Good day folks , i bought an 88 XJS 5.3 after my S type was recently written off.
Car has only 76000kms from new and has always been garaged but had not been started for a year before I bought it.
The engine did turn over but did not fire.
Anyway I Took the risk and bought it , got it home and found a distributor in a box in the trunk. Clearly someone's been here before me . So on that note I pulled a spark plug found TDC , spun the dizzy 180 and she fired up. Only to run for about a minute and quit. Try to restart but no luck. So I readjusted the dizzy a few degrees and she fired up....about 30 seconds later it quit again.
Check spark ..All good...check fuel all good.....moved the spark plug wires back one place and it fires up again.
Pulled the distributor to check the gear and all is good.
Tracing back from there it seems the intermediate shaft gear is the problem. I have an inspection camera in hand and it looks like the gear on the 'jackshaft' is worn. I can see what's involved but wandered if there's any guide or info online to help me with this one. It looks like I have to remove the timing cover etc but perhaps someone can chip in with an easier method.
Thanks in advance Al

 

Al,

BUGGA.

No easy way, front of engine off, timing chain tensioner straightened out and locked, then bit by bit delve into the beast.

 

you sue, never heard of bearing or wear problems on the jack shaft in 30 years of working on V12's. Take the valley cover off and have a proper look.

 

Thanks guys ,
Xjr after looking today in better light the sprocket appears to be fine. This was mentioned to me by someone local and I gave it some thought, glad to say it's not that. In saying that this one has me stumped. It will fire up and sounds fine but then dies and will not start until I retard the distributor timing.then runs Stalls, then I have to advance the timing to get it to run. I've repeated this process several times and can't figure it out. Any advice would be greatly appreciated. Keep in mind this engine only has 76,000kms.

 

If you are needing to retime by just "a few degrees" l can not imagine that the drive gears are your problem. At best they would jump one tooth which would account for much more than a few degrees.
I would be looking more to the cold start and the advance/retard systems for correct operation.

 

Is your car Lucas or Marelli ignition?
Greg

 

OK, drinks are up so here goes from down here.

Firstly keeping to what you have indicated so well, thank you.

Look at the rubber bung at the front of the distributor housing. There are 2 wires running thru this bung, and it is well known that these wires "break" inside that bung. NOT the easiest to find, but the small movement of the "retiming" you undertake MAY make a contact and that enables the thing to run, until the hissy strikes again. With it running, fiddle with these wires and see if anything odd happens.

Is the ign amp (Black box mounted on the LH inlet manifold) getting HOT in this time frame??. If so, ya got coil issues, OR, plug issues, OR, plug lead issues, which are causing a "feedback" that the module has to deal with and it gets HOT, and shuts down, the engine stops, you adjust the distributor, but whilst this is happening the module cools down, and the engine starts. I know its way out there, but I have had it a few times over the years.

The infamous "shielded wire" from the ign amp to the ECU may be an issue, BUT, moving the distributor will have NO affect on that wire, other than the "fiddle factor" that may have you accidently moving that wire/loom whilst adjusting the distributor.

INSIDE that ign amp, tucked in one corner, is a condensor, with a wire attached to one of the +ve terminals of the module, and that condensor LEAKS to earth and will kill the engine. I remove them, all is sweet without them. AGAIN, nothing to do with the distributor adjustments that make it work, just in the pot.

 

Thanks everybody for chippin in, I very much appreciciate the input. I'll take all the suggestions you have at this stage.
thanks Baxtor . I have the distributor out and can see the vacuum advance working.
With timing light attached, everything lines up at 0, around 900rpm give or take, but the mark jumps around plus or neg 10degrees ..maybe more.
18btdc @3000rpm it holds timing and doesn't jump around. Drop revs to 900 and timing Mark jumps around again.
As I was saying before the car had an extra dizzy in the trunk. Looking at them on the bench side by side ! The distributor from the car spins freely and the spare has some mechanical drag to it. .?? Possible the vac advance works but not retarding ?
Greg the car has Lucas ignition.

Grant Francis thanks a million for takin the time to help BIG TIMEthanks .
Iv replaced the ign module inside the amp already, there was no change . Id say the origimnal works fine as does the new one. No heat build up
The ignition spark etc appears good and strong. No issues there.
I'll check ecu wire etc today nd report back .

 

Have you checked that the spring-loading on the rotor arm spindle is working freely? You should be able to move the rotor arm about 15 degrees and it should smartly snap back. If not, carefully lube the mechanism below the star wheel with fully synthetic oil and gently work it until it does. if that spring mechanism is broken, that might produce your symptoms as the rotor arm would be essentially wobbling back and forth at low revs, and settle down at higher ones as the vac took over and general rotational speed-induced inertia held it steadier.

