I drove a Ser III for years. Yeah, it needed some love from time to time but there were long periods of 100% reliabilty.....and that actually worked against me as I sorta stopped paying attention to things. A few minor problems developed that I otherwise would've caught. I learned that Jags are not "drive it and forget about it" cars :-)

I was never on the back of a tow truck, though :-)

Cheers
DD

 

I hear you, as you can see from my signature I'm no stranger to temperamental European 80s cars . I don't even carry AAA and I can't even remember the last time I used a tow truck. One of the things I've noticed so far with this Jag is just how far overblown the hearsay about how difficult they are to work on and how problematic they are is. It's really a quite simple car when you get down to it and even most of the electrical stuff is fairly easily diagnosed with a simple test light. I'll take that over 60 can bused modules any day.

 

Agreed :-).

As you learn about the car you'll find a few engineering/design/quality disappointments but overall they are great cars and built to last. The body structure and suspension are massively built...over-built, really.....and most of the materials used are high grade.

Built like a tank and drive like velvet :-)

I'd really like to own one again. One of these days :-)

Cheers
DD

 

Definitely noticed on the suspension, that's some heavy duty stuff right there. Now if only they had had their rust proofing figured out we'd really be golden. Oh well, that's what garages are for.

 

vwtech, what kind of bit did you use for drilling the holes to the block? im a novice mech, but im assuming the bit drills straight without creating thread and that the screws provided in the kit will create the counter thread when being screwed in?

 

That's correct, you use self tapping screws, you don't thread the hole. Just used a bit designed for metal from home depot, nothing fancy.

 

Well, it's now had a new plugs, wires, cap, rotor, coil and amplifier with no real change. It will sit there and idle for 15 minutes and then all of a sudden the tach's going bonkers and it starts stumbling a bit. Never stumbles under load, though. It can sometimes stall when sitting at a stop in D or R but if you're moving or accelerating it's fine, even though at times the tachometer is just dancing all over the place while you're driving. I've pulled, tugged and twisted on the harness and it doesn't cause the issue to happen or change/stop it when it is happening. I've cleaned all the connectors I can get to in the engine compartment (though not at the computer yet). I think at this point there's really only two options left. The distributor (which is what I suspect) despite the pick up coil ohming out to spec or the trigger signal from the Fuel Injection Computer is partially dropping out here and there. In which case there's a whole other set of wiring, powers and grounds to be checked. In any case, I think I'll take the distributor out at some point in the near future and clean it thoroughly and set the air gap if it's out of spec and go from there. There's got to be something I'm overlooking.

I wish I could make it happen more regularly to establish a trigger but there doesn't seem to be one other than it likes to do it more the sooner I need to be somewhere and the further I am from home and it doesn't like to do it for a solid hour of idling and driving once I've replaced or adjusted something. It waits just long enough till I think I've finally found it (and I'm the obligatory distance from home and tools) and then starts up again. It will do it regardless of temperature, outside or engine completely at random. Ah the joys of old cars. Still having fun tinkering with it, though. Just want to be able to drive it without worrying about spark dropping out all of a sudden and leaving me up a creek.

 

so got the (leaky) valve cover off today on the exhaust side, still waiting for the stakedown kit to arrive. the guides look pretty good, here are some pictures...shall i brake clean the chamber fully devoid of oil before I drill the stakedown plates in?

 

Another pic

 

so my stakedown kit hasn't arrived today, perhaps tomorrow. here is a video of my guides with the cam cover off...the guides looks to be too raised, but they are all in identical vertical positions..wondering if these are the normal positions or are all raised up and need to be reseated down?

tappet guides cam cover off - YouTube

 

Yours do not appear to be hitting yet. The tappet itself is the shiny center directly under the cam lobe. They ride up in down in the guide as the cam lobe pushes on it and the tappet opens the valve. They're at different hits because some are being pushed down by the lobe of the cam and some aren't. The darker outer guide that it rides in is the part that can loosen up from the cylinder head and hit the cam lobe. Look back at my pictures of the damaged ones and you'll see what I mean.

