Hello,

I've been on the forums since March when I found a XJ6 that would not run for sale. I wound up buying it not running. With the help from the forum I got it running and tuned nicely! It's been my daily driver since then. Brilliant car that always gets compliments. Then I found this XJ-S.

Beautiful Sebring red car with no rust and straight panels. Interior is clean and tidy except for busted seams on the fronts. Maintained moderately but consistently. Exotic and very sexy! And not running. Bought it not running too.

Literally the second day I had the new jag in the drive my XJ6 seized. Bizzare. I drove into work with it purring and at lunch he had a terrible knock on starting. Turned once more before stopping for good. But that's another thread for another day. First, I'm going to get this redhead running. And I'm going to have questions for sure.

Here's the patient.



1986 XJ-S

First I'll be adjusting the TPS and cleaning / checking the dizzy and plugs. The compression tests. The installing fuel and vacuum gauges. Hopefully I'll accomplish that all today and possibly try to fire it up tonight.

What's the best plug for this motor?

Oh, and shouldn't this connect to something?.



Loose spades. Drivers side front of motor looking back. Snoot on right edge of frame. Wire route back under right side intake then to 4 beige wires at loom behind throttle capstan.



Center of frame are four beige wires that route to loose spades.

 

Its a V12, simple.

Not sure on US spec for those wires, and on the LH side there are many possibilities. The fuel temp switch fiasco for "hot start" assist rings a dull bell. Someone with US spec knowledge will slide by eventually.

I run NGK BP6EF is all the HE engines. Gapped to 0.025".

I will answer what you post, but I suggest ONE issue per thread, it does make it less messy, and easier to track.

 

Well grant, as it played out that was the important one.

I ran through my list. TPS set. Cruise out for now. Dizzy was clean and both vacuum sand centrifugal mechanisms are smooth and vac holds. Fuel pressure is 35 and steady. Then I went to the plugs.

What mad genius?! I was relieved that is was not as bad as it appears when you first look at the top of this motor. Only the 1A and 1B gave me trouble. Is there an alternative to displacing the AC comp? Couldn't think of one so that's the toute I took. Out easy. In not so much.

So all 12 Autolite 103 plugs were gapped to .44. Regapped. Fired up! Sounds like it's not far off a proper tune!

More testing today and a few more hoses to replace, brake check then a spin around the block!

Now, does anyone know what that pair of loose spades should go to? Two of the four wires peel off at the vacuum switch on the rear of the right intake. Two continue on and deadens on left front near the front of the left intake. Not water, air or fuel temp. Those are in place.

 

You just gotta round up the Jaguar schematic for that car.


Mine for my XJ wuzza six has been invaluable. I've never been much
at deciphering electric schematics. But, this one is quite clear.
As my car is lumped, the GM factory manual for the donor car has earned it's price, a "C' note, brand new.


I've a couple for my Jeep. Quite useful but, it's electrics are far more stable.


Nice car. Well worth the effort to sort out. Odd, that the plugap is so wide in this day of electronic ignition. 045's and even 050's are seen!!!


Was just reading the new Hot Rod magazine. I like the section that describes a master technician dealing with mystery diriveability issues. This issue dealt with a "messed with" 302 Ford in an 89 Mustang. The otherwise modern ways tech resorted to a shade tree
technique for testing coil leakage. He sprayed water on the connections with the engine running. No sparks, no stumbles,
coil exonerated??? Oh, done in a darkened shop.


Different critter, but info definitely transferable.


Carl

 

The color of the wires attached to those loose spades leads me to believe they attach to the auxiliary coil in front of the radiator. I have an '88 coupe which is fairly similar under the hood. Looking at the wiring diagram on my phone, it's a little difficult to trace the whole thing. I'm away from my Jag until Tuesday (vacation). If you haven't figured it out by then, I'll see if I can trace the wires in my car and let you know. You could always hook up a multimeter to see what kind of voltage you get with different key positions, etc.

 

I've got the S57 diagrams. Since these 4 wires come out of the loom it's hard to ID them by tracing. Two are connected to what I believe is the vacuum solenoid. Its at the bottom rear of the right intake. On the diagrams those also connect to the supplemental air valve. Not sure if that's what these go to or where it is.

It's not the aux coil though. That's all connected and functioning. Certainly the right area and wire colors though.

 

Please post a photo of the vac solenoid the wires are connected to. If this is what I think it is, it may be the fuel enrichment switch that is activated at Wide Open Throttle. USA cars also had a second microswitch on the back of the throttle capstan which did the same thing. belt and brcaes, I suppose. Maybe these wires went to that? See if you have it and if so, it is connected to anything.
Greg

 

So... Diodes A&B, the idle relay and idle override relay are missing. They should be on the forward bulkhead in front of the air conditioner compressor if I'm reading the diagrams right.

What does that relay pair do?

