4 Common Dodge 5.2 Magnum Engine Problems

Jake Mayock

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Jake is a founder of 8020 Media and TuningPro. He has over a decade of experience in the automotive industry including parts sales, writing, DIY modifications & repairs, and more. Jake is currently converting his N54 to a single turbo and building a Miata track car. He’s an experienced, hands-on automotive enthusiast who delivers in-depth, well-researched content.

Launched in 1992, the 5.2 Magnum is a naturally aspirated 5.2L V8 engine produced by Chrysler. Despite being a very similar engine mechanically and design-wise, the 5.2 Magnum actually tends to be more reliable and have less common problems than the 5.9 Magnum. Still, the engine is susceptible to problems including the plenum gasket, exhaust manifold, cam sensor, and transmission. I discuss these 5.9 Magnum engine problems and reliability throughout this article.

Dodge 5.2 Magnum Engine Problems

Some of the most common 5.2 Magnum engine problems include:

  • Plenum Gasket Leak (also called belly pan gasket)
  • Camshaft Sensor Failure
  • Exhaust Manifold Bolts & Gasket (ticking noise)
  • Weak Transmission

We will discuss the above 5.2 Magnum issues in greater depth in the rest of the article. It’s important we add a few quick notes, though. These problems aren’t always common in the real meaning of the definition. Rather, when Dodge 5.2 Magnum engines run into problems these are a few common areas.

All engines are prone to their share of design flaws and issues and the 5.2L V8 isn’t an exception. The 5.2 Magnum isn’t the most reliable Dodge engine around, but it’s still a solid engine overall. Anyway, let’s jump into the above problems and circle back to reliability at the end of the article.

Dodge 5.2 Magnum Engine Problems

1) Plenum Gasket Leak

Just like its 5.9L big brother, the most common problem on the 318 Magnum is a leaking plenum gasket. The intake manifold on the Magnum engines is built in two pieces, a stamped steel plate is connected to the cast aluminum manifold. A plenum gasket, also referred to as a belly pan gasket, connects the plate and the manifold together.

The plenum/belly pan gasket deteriorates and wears down more quickly than most gaskets should. The end result is an air leak / vacuum leak that can lead to some significant performance problems and other engine problems.

When the intake manifold leaks, the engine looses vacuum, or its ability to suck air into the cylinders from the manifold. This will affect air to fuel ratios and the engines ability to generate power. Ultimately, a leaking plenum gasket can result in excess oil consumption, spark plug fouling, poor fuel economy, and can even clog the catalytic converters. While a small leak might not be noticeable for conservative drivers, it will quickly expand and can clog the cats.

Once the cats become clogged you will notice a huge loss of performance and be stuck with costly repairs. Additionally, this can lead to cylinder heads cracking as the clogged exhaust pushes hot engine gasses back into the engine and therefore causes overheating.

Plenum Leak Symptoms

  • Misfires
  • Bad spark plugs
  • Poor idling and performance
  • Lack of power
  • Bad O2 sensors
  • Excessive oil consumption
  • Pinging noise from engine under acceleration

Plenum Gasket Repair Options

The two methods for determining whether the plenum gasket is leaking is (1) looking for oil and buildup within the intake manifold, and (2) removing the PCV valve and testing for air pressure or vacuum pressure. It’s important to catch this problem early on before you end up needing to replace the spark plugs, O2 sensors, and catalytic converters.

Since this is such a common problem on the Magnum engines, there are dozens of aftermarket repair kits available. While the OEM gasket was made of rubber, Chrysler also tested metal gaskets which didn’t solve the problem either. Aftermarket kits, such as the Hughes 5.2 Magnum Plenum Repair Kit, use a thicker aluminum plate, high strength fasteners, new bolts, and a new gasket to fix the problems.

We don’t recommend just replacing the OEM gasket as this problem is almost guaranteed to surface again if you do so. The only alternative to the aftermarket kits, which are very reasonable price wise, is replacing the whole intake manifold with a performance manifold that removes the two-piece design. A performance manifold is also a solid idea if you are looking to add some power to your 5.2, albeit it comes at a higher cost.