It does sound from what you posted as if the problem is something mechanical, not electrical. Check also that the gap between the start wheel and the pickup is correct and that the pickup is securely fixed.
Greg

 

It sounds like its either mech or vacuum advance issue to me. Try blocking the vac and restart. Do you have a handheld vac pump to compare both distributors. The fact that the timing holds steady at 3000 rpm (full advance) sounds suspicious to me.

 

Al,

Been thinking, i do that sometimes.

Out on that thin limb again.

The CTS (Coolant Temp Sensor) on the rear of the LH thermo housing may be going AWOL. They do that. Uplug it, bridge the terminals inside the plug, and rest it somewhere it wont short out, and start it up and see what changes.

I will keep thinking.

 

Ok , got a good update and of course the engine has multiple issues.
The distributor has been replaced and now runs without stalling Checked the water temp sensor and the plug was only sitting loose on top of the sensor, no doubt causing hard start etc.
wires on the old dizzy were loose and weak.
i can't get it to run with spark plug wires in proper location on the dizzy cap but when I back the wires up one position it starts but pings bad. Wheni adjust the distributor and rotor ,reposition to where it should be ....it will not start.
I took it for a gentle drive but it was pinging bad when I press the gas past half way ,temp gauge was rising into the hot side when I got home as expected.
Still a little stumped but we are getting there thanks to all ur help

 

Sounds to me that the engine is out of time.

You need to;

1. Remove the distributor and the #1 spark plug.
2. Turn the engine by hand until the #1 piston is at 10 degrees before top dead center.
3. Replace the distributor and make sure the rotor is pointing at the #1 terminal on the cap.
4. Replace the #1 spark plug.
5. Put the plug wires back to the correct order.

The engine should be able to start. Once it is running and warm;

6. Disconnect and plug the distributor vacuum advance hose.
7. Use a wedge to hold the throttle open at 3000 RPM.
8. Use your timing light to adjust the distributor advance until the timing to 18 degrees before top dead center.
9. Lock down the distributor timing advance nut.
10. Remove the throttle wedge and shut off the engine.
11. Reinstall the vacuum advance hose.

Restart the engine and all should be well. If you still get some pinging then loosen the distributor advance nut and reduce the timing a few degrees. Test drive and adjust until the pinging is eliminated.

Mark

 

Further to Safari's good advice: The timing reference is A bank No 1 cylinder (ie cylinder A1). That is, as you sit in the car the cylinder on the front RHS of the engine.


On the Dizzy cap you should see a tiny "1" cast into the plastic on the outside. This "1" is by the socket in the cap into which the HT lead that goes to Cylinder A1 should be placed. Assuming that 12 o clock as you look down on the cap is straight ahead, this "1" is roughly in the "ten minutes to 12" position. That is it does NOT point towards A1. Remember that the HT leads go round the cap in the firing order ANTI clockwise looking down from the top.


Apologies if you knew all of this already, but you would be surprised how often people get confused about it.
Greg

 

All advice greatly appreciated folks.
Before I go digging too far today ,we may be on to another issue with this thing. Has anyone experienced the front crankshaft pulley turning out of position on the crank.
Over the last couple of days Iv been using the timing Mark on the pulley to line Up TDC rather than pulling plug a1. This could account for the problem im having. I'll pull the plug and go that way today.
Feeling better about things thanks To the great advice...im a competent mechanic but that doesn't mean the problems not right under my nose lol. . Will keep you all posted .
Have a fantastic day guys n gals c

 

If the rubber vibration damper in the middle of the pulley is shot, then the timing marks will be all over the place.
Greg

 

It is possible and has happened on occasion but it is not a common issue.

The V12 is very sensitive about its timing and it will not start if it is too far out of sync.

I'd recommend that you pull the #1 plug and get the piston on its compression stroke. Once you see the piston at the top you can verify if the balancer is ok and the timing marks are aligned.

There is a very limited range of motion available to the distributor once it is in the "V" so getting it on the correct tooth can tricky. Don't be surprised if you have to make several attempts to get it on the right tooth and leave enough room to rotate the distributor to adjust the final timing.

Mark

 

Then there is the woodruff keys that actually hold the crank pulley assembly correctly timed.

The V12 is known for them to shear, AND, the cone unit to break.

Safari has the mechanical method down pat, but that front pulley will have to come off to either rebond the rubber, or replace the 2 keys, and maybe the cone.

 

Try firing it up with the lights off, you will be shocked at the sparks escaping and dancing all over the place.
After seeing this treat the engine to a new set of HT leads.

 

Back on the road and all appears to be running good. Temp gauge shows a little on the warm side . Half way between N -H . Still the tiniest bit pinging around 3000rpm .
Happy with the engine for now. I will continue to retard the timing till the pinging is gone.
On to the next problem. I'll start a new post.
Thanks for all your help guys.