We have an 03 Dakota quad cab with the 4.7 Magnum. The drivers side exhaust manifold has developed another hole in it. Good old JB Weld sealed the original hole for well over a year. Now, she's got another one (or the original "repair") has failed. Has anyone bothered swapping to headers? I figure if I'm gonna go through the hassle of replacement (girlfriend LOVES the truck!) what's the best bang for the buck?

My 2001 Dak 4.7V8 developed the usual failed stock exhaust manifold crack back in 2014. I bought a used set of Gibson shorty headers that fit in place of the stock manifolds. Had them installed with new gaskets and stainless steel bolts with the anti-loosening lock tabs. Before I had the headers installed I had them shot cleaned and ceramic coated. They were installed back in early Sept 2015, been great ever since. Never loosened, never had to be re-torqued. Never developed any issues, can't say they improved fuel mileage but certainly never made it worse. Power wise it may be a bit better above 4,000 rpm though I don't get there too often. Oh, and I live in Green Bay so in the winter the road salt and brine applied to keep the roads clear are hell on the old Dak but the headers still look good. So all in all it was well worth it. I would do it again.

I can't say that Ive seen "holes" in a cast iron manifold besides cracks, (I guess that's sort of a long "hole") but I too am gonna be fighting a driver side exhaust manifold on a 4.7 once the weather gets better, I recently bought the Lisle drill template kit last week because I found a deal on one/ most are around $125 that I've seen, I got mine for 1/3 of that...
Hopefully the job goes such that I end up not needing to use it. ..
But id rather have one on hand and not need it then to try and find it/wait for it to be shipped etc with the thing already torn apart.
I've wondered about the headers for this application myself but been scared away from them by the ridiculous pricing I've seen on them.

That's why when I found a deal locally on a pair of clean used Gibson shorty headers I grabbed them. I think I paid $150 for the pair. Then the hot ceramic coating was maybe $125. I didn't have the time to install them so I paid a local shop to do the work, I provided the headers/gaskets/mounting hardware. So all total I spent a good amount. But the exhaust issues were gone and none since doing it right way back 30,000 miles back.

I can't do $600+. That's all I'm finding

A little less than $600. https://www.ebay.com/itm/374570519960?

Saw several on eBay "around"that price, too rich for me

Volaredon, it might've started as a crack, but when I got to it, it was hole! I could almost stick the tip of my pinky in it. It's just above the outlet flange. Like you, I'd rather not shell out $600+ for headers, but a Dorman replacement manifold isn't appealing either...But, at 43 years old now, this is my girlfriend's first vehicle and she loves it, so it's gonna get the love it needs to last her a long time. She has mentioned more than once about getting something else to winter drive so it doesn't deteriorate anymore than it has.

It would be interesting to find the cause of the stock exhaust manifold failing. Obviously it takes some years and exposure to road conditions to cause the failure to start. I've not heard of stock manifolds failing in the first few years of driving. Maybe over time the exhaust manifolds degrade/rust and then get splashed on with cold water when hot and "crack". Perhaps buy the Dorman replacements, and get them ceramic coated? Then install the new manifolds with the upgraded stainless steel fasteners with the lock tabs to maintain the torque. Sure it adds some cost but if it makes a reliable leak free exhaust for a lot less than headers it may be the choice.

I'd guess that exhaust manifolds have fallen victim to the whole "make them thinner, make them cheaper" mentality that has taken over all aspects of manufacturing over the years. of all the cars and trucks I've owned over the years I've never replaced manifolds due to failure. I was looking to upgrade performance wise. Maybe I've just been lucky in over 30 years of driving?

Many of the modern exhaust manifold issues have started with failing fasteners. Past that it may be related to the extra weight of supporting the cats, and then dealing with the higher exhaust temps because of the cats. I'm sure the bean counters "cost reduction" and the inexperienced modern educated engineers that design the exhaust systems as a whole also plays into the manifold problems. When this stuff was designed, it was all supposed to be replaced and junked in 15 years or 150K miles.

The modern exhaust manifolds also live in a much different environment then those of 30 years ago.

Big block Chevy's, 351 and 460 Ford's have been plagued with manifolds that were super prone to cracking for years.
Then it moved to the " mighty" (yeah Right) LS motors, and Ford 4.6s/5.4s ... I've dealt with more of those last mentioned engines than I can shake a stick at for the problem... The 4.6s and 5.4s really suck the worst to repair, most other engines I deal with have the exhaust manifold above the frame not directly in line with it. I've done a couple on newer Ford 6.2 gas engines, and on that application compared to the 4.6/5.4, on the 6.2s Ford finally upgraded the stud diameter from 8mm to 10 mm. Much better success getting them apart with no stud breakage, and I haven't seen one 6.2 yet that "pops*/snaps off
the studs in service just from heat/cold cycles like the 5.4 is so common for ...