2) Camshaft Position Sensor Failure

As the name suggests, the camshaft position sensor measures the position and speed of the camshaft. These readings are sent to the ECU to help determine how much fuel should be sent into the combustion chamber. Additionally, it helps control ignition timing and ensures that the right amount of fuel is being ignited at the right time.

As is with all sensors, the cam position sensor is prone to becoming clogged up or failing. Dirt, dust, grime, etc. builds up on the sensor over time and can cause it to malfunction or completely fail. When a cam sensor fails it sends incorrect readings to the ECU which then sends incorrect amounts of fuel into the engine. Ultimately, timing and air-to-fuel ratios get out of whack and lead to noticeable performance issues.

Failing Camshaft Position Sensor Symptoms

  • Check engine light
  • P1391 and P0340 are common codes
  • Engine no start or hard start
  • Poor performance
  • Rough idling
  • Cylinder misfires

Cam Sensor Replacement Options

You can try cleaning off your sensor to see if that does the trick without having to replace the part. However, a new sensor is roughly a $30 part so I generally recommend just replacing it and having the peace of mind that it isn’t going to become a problem again for awhile.

3) Broken Exhaust Manifold Bolts

The exhaust manifold connects the cylinders together with the exhaust pipes. It collects the used air from the engine and sends it out to the atmosphere via the exhaust. On the 5.2 Magnum, a lot of owners have reported a ticking noise coming from the engine bay area. While most peoples initial reaction is that the sound is lifter tick, it is actually from the exhaust manifold.

The bolts holding the exhaust manifold to the cylinder are prone to breaking which causes an air leak and the associated ticking noise. An exhaust leak is harmful to the environment as it allows engine gases to pass into the atmosphere without being burned in the catalytic converter. Outside of this, it can also decrease performance and lead to other engine problems.

Fortunately, the replacement options are as simple as replacing the broken bolts. However, we also highly recommend replacing the gasket at this time as well as it has likely further deteriorated from being exposed to open air.

Exhaust Manifold Leak Symptoms

  • Ticking noise from engine bay
  • Louder exhaust note or raspy exhaust sound
  • Decreased fuel economy
  • Poor performance and lack of acceleration
  • Gas or burning smell from engine bay

4. 46RE & 46RH Transmission Weakness

Like the 5.9 Magnum, the 5.2 also uses the 46RE and 46RH transmissions. Pre-1996 vehicles have the 46RH transmission with 1996 and onwards have the 46RE. Despite which transmission your 5.2 Magnum has, the outlook for it is not great.

Torque converters and transmission cooling lines commonly go bad on these transmissions. The overdrive assembly and reverse assemblies are known to go bad on the 4×4 vehicles, and the gearing ratios overall are not great. These transmissions do not hold up well with towing or to additional horsepower.

Especially for those with a lead foot or who do a lot of towing, these transmissions usually start giving problems around the 100,000 mile mark. While these transmissions can be bulletproof, they require some internal upgrades to be considered reliable. With the age of these trucks nowadays, any transmission that hasn’t been rebuilt or upgraded yet will likely require one in the near future. We have heard stories of these tranny’s lasting more than 200,000 miles without a rebuild, but I would say that this is rare overall.

Staying on top of transmission fluid changes will help but it’s likely not enough to save the 46RE or 46RH.

Transmission Failure Symptoms

Transmissions don’t fail instantly. They tend to go bad over time. Given this, you usually have a lot of heads up when the transmission is on it’s way out. Here are some common signs of a failing transmission:

  • Slipping gears
  • Hard shifting
  • Noises when shifting from park to drive, or difficulty in doing so
  • Grinding or shaking when tranny shifts
  • Leaking transmission fluids

5.2 Magnum Reliability

The 5.2 Magnum used in Dodge trucks and Jeeps is a pretty solid engine. It doesn’t suffer cylinder head cracks to the same extent that the 5.9 Magnum does. Additionally, the internals and major engine components seem to be fairly strong and adequate for good longevity at stock power levels.

