Hi All . . . This is my first post in the XJ-S section as my Big Cat is gradually coming back to life.

After a "non-start" period of approximately 8 years . . I have gently coaxed my XJ-S to start-up a few times. I did all the pre-start checks and whispered a silent prayer when she growled and coughed into life. I want to take it very gentle for now so only running her for maybe 4/5 mins at a time.

The good news is that the petrol gauge and Volt meter on the right side of display are working and showing 13 volts plus on charge and the small mix of petrol and injector cleaner in the tank. Up to now, the oil pressure gauge and coolant temperature haven't moved or flickered. I'm not too worried about the coolant temperature gauge just yet as not running the car enough to expect it to move.
But I am a bit concerned to see that the oil pressure gauge is not moving at all. The "red oil can" dash light disappears shortly after start up as it should . . . but should I be worried the oil pressure gauge is not moving?

Any help or tips would be much appreciated. Cheers Jag Folks

 

Dude.Day,

I'd start by checking the cleanliness and integrity of the terminals on the oil pressure sender and the coolant temp sender.

Paul

 

Paul is right; check the connections at the senders.

If no joy then you likely have corroded contacts on the printed circuit for the instrument cluster. This is common. The fix is remove the cluster (not too difficult) and gently clean the contacts. Many guys add an extra ground wire at the same time.

Cheers
DD

 

If you start the engine, always run it up to temperature, stopping it after 4 mins is not a good idea. By all means let it tick over gently and rev it a bit from time to time, but it is important to get it fully warmed up before stopping the engine. This enables all the various gaskets and castings and studs to get to their proper settled lengths and positions, water vapour to get purged and the oil to get properly round the system..

 

Thanks folks . . . I'll take all recommendations on-board next time I tummy tickle the purrdy cat to life. I know its not good practice to short run any engine, but I'm but trying to avoid stressing the cooling system too early and add a list of coolant issues onto the "to do" list. So do I take it that the oil pressure gauge should be moving/showing summat even on a 4/5 minute run?

Cheers Jag Guys and Gals

 

Forget the oil pressure guage. It will be the sender or the cluster of guages. You have plenty of oil pressure as the light is going out.

 

Thanks Greg. That's the re-assurance I think I was looking for. If the dash-board light going out is the main check point I'll follow the pointers on the connectors first then the rear of the dash if needs be. Cheers

 

The actual sender unit in the rear of the V on a casting bolted to the V is the most likely cause after the connector to it is checked. If you need to change it, post again, as you do NOT want to snap the casting off.

 

I'm recommissioning a 6 litre and the temp gauge wouldn't read properly until I removed the single connector on the sender and cleaned it and the sender spade terminal properly.

Paul

 

Hi All . . . Update on the instrument gauges (oil pressure and coolant temp).

Gave my big cat another breather yesterday after checking coolant as far a necessary. She definitely got up to temperature with a few higher revs and the top hose getting hot too. No glimmer on either gauge so it does look to be a delve behind the control panel sometime in the future. Also, I tried to clean up the coolant sender after I'd started her up . . and she died immediately I took the sender connection off! I take it that this is a good sign . . means the sender is working and its a safety inhibitor feature to stop you "accidentally" running her without the coolant sender working fully?

Cheers

 

Right.

Some have said the ECU simply won't operate with a signal from the coolant sensor. Others have said that disconnecting it enriches the mixture so massively that the engine instantly swamps.


Well, it tells you that the coolant sensor hasn't gone "open circuit". But it doesn't tell you that it is working correctly.

To test for proper operation you'd check the resistance across the terminals over a range of temperatures. If you have an ohm meter we can give you the temp-resistance values.

Cheers
DD

 

Hi Doug D and thanks for the info.

I'll try remember to take the meter over to the cat next "warm-up" session. I think I've got those resistance readings whilst wandering 'round www land. I'm assuming (as she dies when I disconnect) that I'll have to take readings across the sensor pins as she cools down after getting fully warmed up?

I'm not too worried at the moment on the gauges front now I've had some re-assurance from Greg and others. I need to concentrate on getting the brakes sorted as at last start up on Friday, I jumped on the brake pedal whilst testing all lights (all working BTW) and discovered I've got 3 of 4 of front pistons on right side moving . . . but only 1 of 4 pistons moving on left side.

Cheers Guys and Gals

 

Remember that the sender for the gauge is NOT the one that sends the signal to the ecu. The gauge sender is the single simple spade terminal one, that's next to to the ecu plug sender.

Paul

 

Paul
You might be mistaken, here, assuming you are referring to the coolant temp sensor? If so the guage temp sensor is on the A bank water/thermostat manifold with a spade connector as you rightly state, while the ECU sensor with its injector style EV1 plug is on the B bank manifold on pre facelift HEs.

 

Apologies Greg,

I was relating to the late 6 litre.

The key thing, as we know, is the gauge sensor is the single spade connector on the A-Bank, and doesn't influence the running of the car if you disconnect it.

Paul