Yes i did that. It's always a routine of mine. Tune up and battery terminal cleaning

 

Before you buy parts. Do a compression check. That will let you know how the inside of the engine is. Look at the plug from that cylinder, what does it look like. Do an injector leak down test. A leaking injector can cause miss fires.

 

I would tend to say at this moment you have no reason to dig into the engine past the intake manifold. As others have stated, a compression test would be great for piece of mind. It still probably wouldn't hurt (once everything checks out) to take the covers off and see the state of the springs, my 04 Hemi looked great on the springs. Also +1 on checking the cyl #1 injector out, and to make sure the connector/harness is properly connected & seated and has no signs of wear.


I cured my cylinder #6 misfire by changing the intake gaskets. This problem usually reared itself up around the time of a car wash, mud puddle, water puddle & Rainy day..thats the symptom, problems after/during car wash or rain or even snow once it melts on the engine. All Hemi engines with a plastic intake use those rubber o-ring type seals that eventually overtime fail to expand & seal, the problem has caused many poor Durango Hemi's to suck water in and hydrolock then break a con rod because of those seals and the bad cowl design which is why all the new Hemi engines with plastic intakes have a big cover over them, the Ram 5.7's though identical to the Durango 5.7 have the advantage of a much better cowl design, but that doesn't mean its impossible for water to get on the engine.

 

So a bad intake gasket can make a single cylinder misfire? I dont mind putting money into this truck to fix issues as long as its a related part to the issue.

 

If you need a valve spring compressor to change the springs, I have one avail for sale in the classifieds section

 

A broken valve spring will cause it to run very rough, plus it won't idle. Is yours an early '04? I was thinking it was fixed with the '04s.

 

Yes absolutely.


Intake gaskets are $10, plus I recommend $6 copper permatex to aid the gaskets in doing their job over the lifetime of the vehicle. It should be done regardless of weather or not its the root of your current problem, its money in the bank changing intake gaskets on a hemi with a plastic intake manifold due to the possibility of hydro lock & con rod breakage associated with age & weather conditions on the intake gaskets. Theres no loss of money doing this...in fact I encourage EVERYONE to change their intake gaskets & add a sealer like copper permatex to aid their sealing.


Its not as much of a witch hunt or random assessment as it may seem, I full heartedly think that you should pull the valve cover off on the side that has the misfire and check for broken springs & valve train slop...helps for peace of mind. If there is no valve train slop or broken springs, throw it back together your problem is elsewhere. You can re-use the valve cover gaskets, don't remove the gaskets out of them, they are a good quality gasket and can be reused. Taking your valve cover off to check for a broken spring is a FREE thing that you can do, requiring little more than a 8mm socket, a 10mm socket, flash light/shop light and your lunch hour.


Honestly you really SHOULD do a vacuum test first and foremost before taking ANYTHING apart, its so simple and can help you determine the severity and types of potential problems before getting even one hand greasy. As stated before, these gauges are cheap to buy/rent from a parts store ($10 @ Harbor Freight for your own new vacuum gauge), a jumpy needle that flutters rapidly can indicate a intake or exhaust broken spring, if its smooth you can probably take a sigh of relief and a good breath of fresh air.


If swapping an injector on the offending cylinder and visually checking the valve train produces no explanation of a problem perform a Compression test, IF that is fine then change your intake gaskets & reset the computer.


Remember when diagnosing problems, do the cheapest things first starting from free to expensive (unless you have a HIGH degree of certainty & evidence to back a pricey fix up don't spend the money!) and try not to take other things out that work fine.

Also check your oil for antifreeze and check your antifreeze for oil, a leaky head gasket can cause a misfire, in which case a compression test should be able to rule that out as a possible problem.

Personally I feel you're armed with all the ammo you need to go out and fix the problem. I don't think anything major is wrong with your engine, and honestly don't think its a valve spring.

 

I know this is an old thread and I have the tool I got from Weedahoe years ago. I think I finally broke an exhaust valve spring. I was in tow/haul going about 40 and had to punch it get out of a wreck. I looked down to see the rpm gauge buried at 7k and let off but she would run rough under any load and has a lope in the idle. I think 2nd prime finally caused baby to wind up a little too much. I am curious if it could be anything else. 125k., meticulously maintained, she likes RP HPS and Chevron 89 with a little lucas fuel injector cleaner. Everything is fresh on this truck even though nothing went bad except the rear diff at 92k (replaced with a Detroit tru-trac). It had a noise I thought was water pump (OEM), starter (High Amp $350), fan clutch (OEM), all tensioners and pulley, belt, coils, wires, plugs again 5 times since 06(champion copper). This Hemi is actually quiet and there is very little ticking detectable. I believe the slight tune from the SC Cortex I have been using for over 10 years on this truck with exceptional results from both fuel consumption as well as performance and reliability keeps the timing closer to where it should be for longevity. I am fortunate enough to have another truck to drive(f150 platinum that I would not have if this Dodge had not been so dependable all these years) while I figure out what to do and who to find in my area who is competent to perform the work. I am in vegas 89134 if anyone knows the person who is good with these motors.
Which exhaust springs and seals should I get? Intake Gasket recommendation? Truck was built 11/03
Thanks for any help

 

Hey bud, its been a long time!

I would pull the valve covers and rotate the engine and check the valve train. Another option is to pull the spark plus and buy a cheap bore cam off ebay/amazon that can pair to your phone so you can visually inspect.

As for replacements? If the stock/OEM parts have gotten you this far, I would go back with them. For the age of our trucks, they are cheap these days.

 

Hey Bud,
Thanks for the reply!
I was thinking the same thing so I ordered a set of Mopar high performance exhaust valve springs for the 3rd gen Hemi .
My problem is finding someone I can trust to work on my motor. My mechanic who is good at externals is worried so I don't want him to even try. Probably some speed shop here in vegas is familiar with these motors. I am going to replace the exhaust valve springs and the valve seals and I got felpro blue plastic valve cover gaskets. I heard you to inspect deeper and will have them check it out. Of course I am hoping for a clean bill of health other than the exhaust valve spring break. I have no problem with having a shop open it up and change out to the 6.1 stronger parts.Whatever is best for the longevity.
I just may get a chance to use that tool I got from you at least 10 years ago. It has been peace of mind just having it!
Appreciate you