They are what s57 says should be on those spades.

 

As I understand it, the idle relay (in a black socket) takes advantage of the supplemental air valve (SAV) by grounding it when the A/C compressor is engaged to boost idle RPM. In park or neutral, the RPM would be too high so the idle override relay (in a blue socket) defeats this function while the compressor is engaged.

You are correct, those are normally found attached to the upper radiator support in front of the compressor. I have moved mine back near the right side of the firewall next to the starter relay and A/C relay. I'm not really sure why Jaguar decided to use all that extra wire to mount them in front of the engine. Maybe it was so some of the workers could get a little more time before they clocked out? Interesting design feature.

 

Gotta boost the RPM when the AC compressor is on? Odd,
that the big V12 can't handle that added load with ease?


My "little" 4.0 Jeep six does it with aplomb.... yeah,
low speed torque...


But, surely not a reason for not running.


Ideas:


1. Attach a test lamp in series on the wire from the distributor to the - post on the coil. Crank. It should blink on and off. If no, there is an issue in the distributor and possibly the coil.


2. Attach the lead from a strobe timing light to the HT lead from the distributor to the coil. Crank the engine. Light on and off? If no, no Ht spark! Coil, connectors or distributor.


3. Attach battery + to coil +. Crank. Engine should fire up. If no,
back track to ignition switch. Wires, connectors or the switch itself open...


Carl

 

It can, mine has not been connected for years. I use that solenoid to boost the revs a touch when my main electric fan comes on, that way in traffic the battery keeps up indefinitely.
Greg

 

Just to be clear, since I obviously wasn't, she's running!

Once I got the plugs gapped she fired right up! Autolite plugs meh. But she runs on em. I'll be replacing those. I'm just trying to work out all the little issues I find now. And unconnected wires is a big red flag for me.

Oil pressure sending unit is bad. 3.5 Mohms. Gauge works as does the idiot light and, I assume, the idiot light sending unit. Grounding it's wire activates it. It's not burning when running but that dead gauge is scary as hell. Can't run it like that and I don't have a mechanical gauge to pop in for reassurance that she's pumping oil.

 

Jig:


Much better. Car runs. Details to follow. David Boger is in your neck of the woods. My OP sender went bonkers. A NOS from him fixed all.
But, as I'm wont to do. I had to mess around.


As my lump has hydraulic lifters and they were quite I knew I had OP.
But, I went shopping for a mechanical guage. No luck. I settled for a SunPro electric guage kit. Sensor and instrument. Plumbed it in and confirmed OP fine. It's senmsor is a larger and more robust. Two ohm options. One matched my Jaguar guage just fine.


I did not use it. It is in my "tune up" box as a diagnostic tool.


Greg.


Yeah, I wondered??? Neat idea to spin the alternator up a bit to handles the fan load. My lump has a big 140 amp alternator. Lots of
electric draw on the donor Cadillac Fleetwood Brougham.


I have not only E fans, but an E water pump. So far so good.
But, interesting...


Carl

 

Oil sending unit arrived today. Tomorrow I'll be replacing the old one and, God willin and the creek don't rise, taking a drive. Little southern flavor for y'all.

No indication of any fuel leaks in the boot at all but still a strong odor of fuel. I'll have to research on the vent lines. I understand those are suspect. Hope to sort that too.

If she runs well and I still have the time I'll spend it washing the engine bay. I'm sure that will summon a project or two.

 

Removed the coil, throttle linkage, capstan and pedestal to get to the sender. Whoever designed that pedestal is not my friend. Why? Why would you choose this shape? These mounting bolt locations? A dozen alterate designs for this would have been better and still fit the requirement. But I've cleaned and polished this lovely pedestal. Tried to make friends.



Oil pressure is good! Or is it? Gauge is working! 50psi at idle! But I understand that the v12 runs low pressures at idle. And that there was an update that basically turned the gauge into an idiot light that points a good pressure reading as long as there is pressure of some sort. Was that a change to the sending unit? Did I buy one of those in my rushed ordering?

Regardless I feel relieved to see I have pressure. I'll believe the gauge for the moment.

Lower radiator hose started leaking. Soft and bulging at the engine end. I should have ordered it already, but I was trying to locate a US source for the HK029 kit. Only ones I find are UK or AU. Anyone know a states source?

I did get a good start on cleaning up the engine bay. I'm not used to finding glossy paint everywhere under years of dirt. It's a nice change!





XJ-S bay. Engine is still filthy but the wings cleaned up nicely.

Now I'm trying to check the timing and I'm confused.

I tried following grants article on tuneup. He says set static at 10°. And then drive it see if it pings. I'm assuming that means set static with the vacuum disconnected. Boy does it run bad with the vacuum advance disconnected. I think it wasn't of the 12 it would choke down.

Jaguar says sisconnect vac and while running at 3000 RPM set it to 18°.

