Hi all, i've spent the last hour going through posts. My xj6 vdp 1986 has eaten up at least four starters in the last year, both bosch and lucas, my mechanic is at a loss for what may be the culprit(s) aside from terrible luck with the part. And the latest one installed had more torque, and it fried after three months...

I would really appreciate a "list" of what to check that a jag mechanic with deep knowledge of the idiosyncracies of the persnickity ie pain in the **** Jags have.

The only "unique" issue with my jag is low compression in two cylinders ( approx 20%) discovered a few months ago by same mechanic via leak down test.

If you guys have any questions for me, i'll reply promptly tonight and over the weekend.

Thanks Much
Will

 

I am assuming your 1986 is a Series 3 with the XK 4.2ltr engine, and NOT the very first of the XJ40 style with the AJ6 engine?.

If the XK, then my experience with starter motor issues on these engines is limited, as I have simply had very little issues with them.

The AJ6 starter motors, weeeeell, PITA on a good day. These are NOT discussed here.

1) The common issue with the XK starter is the omission of the spacer at the mounting flange. It can fall out, although not easily, it can happen. Then the starter will mesh too deep and grind up the Bendix drive very quickly. A significant grinding noise is apparent when the starter is operated, and any "normal" person would immediately know something is very wrong, and have it sorted quite quickly. The attached snap shows that spacer as item #8.



2) The other issue I have had, is improper adjustment of the "throw depth" of the Bendix, which will cause it to bind when engaged. Simply resetting that "throw" fixes that quickly.

3) Excessive use of the starter motor for starting the engine. I KNOW, sounds dumb, BUT, the starter motor (any starter motor) is designed for "short bursts" of operation, of about 5 seconds MAX at a time. It overheats very quickly and will melt the insulation eventually if used longer on a constant basis. Some S3 engines do crank a little long to fire, and this should be rectified as a priority.

4) Badly rebuilt units. That can happen anywhere.

Maybe see if a good known working second hand unit can be found. It would be worth a try in my opinion to eliminate bad rebuilds at least.

The words "chewing up starters" is also a tad vague to me. Do you mean chewing up mechanically or electrically??.

 

GRANT, It's a six cylinder, with a vin of SAJAY1341GC461591

My eating up phrase meant to the best of my knowledge Electrical, as they all seem to seize up, my jag is still at the garage awaiting warranty replacement from the "big jag parts company in Maine" forgot the name, garage bench tested starter and it won't spin, i doubt they opened it up to look for possible clues to why...

definitely no over use of turning key, but my suspicion is wiring, to much amp draw leaving one yr old battery weak, perhaps the main wire to the starter with the manufacturers splice needs a test/replacement..

thanks for your reply and follow up!
Will

 

My first thought was a wiring problem since you've gone through so many starters, like a bad ground causing it to short out, but if that was the case the starter should still spin freely once removed. Sounds to me like you are having mechanical failure, not electrical failure.

 

OK, that Vin means nothing to me as I no longer work for Jaguar to be able to decode it out.

The 4.2ltr (Series 3) has the exhaust manifold on the LH side, and the AJ6 (XJ40) has it on the RH side.

The following is for the XK 4.2Ltr engine, NOT the AJ6 engine.

I dont believe the wiring has much to do with it. If the wiring was suspect the starter would not get the correct current (juice), and that would not chew it up in my opinion. Mostly a slow/sluggish starter would be the result. Same would apply for a bad earth.

Flat/low battery volts usually results in severe solenoid chatter, which still does not explain the inability of the unit to rotate out of the car, indicating a seized bush at one or both ends of the armature, incorrect assembly, lack of lube, or many other reasons.

Poorly manufactured brushes will also seize TO the armature and that will cause all sorts of grief.

The wrong Bendix drive will cause the starter to BIND severely with the flywheel ring gear, and that is a savage chew up eventually.

The fact these chewed up units do not rotate out of the car needs some serious investigating, which will give the reason if done properly.