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Chrysler Shop Solutions

Chrysler/ Mitsubishi 2.6L/3.0L

Some of the late 2.6L engines and all of the 3.0L Mitsubishi engines have a very small "auto-lash-adjuster" installed in the tip of the rocker. All too often, air gets trapped in the lower chamber of the lifter and prevents oil from filling the lifter. When this happens, the lifter holds the valve open.

Rebuilder’s survival tip: You can bleed the air out of the lash adjuster by pressurizing the engine with oil and then inserting a .025" drill bit or a bleed wire (p/n MD998442 available from Chrysler or Mitsubishi) down inside the lifter through the hole in the rocker. This allows the air to escape from the lower chamber so it can fill with oil. A word of caution, though: Don’t use a smaller wire or push too hard on the check ball or you may damage it. Then the oil will leak by the check valve allowing the lifter to bleed down and make noise.

Chrysler 2.5L Balancers
When Chrysler introduced the 2.5L engine in 1986, it equipped it with a bolt-on balancer assembly to get rid of the secondary vibration. According to Bruce Chapman at Ontario Reman, Etobicoke, Ontario, Canada, the balance shafts have different weights that correspond with the different piston weights that were used, depending on the year and application.

Rebuilder’s survival tip: These balancers can be rebuilt. Semi-finished bearings are available from Federal-Mogul Corp. under p/n SH1792S-SEMI. Most of the shafts can be reused, but they must be properly matched in pairs. The shafts are all marked with a "DR" for drive and a "DN" for driven, along with a number in most cases. See Chart 1 for all the combinations and applications. It’s best to put the balancers together with the right components and install the right assembly on the right motor, too.

Chrysler 2.5L Balance Shaft Combinations
Years	Application	Identification	Shaft Weight
1986-‘88	w/o Turbo	DR/DN	1465 grams
1989-up	w/o Turbo	DR4/DN5 DR9/DNO	1399 grams
1989-up	w/Turbo	DR6/DN7	1435 grams

Chart 1

Chrysler 2.2L/2.5L Turbo I And Turbo II Engines
Chrysler offered two different versions of the turbocharged 2.2L and 2.5L engines from 1987 through 1991. They are completely different engines on the inside, and parts are hard to come by for the Turbo II so proper identification is very important.

Most rebuilders catalog the Turbo I as "without intercooler" and the Turbo II as "with intercooler," but that wasn’t always the case because there were some Omni GLHS cars that had the intercooler installed along with the Turbo I engine.

There is one foolproof way to tell the difference, though; the Turbo IIs were used only in Dodges and they all came with a two-piece intake manifold instead of the one piece manifold found on the Turbo I engines. That makes it easy to tell them apart.

Chrysler/Jeep 242/4.OL Cranks
Chrysler changed the crankshaft for its 242/4.OL engine in 1992 when it standardized the pilot bearing across its entire line of engines. Rebuilders need to be aware of this change because these cranks are not always interchangeable. Illustration A shows what the 1987-’91 crank looks like. A small pilot bearing (1.055") is installed in a stepped bore inside the crank. The input shaft for the transmission has a long snout that protrudes forward into the pilot bushing.

Illustration B shows what the 1992 and later crank looks like. Notice that there are two differences: First, the hole for the converter hub is approximately .820˝ deep instead of about .550" so that a sleeve and bushing assembly (p/n 53009180) can be installed in the shaft when a manual transmission is used. The input shaft for the transmission is shorter because the pilot bearing is further back in the crank.

Second, the I.D. of the stepped hole is only .995" in diameter which isn’t big enough for the old style pilot bushing.

Rebuilder’s survival tip: Be sure to keep these two cranks separate. The early crank can’t be used on the later engines. The later crank can be used on early engines with an automatic, but it can’t be used with a stick unless the hole for the pilot bearing is opened up to 1.052" so it will accept the early pilot bearing with a slight press fit.

Chrysler 3.3L/3.8L Cylinder Heads
Chrysler made a running change in November of ‘96 to help keep the front rocker stand from breaking off on these heads. The front hole was drilled and tapped deeper and a new, longer bolt (p/n 6100174) was released for the deeper holes. It’s .600" longer than the short bolt originally used. See photo.

Rebuilders who repair the broken rocker stands on these heads should drill and tap the hole deeper and use the longer bolt. It would probably be a good idea to drill and tap the threads for the front stands deeper and install the longer bolt in all of them just to be safe.

Chrysler 242/4.0L Changes In 1996
Chrysler made a number of changes to its 242/4.0L inline six in 1996 to reduce noise, vibration and harshness (NVH). Even though the earlier blocks, cranks and heads look similar, they can’t be interchanged with the ’96 castings. Here’s why:

• The block was modified internally to reinforce the bulkheads for the mains and reduce vibration in several other areas. There are two additional holes in the deck surface for the dowel pins that align the head, too. It’s a 53020569 casting that has "NVH" on the side of the block.

• The mains are all tied together with a stamped steel "girdle" that bolts onto the special studded main bolts. See photo.

• The crankshaft was modified to provide enough clearance for the girdle, so the earlier cranks will not work in the ’96 engines. See photo. The ’96 crank has either a 53010411 or 53020767 casting number.

• The head is different, too. It has two holes for the dowel pins, the ports are supposedly different, and it uses a new rocker cover that requires a special rocker gasket with four reinforcing ribs that tie it together from one side to the other. It’s a 630 casting.

Chrysler 3.0L
When a Chrysler 3.0L engine overheats in a minivan, odds are the cooling system is at fault and the radiator needs replaced because it was marginal even when it was new, especially on the earlier vans. If replacing the radiator doesn’t solve the whole problem, try replacing the heater core, too. Apparently it limits the flow of coolant in the cooling system when it gets a lot of miles on it and that causes the engine to run hot, too.