I'm still hunting the timing mark! I cleaned up the face of the balancer. And I think I see a small triangle off the scale with my timing light. Is that the mark on the HE V 12s? Or is it a notch? I can't find the triangle when it's not running. I know I could pull the fan shroud to turn motor by hand, pull A/C to pull plug 1A and find TDC. Sounds like the hard way. I hope to find it this morning by just spinning her over.

I suppose I'll go with Jaguars method unless someone can confim Grants method "static 10° at idle" means no vac adv.

 

Good that you understand the value of friendship with your Jag. You're already getting into the spirit of things. The relationship will pay dividends, I assure you. A couple points to remember which might help nurture the relationship.

First, there is no such thing as bad design on these cars. Something that looks like a bad design is, in reality, simply "an interesting engineering feature".

Work very slowly and methodically. On this V12s, slower is faster, if you know what I mean. If you try to rush, the car will fight back. You must savor every little step. You've probably already realized this.


Sounds like it, yes.



I'd try any of the 'usual suppliers'. SNG Barrat, Terrys Jaguar, Coventry West, etc




You have to be under the car looking up. It at the bottom.

Cheers
DD

 

I always set the static at 10, and leave ALL the hoses connected, just as you would drive it.

STATIC down here means engine OFF, and you have manually wound the engine to the 10degBTDC timing mark on the plate under the bottom of the crank pulley. DO NOT, again, DO NOT wind this engine bakwards. If you go past the 10deg mark, go around 2 more turns and pay attention to what you are doing. Winding that engine backwards will cost you the National Debt to fix.

As I said in the article, "you go to all the trouble of following the book, and it "pings", so then you retard it a tad until it dont ping".

The drive timing is really only beneficial when the rest of the system is up to snuff. Plugs, leads, TPS setting, air filters, throttle disc cleanlimess and clearences, etc etc.

I see a YELLOW plastic fan in that snap, OOPS.

The V12 will run at about 80psi at idle COLD, and the gauge may or may not show that. It is Smiths electrickery at its best.

Jaguar ALWAYS specified a PSI at 3000rpm. Outside of that, what the heck. Mine runs 55psi at idle, cold, and 45psi at idle with the Efans ON, so HOT. That is using 10W40 oil. Also these readings are from my master mechanical gauge.

I use a VDO gauge sender from a 280ZX, and it is waaaaay more reliable than the Smiths could ever dream of, and dont leak oil.

The fuel smell MUST be waaaay above #1 on your to do list, sorry, these V12's burn NASTY. When (note I did NOT say IF) the injector hoses leak, they spray straight at and in the distributor, fun follows in a heartbeat.

I would take the 3 days and replace ALL the coolant hoses, and there are MANY, remove and professionally clean that radiator, replace that time bomb fan, and the 4 belts.

AGE is now screaming for some serious catch up maintenance on this car.

I use XK Unlimited in San Louis Obispo, Coventry West, and SNG USA, no issues. Look at the sponsors for this Forum, one might be better for you.

 

Must not alarm folks when the gauges tell it like it is, good, bad or inbetween!!!


Carl

 

My Jeep's gauges are "stabilized". The Jaguar's tell it like it is, sorta ???


Carl

 

I appreciate all the info!

I can find the timing scale at the bottom. It's just that the mark on the harmonic balancer is hard to find. Usually a notch sometimes an engraved line etc. I just can't find it on there yet. Taking all belts off didn't solve this either. Hmmm.

All her belts are off and I have replacements but taking them off was all I could do today. That alternator belt was HARD. The pivot bolt was torqued to 40-50 ft lbs. it could not move with the adjuster loose. Finally got the pivot free but apparently the bracket holding it was compressed by the torque job. The alt would not pivot except by cranking the adjuster to shove it loose. 1/16th of a turn at a time.

Hose kit HK029 is ordered. I'm doing all those.

As for the fuel smell certainly has to be sorted. But it's not in the high pressure section for sure. Holds pressure for two days at least. The tank is like new. Not a flaw on it. I strongly suspect the vent hoses.

Thanks for clarifying your timing method Grant! I'll give that a try once she's back together. With the belts off I should be able to pull the plugs and turn her over to find the mark and set it at 10°.

Yellow fan is a known enemy. I gave it a thorough cleaning and inspection and I trust it for getting things set. Not for driving. Im currently torn between quick replacement and a bit more involved swap for a reversible electric.

Manually rotating the engine...
I have heard this admonishing against counter rotation a lot. Please tell me what evil this summons. Valve collision? I've wondered. Just today I was wrastling with that alt belt and thought it turned the main Pully a degree and panic welled up from the memory of this cryptic warning "Turn it backwards and BOOOOOOOOOOOM! I haven't killed it have I? Hell i'm not even sure it moved or which way but the warning works!

And just to be clear, it's turn clockwise only viewed from the front of the motor correct?