Technical Starter Motor brushes abnormal wear
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Technical Starter Motor brushes abnormal wear
I haven't seen any like that in over fifty years in motor trade, very soft cheap carbon brushes? I can't see excessive spring being the cause, I assume not changed anyway. Do the brushes look burnt at all or just worn away, can you dig you nail into the brush material. Am I right dynamo/alternator brushes are softer as cope with much less amperage than starters do?
Hi, as soon as I clean up the rotor the starter works fine until the deposit builds up to a point it starts shorting out and starter goes slowly dead..I have just cleaned it up again and put new brushes in and it is turning ok....but did not try enough times to see if I still get the issue. Will try tomorrow. Hopefully if the starter keeps going ok I can then try and understand why the car will not start...thxs
Is the engine it'self stiff to turn over by hand, putting to much load on the starter, causing it to overheat?
I think @bugsymike is onto something there. Are your brushes a coppery colour? They should be.
Thanks Pete, that is what I was trying to remember, the starter brushes are a sort of granular copper looking part and the alternator ones are a softer more dark almost black carbon.
They are the correct ones. The dynamo brushes apart from being different material do not fit in the slots of the starter as they are bigger.Thanks Pete, that is what I was trying to remember, the starter brushes are a sort of granular copper looking part and the alternator ones are a softer more dark almost black carbon.
I am not suggesting the shape, just the material your supplier has made them from.
Do you still have the original old worn brushes that were fitted by Fiat to the starter to compare the material?
As you have said earlier, once you have cleaned it up and fitted new brushes again the starter works, so the stuff you have cleaned off must be the brush material being unsuitable for the job.
The soft carbon is blocking the grooves in the commutator, which need to be clean and not all shorted together as one lump so they can't act as individual windings to create the energy of the starter motor.
In the past when I was taught how to rebuild starters etc. I was told it was critical to clean out the individual grooves for that reason.
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the hobbler
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Et tu Brute!
Hi, these are the brushes I took out and that I had replaced some time ago. I have put new brushes in after cleaning the armature. Will be trying to get engine going later on. I can't get it started for some reason..checked timing, spark, petrol, spacing for point, spacing for tapets. The engine turns by hand normally. Might be checking compression...but would be surprised if there is any issue as the block was rebuilt recently and was running fine.
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Brushes and wires certainly look like they have got hot.
So what is the history behind the non starting, as you say, recent bottom end rebuilt and running after that OK . Though a compression check is good to eliminate as a starting point. If valve clearances are correct and compressions acceptable, then fuel, timing, spark.
Is spark a nice fat blue spark that jumps a gap of say 5mm. If it is yellow and weak, then I would look at the condition of the contact points closely and if they are what I would describe as "blue and pitted" then I would fit a condensor and new points correctly gapped as a starting point.
I have found often a side issue is when people are checking a car for what ever reason, they leave the ignition on, which with electronic ignition on modern cars is not usually a problem, however with a points setup it can cause condensor failure along with points very quickly and occasionally I have seen coils overheat to the point that oil leaks out of them.
I had replaced condensor, coil (old one was leaking as you mention), distributor points, distributor cap, leads and all was ok. I have also cleaned the weber 28 carburator checking for blockages.... I checked the sparks yesterday and they were ok. I lost my patience and just left before hitting my head on the wall
. I guess I will check again the "quality" of the spark as you suggest but I think they were ok. There is one thing that is in the back of my head and it's that I started having problems when I put new petrol in the car. I am thinking of getting some new fuel today and feeding it to the engine from the jerry can...you never know....Are the brushes free moving in their mounts and are the brush springs applying enough pressure to the brushes and hence the commutator?
Re engine firing if the engine has just undergone a major rebuild has the distributor been installed correctly. Easy to check by simply swapping over the HT leads.
Re engine firing if the engine has just undergone a major rebuild has the distributor been installed correctly. Easy to check by simply swapping over the HT leads.
