RAM 1500 5.7 HEMI Common Problems — Complete Diagnostic Guide

The 5.7 HEMI — A Great Engine With a Few Known Weaknesses

The 5.7L HEMI is one of the most popular truck engines on the road. RAM has sold millions of these things, and for good reason — they make great power, they sound good, and they are generally reliable. But after 25 years of working on these trucks, I can tell you there are specific failure patterns that every tech needs to know. If you work on RAM trucks — especially fleet RAMs — you will see these problems repeatedly.

This is the pillar guide for 5.7L HEMI diagnostics. Every major failure pattern from 2009 through current production, the codes they set, what actually fails inside the engine, and how to approach the diagnosis without wasting time guessing. I am covering the eight most common problems in order of frequency and severity.

The number one issue — and it is not close — is the MDS lifter and camshaft failure. If you only read one section of this article, make it that one. But all eight of these problems are things you will see in your bay, so let's get through them.

HEMI Tick / Lifter-Cam Failure

This is THE problem on the 5.7L HEMI. If you work on RAMs, you have heard the tick of death — a rhythmic ticking from the passenger side of the engine that does not go away when the engine is warm. It follows engine speed, not load. And once you hear it, you know exactly what it is.

The MDS system uses specialized lifters on cylinders 1, 3, 5, and 7 — all on the passenger-side bank. These lifters have an internal locking mechanism controlled by oil pressure. When the PCM wants to deactivate those cylinders, solenoids in the lifter oil manifold assembly dump oil pressure to the lifters, and the lifters collapse so they no longer open the valves. The cylinder stops firing, the engine runs on four cylinders, and the driver saves a little gas.

The problem is those MDS lifters fail. The roller bearing on the lifter can seize or flatten, and when it does, the lifter does not ride smoothly on the camshaft lobe. It gouges the cam lobe. Once the cam lobe is damaged, no amount of new lifters will fix it — you are looking at a full camshaft and lifter replacement. I have pulled camshafts out of these engines where the lobe was wiped completely flat.

Codes you will see: P0300 (random misfire) and specific cylinder misfire codes on the affected MDS cylinders — P0301, P0303, P0305, P0307. If you see a misfire code on one of those four cylinders and you hear the tick, you have your answer. Pull the valve cover on the passenger side and inspect the lifters and cam lobes visually. A collapsed lifter or a wiped cam lobe confirms it.

The repair is significant. On most of these trucks, the standard repair is full cam and lifter replacement — all 16 lifters, new cam, new timing chain set while you are in there. Labor is 12-16 hours depending on the shop and the year. Many techs and fleet managers choose to do an MDS delete at this point — replace all the MDS lifters with standard non-deactivating lifters, install a non-MDS cam, and reprogram the PCM. This eliminates the failure mode entirely and is a popular option for trucks that need to run for another 100,000+ miles.

Exhaust Manifold Bolt Breakage

Exhaust manifold bolt breakage on the 5.7L HEMI is extremely common — both banks, but especially the driver side. The bolts break from repeated heat cycling. Cast iron manifold bolted to an aluminum head, two different expansion rates, thousands of hot-cold cycles. The bolts fatigue and snap.

When a bolt breaks, the manifold separates slightly from the head and you get an exhaust leak. The symptom is a ticking or tapping noise on cold start that goes away within 30-60 seconds as the manifold heats up and the expanding metal seals the gap. This is the cold start tick — and it is NOT the same as the lifter tick, though customers (and some techs) confuse them constantly.

If the customer says "it ticks when I start it but goes away after a minute," think exhaust manifold bolts first. Visually inspect both manifolds — you may see black soot streaks on the head surface near the broken bolt locations. That soot trail is exhaust gas escaping through the gap and it is your confirmation.

The repair involves extracting the broken bolt studs — which can be a nightmare in aluminum heads if the bolt broke flush or below the surface — and installing new bolts. Mopar released updated bolts with a different metallurgy that resists fatigue better than the originals. Always use the updated bolts. If the bolt broke off below the head surface and extraction is not possible without risking head damage, some techs drill and tap to a larger size or use a Time-Sert thread repair.

