On every one of our current and previous vehicles, I've cleaned the engine compartment a couple of times a year by spraying it down with a can of Gunk Engine Brite, letting it soak for 10 to 15 minutes, and then hosing it off briskly with as minimum an amount of water as possible (not even 60 seconds' worth). I've thenclosed the hood, immediately cranked the engine, and allowed it to run for about 5 minutes to evaporate whatever water droplets may remain.Never had a single problem with any vehicle using this procedure.

But withall the ignition coil problems I read about on theseJag forums and knowing that the electronics modules in my 2005 S-Type 3.0 are far more complex than any of my other vehicles, I wonder if spraying the engine compartment down with Gunk and then hosing it off could createa myriad of problemsin this car.

Is itsafe to Gunk-and-hose this engine compartment a couple of times a year, or is there a better way to cleanit that involves far less risk?

 

This is an anecdote that generally applies to your question, but I don't have specific experience with your model.

The first XJ8 engine swap I did was complete, and as a final step before returning the car to the customer I decided to wash the engine bay. Immediately afterwards, I got a check engine light and retrieved trouble codes for both of the knock sensors. I cleaned and dried the connectors, cleared the codes, and the CEL immediately reappeared with both sensors flagged. I removed both sensors and cleaned them and the mounting studs and face of the block where they contact. Refit, restart, same codes. I replaced one of the sensors from the core engine, restarted and now had a code for only the remaining sensor. I swapped that one also, and never saw a knock sensor code again from that car or any other XJ8 I have serviced in the several years since.

Ihaven't washed an engine since, either. WD 40 on a shop towel and lots of elbow grease will get you there, compressed air is safe and effective if you have access. I'm like you, I hate doing things and finding out later it was a mistake.

 

Thanks for your input. I'm leaning more and more towards staying away from washing my S-Type's engine compartment. Too many potential problems given all the complexities of the electronics in this car.

It will be interesting to see what others have to say about this topic, pro or con....

 

I had a momentary problem after going through a car wash with an undercarriage cleaner. I stay clear of those now. I wound up with poor engine performance and a misfire, albeit only for a short time until it dried. I now usse my elbow grease to clean my engine and decline the undercarriage wash while at the car wash. They are beautiful cars but tricky sometimes.