Dodgy starter?

[Simon Daymond]

when I try to start the militant, first attempt the starter always sounds as though the batteries are flat, but on the second attempt it fires straight up as normal.

 

I've checked the leads to the starter, all are clean and tight, the batteries are fully charged, so I'm wondering if the starter itself is suspect, i.e. is something requiring a good clean, or is it about to let me down with a more serious internal fault?

Any ideas, it's a bit big to push if the starter packs up completely

[philb]

From my limited experience, it's nothing to worry about. My Matador does the same thing and I think it is just that the sliding armature of the CAV axial starter does not always make full travel - to then apply power to the commutator. A while ago I had the starter off and took it apart to see if anything was obviously wrong and it all looked perfect inside. I just applied a little oil to the sliding shaft bushes and re-assembled it. It's behaviour has not changed and it has never failed to start the engine (now expect to see a post in the near future to say my engine won't start! As well as overhearing conversations, can old machinery intercept e-mail?).

 

I'll be interested to see if anyone more knowledgeable can shed light on the subject.

[Stormin]

My first thought would be a dodgy earth lead. First flick of the switch causes no action from starter due to high resistance. Second flick overcomes resistance due to heat build up at point of highest resistance improving the connection.

 

I would take all leads off, not just check they are tight, clean up the contact areas, smear with copper grease or vaseline and re-connect.

 

You know the vehicle will ultimately let you down at the most inopportune moment.

 

On my Ward La France the earth lead runs directly from the battery to one of the starter mounting bolts. Non of this earthing through the chassis or body first then a separate lead to somewhere on the engine. In my opinion the less convoluted the path and least connections for the electrons to get round the better.

 

Don't overlook the possibility that the leads themselves may have broken down internally due to age and corrosion. Test the resistance from one end to the other with a multimeter.

Edited August 23, 2010 by Stormin

[marmon]

You need to do a voltage drop test, dead simple, connect voltmeter from

postitve

 

battery terminal to positive starter terminal and crank engine it should read 1/2 a volt or less do the same with negative terminal to starter housing or block and crank should see again less than 1/2 a volt if either lead is bad it will read a volt or two.

 

All you are doing is reading the voltage difference between each end of wire, if all is

OK

 

see what voltage the

battery's

 

read when cranking, you might have a bad cell.

[Simon Daymond]

thanks chaps, I'm going to take it all off for a good look, we go to Durham this weekend, you know it's going to let me down if I do nothing, and it'll probably be raining as well I will let you know what I find.

[N.O.S.]

I have one 24v wheel loader showing same symptoms - if you turn and hold starter switch the starter throws bendix in and tries to turn engine, but stalls on first compression (big V8). After about 2 seconds the starter suddenly spins engine at full speed and we're off.

 

Something must be causing resistance, but once it gets warm (2 secs) current flows ok. I've checked main power contacts on built-in starter solenoid which get pitted with arcing, when I clean them up / replace with new all is ok for a while until problem returns. So I suspect dirty contacts is just another symptom, not the prime cause. I suspect some other poor connection is causing the contacts to arc.

 

Perhaps you can solve the mystery before another one of my starters blows up (had an identical starter on another machine literally blow up last year - blimey, thought a cylinder head had come off! (hadn't been any problem until it 'exploded' and blew brush gear and end cover off) :wow:

[marmon]

Visual inspections are OK but you can have perfectly sound looking cables and cleaned up and nicely greased terminals and you hit the starter voltage drops and amps go through the roof burning contacts melting starters etc,.

 

I highly recomend you diagnose the problem with a simple Volt meter, a voltage drop test, cranking amp test, and battery load/volt test, before you pull things apart. I have seen many vehicles with new battery's, starters, solonoids, grounds polished and greased to perfection, owners pulling their hair out even an engine pulled and stripped and still having problems due to a old length of cable or bad engine to body connection.

 

It takes less than 5 minutes to do all the above tests can you pull a starter and strip it in that time? even if you test it on the bench it can still give good test readings unless you have a starter load test bench.

 

From the discription If I was a betting man I'd put £1p on it being a bad cable (voltage drop test)

50p on Battery's (battery load test) and 25p on starter (cranking amp test).

 

I hope this is of help.

[Stormin]

Visual inspections are OK but you can have perfectly sound looking cables and cleaned up and nicely greased terminals and you hit the starter voltage drops and amps go through the roof burning contacts melting starters etc,.

 

I highly recomend you diagnose the problem with a simple Volt meter, a voltage drop test, cranking amp test, and battery load/volt test, before you pull things apart. I have seen many vehicles with new battery's, starters, solonoids, grounds polished and greased to perfection, owners pulling their hair out even an engine pulled and stripped and still having problems due to a old length of cable or bad engine to body connection.

 

It takes less than 5 minutes to do all the above tests can you pull a starter and strip it in that time? even if you test it on the bench it can still give good test readings unless you have a starter load test bench.

 

From the discription If I was a betting man I'd put £1p on it being a bad cable (voltage drop test)

50p on Battery's (battery load test) and 25p on starter (cranking amp test).

 

I hope this is of help.

 

Won't the cranking amp test involve installing a very heavy duty amp meter in line or is there a simpler method?

 

Also when conducting the voltage drop test during cranking, isn't there a danger of burning out the multimeter, if the leads to the starter are bad and more current takes the path along the meter leads?

[marmon]

Fluke make good multi meters that include a clip on amp shunt built into the top just simply clip it over the wire and take a reading, most good meters have an accessory that does the same job and just plugs into the lead sockets.

 

No you will just get a battery voltage reading if the lead is open circuit, no possible way of harming the meter on volt setting.

 

The good thing is if you hold the point to the post and the other end to the post on the starter you are instantly checking everything from battery to starter and if say it reads 4v when cranking just move one point at a time towards the battery, for example starter wire terminal,

solenoid terminal, solenoid post out, solenoid post in, solenoid wire terminal in etc, obviously when both leads are on your battery post there can be no difference but you will have a map of how much you are dropping and where.

[marmon]

I have one 24v wheel loader showing same symptoms - if you turn and hold starter switch the starter throws bendix in and tries to turn engine, but stalls on first compression (big V8). After about 2 seconds the starter suddenly spins engine at full speed and we're off.

 

Something must be causing resistance, but once it gets warm (2 secs) current flows ok. I've checked main power contacts on built-in starter solenoid which get pitted with arcing, when I clean them up / replace with new all is ok for a while until problem returns. So I suspect dirty contacts is just another symptom, not the prime cause. I suspect some other poor connection is causing the contacts to arc.

 

Perhaps you can solve the mystery before another one of my starters blows up (had an identical starter on another machine literally blow up last year - blimey, thought a cylinder head had come off! (hadn't been any problem until it 'exploded' and blew brush gear and end cover off) :wow:

 

Another possibility for your problem could be Hydra lock from a weeping head gasket or if petrol I've come across American big block v8's with timing issues back firing against the starter, even snapping them.

[N.O.S.]

Thanks, yes it could be a leaking injector (common rail system on Cummins V555). Hadn't thought of that. The engine does stand for long periods too. Must put it on the ever-growing list of things to do........