MDS Solenoid Failures

The MDS system uses solenoids mounted on the lifter oil manifold assembly (LOMA) to control oil flow to the MDS lifters. There are four solenoids — one for each MDS cylinder. When a solenoid fails, the affected cylinder either does not deactivate when commanded or does not reactivate properly. Either way, you get a misfire or rough running condition that occurs specifically when the MDS system engages.

The key diagnostic clue is timing. If the misfire or rough running only happens during light load cruise — when MDS would be active — and the engine runs fine under acceleration or at idle, suspect the MDS solenoids. Connect a scan tool and watch the cylinder deactivation commands versus the actual cylinder status. If the PCM commands a cylinder to deactivate and the solenoid does not respond, you have found your problem.

You can also monitor the solenoid circuits with a labscope to check for proper command signals and solenoid response. A failed solenoid will show no current draw when commanded, or an abnormal current waveform compared to the working solenoids.

Replacing the solenoids requires removing the intake manifold to access the lifter oil manifold assembly. While you are in there, inspect the lifters and cam lobes — if the truck has enough miles for a solenoid failure, it has enough miles for the lifters to be suspect too. Many techs replace all four solenoids and all 16 lifters at the same time to avoid going back in later.

Roller Rocker Arm Failures

The 5.7L HEMI uses hydraulic roller rocker arms — one for each valve, 16 total (intake and exhaust). The roller tip on the rocker arm rides on the valve tip, and over time, the roller bearing can seize or the roller tip can fracture. When this happens, the rocker arm does not actuate the valve properly and you get a misfire on that cylinder.

This is not as common as the lifter-cam failure, but it is a known issue — especially on 2009-2013 trucks. The symptom is a misfire code on a specific cylinder that does not match the typical MDS failure pattern (it can happen on any cylinder, not just 1, 3, 5, or 7). You may also hear a different-sounding tick compared to the lifter tick — a higher-pitched, sharper noise.

Diagnosis: pull the valve covers and inspect the rocker arms. A seized roller tip will have visible wear or scoring on the roller and the valve tip. A fractured roller is obvious on inspection. Check the corresponding valve tip for damage — a seized rocker roller can wear a groove into the valve tip, which means the valve needs replacement too.

When replacing rocker arms, inspect ALL of them on both banks. If one failed, others are likely on their way. Replace them in pairs (intake and exhaust on the same cylinder) at minimum, and check the cam lobes for any corresponding damage from the rocker arm failure.

Intake Manifold Runner Control (IMRC) Failures

The 5.7L HEMI uses a variable-length intake manifold with butterfly valves inside the runners. The butterflies are controlled by a vacuum actuator and change the effective runner length based on engine speed and load — shorter runners for high RPM power, longer runners for low RPM torque. It is a simple system on paper, but it has two common failure points.

First, the vacuum actuator diaphragm fails. The rubber diaphragm inside the actuator develops a tear from age and heat exposure, and the actuator can no longer move the butterflies. Second, the butterfly valves themselves can stick from carbon buildup inside the intake manifold. Either failure causes the runners to stay in one position — usually stuck open.

Codes: P2004 (Intake Manifold Runner Control Stuck Open — Bank 1) and P2005 (Intake Manifold Runner Control Stuck Open — Bank 2). The symptoms are subtle — you will notice a loss of low-end torque and reduced fuel economy, but the truck will still run. Most drivers will not notice unless they are paying attention. Fleet managers might notice it in fuel consumption reports before the driver ever complains.

Diagnosis: with the engine idling, apply vacuum to the actuator with a hand pump and verify the butterflies move. If the actuator holds vacuum and the butterflies move, the system is functional and the issue is the vacuum supply. If the actuator does not hold vacuum, the diaphragm is torn — replace the actuator. If the actuator holds vacuum but the butterflies do not move, they are stuck from carbon — clean or replace the manifold.

Coolant / Thermostat Housing Leaks

The thermostat housing on the front of the 5.7L HEMI is plastic. Plastic housing, aluminum engine block, constant heat cycling. The housing cracks and leaks coolant. This is extremely common on 2009-2018 trucks and is one of the most frequently misdiagnosed leaks on the HEMI.

