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The Ford Ranger 4.0L OHV & SOHC V6
The 4.0L OHV (Over Head Valve) V-6 engine found its way in to the Ford Ranger in 1990 and ultimately replaced the 2.9L V-6. This evolutionary redesign of the American 2.9L solved many of the reliability issues that plagued its predecessor. A beefier cylinder head design eliminated the 2.9L's common failure of cracked heads. Hydraulic roller lifters replaced the simple hydraulic lifters used in the 2.9L, which were sometimes overly sensitive to oil contamination, often requiring the lifters to be replaced prematurely. However, one major design fault was not completely eliminated: Valve rockers and upper pushrod tips still received poor oil supply, resulting in eventual wear to these areas, and consequential valvetrain noise as a result of the increased clearance. Required replacement of these parts is common in older engines.
The 4.0L OHV engine was produced until 2000 and was used in the Ford Explorer and Ranger. Output was 160hp and 225 ft·lbf. Though there is some variation, typically 155hp is quoted as horsepower for 1990-1992 applications.
In 1998 the 4.0L SOHC (Single Over Head Cam) engine replaced the 4.0L OHV engine producing 207hp.
SOHC & OHV Engine Differences:
The difference between a SOHC 4.0L and OHV 4.0L is that in a SOHC engine there is a camshaft sitting on the top of each cylinder head with the valves running directly off the camshaft. It doesn't rely on push rods, rocker arms, or lifters. The SOHC engine uses a jackshaft in place of a camshaft to drive a timing chain to each cylinder head. Three timing chains are used, one from the crank to the jackshaft, one in the front of the engine to drive the cam for the left bank, and one on the back of the engine to drive the cam for the right bank.
The OHV engine has the cam mounted above the crank. The cam and crank are joined in time by a timing chain. Lifters ride on the cam and push rods that extend to rocker arms in the heads which push the valves.
The SOHC 4.0 Usage:
We know that the Ford Ranger switched from the OHV 4.0L to the SOHC 4.0L in 2001, but the Ford Explorer wasn't as defined. The Ford Explorer actually started using the SOHC 4.0L in 1997 along with the OHV 4.0L. It wasn't until 2001 that Ford completely dropped the use of the OHV 4.0L in the Explorer. So that means that a 1997-2000 Ford Explorer can have either a OHV 4.0L or SOHC 4.0L, so you definitely need to look at the intake manifold and see how it's stamped.
Missing or Bogging - There are several things that could be causing this. First off your MAF may be dirty. Check HERE on how to clean it. Then there are the obvious - plugs, wires, dirty injectors. Tune up items basically.
Also, if you get a problem with hesitation, check the wires around the exhaust. One of the oxygen sensor wires may have been damaged by the exhaust.
Loose Intake Manifold Bolts - Some 90's 4.0L's have a problem with loose intake bolts. Click HERE for more details.
Offers stroker kits, camshafts, connecting rods, pistons, cylinder heads
Carries products including new air intake systems for some 4.0L Rangers.
Offers a new camshaft for the 4.0L.
Sells a True-Rev Sport Induction Kit.
Offers heads and intakes for the 4.0L engines.
Offers camshaft# 49-410-8 as an OEM replacement good for towing and all around performance. Camshaft# 49-422-8 is a more aggressive cam for 4.0's with other modifications. It is designed to improve midrange power and torque.
Offers a kit to install an Eaton supercharger on the 4.0L Ranger.
We found this kit on eBay to mount an Eaton supercharger on a newer SOHC 4.0 Ranger. The kit does not include the supercharger. The supercharger required is the 3rd generation m90, from the 1989 thru 1993 Ford T-Bird Supercoupe. (the inlet is oval). The manifold is all (aluminum), each port uses 2"OD aluminum 90 degree ells. There are 3-1/8" threaded pipe plugs in the manifold for sensor, water or alcohol injection, etc. The manifold will handle the weight of the M90 (without) additional support. This kit includes all component parts to install an Eaton M90, 3rd generation Supercharger on a 2002 Ford Ranger 4.0 SOHC.
Offers the X-Charger for the 4.0 SOHC Ranger.
Explorer Express X-Charger
Explorer Express also offers headers, spark plug wires, throttle bodies, and intake tube for the 4.0L OHV Ranger.
Vortec and Paxton had produced superchargers for the 4.0L engine but we can no longer find them listed.
BBK offers 66mm throttle bodies for the 4.0L OHV Ranger.
Offers a throttle body spacer that's said to increase low end performance and horsepower.
Pacesetter offers headers for the 4.0L OHV Ranger.
JBA offers headers and ignition wires for the 4.0L Ranger.
Offers headers for the 4.0L engines.
Both offer cat-back exhaust systems for the Ranger.
Nitrous Oxide Systems (NOS) showed the world how to effectively harness the power of nitrous oxide for automotive use in the 1970's. Since then, NOS has powered more racers than any other brand of nitrous. When you're looking to go fast, rely on NOS to deliver the most power per dollar available. From stock engines to race vehicles, jet skis to trucks, NOS has a kit for you.
Port your upper and lower intake. The intakes don't line up diameter to diameter. Porting opens this up and allows better flow. Knife edge the intake side of the throttle body to remove the front lip. You can use a Dremel tool to grind, sand and buff this area to obtain a smooth airflow in to the engine. You can also mill down the butterfly to blend in to the shaft for a smoother air flow.
For details on how to port your heads, click HERE.
MSD - Manufactures a DIS ignition system along with wiring harnesses. Find their parts at Summit Racing.
JetChip - Makes a module to reprogram the engines computer. Click HERE.
4.0 Computer Numbers Submitted by: skineral
1991 Explorer 4.0 Manual Transmission 4x4
3006 (F07F-12A650-YA) & (F07F-VAMR)
1992 Explorer 4.0 Manual Transmission 4x4
3397 (F27F-12A650-VC) & (F27F-12A650-VCMR)
1993 Explorer 4.0 Manual Transmission 4x4
3729 ( F37F-12A650-XB) & (F37F12A650-CRA)
1990 Ranger 4.0 Manual Transmission 4x4
1991 Ranger 4.0 Manual Transmission 4x4
1992 Ranger 4.0 Manual Transmission 4x4
1993 Ranger 4.0 Manual Transmission 4x4
Cylinder Head Diagrams:
4.0 OHV Cylinder Head Install