Quieting Down Versatile Chrysler 3.3L and 3.8L Engines

Quieting Down Chrysler’s Versatile 3.3L And 3.8L Engines

These engines have a mixed reputation for being high-mileage, dependable powerplants as well as noisy motors that can fail at relatively low mileage.

First introduced as a family back in 1990, these engines have been upgraded and improved to provide good torque for the necessary applications, reasonable fuel economy and a reputation for durability and appropriate performance.

Both have iron blocks and aluminum heads and since 2001 have been used nearly exclusively in Chrysler’s family of FWD vehicles, powering the Dodge Caravan, the Chrysler Town & Country and the Chrysler Pacifica.

In 2007, the 3.8L became the optional engine in the Jeep Wrangler.

Background Check

The 3.3L and 3.8L Chrysler V6 engines have been around for a long time. The 3.3L engine was introduced back in 1990 as a domestically built, low-cost, mass-produced alternative to the 3.0L V6 that Chrysler was sourcing from Mitsubishi. The engine was first used in Chrysler LH-platform front-wheel-drive cars, then the minivans. It continued in production until the end of 2010.

In 1991, a larger 3.8L version of the engine was introduced, and remains in production until this day. This engine has also been used in Chrysler LH-platform cars and minivans, and in the Jeep Wrangler starting in 2007. 

The 3.3L and 3.8L engines are both pushrod engines with cast iron 60° blocks, ­aluminum cylinder heads, and two valves per cylinder. It’s a tried-and-true design that combines simplicity with good low-end torque.

Spark is provided by a distributorless ignition waste spark system (three coils total) and fuel is delivered sequentially by the SMPI fuel injection system. The camshaft is driven by a timing chain, eliminating the need for timing belt service.

Both engines are essentially identical except for the bore and stroke. The 3.3L engine has 93 mm bores and an 81 mm stroke. The 3.8L engine has larger 96 mm pistons and an 87 mm crankshaft. The blocks are designed for transverse-mounting with front-wheel drive.

An engine from an all-wheel drive minivan can’t be swapped into a FWD application unless the third bolt boss on the front passenger side pan rail is machined flat for clearance.

On the later Jeep RWD applications, the blocks have some additional bolt bosses to accommodate the RWD motor mounts.

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Getting a Bad Rap

These engines have a mixed reputation for being high-mileage, dependable powerplants as well as noisy motors that can fail at relatively low mileage. Some 3.3/3.8L V6s have racked up well over 200,000-plus miles on the odometer with no major problems (except some oil burning), while others have called it quits at 70,000 to 80,000 miles.

Engine noise is one of the most common complaints among minivan owners. These include ticking noises, rattling noises, rapping noises, random knocking or scraping sounds, and belt noise. Diagnosis can be challenging because of the variety of conditions that can produce noise. It’s interesting to note that Chrysler has never issued any technical service bulletins on how to address noise complaints on these engines.

Making Some Noise
Valvetrain noise from the vicinity of the valve covers such as tapping or clicking can be caused by one or more collapsed lifters (due to clogging of the relatively small oil holes in the sides of the lifters), camshaft wear or low oil pressure.

In a high-mileage engine that has developed an appetite for oil due to worn valve guides and seals and/or piston ring wear, the engine may run out of oil before it reaches the next oil change interval. On the older (1999 and back) minivans, Chrysler had a recommended oil change interval of 7,500 miles for “normal” service. For short-trip, stop-and-go driving, this is really pushing it. A more reasonable service interval many experts say is 3,000 miles (which matches Chrysler’s “severe” service recommendation). In 2004, Chrysler revised the recommended oil change interval for normal service to 6,000 miles (which is probably still too long for most urban drivers).

If a vehicle owner seldom checks their oil level (or never checks it, which is often the case with a family vehicle such as a minivan), the oil level may become dangerously low. This can starve the upper valvetrain, camshaft, lifters and crankshaft bearings for oil at higher engine speeds. You know the rest of the story. Sooner or later something seizes and it’s the end of the road for that motor.

