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Old 01-09-2016, 04:59 PM
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How common are the broken manifold bolts?

Out of curiosity, how common is it to have the broken manifold bolts?

I bought my 2005 5.7L Jeep used with 110,000 miles. I have no idea if they have been replaced. Not sure if this was a huge problem or if only a few here and there had issues.

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Old 01-09-2016, 09:04 PM
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Re: How common are the broken manifold bolts?

Very common. It's not the easiest job to replace them (tight fit between frame rails and exhaust manifolds) but, it is doable and, n most cases, they break in such a way that the part stuck in the head is relatively easy to get out. I would recommend tracking down a better quality stud or use some stainless steel bolts with wedge washers to keep them from coming loose or breaking again.

Loose exhaust manifolds, if bad enough, will cause a big hit on fuel economy. If left uncorrected (and the leaks are bad enough) for a long period of time, it is possible to ruin your catalytic converters. Also, if you end up taking them off, with the miles you have on yours, it would be a good time to change (at a minimum) the before cat. O2 Sensors. That way you wouldn't have to rip into it again sometime down the line. Normally, O2's start losing efficiency as soon as 50K (I had a bad one at about 60K) and probably should be changed around 100K. See this thread: Oxygen Sensors and Their Role in Engine Management--A Primer
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Old 01-10-2016, 09:49 AM
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Re: How common are the broken manifold bolts?

Thanks for the info. I am debating on if I want to take the plunge and get the ARH headers and then replace the O2 sensors in the process. Headers are a pain to install, not sure if I am ready for the pain. I have a flashpaq and am not sure if the tune on it will work with the headers. Any idea?
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Old 01-10-2016, 03:20 PM
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Re: How common are the broken manifold bolts?

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Originally Posted by hound View Post
Thanks for the info. I am debating on if I want to take the plunge and get the ARH headers and then replace the O2 sensors in the process. Headers are a pain to install, not sure if I am ready for the pain. I have a flashpaq and am not sure if the tune on it will work with the headers. Any idea?
Any tubular header will be a BIG improvement over the stock highly restrictive logs. Yes, they'd be a PITA to install, but so would the R and R of the stock manifolds to fix your problem. With the ARH headers (I assume they're for a 6.1 and are long tube) you'll have to do significant mods. to the "Y" pipe anyway. At that time I'd have the muffler shop move them to a more accessible place like my guy did when he built my custom headers.

As far as the exhaust working with your tuner, it's not a problem. I have an aftermarket cam, both SC and DS tuners, and a bunch of other mods. and both tuners work fine. It's the stock tune, after the mods., that doesn't work very well......too much power causes the transmission to work much worse that it normally does with the stock settings and the idle is too slow for the cam. If I were to have left my transmission settings stock after all the mods., I for sure would have already had to replace it. With the stock shift schedules and torque management settings, it's totally inadequate.
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Old 01-10-2016, 04:48 PM
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Re: How common are the broken manifold bolts?

The headers from ARH are made for the 5.7, not the 6.1. They bolt up to the factory or aftermarket cat back exhaust. No trimming the tranny or anything as I understand it.

I am pretty sure I could do the header install on jacks in my garage. The part that worries me is finding I have broken manifold bolts and I don't have a welder to get the bolts out of the head. I would then need to have the Jeep towed to a shop.

That is where I started to look at doing heads/cam at the same time. As I add up all that is needed though, it is getting rather expensive. So far parts alone would be close to 6K + install. Sure, I would love to have another 100+ HP but hell, 8K would be nearly what I paid for the Jeep. I still have plenty of time to decide on what to do. I will check those manifold bolts and see if they are broken or not. If they are good, I will probably just do the headers and be good with it.

I see people using a torch to get the stock manifold bolts out. Is this necessary? The torque spec is only 18fts/lbs and they have thread locker on them. Has anyone found them difficult to remove without heat?
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Old 01-10-2016, 05:38 PM
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Re: How common are the broken manifold bolts?

It's my understanding that, in most cases, the studs break away from the head and not flush with the head. If this is the case, they're relatively easy to get out. The ones broken flush would probably need an easy out to free them.

On all of your mods., the biggest expenses should be the headers/exhaust system, and the heads. IMO, bigger heads with a stock rotating assembly are not worth the $$$$. That's why I haven't done it. Heads run ~$2000 and will only give you about an additional 30 hp.......if you already have the cam and header back exhaust. Heads alone, without the better cam timing and better exhaust probably wouldn't give you more than 15 hp, if that. The flow through the bigger heads is only about 25-35 cfm more than stock ones. The whole object of the bigger heads is to help the engine breath better, but with all the "good breathing" components in front of the combustion cycle, and all the choke points/restrictions with the cam timing and exhaust behind it, you'd only be doing a little less than half the job, IMO.

Headers/complete low restriction exhaust should easily be a little under $2000 (I paid about $1400 six years ago) and the cam/kit is easily under $1000 (I paid a little over $600 about 4 years ago) and, if you can't do the work yourself, you would have a hefty installation bill. I did all the work myself, except for the exhaust system, which no doubt saved quite a bit.

You'e right though, with the vehicle continually depreciating, big mods. do seem a little useless, unless you're like me and keep your vehicles forever......as long as they remain in good shape. I've had my 05 Hemi LX for almost 12 years now (bought new and one of the first ones out) and, at just over 71K, it is still like new and modded just like the WK. I've had the WK a little over 6 years now (just turned over 100K) and it is still in excellent shape. Since I haven't messed with the WK for a couple years, I am even toying with the idea of putting a low boost (about 5 PSI) supercharger on it. My only real problems are justification to the wife and getting past the price....nearly $7000 for about 100-125 more hp. If I could find one for around $5000, I'd probably be more apt to give it a try. I am on the lookout though.

