@Daniel V – You state that you have a 2000 4.0 SOHC XLT 224,000 miles. Please update your vehicle description to include the following:
- 2WD or 4WD?
- Manual transmission or 5-speed automatic O/D transmission 5R55E?
- Job 1 or Job 2 engine? Job 1 engines were manufactured through 07/23/00; they have aluminum valve covers with the oil fill cap on the driver's side; they have a multi-piece intake manifold whose O-rings don’t last. Job 2 engines were manufactured after 07/23/00; they have black plastic valve covers with the oil filler cap on the passenger side; they have a 1-piece intake manifold with better sealing O-rings and the PCV valve is located at the rear of the driver's side valve cover.
FIRST
Before you remove or disconnect anything! With a cold engine at idle, take the opportunity to identify vacuum leaks. There are MANY parts, gaskets, O-rings, and vacuum hoses that might be leaking vacuum. Given you plan to tear into the intake system, you’ll want to identify leaks now… so you’ll know what to replace. Look for vacuum leaks by spraying the suspected leaking surfaces with Brakleen (the flammable kind). If the engine revs up, then you’ve identified a leak. Make sure to spray at multiple locations around and under the intake manifold, especially in the rear where all of the PCV stuff is located.
SECOND
Know that by taking things apart, you’ll (likely) create new vacuum leaks. Given the age of your truck, this is (almost) inevitable because rubber and plastic become brittle and inflexible over time. After you put everything back together, perform the Brakleen test again.
THIRD
Regarding which parts to replace (since you’ll already have the intake manifold removed), here’s a comprehensive list… and some tips to make your repairs more successful:
Air filter – Inexpensive; use “regular filtration” filters (not “super, extra, incredible” filtration filters) and replace often!
Fuel filter – Inexpensive; get a loaner disconnect tool from the auto parts store.
PCV valve – Inexpensive; use only a Motorcraft valve!
O-Ring on engine crankcase vent valve (aka oil separator assembly) – Check the assembly for leaks; it’s plastic and made of two pieces; seal it where the two pieces are joined. Replace the O-ring.
All O-rings and gaskets between the upper and lower intake manifolds.
All O-rings and gaskets between the intake manifold and the heads.
All O-rings and gaskets where the EGR tube (use Vaseline or assembly lube on the O-ring when installing it to ensure it slides into the correct position inside the intake manifold), IAC, and any other connections are made to the intake manifold.
Fuel injectors – Order by stamp number. Instead of installing new injectors, consider using OEM injectors that have been rebuilt. Consider buying set of flow-matched Bosch injectors; make sure they come with new O-rings!
Fuel injector seats – They’re plastic; they become brittle.
FOURTH
At the rear of the black, plastic thermostat housing, there will be 1 or 2 sensors. They may be threaded in, or clipped in, one or the other.
The ECT sensor is on the driver’s side and it’s gray-colored. It reports to the PCM and affects engine performance. If this sensor was not operating properly on the day you said it was 105-degrees outside, then it’s faulty operation could have been the cause of your truck starting to decelerate when you had the cruise control ON.
The Engine Temperature Sender is on the passenger side and it’s brown or orange colored. It doesn’t report to the PCM and doesn’t affect engine performance. It simply drives the temperature gauge on the dashboard.
Consider installing an all-aluminum thermostat housing.
Install a new thermostat, ECT sensor, Engine Temperature Sender, and all associated gaskets and O-rings.
FIFTH
It can be difficult to remove the intake manifold by disconnecting the EGR tube from the manifold. A way around this is to remove the two bolts holding the EGR tube to the EGR valve. Then, remove the manifold and the EGR tube as one piece.