With that being said, there are a few weaknesses of the 5.2. The plenum gasket is virtually a guaranteed problem and the transmissions are weak. However, outside of these two problems there really aren’t any Achilles heels of the 5.2 Magnum. Broken exhaust manifold bolts and bad sensors really aren’t material problems and there aren’t too many other issues that are common and costly.

It is worth noting that these trucks and Jeeps are pushing 20+ years old now. Age is certainly a factor in reliability and old engines will require more maintenance and overall repairs. The 5.2 Magnum can last to 300,000 miles and onwards, but expect to end up replacing a number of parts before you hit this mileage. You will certainly need a transmission rebuild. Additionally, you will probably have gone through a water pump or two, had to replace hoses, replace the timing chain, various suspension components, etc.

The 5.2 Magnum is more reliable than the 5.9 Magnum but still requires its fair share of TLC to make it into high mileage territory.

What’s your experience with 5.2 Magnum problems? Leave a comment and let us know!

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19 Comments

  1. 2000 Dodge Ram 1500 4×4 with 5.2 bought new was not in mud about 1700 miles out of warranty the torque converter and transmission pump had to be change the dealership said they have seen this a lot and tried to get Dodge to warranty it but Dodge said NO and costed me $1700. The dealership did change out some seals in transmission said they would go out.

  2. Love the 5.2 liter (318) can run 500K miles and do a rebuild. Do 500 more. BUT… get a stick shift! the electronic tyranny’s were junk. Or “upgrade” to a TF727 (3 speed) Those were some solid transmissions. Minor upgrades can get quite a bit more power and better fuel efficiency Most notably the cam is super tiny. In stock form it can barely breath. Even a “mileage master” cam is way larger than the stock.

    1. Looking to use: Lunati Voodoo Hydraulic Flat Tappet Camshaft Mopar Small Block 273-360 Lift: .454″ /.475″
      Part Number: 638-10200701
      I know it’s a roller engine, but the roller lifters shouldn’t mind a “normal” camshaft. RPM zone is 1000 to 5500 Rpm’s

  3. Third owner my father being the second. It was well taken care of by the original owner and now clocked a little over 325k and it still purrs like the first day. I don’t have to worry about transmission as mine is a 5 speed I have replaced crank sensor, fuel pump, power steering and lines, and am now looking into the plenum thanks to this post!

    1. Best price I have seen for parts is (plenumrepairplate.com) But I don’t see any gaskets included…

  4. 280k on 2001 Ram 1500 w 5.2 magnum, CA Truck (no rust) – 3 water pumps, new Heads and one clutch – 5K Oil Change Intervals and steady 75mph Hwy Mileage plus around town
    If I Can Not Dodge It – I Ram It

  5. I had a 97 Dakota with the 5.2, strong motor. Trans leaked like mad, still ran though. Just picked up a 98 Grand Cherokee 5.2 and it feels good. Trans also leaks on Jeep, and it doesn’t like to shift. 179,000 on jeep, even less on Dakota. Both very reliable trucks though, both always start & always run. Buddy has a 97 Grand Cherokee 5.2, Trans rebuilt at 170, now at 303, still runs.

  6. I own a ’99 Dakota, 5.2 with a 5 speed manual. The 318 /5.2 is my favorite engine for durability. The basic design can be easily improved with a cam upgrade of any form (use dependent) The auto trans. has been an issue for many years, and I prefer the more efficient manual anyway. The plenum in mine leaks so bad it sounds like a turbo on decel under 1500 RPMs. Just shy of 300K miles, I plan some upgrades this spring. This would include the cam and porting the heads, Milling 120 to 150 thousandths off the heads to increase compression (10:1?) and balancing all the parts Should push 350 to 400 horses and get better fuel mileage due to needing less throttle during “normal” driving..