Chrysler 3.0L
Oil consumption can be a problem with the 3.0L. Sometimes the guides have moved in the head and disrupted the stem seals, and sometimes the seals themselves just can’t handle all the oil that’s topside on these engines.

Some of the stem seals are difficult to install and end up cocked on the guide while others tend to slip off the guide after a few thousand miles. And, if the engine is on the ragged edge of detonation like most of them are, both the intake and exhaust valves will run too hot and ruin the stem seals. We have seen them get so hard and brittle that they’re no longer effective after only six months on the road.

Rebuilder’s survival tip: The OEM seal works better and lasts longer than anything else we have tried so far, so we would recommend using it. It goes on straight, stays on the guide, and it doesn’t get hard from the heat. It’s available in the aftermarket at a premium price, but it’s well worth the extra cost to eliminate the problems caused by stem seals that don’t do the job.

There’s one more thing that sometimes causes oil consumption on these engines: The PCV system "breathes" through the laminated rocker covers that have a maze of baffles between the inner and outer layer of each cover.

When these baffles get plugged with sludge (see photos), the PCV system doesn’t work right, so two things can happen: 1) The crankcase and rocker covers end up pressurized from the inside, so oil leaks out past every gasket and seal on the engine, or 2) Oil fills all the space in the baffles and can’t drain back into the engine so the inlet for the PCV valve ends up sitting in oil. When that happens, it sucks oil instead of air into the intake manifold and burns it.

If everything else checks out good and the engine is still using oil, remove the intake and look for an oily sheen on the ports. If they’re shiny with oil, the odds are that the PCV system isn’t working right and the covers are at fault. And, if the engine seems to be leaking oil everywhere you look, there’s a pretty good chance that the crankcase is being pressurized because of an inoperative PCV system.

In either case, it’s best to remove both rocker covers and replace them with new ones. New covers will solve the oil consumption problem if the PCV system was restricted. They will also prevent any new oil leaks, assuming everything was assembled right, but they may not "heal" any existing problems, because once a gasket starts leaking, it’s almost impossible to get it to seal back up. So, you may have to replace the seals and gaskets at the same time you replace the covers in order to get the engine sealed up once and for all.

Chrysler Oil Filter Plate And Stud
When Chrysler standardized all of its oil filters in 1991, it changed the block, the plate and the stud on all the 3.9L/5.2L/5.9L engines. See photos. The oil filter boss on the block was about 0.250" shorter, so the revised filter plate was deeper and used a longer stud for the filter. The plates are easy to tell apart – the early one has four oil holes in it and the later one has six.

Rebuilder’s survival tip: A rebuilder can cover the ’91 applications for the 3.9L/5.2L/5.9L Chrysler engines in one of two ways:

1) Catalog a ’91-only application for all three engines that came with the shorter filter boss and use only the blocks that have the shorter boss; or

2) Send the matching plate and stud with the engine so you don’t have to catalog separate engines. The early four-hole plate is a p/n 2402103. It’s used with the shorter stud (1.260") that’s a p/n 3671602. The ’91 and later engines used the six-hole plate that’s available as p/n 53009019, along with the longer stud (1.475") that’s a p/n 53007563.

Chrysler/AMC 150/2.5L
Chrysler/AMC has used two crankshafts in its 2.5L four cylinder. The original crank had a long snout (2.50") for vee belt pulleys. See photo. In 1987, some of the applications used the serpentine belt that required a short snout (2.125") on the crank. By 1988, everything was supposed to be using the serpentine belt, but that may not always hold true.

Chrysler 238/3.9L V6 Timing Chain Rattle
Chrysler encountered a timing chain rattle on some of its 1990 and later 238/3.9L V6 engines, so it introduced a retrofit timing chain tensioner assembly (p/n 53021195AA) that replaces the cam thrust plate and the oil tab. See photo. It should be used with the regular heavy duty, double roller chain and sprocket assembly according to Chrysler.

Chrysler 3.9L/5.2L/5.9L Magnum Blocks
When Chrysler introduced its Magnum engines in 1992 and ’93, it changed the blocks on all three engines. The 318 and 360 had three bolt bosses added on each side so Chrysler could use the motor mounts that had been used on the 3.9L since 1987. And, there was a flat pad with two drilled and tapped holes added onto the back of the deck surface on the passenger side of all three engines so Chrysler could mount the crank position sensor for the sequential fuel injection.

Unfortunately, this extra pad may not be there on some blocks, and that will cause a problem if it gets built as a Magnum engine. The original 318 Magnum block casting (c/n 53006657) was actually used during the latter part of ’91 before the 318 became a Magnum engine in ’92, so the pad was missing on these early blocks. Likewise, when a Magnum block was used as a service replacement for an earlier engine, the pad was machined off before the short block was assembled.

Rebuilder’s survival tip: Be sure to visually check every Magnum block to make sure that the pad with the two holes is actually there before using it for a Magnum application.

Chrysler 3.3L/3.8L Blocks
It appears that Chrysler used the same block castings for both the 3.3L and 3.8L engines even though the cylinder bore is substantially different. The 3.3L has a 3.66" bore while the 3.8L has a 3.78" bore, so there’s a difference of 0.120". That’s a lot, so the walls are real thick when the block is bored for a 3.3L and a whole lot thinner when it’s used for a 3.8L.

Rebuilder’s survival tip: Be sure to check the wall thickness on every 3.8L block, especially on the major thrust side and near the casting seams before boring it oversize. Or, better yet, scrap any used 3.8L blocks and make "new" ones by boring 3.3L blocks up to 3.8L standard.