The 5.2 Magnum, Chrysler’s naturally aspirated 5.2-liter V8 engine, debuted in 1992. Before the Hemi came along, this engine was found primarily in Dodge pickup trucks and Jeep Grand Cherokees. 5.2 Magnums are also known as 318 Magnums because of their 318-caliber bore.
The 318 Magnum, on the other hand, should not be confused with the Chrysler LA 318, which it replaces. From 1967 to 1991, the LA 318 was in production. The marketing department gave the 318 Magnum the Magnum name because it is an improved version of the LA 318.
The 5.2-liter Magnum engine put out 230 horsepower and 295 pound-feet of torque. In many of its vehicle applications, the 5.9 Magnum, the 5.2 Magnum’s bigger brother, offered an upgraded engine option with 250hp and 350lb-ft of torque.
Both the 5.2 and the 5.9 have received poor reviews in comparison to the rival 5.4 Triton and 5.3 Vortec engines due to their reputation for gas guzzlers. The fact that it makes less power and torque while using more gasoline hasn’t helped its reputation much, despite its excellent track record for dependability.
Despite the fact that mechanically and aesthetically, the 5.2 Magnum and 5.9 Magnum engines are very similar, the 5.2 Magnum is more reliable and has fewer problems.
5.2 Magnum Vehicle Applications
- 1992-2000 Dodge Dakota
- 1992-2001 Dodge Ram
- 1998-2000 Dodge Durango
- 1992-1993 Dodge Ramcharger
- 1992-2003 Dodge Ram Van
- 1993-1998 Jeep Grand Cherokee
Dodge 5.2 Magnum Engine Problems
- Plenum Gasket Leak (also called belly pan gasket)
- Camshaft Sensor Failure
- Exhaust Manifold Bolts & Gasket (ticking noise)
- Weak Transmission
1. 5.2 Magnum Plenum Gasket Leak
Leaking plenum gaskets are the most common issue with the 318 Magnum’s 5.9L big brother. The Magnum engines’ intake manifold is constructed of two parts: a stamped steel plate and a cast aluminum manifold. The plate and manifold are connected by a plenum gasket, which is also known as a belly pan gasket.
In comparison to other gaskets, the plenum/belly pan gasket degrades and wears out much more quickly. As a result, you’ll have an air leak or vacuum leak, both of which can cause serious engine performance issues.
Vacuum, or the engine’s ability to pull air from the intake manifold, is lost when the intake manifold leaks. The air-to-fuel ratios and the engine’s ability to generate power will be impacted as a result of this.
In the long run, a leaking plenum gasket can lead to high oil consumption, clogged catalytic converters, fouled spark plugs, and poor fuel economy. For cautious drivers, a small leak may go undetected, but for those who are less cautious, it can quickly grow and clog the cats.
Having clogged cats will result in significant loss of performance and the need for expensive repairs. As the clogged exhaust pushes hot engine gasses back into the engine, it increases the risk of cylinder heads cracking.
5.2 Magnum Plenum Leak Symptoms
- Bad spark plugs
- Poor idling and performance
- Lack of power
- Bad O2 sensors
- Excessive oil consumption
- Pinging noise from engine under acceleration
318 Magnum Plenum Gasket Repair Options
For plenum gasket leaks, look for oil and buildup in the intake manifold or remove the PCV valve to check air pressure and vacuum pressure. Both methods can be used. Detecting this issue early is critical to avoiding the need for spark plugs, oxygen sensors, and catalytic converter replacements.
There are numerous aftermarket repair kits available due to the high frequency of this issue with Magnum engines. Even though the original gasket was made of rubber, Chrysler also tried metal gaskets and found that they didn’t fix the issue.
A thicker aluminum plate, high strength fasteners, new bolts and a new gasket are used in aftermarket kits, such as the Hughes 5.2 Magnum Plenum Repair Kit, in order to fix the problem.
We don’t recommend simply replacing the OEM gasket because the issue will recur almost immediately afterward. A performance intake manifold without a two-piece design is the only option in lieu of the aftermarket kits, which are very reasonably priced. If you want to boost the power of your 5.2, a performance manifold is a good option, but it’s more expensive.