Why misdiagnosed? Because the thermostat housing is close to the water pump. Coolant leaking from a cracked housing runs down the front of the engine and can look like a water pump leak. I have seen techs replace the water pump on a HEMI only to have the "leak" come right back — because it was never the pump. It was the housing.

Diagnosis: clean the entire front of the engine with degreaser, run it to operating temperature, and then carefully inspect with a flashlight. Look specifically at the thermostat housing — check the seam where the housing meets the engine, and check the housing itself for hairline cracks. A UV dye test in the coolant makes this even easier. The dye will fluoresce under UV light right at the crack location.

The repair is straightforward — replace the thermostat housing and the thermostat while you are in there. Use an OEM Mopar housing or a quality aftermarket that uses the updated design. Some aftermarket housings are aluminum, which eliminates the cracking issue entirely. Always replace the O-ring or gasket — do not reuse the old one.

Spark Plug Blowout / Thread Issues

The 5.7L HEMI has 16 spark plugs — two per cylinder. This is a HEMI-specific design for improved combustion efficiency in the hemispherical combustion chamber. Twice the plugs means twice the opportunities for problems during service.

The most common issue is cross-threading or over-torquing spark plugs in the aluminum cylinder heads. Aluminum threads are softer than steel spark plug threads, and a careless installation — especially on a plug that is not perfectly aligned — will strip the threads. Once the threads are stripped, you have a blowout risk. The plug loosens under combustion pressure and either backs out or blows out entirely.

The HEMI is also very particular about spark plug gap and type. The recommended plug for most 2009+ 5.7L HEMIs is a copper-core plug at a specific gap — check the OEM service data for your year because the specification changed across production years. Using the wrong plug or the wrong gap causes misfires, especially under load. I have seen trucks come in with P0300 and misfire codes on multiple cylinders, and the root cause was aftermarket platinum or iridium plugs that the engine does not like. The HEMI wants what it wants.

Service tips: always start spark plugs by hand — thread them in by fingers for at least two full turns before using a ratchet. Use a torque wrench and torque to the OEM specification — do not guess. Apply a thin coat of anti-seize to the plug threads (some techs debate this — I have been doing it for 25 years with no issues on aluminum heads). If you do strip a thread, a Time-Sert or Heli-Coil repair can save the head, but it adds significant time to the job.

Transmission (8HP/ZF) Torque Converter Shudder

Starting with the 2013.5 model year, the RAM 1500 got the ZF 8HP 8-speed automatic transmission. It is a good transmission — smooth shifts, efficient, well-matched to the HEMI. But the torque converter develops a shudder that is unmistakable once you have felt it.

The symptom is a vibration at light throttle between 35-50 mph that feels exactly like driving over rumble strips. It happens when the torque converter clutch applies, and it goes away when you accelerate or decelerate (which causes the TCC to release). The driver usually says "it shakes at highway speed" or "it vibrates when I am cruising." No codes may be set, which makes it frustrating for techs who want a DTC to chase.

The root cause is the torque converter clutch lining material deteriorating and contaminating the ATF. The contaminated fluid then causes the shudder as the TCC tries to apply against a rough surface. This is the same basic failure mechanism as the GM 8-speed shudder — different transmission manufacturer, same torque converter clutch issue.

Diagnosis: drive the truck at 35-50 mph at light throttle and monitor TCC status on the scan tool. When the shudder occurs, note whether the TCC is applied. If the shudder lines up with TCC apply and disappears when TCC releases, you have your diagnosis. Some techs try a fluid flush first — and it is a reasonable first step — but it MUST be done with the correct ZF-specification ATF. Generic ATF will make it worse. The ZF 8HP requires ZF Lifeguard Fluid 8 or equivalent that meets the ZF specification. Not Dexron, not Mercon, not generic "multi-vehicle" ATF.

If a fluid exchange with the correct spec fluid does not resolve the shudder, the torque converter needs to be replaced. On a truck with 80,000+ miles and a confirmed TCC shudder that does not improve with correct fluid, I go straight to converter replacement. The fluid flush buys time on some trucks, but the converter clutch material is physically worn and it is going to come back.

Frequently Asked Questions