You're not that far from me, so I am guessing your weather isn't a whole lot worse than ours. If the road folks don't use salt on your roads, you'd probably not have the problems some of the folks have back east. Here they only use sand and de-icing fluid, but we don't usually get more than a foot to foot and a half of snow a year. Not sure what you get in Logan.....
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Old 01-10-2016, 05:52 PM
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Re: How common are the broken manifold bolts?

They use salt here on the roads, and lots of it. I bought my Jeep used and the original owners were up in Park City, which is up in the mountains. I had to have a shop install my lift because things were already very rusted under the Jeep. I broke a bolt just trying to replace the rear sway bar. Since I am working overseas, I stay at my parents place while home on leave. I knew I couldn't run into problems like broken bolts and tie up their garage for too long.

If the manifold bolt break is not at the head, then yes, that should be easier to remove. Fingers crossed.

My hopes are that the factory head flows enough and the stock manifold is so restrictive that by adding the headers it allows the head to be fully used. I would do just a cam, but the install is pretty much the same as just replacing the heads as well. The cam I am looking at requires new springs and pushrods so there is that too.




I know putting headers on my both my 5.2 and 5.9 ZJ's really waked them up. I hope these ARH ones do too.
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Old 01-10-2016, 09:35 PM
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Re: How common are the broken manifold bolts?

I've read an article in Mopar Muscle Magazine that said the stock Hemi heads are very efficient and that's why the port job doesn't help that much. Usually, if you desire, they'd also take about .030 in. off and increase the compression ratio by about a half point. The increased compression pressure would help a little with the power too but, again, only if the other mods. were in place.

It's too bad they use so much salt. I don't have any rust under mine, but I have the undercarriage washed every spring too. The rust and continued exposure to moisture really plays havoc underneath.

Changing the cam, pushrods (longer 6.1 units) and the valve springs (6.1 exhaust valve springs) does not require removing the heads. I did both my Hemi's without removing them. All you need is a special "heads on" valve spring tool and a way to pressurize the cylinders. I bought my valve tool from Crane Cams and used my leak down tester to pressurize the cylinders. When I changed the cams, all I had to do is remove the valve covers, rocker arms/shaft, front cover and radiator and that's it. I also replaced the valve seals (they didn't really need it though), and installed a 6.1 timing chain tensioner (heavier duty than the 5.7's) and Crower Cam Timing Advance Kit. The hardest part of the whole job, IMO, was the R and R of the radiator. Everything else was cake.
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Old 01-10-2016, 11:37 PM
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Re: How common are the broken manifold bolts?

That doesn't sound too bad. I have never done any work on heads though. How hard is it to install the springs and rods? I know nothing about setting the advance on the cam either. Not sure what a shop would charge to install the cam, maybe if it is not too bad I will go that route.
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Old 01-11-2016, 07:37 PM
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Re: How common are the broken manifold bolts?

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Originally Posted by hound View Post
That doesn't sound too bad. I have never done any work on heads though. How hard is it to install the springs and rods? I know nothing about setting the advance on the cam either. Not sure what a shop would charge to install the cam, maybe if it is not too bad I will go that route.
IIRC, it took me about 4 hours (taking my time) to change all the valve springs and seals. Push rods are just drop in. The most difficult spring to change is the No. 8 exhaust (passenger side rear) spring. Like I said, it's not too bad if you have the valve spring tool and a way to pressurize each cylinder when you're working on it. Depending on which cam you go with, you may or may not want to mess with the cam timing. Installing it "straight up" (stock timing) is as simple as lining up timing marks on both timing gears.

If you're seriously planning this, you should also do some research on the various cams available, as there are quite a few......from mild to quite wild. Generally, the more radical, the more it'll kill your bottom end performance. IMO, unless you're planning to go big somewhere down the line, I'd stick with something that's fairly mild and retains the MDS. That was one of my main requirements and, on the highway with mine now, using the SC 91 tune, my MDS is active more than 90% of the time. With my mods., driving at ~65-68 mph in 4th gear on the highway (~2200-2500 RPM), my normal fuel economy is usually between 21-23 mpg. This is also at higher (3000-7000 ft.) altitude, like we're both at, usually running either 85 or 87 octane fuel.
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Old 01-11-2016, 07:46 PM
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Re: How common are the broken manifold bolts?

I would like to retain the low end and that is mostly what I want. My Jeep is lifted with larger tires, not a 1/4 mile street Jeep.

What cam would you recommend?
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Old 01-11-2016, 11:12 PM
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Re: How common are the broken manifold bolts?

Quote:
Originally Posted by hound View Post
I would like to retain the low end and that is mostly what I want. My Jeep is lifted with larger tires, not a 1/4 mile street Jeep.

What cam would you recommend?
Under those circumstances I'd probably leave the stock cam in and, if anything advance it one tooth (just under 7*) on the cam timing gear to move the torque curve to a little lower RPM. The other option would be to contact some of the cam manufacturers to see if they have something that would equal or better the stock cam's low RPM torque.

As I said, most aftermarket cams are geared for increased performance to some degree and will almost always kill a little bit of the low end and add power/torque at a higher RPM. Comp Cams has quite a few good cams for the Hemi, so you may want to see what they have to offer.

On mine, it is suppose to develop its maximum torque a little bit above 4000 RPM and its maximum horsepower up near 6000 RPM. I have my rev. limiter set at 6500 RPM and my WOT shiftpoints set at 6200 RPM. That's also why, on the highway, I drive mostly in 4th gear so I can keep the RPM closer to the torque range. If I could run it up around 2700-2800 RPM instead of 2200-2500 RPM, I could probably do a little better yet in fuel economy.
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