Just starting to get warm here in Texas and yesterday after driving with AC on in 85 degree weather, I noticed the electric fans stayed on to cool down the engine after shut down. The temperature gauge never went out of normal range...in fact it always seems to stay in same place. So two questions:

Is the temp gauge a "real" gauge or one of those that only goes to "H" when it may be too late? And what is your experience with the fans running on on your XJ300/XJ306?

THANKS!

 

Yes, it's an 'idiot gauge'.

I've checked the coolant temp with my scan tool and on my XJR the needle will just touch the 'N' at 174ºF and remain solidly there until at least 205ºF. I've never had the coolant temp go any higher while checking so I don't know at what point it moves off the 'N'.

My fans stay will often running for a few minutes after shut down on the hot summer days. The switch point must be about 200ºF or so.

Cheers
DD

 

Has anyone tried to run a slightly cooler thermostat and/or reprogram the ECU so the fans come on earlier as a little insurance against overheating and also to keep the engine a bit cooler?

In the supercharged Riviera (and other Eaton SC'd GM cars) using a slightly (180F instead of stock 195F) helps reduce KR a bit, especially if the fans are reprogrammed to come on a bit earlier too.

 

Not sure if anyone has tried cooler thermostats.

The e-fans are not ECU controlled. But speaking of ECUs, the only person I can think of who has ever reprogrammed one is 'XJRengineer', who posts here fairly often. He has a heavily modified XJR/6

FWIW I installed a separate e-fan for the supercharger radiator and divorced the intercooler plumbing from the engine coolant plumbing, both on a "can't hurt, might help" basis. If it made any difference, it was slight.

<shrug>

Cheers
DD

 

That's interesting that the ECU doesn't control the fans on the XJR. The Riviera's ECU controls what temp the fans turn on. What controls the fans on the XJR? Is it a separate coolant temp switch?

Interesting approach divorcing the coolant. Odd that they even had the engine and intercooler mixed I think, even if that is the norm. I would think that would hinder the intercooler's effectiveness sharing hot engine coolant.

 

Yes, a separate thermal switch, and the a/c pressure switches. The pressure switch aspect of the circuit has been modifed on many X300s as per a Jaguar tech bulletin. I can never remember the details but the bulletin has been posted a number of times.




That's what I thought as well but the hinderance must be very slight.

Forget to mention that my intercooler pump failed some years ago and I replaced it with a higher capacity pump but, as with the other changes, it didn't seem to make any difference.....not in the seat-of-the-pants, at least.

Cheers
DD

 

FYI for those who may have experience their auxiliary fan running even if the engine is switch off, you might want to check your thermo switch located on the lower left side of your radiator, this is extremely common , an inborn defect, just change the part, cost around $75 to $80 (brand new).

 

Sorry unable to send picture of actual Thermo switch due to limited sending bytes of this forum

 

To clarify, it's perfectly normal for the fans to continue running with the engine off. Here's a quote from the manual:

"Under hot operating conditions, the fans may continue to operate after the engine has been switched off. The fans stop automatically when the coolant temperature has been reduced sufficiently."

However, if the fans *never* turn off then the radiator switch is a possible culprit, yes!

Cheers
DD

 

You can always put the photo up on a photo-hosting site ... then click "Insert Image" icon (versus creating an "attachment") and provide the URL to the photo.

 

What if the cooling fans never turn ON? Mine don't turn on anymore and if like to sort it out.

 

I had the same problem recently and got it sorted, which I'd strongly recommend. Warmer weather on the way and a temperature gauge that isn't worth a whole lot, until it's too late, can be a recipe for disaster.

The two fans are supposed to run independently and also in tandem with each other. One kicks in as necessary and then the other follows as needed.

However with the modification that was carried out on many x300's, this doesn't always hold true. My problem was that one of the fan motors was suspect and didn't run and so, didn't allow the second fan to kick in at all.

I sorted it by just swapping the fan/shroud assembly from my donor car and all is well. But the causes can be varied, from fuses, to relays to temperature and or pressure switches. One switch is mounted by the thermostat housing and the other is on the lower side of the radiator housing.

Others will chime in.

 

Are you saying that your cooling fans never turn on even with the engine running? If so, I would get that fixed sharpish. If you get stuck in slow moving traffic, your engine will overheat very quickly!!

Check the fuses first, they are in the left side engine bay fuse box F11 and F17.

If you are just saying that the fans do not stay on after the car has stopped, this is quite normal if the coolant temp is not over 205-210-ish. It is controlled by the fan switch that is fitted to the left side of the radiator, midway down. You can test that the fans turn on by pulling the connector from the fan switch and shorting the pins 1 and 2 together. This should turn the fans on even if the engine is off.

To test if the fan switch is bad, you can try to measure the temp of the coolant with an IR gun at the radiator outlet hose. If the temp of the coolant gets above about 210 or so and the fans have not come on, then you may have a faulty switch, though in my experience they are quite reliable.

 

I don't believe this is correct. The fans should always come on together but they work at two speeds, hi/lo, depending on the thermo switch.

 

Is this unique to the Jaguar/Ford products?

I can say with certainty that my GM products of the mid 90s that have two electric fans only have one fan running normally and the second fan kicks on when a certain temp threshold is hit.

They also have warnings on the shroud that the fans can start at any time even with the engine off.

Al

 

I doubt you could characterize It as being Ford/ Jaguar, but the fans on an X-300 run in series electrical connection for low speed, and parallel for high speed.

As to the comment about using a lower temperature thermostat- that is a bad idea. The car will not overheat less and it will screw up the entire engine control mapping to some extent. Heat leaving the engine is a loss of efficiency and the engine is designed to run at the thermostat temperature.

 

I bow to your superior knowledge and thanks for the clarification. I didn't explain clearly as I don't understand clearly! Part due to the various modifications, or not, as the case may be. I knew they were independent and also dependent at the same time, if that makes sense. On my inoperative fans, one didn't run at all when I put power directly to the motor, and the other did. So it seemed that the dodgy one was preventing the good one from running, so, neither worked.

Thanks for the input.

 

sogood:
I don't know if they ever had series connected Christmas tree lights in Ireland, but if one bulb goes out, they all do since the complete circuit is gone. The fans in series are the same!

 

Yes, I recently explained this set up "series/parallel" in a post and used the Christmas Tree analogy also. On my fans, putting power straight from the battery to the +/- terminals on one fan motor did nothing. But it worked on the other motor. Then I tried the same thing on my donor fans and both fans ran, independently when power was applied to each one in turn.

So, yes, they are wired in series.

Anyway, when I was five my father told me that Santa Claus had died after falling from a great height...................................

 

Help needed please!

I have a 1995 X-300 with a 4,0 liter engine with a unique cooling problem. My fans don't turn off if the engine is cool and the ignition is on. When the car runs the fans run all the time. The manual indicates that the fans should engage when the coolant reaches at least 70 degrees. When the ignition is turned off the fans stop. I've pulled the connections at both the thermostat housing and next at the radiator and the fans keep running as long as the ignition switch was on. The fans stop when fuse F7 is removed or when ignition turned off. I've replaced the relay under the left front headlamps and the same result. Do I need to replace the sensor in the radiator or is there another relay that could be stuck open? If so where is it? At least the fans are running instead of not running so i can drive the car but I don't want to burn out the fans prematurely. Any help will be deeply apperciated!