Jaguar Repair: 1985 Jag 4.2 XJ6 Overcharging / Fuel in Oil, voltage drop test, jaguar series

Question
First, the volt gauge runs high in the red when the vehicle is started from cold then drops down after a few minutes.  However the needle returns to the red at any time during driving.  Two alternators in 4 years as well as two batteries and the problem still exists.  I just replaced the 2nd battery with the third yesterday after Interstate determined that this battery was bad after only 4 months use.  I was reading the Jaguar Series 3 manual regarding testing, however there is a very limited trouble shooting section and nothing with regards to this matter.  Secondly, within a normal 6 month period between oil changes, about 2 quarts too much oil appears to be in the pan, but this oil smells of heavy fresh gasoline and looks like a chocolate shake.  How may I be getting fresh fuel mixed in with the oil??  Wonderful site, by the way.  Thank you, William.

Answer
Hi William,
The alternator circuit is simple and you must do a voltage drop test on each wire including the power cable on the battery and the ground cable to the body and the engine to frame cable. Also you need to use "Deep Charge" batteries (diesel batteries) in a series III car. If you don't have a good diagram for the charging system let me know and I will put one up on my web site for you to copy.

As for fuel in the oil in a ser III car, first check the vacuum hose to the pressure regulator for fuel. A broken diaphragm will leak raw fuel into the intake depending on how the vacuum line is routed.

The only other way I can think of is for your car leaking fuel into the oil is if you have one or more injectors that leaks down the residual fuel pressure into the combustion chamber each time the engine is shut down. To test you need to remove all injectors and attach them to the fuel rail and activate the fuel pump to system pressure with no vacuum.
(About 42 PSI)

Howard