1998 XK8 starter has loud clunk, but doesn't turn
 

Several days ago I tried to start my 1998 XK8 and got one loud clunk, nothing else. I tried the second time and it turned the engine over strongly and started right up. I turned it back off to try again and got a loud clunk, nothing else. I tried again and it started right up. I repeated this several times watching the voltmeter, lights, etc. When I got the loud clunk the volt meter showed about 13V and none of the lights dimmed. I went ahead and drove the car for a couple of days with a time or two of clunks only, but then it would start on the next attempt. Yesterday it just had the loud single clunk again, but would not start on repeated attempts. It has only started once since then and doesn't leave the garage now. I put a voltmeter on the starter power lead and had my wife try to start the car (another story for another time). The main power cable had 12.5 V but no starter rotation. The small terminal which I assume is for the solenoid had 10.5V when she tried to start the car. There is a very strong clunk (my descriptive word) when the key is turned and you can feel the hammer of what I assume is the solenoid activating. I jumpered the two terminals and got the same result as turning the key to start. Can this be anything but a defective starter? From what I can tell there are two bolts holding the starter in place. One easy to get to and one on top. The top one, other than being something of a pain, should be removable even though I can only feel it, not see it. Are there any gotchas to watch out for?

1) be VERY careful jumping voltage to the starter. It bypasses several safety features. If she's in drive or reverse, the engine will start and car will take off (dont ask me how I know scariest thing I ever saw).

2) it sounds like you shorted across the starter relay, correct me if I'm wrong. Only problem with that is you are not eliminating the cable bringing the current. Any way you could safely introduce battery to the starter motor terminal with a jumper cable? Brainstorming here, but it would eliminate a bad starter cable connection as the problem. IMO not worth any significant effort.

3) starter grounds through its mounting, not a ground issue unless engine block ground cable bad.

question: if he had a chipped tooth on flywheel, coincidence = starter landed on it, would that "jamb up" the motor? It'd just spin freely right?

a misaligned starter will do what is described, but how could that happen? (Voltage drop while clunk no turn made me think of this)

I'm betting on a bad starter, but let's see what experts say.

John

The car is on jack stands all around so all 4 wheels are off the ground; it shouldn't move if the wheels turn for some reason. I shorted the power terminal on the starter which always has voltage to the small adjacent terminal that usually only has voltage when the key is turned. If the power cable was bad I think I would see a big voltage drop at the power terminal on the starter when the key is turned to start. If the wire or ring terminal was bad on the small connection it should have worked by jumpering directly to the small stud from the power terminal. I'm just a little leery of messing with 20 year old parts and wiring by trying to remove the starter if I'm off track with this. The rubber boot on the small terminal was rock hard and broke off already when I tried to remove it from the terminal stud.

I would say you have a dud starter motor, although I'd expect full battery voltage on the solenoid terminal with the key in position iii (start).

There is a switch inside the starter (operated by the solenoid) that applies power to the motor once the pinion has engaged the flywheel ring gear. Since you're not seeing any sign of voltage drop when it fails, I suspect either the switch is intermittent or the motor brushes are worn & not making good contact. Do check the earthing straps first, though.

It may respond to dismantle, clean & service, but if it's a bear to get at it might be better to replace and only do the job once.

I am trying to get the starter out now and like most posts I see, I am struggling with the top bolt. Any tricks on getting it out. I saw a video a few days ago showing someone putting a long extension on a socket and inserting it from the front of the engine compartment, but I can't find the video back and haven't had any luck figuring out how to get a long extension in to access the bolt from the front.

Thankfully haven't had the pleasure of this yet:- does XK81997's post help?:
https://www.jaguarforums.com/forum/x...4/#post1537315

I was doing something similar to these instructions except I didn't remove the wheel. I took off the plastic air vent for the alternator and was able to get a socket and extension on the upper bolt, but the extension I have is slightly too long and I can't get the ratchet attached to the extension. There is some structure in the way that prevents the extension from fitting with the ratchet attached. I will get a slightly shorter extension and see if I can get the ratchet attached and be able to contort to reach it with enough force to break the bolt free. I can get a box end wrench directly on the bolt, but it is in such a recessed area I can't rotate the wrench without hitting the surrounding structure before the bolt moves. I'm hoping I'm not breaking some part or wire I can't see as I try to maneuver tools by feel. I'm taking this as a challenge, but hope I'm not sorry I didn't just pay the $650 I was told by the local Jag shop was a ball park cost to replace the starter. If I don't get it after one more session of trying it will be off to the shop. (as a side note, the local Jaguar dealer says their shop doesn't work on these old models and refers people to another shop)

Thanks for the link and replies.

Possible reasons
1.Oxidation of contact plate in starter solenoid (clean plate or replace solenoid)
2.Bad connection of big red or black wire, check voltage drop in red wire or presence of voltage in black wire
3.Weak or discharged battery
4. bad spare wheel balancing :)

KLynn, How did this turn out?

John

I couldn't get the top bolt out of the starter. I can get a box end wrench on it but the opening is so small I can't move the wrench to loosen the bolt without hitting structure. I bought some wobble extensions to try to get it from the front starting behind the alternator. I can get the socket on it but I can only get one hand on the wrench in a tight spot and can't get enough force to break the bolt free. I gave up and put it back together resigned to the $650 estimates from a couple of shops, but decided to wait a few days and try again. Sometimes things go better after walking away for awhile. If I remove the oil filter I will have more room to work. I don't know how much oil will come out by removing the filter but maybe I can get two hands on the wrench then.

While you are waiting, spray some PB Blaster on the bolt. Let it sit for a few hours and then spray it again. Repeat one more time. Let it soak overnight and then try to remove the bolt the next day. PB Blaster may indeed allow you to finally loosen the bolt....

Follow up to this. I bought a "S" shaped box end wrench and was able to get on the top bolt from underneath the starter and got just enough of a turn on the bolt to break it free. I then used the long wobble extension and socket from the front above the oil filter to fully remove the bolt. Trying to remove the solenoid ring terminal, I had a socket on it turning it thinking I was loosening the nut that I already had off once. I found out the entire terminal was turning with the nut not loosening. This caused the ring terminal on the wire to twist off. I took several minutes of twisting and turning the starter to finally get it out, but it came out. I can't tell you for sure what the trick was on how to position it to come out. I installed the new starter with the same contortions, but it finally went into place. I installed a new ring terminal on the solenoid wire but it was now too short to reach. I bought some weather proof splices and some 14 ga wire and extended the wire with another new terminal. All was now in place to see what happened when I turned the key - Nothing happened, there were a few small clicks and whirs but not much else. Not even the loud clunk the original starter had. I was pretty disappointed in this and wondered where my diagnosis went wrong. Then I noticed the steering wheel was clicking softly which I determined was the motor that drives the steering wheel in and out or up and down. I noticed the volt meter did not move off the stop. I checked the battery and found 10V with no load. I charge the battery for a short time and tried again. The car started right up. I've never been happier to find I may have to replace a battery since my starter ordeal was over. The battery had been disconnected for weeks while I was going through this so I don't know why it discharged. It is about a year and a half old with no symptoms at all of being weak previously. I charged the battery for a couple of hours and drove it for the first time in a month. I'll keep an eye on the battery. Thanks to all for the input.