Thread: Hard to start

I have reported this before, but quite a while ago. Not quite the same problem, but similar symptoms - poor starting that turned out to be due to slow turning by the starter.

After replacing three sets of burnt contacts in the starter, the problem was fixed by dealing with the real root cause - poor engine to chassis earth. This was the result of oil on the earth strap across the LH front engine mount. I ran a new earth lead from the battery onto the gearbox and put a new earth strap from there to the chassis. No more starting problems.

John

Glad you found that eventually J.

As JDNSW has mentioned, bad earths will ruin starters very easily. Arcing in the solenoid contacts result which burn them very quickly. This goes for Tdi's too, as poor earthing on Discos and defenders is quite common I may just post a quickie in Tech....


JC

Originally Posted by justinc

Glad you found that eventually J.

As JDNSW has mentioned, bad earths will ruin starters very easily. Arcing in the solenoid contacts result which burn them very quickly. This goes for Tdi's too, as poor earthing on Discos and defenders is quite common I may just post a quickie in Tech....


JC

yep starting to sort out all these problems before the RFC next year. Even gone back to sealed beam H/lights as well. Now the funs begun

Justin

Mine gets slower and slower to crank with brush material building up inside the starter and causing internal leakage. I've pulled and cleaned it twice in the last 3 years which puts it back to good. No parts needed.

Last time it was cranking slowly I put my clamp-meter around the battery earth strap. It was pulling 511amps on 24v.
So I guess my earths are okay.

Originally Posted by Dougal

Mine gets slower and slower to crank with brush material building up inside the starter and causing internal leakage. I've pulled and cleaned it twice in the last 3 years which puts it back to good. No parts needed.

Last time it was cranking slowly I put my clamp-meter around the battery earth strap. It was pulling 511amps on 24v.
So I guess my earths are okay.

Not necessarily - in fact that current looks too high for 24v to me. The lower the voltage at the starter, the higher the current (hence the more voltage drop, the higher the current, hence more......)

The measurement to look at is the voltage between the battery negative and the frame of the starter - should be well under one volt, although if the engine and starter are in good shape it will start do quickly that it is a bit hard to measure without disabling the engine, for example by disconnecting the fuel shut-off.

Although I have a 12v system not 24v (so not the same starter), I have never had a problem with brush material build-up.

John

Originally Posted by JDNSW

Not necessarily - in fact that current looks too high for 24v to me. The lower the voltage at the starter, the higher the current (hence the more voltage drop, the higher the current, hence more......)

Of course that measurement was too high. The starter was internally shorting.
My healthy starting current is around 350amps. Due to chassis rail clearance I am using a direct drive starter which draws a lot more current than the geared items usually fitted to these engines.

If there was an connection problem, that joint would have burnt long ago. 1 volt at 500 amps is 500 watts of heat. That concentrated at a poor join kills it quickly. I know because I used to have a dodgy battery clamp.

Originally Posted by Dougal

Of course that measurement was too high. The starter was internally shorting.
My healthy starting current is around 350amps. Due to chassis rail clearance I am using a direct drive starter which draws a lot more current than the geared items usually fitted to these engines.

If there was an connection problem, that joint would have burnt long ago. 1 volt at 500 amps is 500 watts of heat. That concentrated at a poor join kills it quickly. I know because I used to have a dodgy battery clamp.

Thanks for the clarification - I thought you were quoting the current as indicating it was healthy. And note that i said "well under one volt". At starting current there will be a significant drop just along the lead, especially if using the factory lead, but the total drop should be well under one. As you say, one volt at one location will get hot enough to melt things pretty quickly.

But my poor earth contact showed no signs of local heating for a year of use while still being enough drop to cause all sorts of starting problems.

Nothing to do with this sort of problem, but I have also had starter problems where the spring that keeps the gear out of mesh broke, allowing the gear to hit the ring gear. That one you can't blame anyone except the starter manufacturer. All in all, I am not convinced that Nippon-Denso is any more reliable than Lucas!

John