The 2.0 Liter SOHC Engine (1995 - 2005)

This engine was developed for the Neon and was also used in the export PT Cruiser, Plymouth Breeze, and Dodge Stratus. It was similar to the DOHC engine used in the Neon, Avenger/Sebring, Mitsubishi Eclipse, and Eagle Talon; and it was seriously considered by BMW for the 3-series before American BMW owners objected. It was the basis for the 1.8, the minivan-PT 2.4, and the 1.4/1.6 used in the first-generation BMW Mini. The final use of the engine family was/will be in 2010 when the final PT Cruisers are made.

For development and design notes,
see our Neon powertrain development page

Designed and built by Chrysler, the 2.0 liter engine originally produced 132 horsepower, with 129 lb-ft of torque - at a time when most of its rivals failed to beat 100 horsepower. Even the Civic EX, with 125 horsepower, couldn't come close to the Neon engine’s torque, despite variable valve timing. Gas mileage is good given the power and weight of the vehicles it is used in. (The exception, the 2000-2003 Neon, had an unfavorable gear ratio).

See the Neon repairs for repair tips, and the Neon performance section for performance tips.

Dan Minick, a columnist for Automotive Rebuilder, pointed out:

The 2.0 blocks [SOHC and DOHC] have the same casting number. There may be machining differences for mounting.

The SOHC cylinder head is only used on the 2.0 SOHC. The DOHC Neon shares a cylinder head with the 2.4. The Avenger/Sebring/Eclipse 2.0 DOHC head is unique and has reversed flow.

The 2.0/2.4 uses the same bore and bore centers as the old 2.2/2.5. There are quite a few similarities with the lower end of the block of the 'new' 2.0/2.4 and the 2.2/2.5. However the cylinder head of the 2.0/2.4 DOHC is an outright copy of the Mitsu 2.0 G63 DOHC, while the SOHC version of the Chrysler 2.0 borrows heavily from Mitsu's early 90s G15 1.5 colt motor.

A factory worker wrote:

The 1.8 liter neon export engine was based on the Trenton-made 2.0; it was a smaller bore, wtih the same rods and crank as the 2.0 (it’s easier to make different sized pistons than both rods and crank). The block line would change over the tooling for the smaller bore and run a few thousand per month, but you had to make sure there were no 1.8 blocks in the system afterwards — if you tried to bore out a 1.8 liter, rough-bored block to finish the 2.0 liter bore size, the tooling wouldn’t take it. It happened a few times.

The Neon had the same 96 mm cylinder centers and the same bore as the 2.2 engine, with a shorter stroke to give it 2.0 liters of displacement; this made it compact and saved on tooling. The engine was designed with a shallow skirt to save weight; a cast iron bedplate replaced the separate bearing caps used on other engines, to add stiffness. The combustion chamber had a pentroof setup.

Common repairs: head gaskets, coils, and engine mounts

For the 1995-97 models, the Neon head gasket typically lasted about 60,000 miles. Most buyers who called Chrysler got a new head gasket for $100 at most, assuming they had less than 100,000 miles on the car. The new head gasket design was far superior, and one engineer said it was close to the originally specified design which did not make it into production. Symptoms of a bad head gasket are oil in the antifreeze, oil on the engine, or antifreeze in the oil. (A leaking valve cover gasket can also spill oil onto the engine, though this is much less common).

Chrysler’s revised (MLS) head gasket was brought out in 1998 models and eliminated the problem.

The front and rear engine mounts tend to wear out on manual-transmission Neons, especially if they are frequently used in city traffic. The lifespan seems to be about 100,000 miles on average, much less in racing applications. These are easy to replace or repair. Some suggest adding window urethane to stiffen up the front mount, which is more appropriate for racing than daily drivers but may be handy for enthusiasts (the stiffer the mount, the smoother the shifts but the more engine vibration is transmitted into the cabin). Most people recommend the Mopar Performance replacement mounts.

