Starter Problems: TB45E

[Gerrit Loubser]

On Thursday morning I noticed that the starter on my Patrol seemed to swing the engine rather slower than usual. On every subsequent start that day the starter seemed to be swinging the motor slower and slower until it reached the point where the motor would no longer start. This happened when I stopped at the post office on my way home from work. Although I was alone I managed to push start Imvubu (courtesy of a slight incline) and drive home.

Today I removed the starter and partially dis-assembled it. Removing the starter is not difficult, but is a little tricky due to the lack of access and the small angles that spanners can be swung through. I did all the work from underneath the car, as access is better, but it does mean that the top starter bolt has to be loosened and refitted blindly. The bottom starter bolt is in view from underneath the car.

When I removed the rear cap of the starter motor and the brush holder, I immediately saw the reason for the problem: Two of the starter brushes were completely worn away. There are four brushes, two of which (numbered 1 and 2) are attached directly to the power lead entering the stater motor and two of which (numbered 3 and 4) are fed from the first two. I am not sure why, but numbers 1 and 2 were the ones that were worn away completely while 3 and 4 were still fine.

As the brushes wear away to the limit, they are no longer pressed into intimate contact with the commutator segments and start to arc and burn away to the point that they are no longer able to conduct current. This means that the motor loses torque dramatically and eventually fails to swing the engine fast enough to start it.

I had visions of perhaps having to replace the starter and had heard stories of prices of R6000 for a genuine replacement part from Nissan, although I have not checked that out myself, so it was a great relief to see that the root cause of the issue could be addressed by replacing the brushes. Imvubu is my day to day transportation, so I really had to get her going again over the weekend. Fortunately I was able to purchase a set of replacement brushes from the local Midas. They are slightly smaller (same thickness, but not quite as wide) than the originals, but the brush springs ensure that they are centered correctly on the commutator and there is no side load on them in any case. The slightly smaller brushes will probably have slightly higher resistance than the originals, so I will try to get hold of a set of exact replacements in due course. Because of this and because I did not want the hassle of soldering brushes 3 and 4, I decided to only replace brushes 1 and 2 and re-use 3 and 4 seeing as they still have plenty of life left.

When I had the rear cap of the starter off, I removed the armature and cleaned up the commutator by spinning it in a drill-press while holding a strip of fine wet-and-dry sanding paper against it. I also cleaned the gaps between the commutator segments and greased the pinion (sun) gear and end bearing on the armature. The starter looks quite small for the size of the motor, but it does have a planetary reduction gearbox to increase the torque. The actual starting gear looked to be in great condition, bearing in mind that this is most likely the original starter and the car has done over 240000 km.

Everything is back together again and Imvubu starts as she should again. The cost for the brush set from the local Midas was R95 and I also determined that the local Autozone could supply me with a replacement starter at around R1100, although they would have to order it and it would probably take two weeks.

[Jules]

Welgedaan Mechanic Gerrit , bly om te sien there is a MECHANIC ON MY STOEP

Shalom

[Gerrit Loubser]

Thanks, Jules, but this is a really simple job (a "one banana job") , so don't expect too much .

Terloops, jammer oor die Cheetahs...

[Herrie]

Ja, dit is gewoonlik die probleem en as jy dit nie gou genoeg regmaak nie dan veroorsaak dit dat enn van die komutator se segmente loskom en al die borsels afbreek. Dit het in Botswana gebeur - die laaste oggend oppad terug huis toe.

Breno het vir my 'n nuwe starter gekry vir R1600.00 en ook my ou een se komutator reggemaak - nou het ek 'n ekstra starter.

[Tinus lotz]

My 4.8 se starter maak ook snaaks miskien moet ek ook hom afhaal en kyk!!!
Voor daar skade is want dit klink na n duur storie as hy breek