  7. I have a 1996 Jeep Grand Cherokee with the 4.0 i6, it is lifted and sometimes I pull a small trailer. I have a 1993 1500 with a 5.2 mag sitting in the weeds (trans went out). So basically I am wondering if I can pull the 5.2 mag and swap it into the Cherokee, with a 42RE trans.

    1. Looks like the trans was used on a few V-8 applications. If the 5.2 is stock it will survive for a while. Your biggest issue will be wiring I think. If you stay with the FI you need to completely re-do the harness for a V-8. Both the ignition and FI systems won’t accommodate the 6 cylinder wires or computer.

  8. 9-99 1500 5.2 523,257 miles 46re has been rebuilt twice in that time once by a transmission shop at 223,000ish and and I rebuilt it a cupple of years ago around 470,000 but their wasn’t much really wrong with it other than the 5.2 was starting to get wore out had quite a bit of crank walk and was building a 5.2 bord to 323 Australian heads and a decent torque comp cam so I had to build the trans to hold a little more guts BTE torque converter some billet internals but the key is the allison clutches and bands but don’t attempt it your self if you aren’t a transmission guy the tailshaft will get you in trouble every time. But I have yet to change the gear raito from 3.55 mainly because my baby is a 4×4 so I have to do both axles not mention I already did a thick gear swap to the Dana 44 front axle and I’m not really sure what raito would be best but needless to say other than that the plenum had never been touched the oil pan and valve covers had never been off the motor my dad bought this truck brand new when I was a little boy and it has never left anyone stranded. BTW the first time the trans went out the clip for the second gear band fell out so it hust didn’t have second gear

  9. I have an 01 ram 1500 two wheel drive with 348,000 mi in it two transmissions later three water pumps but the engine is solid I feel like I can go another 200k

  10. I own a 93 Jeep Grand Cherokee 5.2 litre engine. Talking about a survivor, I’ve got this engine running like it’s brand new. I have had lots of Jeep Grand Cherokees try and run me down the interstate and I’ve left them all way back in my rearview mirror. I love it

  11. Just started working on my late father’s.. well guess it’s mine now, lol, just started working on MY 1990 Dodge Ram D150 5.2L V8. Can’t said I ever imagined I’d be driving this truck and I’ve had to replace a lot of my carpenter father’s “redneck enginering” as my uncle calls it. But after reading this post I’ll be looking into the dreaded transmission failure. She’s shifting hard from park to drive and when driving I sometimes have to let off the gas before she’ll shift. Thank you for this article, lol, now I have some more research and part hunting to do. 🫠

    1. The issue with the automatic transmissions can be traced back to the parking gear. These transmissions do not pump fluids while in park. If yo want it to last, yo have to start the motor, then put the trans in neutral for a while (especially if it’s cold) before trying to drive forward or back. This gives the clutches some fluid flow so you aren’t “Dry shifting” it into gear.

  12. I have a 1993 Dakota 4×4 with the 318 in it truck has 270,000 miles and is all original the truck hasn’t had the easiest life but keeps on going. The motor is all original along with the transmission. I wouldn’t hesitate to buy another truck like it.

  13. I have 99 1500 bought it new 1st motor had 77,800 on it founds bearings in pan. Replaced it w/crate motor from Chrysler , that one had 45,697 on it both heads had cracks & the block had a crack. Getting ready for no. 3, this time going with a Jasper motor

  14. What have you been doing to your motor? Lacking maint? Running around in 1st gear? driving in deep water?
    I only ask as I have had several 318 / 5.2 engines hit 300K with only normal maintenance. Fresh bearings and timing chain and you are usually good to go again.
    My current ’99 Dakota sport 4wd is pushing 275K and hasn’t been touched. I have the nasty “plenum leak” but it still runs O.K. I plan on freshening up the motor this summer as I’ll gather parts this winter.
    As for the “Cracked heads” They are usually fine unless you are running a turbo or Nitrous. The cracks don’t normally torch out and join cylinders without “help” .

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