Early coils also seemed to fail early, resulting in a loping idle and misfiring. The problem is barely noticeable but can hurt gas mileage and power. Replacing the coil is a ten minute job.

Finally, the timing belt can skip a tooth, leading to poor performance and gas mileage, as well as gurgling noises when driving uphill with the air conditioning on.

Engine Specs (1994-99)

Power @ rpm -- 132 bhp (98 kW) @ 6000
Torque @ rpm -- 129 lb-ft (174 N-m) @ 5000
Gas mileage in the Neon: 29 city/38 highway (1995 figures). Mileage in other vehicles should be slightly lower due to weight. Gas mileage with the automatic transmission (Neon) is about 33 highway. Note that 2000-2002 Neons have far worse mileage due to inappropriate gearing.
Bore -- 3.44 (87.5)
Stroke -- 3.27 (83)
Bore-to-stroke ratio -- 1.05:1
Block height -- 8.35 (212.0)
Rod length -- 5.47 (139.0)
Connecting rod L/R -- 3.35:1
Compression ratio -- 9.8:1
Displacement -- 121.8 cubic inches (1996 cc)

Chrysler 2.0 liter engine cylinder head

Cast aluminum, low profile, cross-flow cylinder head, with pent-roof combustion chambers. Four valves per cylinder. Camshaft is installed axially, from the front of the head. Spark plug tubes are pressed into the head and held with anaerobic sealer. They seal against the underside of the cylinder-head cover and are covered by the spark plug boots. Powdered-metal valve seat inserts and valve guides are pressed into the head.

The intake ports develop turbulence in the cylinders to speed combustion for low emissions and efficient operation on regular gasoline. Incoming air tumbles from top to bottom of the cylinders. Turbulence is balanced against the need for high air flow to provide high power.

Block and Bedplate 

The cast iron block is 8.35 inches (212 mm) high, to clear the low hood. The block ends at the centerline of the crank shaft. Bore spacing allows coolant to flow around all cylinders. To further reduce weight, the top deck is open. The housing for the water pump is cast into the front of the clock.

A bedplate under the block, made up of a perimeter wall and transverse webs, supports the crank shaft. It also gives structural rigidity to the engine assembly for durability at high rpm, and also for quiet operation. The bedplate, which also provides a flat sealing surface for the oil pan, attaches to the base of the block.

Manifolds

The intake manifold is injection molded of 30 percent glass-filled nylon. It features 16.5 inch (420 mm) primary runners which contribute to low-speed torque. The runners are curved for maximum length in the compact engine compartment. One runner feeds both valves of each cylinder. A tapered plenum and elbow section deliver air to the runners.

The plastic manifold weighs only 4.1 pounds (1.8 kg), less than half the weight of the same design in aluminum. In addition, the plastic molding gives the manifold good dimensional accuracy. Pipe-threaded brass inserts. Manifold attachment points at the head include compression limiters that assure proper sealing without damaging the plastic material.

The exhaust manifold is a compact, lightweight nodular iron casting that allows exhaust gas to quickly heat the catalytic converter to operating temperature for low emissions.

Valve Train

A single, centrally-mounted camshaft sets four valves per cylinder in motion. Intake valve diameters are 1.3 inches (33 mm); exhaust valve diameters are 1.1 inches (28 mm). Valves have a 42 degree, included angle; exhaust valves rearward, intake valves forward. Intake valves are splayed 3.6 degrees for clearance to the spark plug tubes.

The valve train can control valve actuaction to 7200 rpm. The camshaft is post-hardened nodular iron with three lobes per cylinder; two for intake valves and one for exhaust. The camshaft operates aluminum center-pivot rocker arms that have roller bearing cam followers and miniature hydraulic lash adjusters above the valve tips. Exhaust rockers are forked so they can operate two valves. The rocker arms pivot on shafts that are clamped to the head. Lightweight valves need only single valve springs.

