2008 xc90 V8 - slow start

ken_f · Post by **ken_f** » 28 Feb 2014, 02:54

Hi all, My 2008 v8 xc90 is having some starting issues, and I can't quite figure it out.
Turning the ignition to start the car produces very similar symptoms to a flat battery, with out the pro longed clicking a flat battery normal gives you. Some times its reliably slow to start, other times it start fairly well. Temperature nor cold start vs warm start seem to make a difference.
It has a new 750CCA battery, fully charged and working well, infact after completing a quick charge with a 5 stage(quality) charger, it shows the hard to start symptoms right away.
There's no voltage drop between the battery and starter motor positive terminals.
I've checked and loosened/retightened the positive leads at the starter motor.
I've run a load test on the alternator with VIDA and all reading are in the middle of the acceptable parameter range (figured maybe it was a charging issue)
I've checked the MAF sensor, and throttle body, air filter and electrical connections to them.
So far all I can suspect is that the starter motor is beginning to fail. There's no grinding noises, or anything abnormal coming from the starter either, its just hard to start.
Heres a link to an audio recordingof the issue, you can clearly hear whats happening.
Any ideas? I'm all out except for splashing out on a new starter motor!
Thanks,

Ken.

Post by **precopster** » 28 Feb 2014, 04:21

Nice recording. I wish more users here would employ sound files if they can't upload a video.

Looks like you've eliminated all the potential gremlins APART from the starter motor.

I had the same thing happen to a Subaru I once owned. There are two large copper plates inside the starter solenoid which contact when voltage is applied to the solenoid. These wear thin and almost don't contact causing arcing which in turn causes pitting of the copper. This decreases the surface area of the plates and the resultant slow starting is what you experience.

Part number you require is 36000040

ken_f · Post by **ken_f** » 09 Mar 2014, 15:11

Thanks for the reply, new one ordered and on its way. Will pull the old one appart and see if I can see those symptoms. Might turn out its something user repairable.

ken_f · Post by **ken_f** » 16 Mar 2014, 02:59

Confirmed, it was the starter motor. New part arrived, about 4 hours to swap over, and the difference is like night and day. The old one looked like it was in good condition, didn't notice anything visibly wrong from the outside either.
It was a bit easier to turn the gear on the old one by hand, but not an alarming difference as compared to the old one. Will open it up tomorrow and see if there's something obvious, that might save someone some cash in the future.
Will record some audio of what it should sound like too. Again could be useful in the future.
FYI, the swap out necessitates the removal of (in no particular order):
1. Motor hoist point (lifting eye), right hand side.
2. The aluminium mount the hoist point connects to (housing, contains a water in/outlet of some kind)
3. The upper torque mount and engine mount.
4. The odd piece of coolant pipe.
5. the throttle body and piece of pipe connecting to the air filter box.
Also plan on replacing your coolant, at least half of it will drain out when disconnecting things.

Post by **precopster** » 16 Mar 2014, 05:51

Thanks for completing the thread

ken_f · Post by **ken_f** » 19 Mar 2014, 03:04

So, after a quick tear down of the old starter motor, here's how it appears to have failed:
The starter is made up of a couple of components:
1. The solenoid/actuator that engages the gear, its the small cylindrical attachment on the outside of the motor.
2. Gearing; planetary, a shaft or two and some general cogs to reduce the output speed of the electric motor.
3. The electric motor itself. It takes up most of the room in the large part of the starter motor.
After opening up the old one it gradually became clear what has happened.
1. The old motor was coated with fine particles (dust from the brushes on the electric motor)
2. This dust coated the bottom part of the electric motor, covering the rotor shaft and the inside of the coil the shaft sits in. This dust had also then made it way into the rather cheap sleeve bearings that normally hold the rotor shaft in the center of the coil.
4. So after the sleeve bearings became contaminated, it became just a matter of time. The bearings became loose, the rotor started scraping against the coil housing, and slowly the electric motor became less efficient.
So some simple sleeve bearings was the culprit. Happened at both ends of the shaft too.
Now to find some replacement bearings and some time and it looks like I'll have a starter motor ready for when the new one fails in 90,000 Ks time.
Bearings appear to be pressed in bronze, 8mm internal diameter, 11mm outer diameter.
Hopefully this helps someone in the future, could be a really cheap fix for a motor rebuilder!

VFLXC90 · Post by **VFLXC90** » 26 Mar 2014, 04:34

Thanks for the write up. I will keep this one on file.

ken_f · Post by **ken_f** » 29 Mar 2014, 01:50

Having some fun with this. Looked at replacement sleeve bearings. I don't like sleeve bearings, cheap for a reason, and if there's a needle bearing option available, its the one for me. Turns out there is. The measurements for the bearing are 8mm ID, 11mm OD and 10mm long. One end also needs a small washer to keep the rotor from rubbing against the bearing.
Purchase the following from amazon
needle bearing .
Will be interesting to see if it works. The bearing is rated for 120 degrees celsius, 32000 rpm, and for harsh environments like small engines, transmission etc, so it should stand up to a starter motor environment with any luck.

Post by **xc90v82007** » 02 Nov 2014, 04:55

Could you give me detail replacement of starter motor, mine has same issue and I'm thinking I need to replace the starter motor! Just order the starter motor at my dealer.

Thanks.

VFLXC90 · Post by **VFLXC90** » 25 Nov 2014, 14:56

ken f,
Were did you purchase the starter from and the cost please.
Thanks
vfl