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How Important Is Fuel Cooler in Air Cond. 87 XJ6?

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Michael J.

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Repair Manual discusses a fuel cooler in the airconditioning circuit for an 87 XJ6, but it appears to have been removed at some point.

Is it as important on 4.2 Liter 6 cylinder cars as it is on the XJ12?
 
I was discussing the same subject with another XJ owner; He did away with the Air Pump system, (everything related to it), and now he's going to remove the Fuel Cooler system. In my '84 XJ-6, those systems are there just like they came from the factory. My opinion is that they were installed for a reason. I am not an engineer, so trying to outguess them about their reasons for adding a Fuel Cooler or Air Pump is preposterous. It's one thing to ADD improvements like making the sidelights act like turn signals, or replacing the air filter with a K & N filter, or adding seat heaters; But it's another to start dismantling away at the integrity of the engine sub-systems. Why does the fuel need to be cooled? Only they know. It's a Jaguar after all, not a '57 Chevy.
 
My question has more to do with the fact that the fuel cooler is missing on this car already, rather than whether it is beneficial as a performance mod to remove it. I'm going to have to find a serviceable unit to purchase, but was curious why anyone would remove it in the first place.

Were the fuel coolers on this car prone to leaks or something?

On the V-12, there is so much underhood heat that I can see the need for the cooler in order to cool fuel being returned to the fuel tank whenever the air conditioner is on adding additional underhood heat. Is that as much of an issue with the Inline 6?

The parts book that I ordered has not arrived yet. On which side of the engine, and about where, is the cooler properly mounted on the XJ6? I don't see any unused brackets on either side of the engine where it might have been mounted.

Attaching a digital photo depicting location and mounting as it appears on your car to your reply would be helpful.
 
I remember building a "fuel cooler" for a friends drag-racing car... Consisted of a coffe can with a coil of fuel tubing... They'd fill the can with ice before each run. I saw the idea yaers ago in hotrod or car craft magazine and he thought it would be neat to try.
 
Michael, The fuel cooler is installed attached to the air conditioning compressor. It cools the fuel returning to the gas tank(s) by heat exchanging with the air conditioning freon that is still at a cool temperature prior to entry into the compressor. It is used to cool the fuel since the fuel being cycled through the fuel injection system on the intake manifold is exposed to engine compartment heat. If the gas tank is low then there is a possibility that the fuel would heat to temperatures that encourage vapor locking as the heated fuel would be recycled into the fuel injection system at a faster rate. Apparently the gentlemen at Coventry were concerned about vapor locking in the series 3 fuel injection since there is yet another sensor that was added circa 1986 devoted to alleviating vapor locking. I have had little trouble with vapor locking in Alabama summers. Maybe parts of Africa present the problem. With regard to why yours has been removed, they can develop interesting leaks from the freon into the gasoline. Those leaks are very hard to detect. I dont think that the absence of this heat exchanger is a big deal. If your car vapor locks this summer however, I would replace it. Best regards, Jack.
 
I had never heard of a fuel cooler until my XJ-6. it looks like a small receiver-dryer, and frankly I know its there but I have never investigated it much. One of those subsystems that I have no time for. So far no leaks that I am aware of. The day that thing leaks I sell the car. The last time I serviced my A/C was 1999 and it still freezes me in the heat of August. I love R-12. (knock on wood!). Talk about '57 Chevys, the compressor in the XJ6 is a GM A6 compressor, the mother of all compressors. If I had a digital camera I would not mind getting you a pic, but I'm camera-less these days, and besides, you can't really see much of it unless the compressor is removed.
 
On Saturday, I brought the car to the 16th Annual British Motoring Club of New Orleans car show. I was parked beside an 86 XJ6 and was able to compare what was under his hood with mine. The fuel cooler is indeed mounted on the left side of the air conditioning compressor between the compressor and the L/H inner fender well. It is in place right where it should be.

The mounting is much different from the V-12 XJS location on top of the L/H air filter housing. John, You are right about the preferred R-12 cooling capabilities!

Thank you everyone for your comments and suggestions.

Mike Baker
 
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