The camshaft is driven by a cog belt. The belt system requires no adjustment. The belt is made of a special high-temperature rubber material and features unique construction so it can withstand the high belt loads that result from operating 16 valves. For proper belt tension, a spring- loaded automatic tensioner with hydraulic damping pushes an idler pulley against the back of the belt. Low-inertia sprockets made of powdered metal, are spaced away from the clock to reduce the belt operating temperature. the belt is completely enclosed by a two piece close- fitting molded plastic cover. The cover protects the belt from damage by debris and moisture. This protection lengthens belt life.

Pistons and rods

Cast aluminum pistons with a shallow crown keep the weight light. Piston pins are held in place by a press fit in the rods.

Connecting rods and rod caps are forged from powder metal and machined in one piece. Powdered metal rods and camps are lighter than conventional steel forgings. Weight is reduced due to greater dimensional control and the elimination of the small-end balance pad.

After machining, the cap is separated from the rod. The parting line between cap and rod is scribed on both sides of the rod by a laser beam -- a patented process used here for the first time in the industry. Hydraulic pressure applied to the inside diameter of the rod end fractures the rod along the scribe marks. The uneven mating surfaces created by the fracturing process provide perfect alignment during engine assembly. Rod manufacture is further simplified by threading the cap bolts directly into the shank of the rod, rather than using through-bolt and nuts.

Crankshaft and bearings

The crankshaft is cast of nodular iron. It has counterweights on both sides of each crank pin to balance the bearing rods for smooth, quiet operation. The crankshaft weighs only 33 pounds (15 kg). Counterweights straddling each crank pin allow smaller bearing diameters. Smaller diameters reduce friction and, therefore, increase fuel economy and power. Diameters of the main bearings are also 20 percent smaller than past practice and diameters of the rod bearings are 8 percent smaller.

A conventional inertia-ring vibration damper is mounted on the nose of the crankshaft. The inertia-ring has machined-in pulley grooves to drive the alternator and accessory belts. The damper minimizes engine noise and vibration.

The camshaft operates directly in the cylinder head without bearing inserts. The main and rod bearings have high-load bi-metal inserts.

Neon engine lubrication and cooling

The powdered metal gerotor oil pump mounts in the front of the block and is driven by the crankshaft. The system that returns oil from the head is designed to prevent aeration during high rpm running.

The block is inclined to the right (rearward in the car) to allow the oil to drain from the head at the right face of the block. The crankcase is ventilated through openings on the left side of the head. oil capacity is four quarts, plus filter. SAE 5W-30 oil, grade SG/SH, is recommended. A half quart oil filter mounts vertically to an extension of the bedplate, providing easy access for service.

The water pump housing is built into the block to reduce complexity. The water pump is driven by the timing belt. A single molded plastic unit combines the functions of thermostat housing, filler neck, radiator hose nipple and overflow nipple. The cooling system filler neck is attached to the engine, not to the radiator. Because of a low hood line, this is the highest point in the cooling system. A conventional pressure cap is used.

The thermostat has an air vent and a check ball that allows air in the coolant to escape when the system is cool, but seats with a tight fit to assure rapid engine warm up. Allowing air to escape the vent help prevent swings in coolant temperature during warm up. The vent also makes refilling the system easier because it prevents air entrapment.

Sealing

• The crankshaft rear main seal is pressed into the black-and-bedplate assembly, instead of into a bolt-on housing. This arrangement eliminates a potential leakage path. The seal has a Teflon(R) lip for longer life.
• The oil pump cover also houses the crankshaft front main seal.
• The oil pan and cylinder head cover gaskets are state-of-the-art in both design and material. They're made of molded silicone with a steel backbone and compression limiters.
• The block bedplate design creates a secure oil pan seal, because it provides a flat, continuous, machine sealing surface.
• The top surface of the cylinder head is machined flat for easy, precise sealing.
• The spark plug tubes are sealed to the cylinder head covers with individual molded seals.
• A silicone-rubber gasket, molded onto the thermostat, creates a high- integrity seal between the thermostat housing and the cylinder head.
• A molded seal on the oil pan drain plug prevents leakage.
• The camshaft sensor is sealed to the cylinder head with an O-ring.

