Hi
I would say you have two issue here, one been the starter motor and one been a possible sensor
but from what you have said, I would start with swapping the starter motor first, if your handy with cars then the starters are usually quite easy to strip and rebuild, usually they just dry up and go quite stiff, stripping them, cleaning and relubeing them usually fixes them. but may be just easier to swap if you have not go access to the right kit
but would get it cranking reliably first, then look for the lumpy running after.
Maybe worth checking the ecu connector and main harness connectors, as a bad or corroded connector could be related to both problems
cheers
Joe

 

Still waiting for my starter motor to arrive................................

 

New starter motor has arrived, hopefully going to fit it on Saturday

 

Planned to fit it today.

Got the car up on the ramp and removed the undertray, according to 'Topix' the starter motor on the V8 is only held on by two 'bolts' (they actually appear to be nuts ?)

The V6 and diesel models are different.

Bottom nut is clearly visible, it has a second nut attached that secures the earth lead.

The top nut cannot be seen using any method that I have at my disposal.

I can reach in and feel it, it's a 13 mm, but trying to get anything on it to loosen it is proving to be very awkward.

Managed to get an 'S' shaped spanner onto it and managed to move it by a fraction but can't seem to get any of my 13 mm ratchet spanners onto it.

Has anyone tackled this job who can provide any hints or tips ?

Starter motor

 

Please see the video in post #10 above. The guy had quite the battle getting that upper fastener removed. He posted some specific details showing what finally worked.

He also said the fasteners were an oddball design that looked like a stud and nut. Instead, it was a one-piece style like this:


​​​​​​

 

If nothing works and your battling space to work. On the STR I found removing the two nuts on the motor mounts. Then using a bit of plywood to protect the oil pan I was able to jack up the engine a significant amount. I have not changed a starter on that car but using this technique I did swap the AC compressor and PS pump.
.
.
.

 

Good idea club. Also be aware of air intake tube at the throttle body in relation to the windshield cowl support when jacking the engine up. It is an issue on my 06 str. Not sure about your year but good to take a quick look

 

Karl, thank you so much for taking the time to help me with this.

I thought that the video was one that I had already viewed, this wasn't the case !

It has given me the information that I need to have another go at removing the starter.

Interesting type of fastener, I have no idea what the technical description is but it looks like a stud with a nut welded on (I don't think that description will catch on in engineering circles !)

Looks like all of the various 13 mm spanners I have been ordering will be redundant

 

If I try the option of jacking up the motor, I will have to remember to open the bonnet !

My car has the Range Rover Sport intake with the 'fins' ground off to allow it to fit under the strut brace near the scuttle.

The strut brace had to be removed and 'persuaded' to create a little bit of extra clearance as well

 

i have the same and removal is necesarry for any meaningful engine lift

 

shock tower brace doesn't need to be removed to be at motor mount removal height

 

I also left the cowling in place but removing that would give even more room. Yes when jacking the engine up take care and I found some rocking of the engine side to side helps you to tell if anything is in a bind and might get damaged. Sometimes just a small bit of space can make all the difference in the world. But I was surprised how far I could lift the engine.

I also rock the engine a bit on the way back down to help align the engine mount studs so they go in the holes.
.
.
.

 

If raising the engine for clearance, here's something I learned the hard way on a different vehicle. Put the chassis up on jack stands first to unload the suspension. Otherwise, when you raise the engine, the chassis moves with it for the first couple of inches before they separate. It's a lot easier to see what is happening if the chassis stays put.

 

Boy Karl I learned that lesson the hard way! You are so right! (As usual I know!).
I started jacking the engine up and ran out of jack height before the engine moved very much.
.
.
.

 

Finally managed to get time to fit the new starter today.

No idea why I bothered, as ironically the car has started first time, every time for the last 2 weeks !

I can honestly say that extricating the top 'hidden' bolt is one of the most stressful car maintenance jobs that I have ever undertaken.

It is a 13 mm headed bolt, not a 'stud / nut' like the lower one.

Access is absolutely awful, you cannot even see it to get a spanner / socket on it.

I managed to get about another half turn using an 's' shaped obstruction spanner and then after dozens of attempts, got a 13 mm 1/4 drive socket on it by attaching it to a 150 mm extension and a universal joint to clear the engine mounting.

You have to basically feed the extension in down the side of the starter motor and then try to guide the socket onto the bolt head.

I was then lucky enough to be able to undo it with another long 1/4 extension connected to the universal joint.

So far, so good..................................

Then actually getting the starter motor out of the gap is another excercise in frustration.

You have to twist and turn it at every angle imaginable to avoid damaging the oxygen sensor wires on the catalytic converter.

Of course everything has sharp edges, wearing nitrile gloves is a waste of time, as they either split almost instantly or get cut to ribbons.

My hands look like I have been attacked by angry cats.

Once removed, you have to repeat the same process to get the new one back in place.

The bottom stud is easy to get back in but the top bolt was hell on earth.

Once again working blind and mostly by 'feel', it must have taken 30 attempts to get the bolt and the extension assembly into place, as there is no room to 'start' the bolt into the hole by hand.

Using the same combination of extensions and the flexible joint allowed me to tighten it up for several turns, but it then became almost impossible.

The bolt is approximately 50 mm long, so needs a lot of turns to get it tight enough to do the job.

At this stage I was worried that I had managed to cross thread it, so had to call on the assistance of one of our technicians, who was doubt muttering 'bloody amateurs' under his breath.

He kindly had a look and had to undo the bolt to be able to check for any damage to the threads.

Again, by a stroke of luck, the threads weren't damaged.

He then had as much trouble as me trying to get the bolt / extension assembly back into place, when he did, the same problem occurred, seemed to be tightening up well, and then became very hard to turn.

Only thing we could think was that the universal joint was now binding against the starter body as the bolt tightened.

This resulted in him raiding everyones toolbox to try to find a different universal joint or alternative extension / socket combination.

A different joint and a longer handled 1/4 ratchet allowed him to finally tighten the bolt, with much colourful language when he had to hold everything in place whilst one of the other technicians had to find an alternative ratchet to the first one he tried.

I then finished up connecting the cables and made sure it would still start before refitting the undertray.

Still starting first time, so no idea whether the new started has fixed anything or whether the fault has just 'gone to ground' for a while ?

A couple of things have subsequently occurred to me:

If doing it again (please, no !), I might be tempted to try a flexible extension drive, usually used for power screwdrivers.

I have one the seems quite sturdy and allegedly rated for use with an impact driver.

If I put a 13 mm 'nut driver' on the extension and then push it down the starter motor body, I wouldn't need a universal joint, as the extension itself will bend to clear the engine mount.

By using the 13 mm 'S' spanner to get a couple of turns on the bolt to initially loosen it, the flexible extension won't be under as much strain when undoing it the rest of the way.

The second thing that has been on my mind is the following:

On my first attempt at the starter, I gave up and got on with replacing the headlamp washer pump instead.

When I removed the wheel arch liner, one of the wires had come out of the plug going to the headlamp washer motor and was just 'floating' with a metal spade connector.

The wires themselves also looked as though they had been trapped or damaged at some point, with some technical assistance, the spade connector was refitted to the plastic housing and the wires covered with insulating tape.

I don't see how this could have any bearing on the intermittent 'non start' problem, but from that day, it has always started first time ?