2004 Nissan Micra Not Starting Warm

Warning

!!! Always disconnect the car battery when performing tasks under the bonnet which involve removing parts and using spanners. Especially in this case there can be live cables which would cause powerful sparks and possibly electric shock if the spanner touches engine while you're undoing the cables. !!! If you're not a confident DIY mechanic please take your car to a proper mechanic.

TLDR:

2004 Nissan Micra won't start when warm, doesn't turn over the engine at all. Starts fine with jump start and starts fine with bump start. Replaced starter motor addressed the issue.
Changing the starter motor not as tricky as some descriptions suggest.

History

Looking back at this now I think this has been a problem since I first got this car but I'd not tied it down and had partly addressed it by other means.

Not long after I first got the 2004 Nissan Micra 1.4 I had trouble starting it after a visit to a hospital. With the car being relatively new to me and still having the factory supplied battery I jumped to the conclusion that the battery was at fault and replaced it. Indeed replacing the battery appeared to address the issue. The non-start was a one off thing and I replaced the battery the next day, a reasonably simple task.

Just recently, again the car has had trouble starting. I hadn't pinpointed the exact problem because first thing in the morning and in the evening when coming home from work, the car would start without problem. It hadn't twigged to me that on the increasing number of times that the car had failed to start the engine had not long been turned off after a drive.

Vid01 shows the problem, the various beeps and pings are from the dash cam. The engine isn't turning over at all. It got to the point where even when cold the starting would be hesitant.

I took the car in for it's annual service and frustratingly the car didn't show the starting problem. After that point the issue became more and more frequent.

Most of the suggestions on the Internet were around a faulty heat sensor, suggesting putting a resistor across the sensor or unplugging the sensor to get to the vehicle to start. However, the symptoms reported by other owners suggested that the engine would turn over but not fire, this didn't match the symptoms I was seeing.

With a reasonably new battery I decided the next thing to try, before getting an expensive diagnostic, would be to replace the starter motor.

Changing The Starter Motor

Much of my Internet searching referred to different vehicles, it seems that there are different vehicles branded as "Micra" in different countries and I couldn't find anything specific to the car I have. I bought the online version of the Haynes manual for the car and it suggested that the replacement was a reasonable job to do for a confident DIY mechanic.

The manual suggested that there were two ways to remove the starter motor, either by jacking the car up and accessing from underneath  or by removing the wiper motor and "support panel" to allow access from above.

Initially I tried removing the wiper motor but failed at step one trying to get the wiper arms off.

Looking at jacking the car up and accessing from underneath I couldn't really see a clear access even if jacked up. The starter motor is at the top of the block at the back of the engine, access from the top is more logical.

First things first, when you're going to be reaching around in the dark for the solenoid ensure you've disconnected the battery (see warning above). The starter motor has a cable direct from the battery and if you were to try undoing that lead and were to short it to the engine this could cause dangerous, high power sparks and possibly electric shock.

I reached in behind the engine and used my mobile phone to take some pictures of the starter so I would get a better idea as to how to reach it.

On looking at the pictures I could see corrosion on the cable from the starter solenoid to the starter motor, this gave me a little more confidence that it was the starter motor that was wrong.

The pictures also gave me more confidence that there was space to get my hands and tools in from around the side/top of the engine without the need to remove the wiper assembly.

With the battery disconnected I used a 13mm socket to remove the main feed cable from the solenoid.

Pic 01 shows the solenoid after the main feed cable was removed.

After removing the feed cable I then used a 10mm socket to remove the switched feed, the smaller cable at the bottom.

With these two cables now out of the way I was able to get a 14mm socket with a half bar extension in to remove one of the two bolts. While the ratchet was able to fit without the half bar extension there was no room to move the handle.

The bolt is quite close to the solenoid (just visible in the picture above, below the switched feed). I did initially make the mistake of removing another bolt from the clutch housing, when it was clear that the starter motor wasn't coming off I realised my mistake.

The lower bolt can be fully removed.

The upper bolt is visible behind the battery and threads in to the starter motor from the opposite direction. I was able to reach in and support the starter motor with one hand while undoing the top bolt with the other.

Once the top bolt was out the starter motor could be lowered onto part of the engine allowing you to then withdraw the ratchet, bolt and your hands, then you can approach the starter motor from a more convenient angle to remove it from the engine compartment.

There was a lot of working by feel for this removal but with care and patience it's certainly a job I was comfortable doing.

Fitting the new starter, as Haynes is so fond of saying, is "reversal of removing". However there's a couple of points that I feel are missing from this vague instruction.

It's definitely easier to remove the bottom then bolt, then the top and when fitting the new motor it's certainly easier to fit the top, then the bottom. As always when tightening bolts it's best to do a little on each rather than tightening the top all the way only to then find the bottom isn't aligned.

Pic 02 shows the new starter motor fitted with the switched feed connected.

There's a potential for the switched feed and the main feed to be touching when they are fitted. If these were to short out then the car would try to start the moment you reconnect the battery. Make sure that the smaller, switched feed cable at the bottom of the solenoid points directly down. As you tighten the nut there is a tendency for the cable to move. As I have done above, I'd suggest taking a photograph with your mobile phone after you've affixed the cable to ensure it's correct.

I then attached the main feed and took further pictures to ensure there was no shorting then slipped the rubber cover back over the main feed.

A further step in being cautious I removed all tools from the engine bay in the expectation that the car would try to start, or the at least give a large spark, when I reconnected the battery.

Now fully prepared, I reconnected the battery and nothing happened. It's always good when you plan for the worst but actually things go well.

After tightening the battery terminal I tested the start and it fired straight away. Leaving the car running for five minutes I stopped the engine and tried starting again. Again the car started without fault.

Vid02 the car now starts consistently.