Chrysler electronic fuel injection and ignition systems

The sequential multi-port injection system uses four cone-spray injectors to balance the fuel delivery to all cylinders. Injectors direct separate sprays to the intake valves. A small slot in the top of each intake port allows proper location of the injector spray.

Variable injection timing uses the same sensors as the ignition system to provide speed, timing and cylinder-selection data.

The throttle body has a 2.05 inch (52 mm) bore to minimize restriction at high rpm. To improve the driveability the throttle body has a contoured bore in the off-idle area that limits the amount of air flow to the engine at low throttle.

Fuel-flow control software in the PCM (powertrain control module) helps minimize driveline shock and resulting oscillation that follows a rapid change in throttle opening. The control procedure works together with driveline refinement to minimize the effects of deflection and free play. The fuel injection control software in the PCM also is calibrated to work with the returnless fuel system. The PCM calculates a compensation factor that adjusts the injection pulse duration for variations in pressure differential between the fuel supply system and the intake manifold.

The 2.0-liter engine had a direct ignition system (DIS). Two sensors (one for crankshaft timing, the other for camshaft reference) provide the data to operate the ignition system.

The crankshaft sensor, inserted through the side of the block, senses two patterns of four slots each in the number 2 counterweight, 180 degrees apart. The slots feed data for engine speed and timing calculations. The positions on the crankshaft establish engine basic timing. The fact that they sense directly from the crankshaft means more accuracy than conventional systems. Individual slots are spaced 20 degrees apart. Spark advance and injection timing are computed from these points. One slot, called the "signature" slot, is 60 degrees wide; the others are approximately 5 degrees wide. The sensor output that comes from the "signature" slot combines with the signal from the camshaft sensor to determine the cylinder ready for fuel and ignition.

The camshaft sensor is mounted on the outside rear of the cylinder head. It is triggered by a ring magnet in the end of the camshaft. The magnet's four poles are arranged at 150-degree and 210-degree intervals. Their relationship to the signature slot is established in less than one turn of the crankshaft, allowing injection and ignition to begin.

The four-lead direct-ignition coil is mounted above the cylinder head cover. As a result, only short secondary-wire leads are required.

Praise

Wheatking wrote:

It will run for a LONG time on just regular maintenance. My father has the same engine in his Avenger and it's about 200,000 miles now. This is on the original head gasket. After some long research, my father and I found out it's not so much a problem with the gasket, but a problem with the block on the 2.0L engine.. seems the head bolt on the back outside of cylinder #4 can bottom out on some blocks.. meaning it doesn't exert enough pressure on the headgasket to make a good seal.. grinding a few threads off the bolt does the trick if it's leaking a little. The new MLS gasket is a bit thicker than the old gaskets.. probably why it works better.

Change the timing belt and the pullies for the timing belt at 60,000 miles.. and do regular oil changes. The pullies for the timing belt... the bearings aren't good for more than the 60,000 miles. Most timing belts I've done on the 2.0L, the pullies are just about dead (lots of play in the bearings). [The webmaster changed at 90,000 and didn’t have this problem.]

As for the engine... stock it can hold about 330hp at the crank.. the rods start to stretch at this point...

Another neat bit about the engine.. it's one of the first engines that's produced in America to be used in a Japanese vehicle [in DOHC form].

Links

• For development and design notes, also see our Neon powertrain development page
• Allpar
• Head gasket replacement TSB
• Neon pages, including repairs
• 2.0 DOHC
• 2.4 liter engines
• 1.4, 1.6 liter engines
• 1.8 liter version
• Other Mopar engines 

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