Hi, I have replaced the brushes and fingers crossed the starter seams ok now, but will only be sure after I keep trying to turn car on a few times more. I think the previous brushes that had been put new must have had something wrong with them, but nothing do do with springs or free movement. I installed the distributor having cylinder 1 at TDC so that distributor shaft would have the cylinder 1 ignition lead as per the markings on the distributor cap (away from engine..towards the coil ). I know some people have the leads in the opposite way..but I guess that is because the distributor shaft was incorrectly positioned during installation. At least that is what I think....but I am no expert
. I have also just checked the coil and condensor. The coil is a Magneti Marelli BK2A and gives 4.3 Ohms and 9k Ohms on primary and secondary which I think is ok. The condensor I think is also ok although the capacitance may be higher than what I have read elsewhere as I am getting 245nF instead of about 200nF to 220nF mentioned else where. I think I have the old condensor somewhere...will make a reading to compare. Thxs for your help Good idea, trying clean fuel directly.Hi, I have replaced the brushes and fingers crossed the starter seams ok now, but will only be sure after I keep trying to turn car on a few times more. I think the previous brushes that had been put new must have had something wrong with them, but nothing do do with springs or free movement. I installed the distributor having cylinder 1 at TDC so that distributor shaft would have the cylinder 1 ignition lead as per the markings on the distributor cap (away from engine..towards the coil ). I know some people have the leads in the opposite way..but I guess that is because the distributor shaft was incorrectly positioned during installation. At least that is what I think....but I am no expert
Re condensors as long as they are working and roughly a similar size should be OK.
In the past I have gone out to a breakdown where condensor fault (usually just a very rough misfire), cleaned the points, disconnected the original condensor and moved the radio suppressor often fitted at coil and repositioned from switch side of coil to points/cb side so it acts as a condensor and the customer has been able to drive back to garage to fit correct parts. It's purpose is to prevent arcing at the points so you get a nice clean break as the points open and a good spark at plugs.
On a 4 stroke engine the piston is at TDC twice in any cycle, at ignition and again between exhaust and induction. You would have to check the valve openings to determine where you were on the cycle which is why just swapping the leads is a simple test.Hi, I have replaced the brushes and fingers crossed the starter seams ok now, but will only be sure after I keep trying to turn car on a few times more. I think the previous brushes that had been put new must have had something wrong with them, but nothing do do with springs or free movement. I installed the distributor having cylinder 1 at TDC so that distributor shaft would have the cylinder 1 ignition lead as per the markings on the distributor cap (away from engine..towards the coil ). I know some people have the leads in the opposite way..but I guess that is because the distributor shaft was incorrectly positioned during installation. At least that is what I think....but I am no expert
Quick test for TDC on firing stroke is with plugs out turn engine by hand in the correct rotation, (if not sure have someone give the starter a quick flick of the key/lever to see which way it spins the crank pulley) then turning by hand feel with finger covering plug hole the compression blowing past you finger as piston come up towards TDC , just before TDC the distributor rotor should be pointing at the lead in the cap that corresponds with that cylinder.
If timing correct the the contact points should be on the verge of opening also.
If no compression you have the wrong cylinder or a dodgy engine
Hi everyone, so I changed the brushes and the starter turns fine. After several investigations and attempts including carb rebuild and checking spacings of tappets and points I still had no luck. Out of desperation and just to tick an extra box I changed the spark plugs even though the ones that were in were fairly new. Guess what..the car started so quickly I had hardly turned the starter. I am baffled as to why the sparks taken out were not working as they should. The plugs taken out are the Bosh wr7bc and the ones put in are NGK B6HS. Thanks to everyone that shared their thoughts
Glad it is "on the button" now.Hi everyone, so I changed the brushes and the starter turns fine. After several investigations and attempts including carb rebuild and checking spacings of tappets and points I still had no luck. Out of desperation and just to tick an extra box I changed the spark plugs even though the ones that were in were fairly new. Guess what..the car started so quickly I had hardly turned the starter. I am baffled as to why the sparks taken out were not working as they should. The plugs taken out are the Bosh wr7bc and the ones put in are NGK B6HS. Thanks to everyone that shared their thoughts
I am a great fan of NGK plugs, after using many varieties before working at a Mazda dealership were it was all they used and finding them totally reliable, so since 1975 in fact .
Just a thought the Bosch with the R in the code resister? I know NGK use R to signify that and given the option I prefer non resister as they take slightly less kilovolts to fire/spark, so less likely to breakdown under load.
I found that out in testing on a Crypton Garage Oscilloscope and a plug cleaning machine showing the increase in the KV scale using brand new plugs.