 

I see the obvious wear on your guides and mine look undamaged but I definitely have an intermittent clacking that by all accounts, are guide noises. Incidentally, I just received my stakedown kit today and seems that the guides are too raised (all 6), causing the stake down plates to not be sitting flush against the head.. do I need to hammer the guides down or reseat them?? Also just found out that my 79 car is late production series 2 (early 79) car, not early production (late 79) series 3... dont think the engines are different...

 

Think I've finally got the ignition issue figured out (knock on wood). I was on vacation in FL the last two weeks and got back yesterday, fiddled with it today after work. I went ahead and unhooked the white wire from the ignition/starter switch at the + side of the coil and ran a wire straight from battery positive to it. Ran and drove it a solid hour with no hint of the issue returning. What's amazing to me is just how briefly the power is dropping out. It's quick enough that no change was ever seen on a multimeter (I'm sure a DSO would pick it up) and no flickering at all from a test light (less surprising than the meter). Voltage drop was pretty minimal, too. I haven't decided what route I'll go for a permanent fix, possibly relay it, maybe just an inline fuse. Ignition switch was replaced by a shop a couple years ago, should probably check their work, make sure the wire isn't loose there or anything. Only drawback was it was cool, foggy and rainy today so I was able to test the heater for the first time and discover it doesn't produce any heat . Oh well, add it to the list.

 

Spoke too soon, this car just loves messing with me, haha. Went to start it to go to work this morning and the issue was back as soon as I started it. Back to the drawing board. Everything except the fuel injection computer, wire from the computer and the distributor itself has been ruled out at this point.

 

I'm coming in late on this, so sorry if this has already been discussed.

Check the back of the ignition switch. It's simply crimped together. It's very common for the crimp to weaken and the unit will come apart briefly then slide back into place like nothing happened. You can't crimp them down further, the only answer is to replace them. They are extremely prone to fail and should almost be considered a maintenance item.

Don't drop the screw that holds it to the back of the tumbler. It's the tiniest screw every made. If you drop it, you will add more hours looking for it than you ever thought possible to a very simple repair.

 

The ignition switch was replaced at a shop a year or two ago because the car wouldn't start so it's relatively new. However, who knows the quality of work they did and what not which is why I unhooked the wire from the ignition switch and ran a wire to the coil straight from battery positive to eliminate it as a possibility. It did not change the problem. I kind of figured as much, too, as you would expect a faulty ignition switch to give you problems on more than one single component and I don't have any other electrical issues.

Just to recap,
- Plugs, wires cap and rotor have been replaced
- Tried another ignition amplifier
- Tried a new ignition coil
- Tried removing inline resistor from + side of coil
- Cleaned all connections I could get my hands on in the wiring
- Eliminated wire from ignition switch by running a wire straight from battery positive
- Have tugged, yanked and pulled on the harness in every way I can and it neither stops nor starts the problem

So at this point there's essentially 3 things left in the ignition system. 1) the signal from the fuel injection computer to the coil 2) an issue with the wire between the computer and the coil and 3) the distributor itself. I'm having a hard time believing it's the distributor just because of the nature of the problem. As I said before there doesn't seem to be any rhyme or reason to when it occurs. Sometimes it will happen as soon as you start the engine, sometimes not until it's driven for awhile, sometimes not at all. Nothing I have found yet will make the problem happen if it's not happening or stop it if it is happening.

 

Just thinking out load...what about running some secondary grounds?

 

Thought about it for a moment and realized, obviously, computer just gets signal from coil and isn't involved. It's pretty much down to the distributor or a ground issue like you suggested. Where are the main chassis grounds on these things, out of curiosity? I'll have to give that a shot. Probably wouldn't hurt to clean the battery's ground connection, too.

 

I'm not sure about ground locations. I've just seen the guys in our shop add grounds because the factory setups corrode and are just plain weak. I don't believe there exists a common place to add them. Everyone seems to find their own place.

 

I will try that tonight, I'll add a ground from the engine to the chassis somewhere and clean the ground cable from the battery and see what happens. Still a good chance it's the distributor but this is cheaper and easier so I'll try it first.