The Garage 354

DIAGNOSTICS
FAI Automotive
advises on
common valve
clearance issue
FAI Automotive has released advice on a common
issue with the Mitsubishi 4D56/T, offering tips on valve
clearance, recommending that essential adjustment
between the valve and rocker arm is necessary.
FAI’s comprehensive range of valves and guides are
manufactured to high-quality standards, with each
part produced from high grade materials.
This is essential for modern engines that run at very
high temperatures with a reduced stem diameter to
minimise friction.
As a specialist in this area, FAI advises that in
older applications that do not have a self-adjusting
hydraulic tappet or lifter, such as the Mitsubishi
4D56, manual adjustment between the rocker arm
and valve stem is a necessity.
When rebuilding the rocker shaft assembly, technicians should
adhere to the manufacturer clearance specifications, says FAI.
To begin, the engine should be at operating temperature,
before the technician ensures the timing marks are aligned
correctly by rotating the crank manually.
The engine must be at operating temperature when setting
valve stem clearances.
When these steps have been carried out correctly, FAI
instructs that you will see that the following valves are in the
raised position: Cylinder 1: Inlet & Exhausts; Cylinder 2: Inlet;
Cylinder 3: Exhaust.
The technician should then adjust the clearances by firstly
releasing tension on the rocker nut in preparation for the gauge.
Next, they need to place the correct feeler gauge between the
valve and rocker (size will be specified by the manufacturer).
After this, the technician should begin tightening the screw
while ensuring that the feeler gauge is met but not pinched, and
then the lock nut needs to be tightened to secure setting.
Once this has been completed, the feeler gauge should be
removed, before being reinserted to check there is a slight
interference between the valve stem and the rocker arm.
Following this, the crankshaft needs to be turned 360 degrees
clockwise.
They then need to once again adjust clearances by releasing
tension on the rocker lock nut, ensuring the correct feeler gauge
is in place, and ensuring the screw is tightened and the feeler
gauge is met, before tightening the screw and removing and
reinserting the feeler gauge.
While carrying out this step again, the following valves should
be focused on: Cylinder 4: Inlet & Exhaust; Cylinder 2: Exhaust;
and Cylinder 3: Intake.
Finally, to ensure the correct clearances are set and
maintained, the technician should replace the rocker cover, run
the engine for 10 minutes and then remove the rocker cover and
check tolerances are still correcting the same gauge(s).
As a conscientious supplier, FAI has initiated a programme to
mark every valve produced with the FAI part number, a factory
code, and batch number.
This information enables FAI to identify the valve or guide to the
factory it was manufactured in and the date it was produced on.
As its factory partners are ISO9001 & TS16949 certified, using
this information the company can identify the material used,
the foundry it was produced in, the QC records taken during
its production, and even the workforce on that shift, providing
complete reassurance and traceability.
For more information on FAI Automotive’s range of valves and
valve guides, visit: https://faiauto.com/parts/example-part-7/
1
32 THE GARAGE
28-32 Feature Diagnostics.indd 4 30/08/2023 15:23