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Unread 11-11-2008, 09:15 AM   #1
chocflip201
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1988 YJ Wrangler 
 
Join Date: Mar 2007
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Reduce Underhood Temps- Exhaust Wrap

Like many of you out there with the 4.0 I6, high-under hood tempuratures are a factor in the overheating of your engine, resulting to shortened engine life and frustration with your Jeep! This problem has lead to undesired modifications such as finding a place to add another electric fan, or even worse, cutting holes in your hood for hood louvers to let the hot air escape! There is an easy, effective, cost efficient fix to this problem all together- just don't let the heat happen! The stock 4.0 Exhaust manifold is a pretty easy item to tackle. In this Write-up I will show step-by-step procedures, along with a total cost of supplies and time frames of engine down time.

Starting out- Pulling off the exhaust manifold comes off pretty easy. The Intake manifold and the Exhaust come off of the engine in one complete assembly. Disconnecting vacuum lines first, amd the air filter assembly, along with fuel and wiring harness gives you access to the bolts holding the manifolds to the engine block, after removing the bolts, you should end up with something like this-



Undo the metal tube going into the bottom of the EGR valve (the tube holding the Exhaust to the Intake, and it will separate itself. My exhaust has its fair share of Oxidation (Corrosion due to heat and gases, commonly mistaken as rust) but overall, its in good condition, no holes, no cracks, just brown!



Remove the O2 sensor, and for best results you should sandblast the exhaust. I had access to a sandblaster with 40 grit sand (removes material very quickly) but quotes from local shops were around $10-20 but its well worth it in the end. After sand-blasting it will look like this.



Now for Coating. There are a few different options out in the market. If this was going to be a show-rig I would opt out to have http://HPC.com (located in Utah) coat it with their ceramic but that just wasn't in my budget so I chose the rattle can method bought at the local car-parts store. (Different colors available such as Black, Dark Grey, Flat aluminum, Red and White, along with Different heat ranges from 1000 degrees to over 2000.) I Chose the Flat Aluminum, during painting I had to be cautious to make sure that I covered every surface because the paint color was almost the same color as the metal after sandblasting. All finished painting-



As per direction on the Ceramic Coating rattle can, the exhaust needed to be baked at high tempuratures to cure the coating and to make it chemical resistent. A local Powdercoating shop baked it per directions on the can for $20 and took one night.


Reduce Under Hood Temps- Exhaust Wrap
Now it was time for the pipe wrap, as I understand the Ceramic coating helps retain the heat inside the pipes versus no coating, but I wanted to go a step farther to really keep the heat inside my exhaust, and not inside my engine bay. Most car part places should carry the supplies you need. My options were some 2" wide black tape and some 1" wide cream-colored tape. although I would have preffered black, I thought the 2" wide tape might be a little more difficult to work with the sharp bends so I purchased the 1" wide tape. Along with some Stainless Steel locking ties (like plastic cable ties, but wont melt! and beware, these things hold together and do not release! so don't push the end of one in thinking you may be able to get it undone, I Found out the hard way. I also purchased some Silicone spray to go over the tape after it was all wrapped to help aid in the chemical resistance and durability of the tape itself.



Starting wrapping- Following instructions provided with the tape, I measured and cut strips of the tape and soaked them in water to loosen up the fibers of the tape and make them more pliable. Here are the lengths of the strips I cut. Cyl 6- 85"... Cyl 5- 70"... CYL 4, 3, and 2, - 63". and Cyl 1 was left uncut of the rest of the roll to make sure I had enough to complete the project. Start at the upper side of the exhaust (towards the engine block) and work your way towards the collector, wrapping very tightly (tighter the better as it is less likely to come unwrapped) and overlapping the previous wrap about 1/4". Here are pictures of cylinders 6 and 5 wrapped (before I soaked the wrap in water to make sure I had enough to reach main pipe)






After I was sure I had cut the strips long enough I unwrapped them and soaked them in water for a few minutes, and started wrapping, starting at cyl 6 and working towards cyl 2. remembering to wrap very tightly.

All Cylinders are wrapped now except for number one and the main pipe as I will be doing them with one solid peice of tape.



And finally, wrap cyl 1 and the main pipe starting at the flange closest to the engine block, and working your way down to the collector making sure to overlap all of the ends of the other cylinder pipes to keep them from coming undone. Use the Stainless steel locking ties on the ends of all tape to keep from unraveling and you will end up with a finished product like this! Your color may vary but if done correctly it will drastically decrease your underhood tempuratures, aiding in the overheating problem.



Wait for the wet wrapping to air dry and reinstall the manifolds back onto your engine! Here is a cost breakdown, your cost may vary slightly depending on access to a sandblaster and cost of supplies.

Sandblasting- Free
Ceramic Exhaust Coating- $6
Baking and Curing coating- $20
Pipe Tape- 29.99 (for 50' roll. I had about 2' left over)
Stainless steel ties- $5 for a 8 pack.
"Optional" Silicone spray- $7

Total- Should cost you around $70. And can be done in 2 days.

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Unread 11-11-2008, 01:40 PM   #2
archimeech
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Fantastic idea. I have a question and a suggestion.

1. suggestion: If you're in need of a new exhaust manifold that's the best time to do this operation. Before you replace it, you can prep the new one in this manner and save the down time on your engine.

