JK CRD Starter Motor
Hi all,
Just replaced the starter motor on my JK CRD. After looking everywhere for a replacement (and receiving the wrong unit etc), thought I'd share the info.
Aftermarket replacements:
Bosch #0001139047 for manuals
Bosch #0001109401 for autos (also suitable for KK & KA CRD's)
Jaylec #70-6273-1 for manuals
Jaylec #70-6273-2 for autos (also suitable for KK & KA CRD's)
Repco, Veale, Covs, all have access to the above units. They can also be found on eBay and other online vendors.
Bosch's catalogue will show contradicting info to what I have posted (says the above part numbers are 2011+), but I have physically seen the units and they are only different for auto vs manual (autos have a longer snout i.e. the gear is further away from the body of the starter motor, and they have a smaller locating hole in the block). Refer 4th and 6th pic.
I have a 2009 manual and used the 0001139047.
I haven't seen the Jaylec ones in person (only pics) but speaking to the WA distributor (Cool Drive), who were very informative and helpful, we were able to confirm the above results from some measurements, but their catalogue is also contradicting as well so don't believe it.
My starting issue and diagnosis:
I've owned my JK for 3 years now. Never have I had a prob with starting it, however it always took longer than what I would consider normal comparing with other vehicles.
Over time I have been monitoring my fuel rail pressure during cranking (and driving) and noticed that just prior to realising my starter was dying that the rail pressure was only around 2,200 psi. This is pretty much the bare minimum that the injectors need before they will fire diesel into the cylinders. This is where I began to experience longer than normal cranking times. And on the odd occasion it wouldn't start for ages and take multiple turns of the key.
Side note, at this stage I did a batt test and saw that the Optima Yellow Top had lost 50% of its CCAs (original batt from 2009), so I figure this was the cause. As lower CCA's meant slower cranking from the starter motor which didn't allow the fuel rail pressure to come up high enough for the injectors to fire and therefore start the engine.
So I replace the batt, and immediately it started better. Not amazingly, just didn't have the extended cranking times like before. During cranking I couls see the fuel rail pressure increase and get to 2,200+ psi faster and therefore start the motor.
Over the Christmas and NY holidays, with some friends and family, did a camping trip into some remote areas which meant at least 50% of our driving was done on dirt roads and needed low range for some of it.
Thank God that only on the day after we got home, I started experiencing starting issues again. Now it was worse than before, very long cranking times, multiple turns of the key and some times not starting at all. Became very unreliable. Strangely it would always start fairly normally at the start of the day (filling me with false hope).
During the extended cranking, fuel rail pressure would always reach around 1,900 psi, causing me to suspect that the injectors were leaking (common prob with common rail diesels) and therefore bleeding off pressure.
During all the cranking etc I began to notice a slight change in the cranking rpm, sometimes it would be slightly faster. Everytime it was that little bit faster the rail pressure would get to 2,200 psi and the engine would start, but this was intermittent.
This had led me to suspect the starter motor which I hadn't in the past as like I said the JK had always started, and never have I ever turned the key and it not crank.
I removed the starter to examine it and give it a clean at least. As I was undoing the power cable, the initial torque I put on the ratchet broke the post out of the back of the solenoid.
It was obvious to me now that the plastic back end of the solenoid was cracked for some time and slowly over time breaking even more and the power cable post was not contacting inside properly. Amazing that it always cranked and tried to start depsite this, and amazing that it didn't completely break or disconnect driving on the corrugations etc.
So 3 days later, after much research trying to source a starter motor, speaking to heaps of different people in shops that had no idea, looking at replacing the solenoid only, and receiving a Bosch starter motor for an auto and having to return it, and then source the other Bosch starter motor which we knew now was for a manual from another supplier, finally got the correct unit and fitted last night. 3 days to do all that was not bad considering.
Now it cranks faster than I've ever heard it crank and fires into life within a second of turning the key. Has as different sound when cranking, higher pitched and much quieter too (used to sound very loud and mechanical, and could feel the JK rocking side to side). So very happy with outcome and even happier that the prob wasn't anything more sinister.
Also I cannot check the fuel rail pressure on cranking now as the engine starts before my Torque app can read it (has approx 1 sec lag). But it is safe to say that with the new starter motor the fuel system is able to build sufficient fuel pressure much faster to fire the injectors (and therefore start the engine).
Hopefully my troubleshooting and research can help someone else.
Last edited by Turismo07; 18-01-2019 at 10:31 AM.
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