Dodge Ram Truck 1500-2500-3500. Manual — part 2089

5.7L V-8

The 5.7L V-8 engine is equipped with a closed crank-
case ventilation system and a Positive Crankcase
Ventilation (PCV) valve (4).

This system consists of:

•

a PCV valve mounted into the top of the intake
manifold, located to the right / rear of the throttle
body. The PCV valve (1) is sealed to the intake
manifold with 2 o-rings (2).

•

passages in the intake manifold.

•

tubes

and

hoses

to

connect

the

system

components.

25 - 28

EVAPORATIVE EMISSIONS

DR/DH

OPERATION

A typical enclosed crankcase ventilation system is
shown in the graphic.

The PCV system operates by engine intake manifold
vacuum. Filtered air is routed into the crankcase
through the air cleaner hose. The metered air, along
with crankcase vapors, are drawn through the PCV
valve (4) and into a passage in the intake manifold.
The PCV system manages crankcase pressure and
meters blow by gases to the intake system, reducing
engine sludge formation.

The PCV valve contains a spring loaded plunger. This
plunger meters the amount of crankcase vapors
routed into the combustion chamber based on intake
manifold vacuum.

When the engine is not operating or during an engine
pop-back, the spring forces the plunger back against
the seat. This will prevent vapors from flowing through
the valve.

During periods of high manifold vacuum, such as idle
or cruising speeds, vacuum is sufficient to completely
compress spring. It will then pull the plunger to the top
of the valve. In this position there is minimal vapor
flow through the valve.

DR/DH

EVAPORATIVE EMISSIONS

25 - 29

During periods of moderate manifold vacuum, the
plunger is only pulled part way back from inlet. This
results in maximum vapor flow through the valve.

DIAGNOSIS AND TESTING

PCV VALVE - 3.7L V-6/ 4.7L V-8

1. Disconnect PCV line/hose (5) by disconnecting rub-

ber connecting hose at PCV valve fitting.

2. Remove PCV valve at oil filler tube by rotating PCV

valve downward until locating tabs (2) have been
freed at cam lock (3). After tabs have cleared, pull
valve straight out from filler tube. To prevent dam-
age to PCV valve locating tabs, valve must be
pointed downward for removal. Do not force
valve from oil filler tube.

3. After valve is removed, check condition of valve

o-ring (1). Also, PCV valve should rattle when
shaken.

4. Reconnect PCV valve to its connecting line/hose.

5. Start engine and bring to idle speed.

6. If valve is not plugged, a hissing noise will be

heard as air passes through valve. Also, a strong
vacuum should be felt with a finger placed at valve
inlet.

7. If vacuum is not felt at valve inlet, check line/hose

for kinks or for obstruction. If necessary, clean out
intake manifold fitting at rear of manifold. Do this
by turning a 1/4 inch drill (by hand) through the fitting to dislodge any solid particles. Blow out the fitting with
shop air. If necessary, use a smaller drill to avoid removing any metal from the fitting.

8. Do not attempt to clean the old PCV valve.

9. Return PCV valve back to oil filler tube by placing valve locating tabs (2) into cam lock (3). Press PCV valve in

and rotate valve upward. A slight click will be felt when tabs have engaged cam lock. Valve should be pointed
towards rear of vehicle.

10. Connect PCV line/hose (5) and connecting rubber hose to PCV valve.

11. Disconnect rubber hose from fresh air fitting at air cleaner resonator box. Start engine and bring to idle speed.

Hold a piece of stiff paper (such as a parts tag) loosely over the opening of the disconnected rubber hose.

12. The paper should be drawn against the hose opening with noticeable force. This will be after allowing approx-

imately one minute for crankcase pressure to reduce.

25 - 30

EVAPORATIVE EMISSIONS

DR/DH

13. If vacuum is not present, disconnect each PCV

system hose at top of each crankcase breather
(1). Check for obstructions or restrictions.

14. If vacuum is still not present, remove each PCV

system crankcase breather (1) from each cylinder
head. Check for obstructions or restrictions. If
plugged, replace breather. Tighten breather to 12
N·m (106 in. lbs.) torque. Do not attempt to clean
breather.

15. If vacuum is still not present, disconnect each

PCV system hose (1) at each fitting, and at each
check

valve

(2).

Check

for

obstructions

or

restrictions.

DR/DH

EVAPORATIVE EMISSIONS

25 - 31