Hi,
Sorry about lenghty description ...

Finally picked up my xjs v12 conv 2+2 and put about 250 miles yesterday. However, I noticed that the battery gauage was fluctating during the drive and eventually it got lower and lower even when I was driving on highway at 75 mph. In the morning I noticed both floorwells were sopping wet but car drove fine. (My mechanic unclogged the ac drain and I am hoping this cured the problem). Later in the day, got caught in sudden thrunderstorm and had to pass through 10 feet of flooded roadway. (about 12 inches high) About 5 minutes thereafter the battery warning light came on while the gauge dropped to red zone. Drove for another 10 minutes and parked the car but it would not start when I came back. Jump started it but it wouldn't stay on. Jump started another 5 or 6 times more but each time the car died after few minutes. Even around 2500 rpm, the gauge did not move. I noticed that the gauge no longer moved at all after 4th jump start. Finally had it towed to shop but i noticed the gauge started moving towards 1/4 mark when the booster pack was left connected. (The car died after starting if the booster pack was disconnected.)

Is this a dead battery or a bad alternator? As always, thanks for your valuable help.

 

Measure what is going to the battery. Commonly the gauge will be faulty...

 

I expect your alternator is toast. But any garage can test the battery.

 

I was told alternator belt will slip when they get wet after going through puddles. Are there any solutions to this problem when puddles can't be avoided? I can't see owning a car that has this issue.

 

HAHAHAHA, new belt, tightened correctly, no issues.

Mine waded through flooded water ways many times, and NEVER ever had that nonsense.

Engine EARTH strap, WELL documented, is the weak link on a V12. Fit a dedicated cable, engine TO chassis, and move on.

Battery is probably toast due to the alternator not doing as designed (charging said battery),

As mentioned, either is EASILY tested by any half decent mechanic.

 

Hi Grant,

Thx for the info. I will tell the mechanic to look into the earth strap.

On a different topic, my temp gauge is always around 7/8 towards the end of the gauge. Is this normal? Feel a little paranoid after reading over heating problems.

I really liked how solid and strong the Jag ran the 1st day from the shop but I am scared about having had to tow it the next day. Is this what I can expect as a 94 XJS V12 owner?

 

No !

It should hover around the middle.

Some needlessly worry if the needle moves one twitch above center. Some increase isn't anything to worry about under certain conditions. BUT consistently running at 7/8 towards the top is not normal and merits investigation, and quickly


In my experience the vast majority of these cars have not been properly maintained over the decades so it's typical that they need some sorting-out. Also, in my experience again, it's well worth the effort.

When I bought my XJS ....which was nicer than many others....I spent 6 months (and a fair chunk of cash) in sorting out all the repairs and services neglected by the previous owner. After that it was pure enjoyment with only routine services and minor tinkering for several years.

Cheers
DD

 

Thx.
I think I may have over estimated my mechanic. He says its ok as long as it doesnt get to red zone.

 

Oh my! Where is this mech? I'll be sure to stay away.
Where are you in NY? I hover around the NY CT area.

 

im in long island. sadly, im looking around for a new one. let me know if you know any in long island. thx

 

 

thx. looking for new mechanic now.

 

Download and read Kirbert Palm's book from Jaglovers. Before asking your new mechanic to do anything, make sure you have read, and that the mechanic understands what the book says about how to fix a given fault, and what preventative maintenance is needed.
Your over-hot coolant is very likely down to blocked radiator fins. There is a front stack (oil cooler and aircon condenser) and behind them is the engine coolant rad. Rubbish gets in between and all the fins get blocked up. Removing the rad is not hard and cleaning out the fins is straightforward too, for a mechanic. If overheating persists, and anyway this is worth doing while the rad is out, renew the thermostats (one each side where the coolant hoses emerge from the engine). Buy all the required parts yourself from reliable Jaguar specialists, and supply them to your mechanic. For example the wrong thermostats, wrongly fitted can be a disaster for the engine.
You will have to accept, as Doug so sagely said, a period of catch up maintenance and the costs involved if you do not do the work yourself.
You will be very well advised, also, to ensure you get the advice from the guys on here about how to solve a given problem, before you entrust the car to someone who may very well not understand the required actions needed, without explanation and direction from you. If you stick with it, you will end up with a lovely. stylish, fast, well handling car that is a joy to drive.

 

thanks for your advice. will let you know how i mske out.

 

My voltage gauge sticks all the time, so its probably more useful to check voltage at the battery.

That being said you just got the car, so more than likely it has an old battery that needs to be replaced regardless of any other issues. All the issues I've ever had with my alternator have been voltage regulator issues, if that information is at all helpful to you.

The temp gauge should not be at 7/8ths, you likely either have a fan issue or thermostat issue. The fans are easy enough to check without digging into anything, but the thermostats will required a IR thermometer. If the car is new to you, it is best to just replace them as a matter of maintenance.

 

If the gauge is steady at this point and the engine is not spewing coolant, I would think the problem is either the gauge or sender. I can tell you from experience when my gauge is at that point the engine is spewing coolant, yep I forgot to put the thermo fan fuses in on a 40°C day.

I broke the spade off my sender and ordered a new one from my Jag spares guy. When I installed it the engine ran near the H, while engine temperature was around 95°C.

Point here is check the engines actual temperature, you can use an IR but be careful and hold it close to the top radiator hose, it will give you an idea of where the temp is.

 

Thanks, Warren.

What should the temp be?

 

92C at the top hose on each side.

NEVER acurate, just near that.

If you have 82c stats, the 92-94 is "normal".

If the 88c stats, then 98ish is the new norm.

Overheat a V12, and your countries national debt is petty cash, NOT REALLY, just an Aussie banter here.

The gauges are as Warren said, and AGAIN, earths play a HUGE part here, as in engine earth, dash earth, get the picture?????

When I get a new to me Jag, ALL the fluids come out, and refreshed, radiator OUT, and professionally flushed, or recored, ALL the under bonnet rubber bits REPLACED, then repeat in 10 years.

The V12 is more reliable than any other car bar none, its simply the "nut behind the wheel" that lets the car down, or in your case, the "mechanic" who is just plain lazy, and only wants your money.

NO ONE cares for YOUR car like YOU.

This might help, along with Gregs suggestion.

 

as always, thank you.

 

My car is only similar. But, I've learned a bit about them that is common.

1. Get a VOM. I have three!!! Digital, analog and inductive. I made a patch cord for the digital unit. I can plug in the cord at the cigar lighter. I can read volts in ral time under various load and RPM conditions. I acquitted an alternator and convicted a battery with it. The dash guage is a mere indicator

Oh, and I check household batteries with it. 1.5 is barely adequate at best. My cameras prefer 1.6 or better...

2. I got an IR temp guage. Neat to sense real F's or C's.

3. My lump is happy at 90 - 100 c. It's guage is very misleading!!!

Carl