Got a old car, 1997, 5 speed, which sometimes won't start. Plenty of batt power, but turn key switch with no result. No starter noise. On, off a few times and finally starts up. Seems could be ignition switch or starter solenoid but how can i isolate which of these two is the problem.

Mira or Merc?

With the car in gear, gently push the car a little bit forward ... as in millimetres.

That will move the starter motor a little bit as the solenoid could be OK but quiet.

If the car starts then, maybe it's the brushes on the starter motor.

Just guessing though ... I'm no mechanic.

could be a bad earth strap connection. check the negative battery cable where it mounts on the body of the car to see if loose or there is corrosion. also tighten nuts on the starter motor where the cables are.

a couple of links if you want to try and check yourself.

https://mercedessource.com/problems/engine/engine-wont-crank-over-the-starter

http://www.agcoauto.com/content/news/p2_articleid/254

http://www.wikihow.com/Test-a-Starter-Solenoid

With the car in gear, gently push the car a little bit forward ... as in millimetres.

That will move the starter motor a little bit as the solenoid could be OK but quiet.

If the car starts then, maybe it's the brushes on the starter motor.

Just guessing though ... I'm no mechanic.

Sorry Dave this is a wives tale, starter isn't engaged to anything that moves without it being turned over, and then the Bendix kicks it back off the fly wheel once the engine kicks over.

Op need more info. what kind of car? Manual or auto tranny? So on, but just out of hand it sounds like Dave might be on the right track and it may have a bad starter solenoid or motor with a dead spot and when it stops on this dead spot it won't start until it can be rotated past it or by giving it some quick clicks to inch it past, or sometimes, if it's accessible from up top, or easily below, a few light taps with a hammer on the top or side of the motor will help out at times. If a new solenoid is not readily available or it ends up being the motor a new starter is the next best option IF that is the problem?

^^ Could also be a hot lead as well..

Op it is more likely to be the starter so I'd definitely begin there.

^^ Dead Spot ... that's what I was alluding to.

... and, of course, you are correct.

Nothing in the Starter motor turns unless the solenoid has fired and the gear engaged ...

ps ... no more likes left.

Likes are limited? That figures! Never knew that? I guess I don't give out so many?

BTW Op the way you can check it is to locate the wires on the back of the solenoid, they are much smaller then the starter hot lead which also in most cases runs directly to the motor from the battery. Often times they are located in one plug that plugs into the solenoid on top of the starter or 2 separate wires, use a multivolt meter or even easier, a simple 12v light tester and figure which one is hot by connecting the ground end to the ground side of the battery and testing both wires while someone turns and holds the ignition key to see which one has juice? Of course you need to check your work by testing both sides to confirm you have the hot lead, but usually the hot lead is larger and maybe red if you can see a color? Then while someone is turning and holding the key in the start position if one is hot then you have power which confirms the ignition is most likely good & the solenoid or motor is most likely bad.

BTW If the starter happens to be in the start position at that moment then test quickly as you don't want it to run for a long time as it will over heat cranking the engine so long and it would also be wise to disconnect the coil wire to prevent the engine from turning over or else it may (read will) damage the starter or the flywheel/flex plate if you keep cranking the starter while the motor is running, if you did't go deaf or have a heart attack from the noise first.

Mate ... 20 in a 24 hour period.

I'm across a lot of stuff.

Still appreciating how you helped my with my car ...

Glad I could help..

^^Geezz! Disregard most of the last part, if the starter spins you know you have power to it, just check which wire is hot at that point.

Sounds like starter solenoid or ignition (key) switch...........You can test for both but not for anyone who is a bit motor "green".

Use the Starting Handle. ....Bendix often stick,and wires get tacky on older motors.Solenoids are a cheap,quick change so that wont be wasted.

Use the Starting Handle. ....Bendix often stick,and wires get tacky on older motors.Solenoids are a cheap,quick change so that wont be wasted.

You and T/A do realize I covered this half way up the page right? Just sayin like...