Hello All,
My second week of Jag ownership and have a few minor questions. It's a 1988 XJ-SC, 29,500 miles. I fueled up today and went for a 15 mile or so ride.Once on the road I noticed the fuel gauge went from full to about a quarter tank,is this a common thing or a sending unit issue? I also noticed the temp gauge went over 50 when I got into the pedal and when I came to a stop it went right down.What would be the normal temp. reading when just cruising down the Highway? I ask this question because I understand the Jag's may have overheating issues and i am trying to be proactive to avoid a problem. Other than that she humms like a bee and I love it!! Thanks for any and all responses

 

Probably a faulty sending unit. However, dirty contacts and poor grounding at the back of the instrument cluster can cause strange readings....also common






Sounds like you're talking about the oil pressure gauge, not the temp gauge. The temp gauge does not have numbers. It is marked with "C-N-H".

The oil pressure gauge is marked 0-50-100 (or something lake that)

It's normal for the oil pressure gauge to move up-n-down a lot with engine RPM. It'll also read lower as the engine oil heats up. An almost-zero reading at idle is normal with the V12




Ideally you want the temp gauge to read roughly "middle of the N" under normal conditions. Problem is, the temp gauges are not very accurate so even a "middle of the N" reading gaurantees nothing. Plus, coolant flow is every bit as important, if not more so, than coolant temperature....but a flow problem might not be seen on the temp gauge.

A hand held infra-red thermometer will give a rough idea of actual coolant temp so you can 'gauge' how your temp gauge reads.

As for flow, the best bet with an old V12 is to remove the radiator and have it professionally cleaned, flush the system, install new thermostats, and properly bleed the system. You can then be pretty confident the the flow is good. Cleaning the vapor/steam pipes is a good idea as well, as they're probably clogged. If the hoses and fan clutch are iffy, replace 'em at the same time. Get all the misery over and done with at once.

Cheers
DD

 

Thanks Doug,I am sure it has been sitting for awhile, just need a good mechanic in the area.