2. Camshaft Position Sensor Failure
The camshaft position sensor, as its name implies, measures the camshaft’s position and speed. These data are sent to the ECU, which uses them to figure out how much fuel to put in the combustion chamber at any given time. To make sure the right amount of fuel is ignited at the right time, it helps regulate ignition timing.
Because it is a sensor, the cam position sensor will eventually get clogged or stop working. Over time, dirt, dust, grime, and other contaminants accumulate on the sensor, causing malfunctions or outright failure.
Erroneous readings from a failed cam sensor go to the engine control unit (ECU), which in turn uses the wrong amount of fuel in order to keep the engine running. Time and air/fuel ratios are thrown off, which results in poor performance.
5.2 Magnum 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
Remove the sensor and clean it to see if that fixes the problem without having to buy a new one. However, a new sensor costs around $30, so I recommend simply replacing it to ensure that the issue won’t arise again for some time.
3. Broken Exhaust Manifold Bolts – 5.2 Magnum
To make things easier, the exhaust manifold joins all of the exhaust pipes into one place. It uses the engine’s exhaust to expel the used air back into the atmosphere. Many owners of the 5.2 Magnum have complained about a ticking noise coming from the engine compartment.
Despite the fact that the majority of people assume the noise is coming from the lifter, it is actually coming from the exhaust manifold.
As a result of brittle exhaust manifold bolts, air leaks and ticking noises can occur when driving. An exhaust leak is bad for the environment because it allows exhaust gases to escape the catalytic converter and go straight to the atmosphere. In addition to this, it can reduce engine performance and cause other issues.
Because the broken bolts can simply be replaced, there are no other options. However, since it has been exposed to open air, we strongly advise replacing the gasket at this time as well.
318 Magnum 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
The 5.2 Magnum also utilizes the 46RE and 46RH transmissions, just like the 5.9 Magnum. The 46RH transmission is found in vehicles manufactured prior to 1996, while the 46RE is found in vehicles manufactured after 1996. No matter what transmission you have on your 5.2 Magnum, the future doesn’t look good.
These transmissions frequently have problems with their torque converters and transmission cooling lines. 4WD vehicle overdrive and reverse assemblies are notorious for failing, and the gearing ratios themselves aren’t all that impressive. This type of transmission isn’t built to handle a lot of extra power or towing.
These transmissions usually start giving problems around the 100,000-mile mark, especially for those who have a heavy foot or do a lot of towing. These transmissions are bulletproof, but only after they’ve undergone a few modifications on the inside.
As trucks get older, any transmission that hasn’t been rebuilt or upgraded will almost certainly need to be at some point. The tranny has been known to last over 200,000 miles before needing to be rebuilt, but this is a very rare occurrence.
The 46RE or 46RH can be saved by keeping up with transmission fluid changes, but this is unlikely to be sufficient.
Transmission Failure Symptoms
Transmissions don’t go down right away for no apparent reason. Their quality deteriorates with time. As a result, when the transmission is on its way out, you usually have plenty of warning. Listed below are a few warning signs that your transmission is on its way out:
- 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 engine found in Dodge and Jeep pickups and SUVs is a good one. The 5.9 Magnum is more prone to cylinder head cracks, but not as bad. Furthermore, the engine’s internals and major components appear sturdy and long-lasting at stock output levels.
Having said that, the 5.2 has a few flaws. Plenum gasket failure is virtually certain, and transmission failure is common. However, aside from these two flaws, the 5.2 Magnum’s weak points are nonexistent. Unfortunately, there aren’t many problems that cost money, such as broken exhaust manifold bolts or bad sensors.
It’s important to remember that these Jeeps and pickups are well into their 20s. Older engines will require more maintenance and repairs due to their lower reliability.
The 5.2 Magnum can go up to 300,000 miles before needing to be replaced, but don’t hold your breath. Transmission rebuilding is unavoidable in your case. You may have also had to replace a couple of water pumps, hoses, the timing chain, and various suspension parts.
Although the 5.2 Magnum is more dependable than the 5.9 Magnum, it still needs some TLC to reach high mileage levels.
Share your thoughts on the 5.2 Magnum in the comments section below!
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