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Chinese exhaust manifold


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After 10 years of daily driving I had to be towed home for the first time.. One of the plugs on my manifold worked its way off. I heard the exhaust leak and traffic was bad with no shoulder at that part of the freeway.so after 10 minutes of driving I pull over and my distributator cap is half melted. If you have one of those eBay manifolds that have the 2 plugs in them for the variations of our egr configurations. Check those threaten plugs they do work there way loose..

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No, the 720 4x4 had two AIV (air induction valve) pipes from the air filter housing to the exhaust manifold. It works using the vacuum pulse behind every exhaust pulse to draw air into the exhaust so the catalytic converter can burn the emissions. The air filters had one way reed valves so air only moves one way. Two wheel drive tend to have only one pipe.

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Racerx, that was my first thought.I've pulled at least 5 manifolds this year and everyone of them had the same cracking on the back side of the manifold.

Bummer !!

Yep factory z manifolds all seem to crack along that back side. I ground one out and welded it up recently. It took a few tries to keep it from cracking, but i got it. I haven't run it yet though so it could definitely crack again.

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I can see why you would ask that.. This exhaust manifold from China via eBay is the 2nd one I've gone through in 4 years. The original nissan manifold lasted 29 years.. The ones made in China last 2 years .. I'm speaking in regards to the quality of the manifolds sold on eBay for our trucks.. I'll keep pulling manifolds at pick your part and ecology until I find a uncracked one.

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Is there anything wrong with having a machine shop weld up a cracked manifold?

No, but as Mike stated it takes some skill that might be expensive. I preheated mine with an oxy-propane torch, kept the torch in the manifold heating the area while my buddy welded, then continued heating the welded area as i slowly turned the torch down. I took about 15 minutes to go from full heat to turning off the torch. That was my 4th try to weld it including preheat and post heat but it cracked each time.


Mike had also posted the genius diy option of drilling a hole, threading it, then putting in a bolt. Cut off flush then do it again slightly overlapping the first bolt. Basically threaded stitches to close the crack.

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