2. question: The floor boards get pretty hot all ready, now that you have yours installed do you notice any more heat in the area of your feet? This would be the first place along the exhaust line that wouldn't be covered and I'm guessing that a lot of the heat that used to excape in the engine compartment is now under the floor boards baking the underside of the tub? If so how do you take care of that heat issue?

thanks for the article, very good, well thought out and good pics to go along with it.
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Unread 11-24-2008, 08:05 AM   #3
Recoil
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I did this to my new pacesetter header and all the fiberglass did was become a sponge for everytime i hit deep water and seriously my two month old header rusted so badly one of the pipes fell out. So I had to replace my two month old header...Its great for heat but not if you do any water crossings
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Unread 12-28-2008, 09:12 AM   #4
josh9465
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i too did the heat wrap on my stainless steel header. it rusted so bad and the tape became so brittle it fell off in chunks. eventually the header cracked and had to be replaced.
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Unread 12-28-2008, 02:59 PM   #5
cathleen
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heat problems

Not sure why your having problems? We have 97 with the il6 lifted with 31's and it always runs the same.
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Unread 12-28-2008, 03:00 PM   #6
cathleen
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heat problems

Not sure why your having problems? We have 97 with the il6 lifted with 31's and it always runs the same with 160k runs like new
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Unread 02-04-2009, 08:40 PM   #7
Marc10
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wow pretty sick man any outcome?
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Unread 02-12-2009, 12:48 AM   #8
gojeepgo
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I did this to my headers and my exhaust all the way back to the muffler in my CJ. Awsome. It dropped the under hood temps. I did the exhaust because I didnt like how close it came to some of the fuel and brake lines. Dropped the temp a lot ont pipes. I can touch them after the Jeep is running without getting burnt. Worth it 100% in my book.
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Unread 03-23-2009, 05:12 PM   #9
SimonsTJ
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i dont have experience with header wrap on a jeep, but on the formula sae team at my school, we used header wrap on the race car until we realized that the header wrap keeps the heat in the pipe and our exhaust got so hot that we managed to crack our titanium header. After discovering this, we talked to a guy at a custom motorcycle shop in the area who said that it was almost unheard of to use header wrap on bikes. The high temps in the pipes tend to make them brittle and susceptible to cracking.
hope this helps
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Unread 05-13-2009, 02:48 AM   #10
kudzu35
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A lot of bikers use heat wraps on their exhaust to keep the heat in the pies as 1997TJWrangler mentioned. That heat has to go somewhere and hopefully out the back of your exhaust but it will radiate within the pipes. I imagine the reason why his headers cracked is because of the high performance engine and RPMs that come out of a racing engine. With water, yes you're going to trap the moister under the wrap and over time it will corrode the work you did so fording may be out of the question if you do this. This is common with bikers who wrap and wrap but forget that over time despite the air cooled engine/headers you still have rain that the bike was in, washes, and the constant high RPMs.

Its a choice to make. I see the benefits with wrapping in reducing exterior heat radiation which affects overall immediate performance but what about the long term affects? Hopefully the OP will let us know. Great job on covering all the bases with removing the oxidation and applying a preventive coat, despite the rattle can it looks very professional and definitely would work. I'd be interested in knowing the affects of using it over time and in what conditions.
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Unread 06-10-2009, 02:57 PM   #11
BowtieNut
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I see that this is a little old, but in case anyone reads this in the future, I just want to make sure they make an informed descision. I've always heard that header wraps are BAD NEWS!!! They keep TOO much heat in, and the header can't handle it, and will crack. And from what I hear, the Jeep 4.0 header is already a little prone to cracking. I know, the first time I heard that I was like "whatever", but I've read plenty of articles since then that have changed my mind. In fact, most header manufacturers will VOID the warranty if there is any evidence that header wrap was used. Here's one article I managed to go back and dig up http://www.centuryperformance.com/ex...e-spg-138.html

I'm not saying there may not be benefits to it too, but to me the drawbacks are far worse. You make your own descision on your Jeep, but hopefully make an informed one.
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Unread 07-08-2009, 03:32 PM   #12
fitbmxseries1
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Quote:
Originally Posted by sgv209 View Post
i dont have experience with header wrap on a jeep, but on the formula sae team at my school, we used header wrap on the race car until we realized that the header wrap keeps the heat in the pipe and our exhaust got so hot that we managed to crack our titanium header. After discovering this, we talked to a guy at a custom motorcycle shop in the area who said that it was almost unheard of to use header wrap on bikes. The high temps in the pipes tend to make them brittle and susceptible to cracking.
hope this helps
most every one i know with street bikes has been wrapping their pipes. I have a full TI exhaust on my kawi and its been wrapped for 3 years with no problems. Also the hotter your exhaust the faster it flows, the faster it flows the better MPG and power you get. So trapping the heat in the pipe is a good thing and i rarely hear of any pipes getting too hot unless your running lean or a cat or somthing is plugged up. I think that header cracking was just a manufactures defect when it was being welded up.
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Unread 12-16-2009, 03:25 AM   #13
Deezelweazel
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Quote:
Originally Posted by josh9465 View Post
i too did the heat wrap on my stainless steel header. it rusted so bad and the tape became so brittle it fell off in chunks. eventually the header cracked and had to be replaced.
What kind of stainless steel was that???
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Unread 12-17-2009, 02:03 AM   #14
josh9465
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Quote:
Originally Posted by Deezelweazel View Post
What kind of stainless steel was that???
the stainless steel that rusts. made in china i suppose.
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Unread 10-28-2010, 10:33 PM   #15
Sunnygrill
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hi

would this wrapping cause prmature rust due to remention of water. I've done it before and it rusted the metal a lot faster. my 2 cents
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