Er det "good or bad" ? ;-)
Må denne skiftes på intervaller slik som en reim?
Eller er dette kjedet som andre kjeder at det bare ettersees?
Dette sier vel alt, den er helt fantastisk.
klipt fra
http://en.wikipedia.org/wiki/AMC_straight-6_engine4.0
Engine bay of a 1993 Jeep Grand Cherokee with 4.0 L
The 5 millionth Jeep 4.0 engine produced on the "Greenlee Block Line" dated June 15, 2001
The 242 cu in (4 L) engine was developed by AMC in just 26 months using many off the shelf components while featuring, among others, additional strength, improved combustion chamber, port setup, and cam profile.[12] The total weight of the new engine was 483 pounds (219.1 kg), only one pound more than the 258 six despite its more weighty components and parts.[12] For example, the cast aluminum valve cover featured 15 bolts, the industry's most, to achieve a positive seal.[12]
The new engine was introduced in 1986 for the 1987 model year was a further evolution of AMC's 258 six.[13] It had the same 3.895 in (98.9 mm) bore as the 2.5 with a longer 3.414 in (86.7 mm) stroke giving it a displacement of 241.6 cu in (3,959 cc).[14]
The 4.0 is one of AMC's best-known engines.[15] It was one of four AMC engines kept in production when Chrysler bought AMC in 1987. Chrysler engineers continued to refine the engine to reduce noise, vibration, and harshness. The last in the line of the AMC inline sixes, the 4.0 is regarded as one of the best 4x4 off-road engines.[16] A Motor Trend long-term test of a 1997 Cherokee XJ noted "this long-lived OHV powerplant has a reputation for getting people where they need to go" as well as "much love expressed by owners for the torquey 4.0-liter/190-horsepower inline six."[17] The engine is known for longevity and to go more than 300,000 miles (482,803 km) without rebuilding.[18][19] There are many aftermarket parts available.[20]
When introduced, the block-mounted oil filter check valve was eliminated on the 4.0 (along with the 2.5) when Chrysler engineers standardized their oil filters. The pre-1987 engines had an oil filter adapter with 3/4 and 13/16 threads (which used a GM oil filter common to Buick, Oldsmobile, Pontiac, and Cadillac V8 engines) while the 1987-06 engines were originally fitted with a 20 mm metric thread filter (later revised in 1991 for the common 3/4 threaded Mopar and Ford V8 oil filter).
The first 4.0 engines in 1987 had a RENIX (Renault/Bendix) engine management system considered quite advanced for their time.[10] A knock sensor allowed the ECU to control spark advance in response to fuel octane and engine load. Unfortunately, there are few scan tools capable of interfacing with the system to pull diagnostics codes. RENIX systems also have no permanent memory for diagnostics codes thus making the diagnosis of intermittent problems more difficult.[21]
The 1987 RENIX 4.0 made 173 hp (129 kW; 175 PS) and 220 lb·ft (300 N·m). In 1988, the 4.0 received higher flowing fuel injectors, raising output to 177 hp (132 kW; 179 PS) and 224 lb·ft (304 N·m)—more power than some configurations of the Ford 302, Chevrolet 305, and Chrysler 318 8-cylinder engines, and more than any of the Japanese 6-cylinder truck engines, but with comparable or superior fuel economy.[22]
In 1991, a Chrysler fuel injection system replaced the RENIX system, and the intake ports were raised approximately .125 in (3.2 mm) for a better entry radius. Chrysler also enlarged the throttle body and redesigned the intake and exhaust manifolds for more efficiency, and the fuel injectors were once again replaced with higher flowing units. Camshaft timing was also changed. The net result was an engine that made 190 hp (142 kW; 193 PS) and 225 lb·ft (305 N·m). Badging on most Jeeps equipped with this engine read "4.0 Litre HIGH OUTPUT." The new cam profile combined with altered computer programming eliminated the need for an EGR valve and knock sensor, but made the engine more sensitive to alterations, especially where emissions are concerned.[citation needed]
Small changes were made to the cylinder head for the 1995 model year. In 1996, the engine block was redesigned for greater strength. The new block had more webbing and a stud girdle for added rigidity of the crankshaft main bearings. Engines installed in 1999 Grand Cherokees carried the PowerTech name, which had been used intermittently in prior years and on other Chrysler truck and SUV engines[which?]. The name was subsequently passed on to 4.0s in the other Jeep models that used the engine, the Cherokee and Wrangler. The cylinder head was again changed for the 2000 model year to a more emissions-friendly design.[citation needed] This head was designated as "0331" in the casting number. Early 0331 heads are prone to cracking and causing coolant to contaminate the oil, which can eventually lead to catastrophic engine failure. The head cracks right in the center between #3 and #4 cylinders. The crack is usually discernible with the valve cover removed as a "milky" tan line. This condition is usually discovered before catastrophic engine failure, but can lead to that if not corrected in a timely manner. The casting was fixed sometime in mid to late 2001, but the same casting number was retained. The "fixed" heads have "TUPY" cast in the center where the cracks used to occur. [23] Also new for the 2000 model year, was the distributorless, coil on plug ignition system.[24]
Output: 1987-90: 177 hp (132 kW; 179 PS) at 4500 rpm with 224 lb·ft (304 N·m) at 2500 rpm. 1991-95: 190 hp (142 kW; 193 PS) at 4750 rpm with 225 lb·ft (305 N·m) at 4000 rpm. 1996-01: 190 hp (142 kW; 193 PS) at 4600 rpm with 225 lb·ft (305 N·m) at 3000 rpm. 2001-06: 190 hp (142 kW; 193 PS) at 4600 rpm with 235 lb·ft (319 N·m) at 3200 rpm. [25]
The 4.0 was discontinued at the end of the 2006 model year, replaced in the redesigned 2007 JK Jeep Wrangler by Chrysler's 3.8 L OHV V6 which originated in the company's minivans. The 4.0 engine was also made in China, where a slightly modified version of the XJ Jeep Cherokee with 2.5 and 4.0 engines were produced alongside the Chinese-produced WJ Grand Cherokee since 2006.
