A friend's wife's V8 4Runner has the very common cracked manifolds. He wants to trade a lot of tile & custom shower work for the manifold replacement. I know the best are the Thorley's but will the Dorman's be good & last?
A friend's wife's V8 4Runner has the very common cracked manifolds. He wants to trade a lot of tile & custom shower work for the manifold replacement. I know the best are the Thorley's but will the Dorman's be good & last?
Dorman basically re-casts the factory manifold but with a different alloy that lasts considerably longer.
They are the go-to replacement. Good stuff.
Cool thanks Curtis. My son says get the Doug Thorley's. But they don't care about increased power & i know they don't want the issue of no pre-cats.
Curtis73 (Forum Supporter) said:Dorman basically re-casts the factory manifold but with a different alloy that lasts considerably longer.
It is my understanding that Dorman uses factory casting molds for various products. I was not aware that they changed metallurgy on any of their parts.
The alloy comment came from Dorman. Its possible that they use simply a different alloy and not a better one, but they advertise it as a better alloy.
The factory F150 passenger side manifold on my 5.4L lasted until 70k, and the Dorman that replaced it lasted until 223k so at least there is that anecdotal single example.
The castings are slightly different. I can't find a picture right now, but I noticed the factory manifolds had kinda squared-off pads above the bosses and the dormans didn't. Makes me wonder if they copied but changed it enough to skirt forgery laws.
TL;DR... Dorman makes very good quality factory replacement things.
Ih8mud.com and GXor (GX off road, the Lexus version) universally pan the dorman replacements as only lasting a short time before cracking themselves...no personal experience, my manifolds ('07 GX w/80k miles) don't leak/haven't cracked yet. Not sure what my fix will be when (not if) it happens...but there you go.
R
I always swap (quality) headers on when replacing cracked manifolds because I don't want to do it again.
Other than that, the foundry that re-casts manifolds for us when we need them makes them from ductile iron rather than cast iron. They claim it holds up far better and so far it's been fine. The fellow I deal with there said that it's pretty common procedure in their industry.
Just did the ones on my Sequoia (same ones). I got the JMAs and they fit fine.
It was NOT a fun job at all. Hope her 4Runner is less rusty than mine.
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