Purpose of Heat Shield?

[Kimber6331]

My XJ has had this heat shield since I've purchased it. Just trying to figure out what is the purpose, obviously besides looking awesome:thumbdown: . Where there any recalls for 01 XJ? Common problems? Anyone know what this is for? thanks guys.


http://picture.vzw.com/mi/554074214_1962368476_0.jpeg?

http://picture.vzw.com/mi/554071985_1962360016_0.jpeg?

[4.3LXJ]

Love to answer, but the pics are not showing up.

[Kimber6331]

ill try again

[Kimber6331]

Its showing up for me now

[4.3LXJ]

Kimber

The best way to post pics is to use a free website called Photobucket. Once you get your account established, and you are ready to upload pics set your preferences to a 15" screen. That will probably reduce them automatically so they will fit everyones screen. Then put the mouse icon over the pic and a menu will drop down. Copy and paste the image code into your post and it will show up.

[Kimber6331]

This better?

http://i985.photobucket.com/albums/ae332/Kimber6331/xj2.jpg?t=1280940319

http://i985.photobucket.com/albums/ae332/Kimber6331/xj.jpg?t=1280940319

[4.3LXJ]

The purpose of that shield is to keep heat from your exhaust manifold from boiling the gas in the injectors and fuel line. If that happens, you get the famous "heat soak" misfire on start up.

[Kimber6331]

Thank you I had no idea. What if i bought aftermarket manifold or replaced it, would that be enough to remove the shield or does it not matter what type of manifold I have Ill always need it? How long do you think would it take for the heat soak to cause a misfire? When your starting up or after you've been driving a little while? Apologies for so many questions I am just trying to learn.

[4.3LXJ]

The heat soak is a common problem that occurs after the exhaust manifold has attained operating temp. When the engine is running, it is not a problem because gasoline is constantly moving through the system, except on the 96 and up models. They do not have a return line, so if there is vapor in there it either needs to recondense, like when the engine compartment cools or purged through the injectors on start up, which causes a misfire for a little bit. A new intake would not solve the problem, as it is caused by exhaust temps and fuel rail design.

[Kimber6331]

Well that was genuis design. hah. OK thanks man I appreciate it. Just wasn't sure if it was necessary, but now I do.:thumbsup:

[Mudderoy]

Well that was genuis design. hah. OK thanks man I appreciate it. Just wasn't sure if it was necessary, but now I do.:thumbsup:

Specifically for the heat soak problem, which may not be your issue, I read that once a Jeep XJ owner put in some vent hoods the problem went away. This made sense to me because this would allow some of the heat, and it does get quite hot under that hood, to escape.

I don't know how you feel about cutting up your hood, I found it scary :smiley-laughing021: but you can make this modification easily and cheaply.

One hood vent modification that I really thought was nice was done by an xjtalk member McJCRod. There is a full right up in our articles area. You can find it on the home xjtalk page, or just click this :link: (http://www.xjtalk.com/showthread.php?t=2033)

This may not cure your starting problem but it won't hurt and certainly won't cost you much in time or money. :thumbsup:

[Kimber6331]

I did read hood vents might help. Thanks alot ill def look into it. I gotta do what I gotta do I cant keep stalling on side of the road couple times a day

[Kimber6331]

Someone brought up that one of the reasons for the excessive heat is due to the two-piece cat exhaust the 00 and 01s have. What if i replace the two part cat with a single part cat? Do you think that would make a difference?

[4.3LXJ]

The cats are underneath. The heat soak problem is from heat under the hood. Might help the floorboard heat though. The addition of a heat shield above the cats would help too.

[Kimber6331]

ok. I know where cats are the guy just made it seem like the two part cat was making the manifold hotter than normal thus needing a heat shield. Buuuut i dont know if he knew alot of what he was saying. ..

So is there anyway besides hood vents or raising hood that i could do something to reduce the need of the heat sheild? bring down temp?

[4.3LXJ]

Vents are the only real way. I would caution you against raising the back of the hood. This can be very unsafe, or even lethal in an accident. Check out a post here from a guy that made some very nice looking hood vents.

http://www.xjtalk.com/showthread.php?t=2007&highlight=hood+vents

[Kimber6331]

that actually looks pretty nice. thanks for the link