On the older 318s/360s I've pulled my share of manifolds and I see more busted bolts in intakes than exhaust on these engines. I've never had to drill a single exhaust manifold bolt on a Mopar small block, whether LA or magnum.
I'm hoping my luck with Mopar small blocks continues when I tackle the 4.7 in my Durango this spring. (It ain't gonna happen until then)

Don't think I wouldn't like to replace these crappy manifolds with headers... Id love to. But it won't pay to go with something less than stainless ones if I did.

The Gibson shorty headers I had installed on my 2001 Dakota 4.7V8 had no impact that I could perceive performance wise, or fuel mileage wise. If there is any change it is so slight to be imperceptible. Probably does improve higher RPM power, but I rarely if ever get over 4,500 rpm so again nothing that I noticed.

Seems little results for anything I changed on my Dak, which I bought used with 153k on it, now at 203k. Five years ago I had to pull the plugs checking out a failed coil pack issue. Found that every spark plug had NO visible ground electrode whatsoever, so the "gap" had increased to well over 0.063", maybe more like 0.125". The spark would have to travel sideways from the center electrode to the body of the spark plug. In a sense, the old plugs had retarded the timing slightly. The truck ran fine, started easily, idled smooth, typical Dakota 4.7 fuel mileage. So I thought new plugs would make it even better, maybe better fuel mileage. Nope, no difference that I could perceive. It just runs fine even after 200,000+ miles.

I came close to spending $3300 for custom long tube 42 inches) stainless steel tri-y style headers for a 5.9 Magnum V8 fifteen years ago.

Only reason I didn’t was a family medical emergency tied up my time.

I am now glad I didn’t.

With 20/20 hindsight I wish I had bought a near identical used Ram and spent a few thousand putting a Megasquirt in place of the factory PCM.

If you can find a good used manifold, take it and the one that isn't broken to a competent machine shop and have the flanges milled flat.

The manifolds are green when new and they will try to twist and contort after a few bazillion heat cycles. Because they can't move they crack, break studs or both. A seasoned casting will have done all the contorting it's likely ever to do and a trip through the Bridgeport will square everything up and insure its continued longterm good health.

Kevin

as i have never seen a picture of a factory manifold, does anyone have a picture of one to share ?

dorman replacement


The reviews on the Dorman replacement aren't terrible...I may end up just going that route. If there aren't any appreciable gains to be found with headers, why waste the $$$ ?

I'm gonna get mine off and see what's up before I decide how to proceed

Not my post but, here is where I found this post. I hope this helps you.

https://www.dakota-durango.com/threads/4-7-headers.476373/ and Post #6.

You will get two responses to this question. Some will say NO they dont make a difference and some will say YES they do make a difference.

They are both right!

Short answer is -YES, headers do make a noticeable difference on the 4.7L>>>>> but only IF you address (replace) the restrictive factory "Y" pipe with a high flow "Y". Simply adding headers to a stock exhaust system with the factory "y" pipe does not address the most restrictive point in that system and will make for disappointing gains.

Those who say NO, headers dont make a difference tend to install headers on their 4.7L without addressing the restrictive factory "Y" pipe. Sure they may have added a CAT back system which does little but change the sound and make your pockets lighter... but they are still forcing everything through the restrictive factory "Y" pipe. Very little gains will be noticed if the factory "y" pipe is left untouched.

Those who say YES headers did make a noticeable difference on their 4/7L have replaced the factory "Y" pipe with a high flow "Y" pipe and upgraded to a true 3" single exhaust.

If a customer calls me and asks what they should upgrade on their exhaust system, I ALWAYS suggest the first mod should be to replace the factory "Y"pipe with a high flow "Y" and have it merge into a true single 3" exhaust from the the "Y" back. So you would need a (2.25" dual in / 3" single out) "Y" pipe and then EVERYTHING past that point must be single in single out 3" Pipe/CAT/Muffler...

If you convert your system into a true single 3.0" system with high flow "Y"... adding headers at that point WILL add noticeable gains to the 4.7L.

If you have any questions or concerns please feel free to reach out, I can help you get the most out of your 4.7L.

And now you know the rest of the story...

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