Dorman exhaust manifold cracked in 3 months.

[Colorado4]

08 Jeep Wrangler JK exhaust original exhaust manifold cracked at 54,000 miles.

Replaced with Dorman exhaust manifold, cracked in 3 months, 3100 miles.

Stock mopars on back order until June.

 

[wayoflife]

Bummer. More than the lack of power, one of the things I really hated about the 3.8L was the manifold cracking all the time.

 

[Cousin Clyde]

08 Jeep Wrangler JK exhaust original exhaust manifold cracked at 54,000 miles.

Replaced with Dorman exhaust manifold, cracked in 3 months, 3100 miles.

Stock mopars on back order until June.

I imagine Dorman would replace it for free. They seem pretty reputable. Maybe had a QC issue with a bad casting. Is it a cast part?

 

[monstrousmac]

So I found a way to prevent it. At least it worked for me and I know it sounds crazy but hear me out. I have changed 3 out on my 2010 JKU, I went to a local exhaust shop here in Tucson AZ. The technician who is a friend of mine installed a new one, I believe he got it from NAPA, so I am unsure of the brand, but he took of the installed heat sheild that comes attached. He said he has found when you remove the heat sheild for what ever reason they dont seem to crack. My 4th one has been on for the last 65K miles and still has not cracked, knock on wood.

 

[JimLee]

Unfortunately, Doorman products in my experience are hit or miss in quality. I've woked at a few of the auto part retailers (part time while I was in the military and stationed stateside) and Doorman products were almost always one of our highest return items. I'd love to go to their aluminum oil cooler on my JL, but worry that might actually be introducing a problem.

 

[Cousin Clyde]

Unfortunately, Doorman products in my experience are hit or miss in quality. I've woked at a few of the auto part retailers (part time while I was in the military and stationed stateside) and Doorman products were almost always one of our highest return items. I'd love to go to their aluminum oil cooler on my JL, but worry that might actually be introducing a problem.

Interesting. Appreciate the experience. I have no previous experience with them. I’m hoping for the best on this damn oil filter housing.

In steel construction equipment, I’ve definitely handed some brand new equipment back to my vendors because I can see visual impurities in castings. New one comes, looks clean, no problems.

Sounds like this problem may also be inherent to the ol 3.8 regardless of manifold manufacturer???

 

[JimLee]

Interesting. Appreciate the experience. I have no previous experience with them. I’m hoping for the best on this damn oil filter housing.

In steel construction equipment, I’ve definitely handed some brand new equipment back to my vendors because I can see visual impurities in castings. New one comes, looks clean, no problems.

Sounds like this problem may also be inherent to the ol 3.8 regardless of manifold manufacturer???

Yea, the 3.8 seems to have a rep for eating those manifolds. I don't think all the Doorman stuff is bad, but form what Ive heard they farm out most of their manufacturing to many places, and they make a million things, thats probably why the quality doesn't seem very consistent across their products. Let us know about the oil filter housing, I'm still interested in the one they make for the 3.6, luckily I haven't been forced to make that decision yet

 

[Colorado4]

Well the dorman replacement lasted 4 months this time and has since cracked... At this point I will try the suggested method above and remove heat shield.

 

[jeeeep]

on my 2010 JKU I've used dorman, crown, omix-ada all cast iron, all have cracked.
I've driven the JKU about 500 miles since they were last replaced, and the driver side is already cracked.
Mopar has discontinued the manifolds for 2007-2011 3.8L
Thinking about spending the extra money for ductile iron manifolds from AFE

 

[GP NOIR]

What about tube headers?

 

[Colorado4]

I thought of stainless but heat tends to melt plug wires. I saw the dorman instruction sheet and it says "correct mounting surface runout prior to installation or new manifold cracking will recur." I suspect mechanic thought it was a normal replacement and did not bother correcting surface as instructions said. That's prob a clue.

 

[jeeeep]

What about tube headers?

I tried a set of Gibson headers, aside from melted wires which I replaced and wrapped with heat sleeves, my JKU never ran smooth and removed them after 200 miles. I figured that was ample time for the relearn curve.

 

[Bierpower]

Anybody have any experience with these?

BladeRunner Ported Ductile Iron Exhaust Manifolds

Bolt on instant performance by upgrading your restrictive factory manifold with this BladeRunner ported manifold. Designed to outflow the stock manifold by 12% for improved throttle response, this BladeRunner manifold has both the inlet and the outlet ports machined for a smooth transition and...

afepower.com

 

[jeeeep]

Anybody have any experience with these?

BladeRunner Ported Ductile Iron Exhaust Manifolds

Bolt on instant performance by upgrading your restrictive factory manifold with this BladeRunner ported manifold. Designed to outflow the stock manifold by 12% for improved throttle response, this BladeRunner manifold has both the inlet and the outlet ports machined for a smooth transition and...

afepower.com

I'm thinking of trying those, as much time and money as I've spent on all the other crap if these last a year it'll be worth it.