Several questions about my '98 Cherokee XJ:

1. My Jeep has been making a hissing noise upon start up, its only lasts for a split second. Since I'm a college student my Cherokee sits on my driveway at home monday through friday, until about friday night when I get home crank it up and then drive it around on the weekends. The issue I have is that I don't know which causes this to happen the sitting for almost a week or something mechanical.

2. I really want to get all the mud, dirt, and grime out of the engine bay, I tried A gunk remover but that didn't help me at all. Any suggestions for anything stronger than that that works really well?

 

If it is just prior to start (like when you turn the key to "on"), it is probably the fuel pump priming the system. You may want to check the fuel rail to make sure you don't have a leak there.

You can always have the hood up while someone else starts the jeep for you. That may help you pinpoint the source of the hissing.

G

 

check if you have the a/c turned on, my old vehicle would always hiss when i turned the a/c on and hiss when i turned it off. ended up being a leak.

edit to ad, grab a dust pan brush with some firm bristles, any grease cutting soap, simple green, purple power, even dish soap, bucket and time, scrub a dub dub.

 

I don't think its the fuel pump priming because that is usually a really quick whirring noise I hear from the back of the Jeep. I really hope it is not a seal issue, and it is very unlikely that it is simply because the engine has 30,000 miles. But I think tomorrow that when I get home to start it up I will pop the hood and have someone else start it up for me while I listen.

 

I also don't think that the A/C is the issue because I always switch all my dials to the off position. My A/C compressor was recently replaced when I bought the Jeep.

 

Thanks for the input so far guys, however I think I can safely rule out both the fuel pump and the A/C, however the fuel rail may still be suspect as the problem. Again appreciate the input so far, but keep the suggestions coming.