Vehicle & Technical > Military

3.5v8 starter question

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thermidorthelobster:
Having burnt out the starter solenoid on my 3.5v8 I bought another starter from Brookwells (not much more expensive to get the whole thing than just the solenoid).  Somebody warned me that the alignment / teeth would be different on the SD1 engine I have, from the standard Range Rover / 101 V8, but it looked OK and fits fine.

However, when starting the engine, particularly when cold, the starter usually spins without engaging the pinion for a few times.  After a few goes it engages and everything starts OK.

If it spins freely and I try to turn it over again on the key before it's stopped, I get a grinding noise like it's attempting to engage.

I always thought that these starters worked by the rotation of the shaft pushing the pinion to engage with the engine, but the guy at Brookwells said that the pinion itself is actually engaged by the solenoid - ???  Which is correct?  If he's right then maybe there's enough juice at the solenoid to engage the motor contacts but not the pinion.  But I didn't think the motors worked in this way.

Cheers,
David

thermidorthelobster:
Duh...  just remembered I still have the old starter, so took a look.

The solenoid does indeed cause the pinion to engage, but then, so does turning the shaft.  So maybe we were both right, assuming they both work the same way.

So it looks like lowish voltage to the solenoid could potentially cause the motor to turn but not be enough to engage the pinion.  Sound feasible?

MuddyMike:
1.It should be a "pre engage" starter.

2. Check the engine earth, strap poor connections here can cause the starter to be slow to engage. A simple test is to use a decent jump lead from neg terminal of battery direct to a nice clean unpainted bit of engine to back up the earth strap. If this improves starting you have found the problem.

Mike

Range Rover Blues:
OK if it's a pre-engager then it works like this

The solenoid is made 'live' by a starter relay (on my car at least) and the solenoid earths through the starter motor, so as the gear throws in the motor is turning but slowly and with little power.  This only ensures is engages fully.
As the solenoid hits full throw it then connects the starter to full battery power and starting occurs.  This has affectively shorted out the solenoid so the drive of the motor is all that's holding it in mesh until you release the key.
As the engine fire and over-runs the starter it should throw the starter gear clear of the ring gear, even if it is still running.

thermidorthelobster:
Thanks for the info.  This seems to make sense.

So can you see how the motor would be getting full power without the solenoid engaging the pinion?  Could it be that the starter motor is wrong for the engine?  I was warned about this but assumed it'd either work or not work, not fall somewhere in between.

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