So this should be a fun and informative thread. If you ask about common engine failures, the list could be a mile long- so more objectively, what spares do you carry around with you? My partner owns an old 420 merc and will always have a spare fuel pump relay in the glove box. This makes me wonder what would be a good idea for my same era jag. So, what are your essentials?

 

Great question, BeckBeck!

In addition to the typical small set of tools, jumper cables, spare quarts of oil and roll of duct tape, I put together this kit for our '93 (sorry the large photos are not currently working):

XJ40 Roadside Breakdown Kit

Obviously some of those parts, like the brake accumulator and pressure switch, are not necessarily "essential," but if I ever needed them on a road trip it might take days to source a replacement. A spare known-working CPS and known-working relays are must-haves, as are some spare bulbs, especially for the low/dip beam headlamps and brake lamps.

Cheers,

Don

 

Thanks Don! Exactly the kind of million dollar info I'm after nothing worse than a no start and having no access to that simple little part that could fix it in a jif!

 

Question though, with relays etc, how easily can they be sourced and from where? My partner finds his needs on ebay but I'm not sure exactly what I'd be looking for as an absolute jag newbie. Is there a good resource for this?

 

Most of the replaceable relays on an XJ40 are of the standard cube shape with either 4 or 5 terminals. Major manufacturers include Bosch, Hella, Omron, Siemens, ACDelco, DENSO and others. Current or amperage ratings range from 20A to 40A or possibly 50A. I keep 40A relays to serve most purposes.

Some of the original relays have built-in suppression resistors or diodes, so for a long-term replacement you have to consult the Electrical Guide. If you can't find the correct type, you can solder a resistor or diode across the relevant spade terminals and position it alongside the base so the relay will seat properly in its socket.

Here's a photo of a 5-terminal relay I just grabbed off the web:



Some relays, like the one above, come with a mounting tab molded into the body. If that tab interferes with proper placement in the car, you can just cut the tab off.

Cheers,

Don