Many motorists are under the mistaken impression that the oil pressure warning light will come on if the oil is low. It will, but only after the oil pressure drops to practically nothing. By that time, the damage has already been done. So be sure to educate your customers about the importance of checking their oil level regularly, especially in older, high-mileage vehicles that may be using (or leaking) oil.

Many engine failures in the 3.3/3.8L V6 have been attributed to cam bearing failure, which can usually be traced back to a low oil level or loss of oil pressure due to a worn oil pump. When the cam bearings are starved for oil, metal particles can flake off and circulate throughout the engine. This can lead to the plugged lifters we mentioned earlier, camshaft wear, and rod or main bearing failure. Any debris that ends up in the crankcase will also be sucked into the oil pump (which is unfiltered) to cause wear there, too.

A tapping or rattling sound from the middle area of the engine following a cold start can be caused by a slow buildup of oil pressure. This may be due to the viscosity of the oil in the crankcase being too thick, a worn oil pump (low oil pressure), or a poor quality oil filter that does not have the proper anti-drainback valve.

Up until 1999, Chrysler recommended using 10W-30 oil in these engines, with 5W-30 approved for cold weather use (below 32° F). As oils improved, Chrysler changed their recommendation to a 5W-30 oil for year-round driving. In 2005, they changed their recommendations again (but only for 2005 and newer engines) to a 5W-20 oil. The lighter viscosity oil sped engine lubrication following a cold start, and improved fuel economy a bit. The capacity of the oil pan was also increased from four to five quarts (with filter).

Some owners of older minivans who were using 10W-30 or 5W-30 motor oil say they have quieted their valvetrain noise by switching to a lighter viscosity 5W-20 synthetic motor oil. The thinner oil seems to fill the lifters more quickly after a cold start so the lifters can take up the noise-producing lash in the valvetrain. Switching to a heavier viscosity oil (which is often recommended to quiet noisy high-mileage engines), apparently doesn’t work with these applications.

In some cases, valvetrain noise on 2000 and older 3.3L engines can be caused by a broken rocker shaft pedestal. The expensive fix is to replace the cylinder head. The less expensive fix is to drill out the broken pedestal, install a Heli-coil insert and use a longer bolt to support the rocker shaft.

In 2001, Chrysler redesigned the heads and rocker shafts to reduce the risk of breakage. The later model engines have seven bolts to support the shaft instead of four on the earlier shafts. Also, they changed from stamped steel rocker arms to stronger (and lighter) welded steel rocker arms.

Rapping or tapping noise from the bottom area of the engine may be nothing serious, as many 3.3/3.8L engines have reportedly been noisy since they were new.

But, if a noise suddenly appears where there was no noise before, it could be a bad rod bearing or a worn oil pump. A noisy rod bearing means the engine’s days are numbered and it’s time to start considering the alternatives: rebuilding the engine, replacing the engine with a remanufactured or used engine, or getting rid of the vehicle altogether.

Other causes of deep engine noise include excessive crankshaft end play due to a worn thrust bearing, or a cracked flywheel.

noisy oil pump can be changed by removing the oil pan, but first you have to remove a brace and dust cover from the transaxle. Although the oil pan has to be removed to change the pump, the pump is actually located inside the front timing cover. Removing the oil pan will allow you to change the front timing cover.

The oil pressure sending unit should also be replaced at the same time to make sure the system is working properly. The electric fuel pump is energized through the oil pressure sending unit when the engine is running. If the contacts inside the sending unit are oxidized or pitted, it may cause a no-start if it fails to energize the pump.

Rattling or scraping noises from the vicinity of the timing cover usually indicate timing chain noise. Chrysler says some noise is “normal.” Other possible causes include the water pump, serpentine belt tensioner and other engine pulleys. If the noise is still there after temporarily removing the belt and starting the engine, it’s probably a stretched timing chain or excessive end play in the camshaft or cam drive gears.

Chrysler has used three different cam drives on these engines, so make sure the replacement timing gear set is the correct one for the application if you have to replace it. The cam gear is notched for the camshaft position sensor. Up to 2004, the gear had nine notches on the back.

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