4.0 Engine OEM manifolds - beware! - JeepForum.com
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Unread 03-18-2013, 04:23 AM   #1
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1996 ZJ 
Join Date: May 2012
Location: Yarraville, VIC, AU
Posts: 413
4.0 Engine aftermarket manifolds - beware!


Just wanted to share some negative experience.

First of all, my old manifold developed a crack, as it often happens. I noticed it from the ticking noise which became louder under load.

I was stupid enough to try welding it. Sure, my welds held well, but a month after it cracked again in another place. Fault by design, I presume.

So, I got an aftermarket Ebay kind of a manifold, $100 variety with bellows on sides. Hundreds of them for sale, $80-$120 with free shipping. Pulled the manifold second time.

First of all, I had trouble fitting it on. It just didn't want to go with intake manifold in place. When I (long after) pulled the gasket, found that one intake port and exhaust port were sitting right next to each other. Some grinding on the exhaust ports would have sorted this out.

Anyhow, I jammed it on. Shortly after fitting - surprise! Ticking is back again.
Pulled the manifold, for the THIRD time - found the reason. The ports on the aftermarket manifold don't sit where they're supposed to sit! Gasket holes didn't overlap properly with the manifold, and the gasket just blew in the thinnest place - wasnt even a hairline worth of gasket there.

Anyway, just an advice: check fitment with your gasket too, check how much actual gasket you have between the inside hole in gasket and the outside edge of the por! Don't just assume it's done properly by the manufacturer, since it's all made in China and they don't give a crap.

manif_welded.jpg   cracked_again.jpg   manif_new.jpg   manif_new_1.jpg   manif_new_2.jpg  

Last edited by shaban; 03-18-2013 at 04:59 AM..
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Unread 03-18-2013, 05:24 AM   #2
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1993 YJ Wrangler 
Join Date: Jun 2012
Location: Fairbanks, Alaska
Posts: 64
Borla, expensive but worth it in my opinion. Have had mine for 10 years and 125 thousand or so miles, have 875 thousand more till the warranty runs out !
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Unread 03-18-2013, 04:57 PM   #3
2004 TJ Wrangler 
Join Date: May 2008
Location: Lake in the Hills, illinois
Posts: 2,044
First thats not an OEM manifold. Its a cheap Chinese replacement. Do a search for the ones that last and have good fit up.
I weld the cracked ones Ive had with excellent result, though it takes 3-4 hours to clean-weld and normalize after welding.

Of all the things Ive lost
The one I miss most is my mind

Its like a fart in a windstorm
It smells good but thats about it

Registered Six Offender
Home of the Buzzin Half Dozen
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Unread 03-18-2013, 09:18 PM   #4
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1996 ZJ 
Join Date: May 2012
Location: Yarraville, VIC, AU
Posts: 413
Yes, I figured that's not OEM later, just don't know how to change a thread name now.

Anyway, regarding the welds - mine held well until it cracked in another place (where cylinder #4 pipe joins bigger pipe). Could have welded this one too but decided to go for a new manifold.

I'll be redrilling some mouning holes in this chinese manifold to ensure a better fit.
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