. All was good with the power loss, the voltage on ignition dropped only to 11.99 V.
But there is a problem that first appeared after I’ve replaced the starter brush holders: on the first ignition in the day, the engine does not start normally, there is an hesitation. It starts if I press the acceleration pedal. And all the next engine starts on the day are without problems. The next day... the same!
I’ve cleaned all the cables connectors. I had no problem with starting the engine (except voltage dropping down on battery) before I took down the starter.
What do you think is causing this?
The starter is Hitachi S114-903A and here are the components of it.


A friend told me that the bushings need to be replaced if you work on the starter because even 0.1 mm play inside bushings can give a lot of trouble. Is this true? Do you know about this? Will replacing the bushing solve this problem?
And if so, can you guys guide me on how to replace them? I’ve spotted 2 bushings inside the starter: one in the housing, the Bendix drive shaft sits in it and another one in the middle, the rotor shaft sits in it. But the ones in the link above look to be bigger than the ones inside starter.

 

[Mike1alike]

And some pics...

 

[judderbar]

It is fairly normal to get a large voltage drop when the engine starts. Your current 12v at the battery when you start the car seems high to me. If the bushes were worn out I would expect the starter to take more current and you would have more voltage drop.

At the moment I am thinking 12 volts is so high there must be a poor connection to the starter or the gearbox earth - something to cause the starter to use insufficient current. A current test on the starter wire would confirm that. How many volts do you get if you turn everything on without the engine running?


I just tested my car in a warm garage. It must be at least 12C there. The voltage dropped to 10.15v first time and 10.3 second time.

If I turn on all the lights, spots front and back, blower motor, heated seats I get 11.3V. The blower motor uses about 6amp. The car has not been used much recently. the battery is 2 or 3 years old.


Unless you have fitted a truck battery I think you have a connection problem to the starter.

I suppose one possibility is new brushes on a worn commutator prevent good connection until the brushes have got the same profile as the commutator and the problem will correct itself after a few weeks of starting

 

[Mike1alike]

Neh, it's normal for a diesel maybe. For 1.2 petrol it's a lot, especially if the engine is already hot. And I had the same drop on hot engine.
I did test the wires and all looks very good. I have the same voltage on the starter as on battery.
This bushings scenario seems to be the one to chek, kind of the only one. I'll replace them as well. There is a 3rd bushing in the starter, I didn't pay enough attention maybe, but there must be one on the starter lid. These are the codes for the ones I've ordered and in the pic we can see where the bushing should be placed.
140311C
140870C
They are 2 bushings of a kind (I think the larger ones) and one of the other kind.

 

[judderbar]

Neh, it's normal for a diesel maybe.

This link says battery voltage should be 10v or higher when starting. And as I already said I tested my car and got the same 10.3V.

Car Battery Voltage | Chart | Range | Testing | Tontio.com

The voltage of your car battery is a good indicator to the status of its health, and could prevent you from being inconvenienced from a battery failure!

tontio.com

If you have 12V when starting something does not sound right. One possibility is the new brushes are not bedded in and so cannot handle the current required.

 

[Mike1alike]

Yes, that value is good, but for cold start. If the engine is hot, it shouldn't drp to 10 V.
I've solved the problem!
I've put back the old brushes (with holder) and it started just great. The voltage dropped to 10.5 V on cold start and 11.5 V on hot engine start.
The higher than usual drop of voltage was caused by the very bad state of the starter armatures's collector.
Here's a picture of it. And another pic with my old brushes, they are in good shape. And in the 3rd pic, I think I've spotted what the problem is with the new brushes: 2 of them, one (+) and one (-) on the same side, did not make contact with all their surface on the collector. I think that little piece on the edge, not touching was giving me the problem only on the first start of engine in the morning.