6.2L diesel tech
GM 6.2L diesel
Water temperature sensor. Block-off plate for pass side head, rear:
- GM part # 14028949 Water jacket cover w/ threaded bung
- GM part # 10137488 gasket
Jeep 4.0L gauges
gauge compatibility with 4.0L swaps
Tachometer
Later models with distributorless ignition will require an adapter to generate a tach signal for an aftermarket tach.
- Auto Meter 9117
Jeep 4.0L VSS
Vehicle Speed Sensor
All engines from ‘91 and up make use of a speed sensor to send the speedometer signal to the computer. 87-90 Renix systems did not use a vehicle speed sensor.
‘91-96 OBD I
While a VSS is part of the factory system, it is not clear how important this component is to the system. With a manual PCM, the engine will still run and drive.
- Cable-driven speedometers on CJs and SJs require a 7/8″ thread
- There is a stock speed sensor that provides the 91-96 VSS signal and mechanical 5/8″ output:
- Wells SU3008 [pic]
- Niehoff SN7005 [pic]
- Mopar 56027015
- An adapter is available toconnect this 5/8″ thread VSS to 7/8″ speedo cable [ ? ]
Jeep 4.0L Fuel System
Fuel System Info
As with any fuel injected motor, it is critical to have a fuel system designed to deliver fuel to the FI system’s needs that is in good condition.
91-96 (Mopar) fuel system
The following information mainly applies to the 1991-1996 HO system.
The ‘91-’96 fuel rail has 2 fuel line connections, one for supply and one for return. The pressure regulator is built into the fuel rail, unlike the later 4.0 systems which are regulated by the in-tank pump. For vehicle swaps, one can either get a tank with an in-tank pump or use an inline pump. With an inline pump you should use a fuel filter before and after. When a pump dies, little parts of it go through. All Jeep vehicles that came with a 4.0L use an in-tank pump. In-tank pumps are more effecient, as it is easier for a pump to push fuel than to pull it.
The regular in the fuel rail regulates fuel pressure down to ~45 psi, so the fuel system should deliver fuel pressure higher than this, 60+ psi is recommended.
In-tank fuel pump
Since all stock applications of the 4.0L use an in-tank fuel pump, I strongly recommend it for reliability. All ‘76-90 CJs and YJs used the same general fuel tank hose locations and sending unit bunghole. This includes the standard steel 15 gal tanks as well as poly 20 gal tanks. ‘87-90 YJ Wranglers had a MPI 4cyl, with an in-tank pump that will deliver the proper fuel pressure and volume for a 6cyl as well. So, a common solution for those swapping a 4.0L into a CJ or early YJ is to retain the stock fuel tank and drop in this ‘87-90 YJ 4cyl in-tank fuel pump.
- ‘87-90 4cyl YJ sending unit: Mopar 83502990
Another option for 4.0L swaps is to retrofit a later model fuel tank. Since the hose locations changed, this will require some modifications.
All ‘91-95 YJs used a 20gal tank. The 15 gal tank was really just a different filler vent hose [source]
‘97 and up (Mopar) fuel system
Starting in 1997, the fuel pressure regular was moved from the fuel rail on the intake manifold to the in-tank fuel pump assembly.
Jeep 4.0L CPS
Crankshaft Position Sensor
The Crankshaft Position Sensor sends a signal to the computer in indicating the position of the crank. The ignition won’t spark if this isn’t working properly. From the factory, all ‘87 and up 4.0L engines have the CPS located at the top of the bellhousing, and read the signal off of the flywheel or flexplate. *The 87-90, 91-96, and 97+ HO flywheels/flexplates as well as CPS are NOT interchangeable!!!
91-96 (Mopar) CPS
The following information mainly applies to the 1991-1996 HO system.
Here are the options for using a CPS when swapping a 91-96 engine into a different vehicle:
- Retain the automatic transmission or manual transmission bellhousing from a 91-96 4.0L application which is already fitted for a CPS. This is the easiest if you have the transmission or bellhousing anyway.
- Buy a automatic transmission & flexplate or bellhousing & flywheel from a ‘91-96. Be sure that you get one that is from 91-96.
- Have a shop machine your bellhousing to fit a CPS. This is a service that Novak Adapters can perform. Purchase a ‘91-96 flexplate or flywheel.
- Use a CPS relocation kit
- Advance Adapters 716012-C (includes ‘91-96 sensor)
- Advance Adapters 716012 (includes ‘97-05 sensor)
- Hesco HES9199ED application: ‘91-03, no sensor included, use stock sensor.
Jeep 4.0L Swap
One of our topics of study will be the Jeep 4.0L sixer and everything involved in swapping it into different vehicles. I will start with covering the swap I did in 2003. This swap was a 1993 4.0L HO from a YJ into my 1982 Jeep Wagoneer.
The Wagoneer originally came with the 258 6 cyl, the big brother of the 4.0L. Here is a breakdown of the parts I used:
| Part | Purchased from | Price |
| 4.0 complete engine from a ‘93 YJ with 77k miles. I drove to Alabama to pick it up, about 700 miles. This engine came with the harness, PCM, Helix throttle body spacer, air intake, starter, P/S pump, and headers. | ebay auction | $600 |
| Hesco’s Harmonic balancer and sensor kit. Includes new machined balancer, sensor, and bracket that attaches with 3 oil pan bolts. | Hesco | $289 |
| 90 psi inline fuel pump | Hesco | $85 |
| Accelerator cable from a ‘93 Wrangler 4.0 Motormite part # 16635 |
Advance Auto Parts | $17 |
| New Wagoneer radiator. What better time than an engine swap to buy a new radiator? | Advance Auto Parts | $191 |
| non-power brake master cylinder for a ‘78 J-10 | Advance Auto Parts | $28 |
| MAP sensor | Advance Auto Parts | $30 |
| 7/32″ vacuum hose for MAP sensor | Advance Auto Parts | $5 |
| (2) 12 volt 30 amp relays for: ASD (auto shutdown) relay and fuel pump relay | Advance Auto Parts | $5 |
| 12v panel indicator light for new Check Engine light | Advance Auto Parts | $5 |
| Machine shop drilled out the front hole on the passenger side motormount to fit a 12mm bolt | machine shop | $10 |
| low restriction fuel filter before pump NAPA part #18-7831 3/8″ inlet 3/8″ outlet |
NAPA | $5 |
| regular fuel filter after pump NAPA part #3482 3/8″ inlet 3/8″ outlet |
NAPA | $10 |
| 5 feet of 5/16″ fuel injection rated hose and hose clamps | NAPA | $33 |
| Lokar Kickdown cable part# KD-2727HT for TF-727 | Summit Racing | $60 |
| Longer cable to replace the one from the Lokar kit | $5 |