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4.0L OHV & SOHC V6 Tech General discussion of 4.0L OHV and SOHC V6 Ford Ranger engines.

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Old 04-02-2007
BigRed911's Avatar
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I am: Jonathan Hoog
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Best maintance for your 4.0L V6 OHV

I have the OHV, and I was wondering what can be done to enhance and get the most out of my engine. It has 145,XXX on the clock and its running like a champ...just underpowered, but what can ya do. All the engine has is a K&N Air filter. Besides regular oil changes...any recommendations?
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Old 04-02-2007
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I am: Maurice Jones Jr.
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follow exactly what is in the owners manual.....that is the best maintence schedule you can follow...
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Old 04-02-2007
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Nothing is going to give you all that much power. You can give it a new exhaust and get a programer for it. If you are looking for more than that go with some different gears. If yet more than that do a 5.0 swap.
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Old 04-02-2007
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I am: Josh Yates
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Oil, Plugs, Fuel Filter Yearly, shot of grease monthly on suspension, u joints etc.(every other week or so)
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Old 04-02-2007
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I am: Blhde Was here
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At 145k i would start with a compression test.

If one or more cylinders reads low, squirt approximately one tablespoon of Super Premium SAE 5W30 Motor Oil, XO-5W30-QSP meeting Ford specification WSS-M2C153-G on top of the pistons in the low-reading cylinders. Repeat the compression pressure check on these cylinders.

Compression Test—Interpreting Compression Readings

1. If compression improves considerably, piston rings are faulty.

2. If compression does not improve, valves are sticking or seating improperly.

3. If two adjacent cylinders indicate low compression pressures and squirting oil on each piston does not increase compression, the head gasket may be leaking between cylinders. Engine oil or coolant in cylinders could result from this condition.Compression Test—Compression Gauge Check

1. Make sure the oil in the crankcase is of the correct viscosity and at the proper level and that the battery (10655) is properly charged. Operate the vehicle until the engine is at normal operating temperature. Turn the ignition switch to the OFF position, then remove all the spark plugs (12405).

2. Set the throttle plates in the wide-open position.

3. Install a compression gauge such as the Compression Tester in the No. 1 cylinder.

4. Install an auxiliary starter switch in the starting circuit. With the ignition switch in the OFF position, and using the auxiliary starter switch, crank the engine a minimum of five compression strokes and record the highest reading. Note the approximate number of compression strokes required to obtain the highest reading.

5. Repeat the test on each cylinder, cranking the engine approximately the same number of compression strokes.
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Old 04-03-2007
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At that many miles there are a lot of things you can do. A full tune up would be first on my list. (maybe a demon coil pack to replace the aged stock one)

Next, clean the throttle body, idle air valve, and pcv valve with spray cleaner that's specific for TB cleaning.

Then I'd put in two bottles of techron (by chevron) injector cleaner and fill that tank with shell V-power. (you'll clearly see an improvement) *then* after you've run that tank out replace the fuel filter.

IMO at that many miles your real power robber is going to be dirty intake valves and dirty injectors. The V-power gas and two bottle of techron should clean most of it up.

Those things will get you back to where it's supposed to be.. given that many miles of coarse.

Beyond that.. e-fan, underdrive pulley, tune, exhaust, ect...


He who is enslaved to the compass is free to sail the seas
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Old 04-03-2007
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I am: Marc Consic
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Mine has 188,000 miles and it runs perfect.I have used Mobil 1 synthetic since 1,000 miles.Keep up on the oil changes and it should last a long time.
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Old 04-03-2007
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The 4.0L tends to get carboned-up over time. Before you change out the plugs, you might consider a de-carbonization process:

Article No: 01-19-7

Some vehicles equipped with the 4.0L OHV engine may exhibit an engine noise which may be perceived by the customer as a piston/connecting rod bearing knock. This carbon knock is heard only under load during the drive cycle. Carbon knock is a customer drive duty-cycle phenomenon that cannot be repaired with an engine exchange. This may be caused by carbon build-up within the combustion chamber.

Verify condition. If normal diagnostics fail to correct the condition, de-carbon the combustion chamber to help quiet the carbon knock noise. Refer to the following Service Procedure for details.


1. Use Motorcraft Carburetor Tune-up Cleaner PM-3.

2. Carbon removal:
a. Disconnect canister purge line from throttle body.
b. Attach a vacuum line to the canister purge port.
c. At hot engine idle, allow the engine to ingest 1/2 to 2/3 of a can of Motorcraft Carburetor Tune-up Cleaner. Use caution not to ingest too quickly due to potential hydro-lock issues.
d. Shut engine off and allow it to soak for one hour.
e. Start engine, allow engine to ingest the remainder of the Motorcraft Carburetor Tune-up Cleaner.
f. Remove vacuum line and re-install canister purge line.
g. Road test vehicle at 3500 RPM for 2-3 miles.
h. Repeat above procedure two times for a total of three times.
i. Change oil and filter.

3. Review the customers' driving habits. The recommended drive cycle should include daily periods of engine operation above 3,000 RPM, such as a brisk acceleration from a stop position. This will break/burn the carbon off the piston head.
A product like Berrymans or Seafoam can be substituted for the the Motorcraft Carb & Tube Up Cleaner. See:
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