Diesel Data: Automotive Repair

Road Test

DIAGNOSIS AND TESTING - ROAD TESTING





CLUTCH APPLICATION

Before road testing the vehicle, be sure that the fluid level and the control cable adjustments have been checked and adjusted if necessary. Verify that all the diagnostic trouble codes have been resolved.

Observe the engine's performance during the road test. A poorly tuned engine will not allow an accurate analysis of the transmission's operation.

Operate the transmission in all gear ranges. Check for shift variations and engine flare which indicates slippage. Note if shifts are harsh, spongy, delayed, early, or if part throttle downshifts are sensitive.

Slippage is indicated by engine flare, this usually means that the transmission has a clutch concern an overrunning clutch or a possible line pressure problem.

A slipping clutch can often be determined by comparing which internal units are applied in various gear ranges. The clutch application chart provides a basis for analyzing road test results.