When your customer complains that their vehicle’s engine surges, you’re first thought is to look for an engine performance related cause. That’s not always the case. Follow this Real Fix to see how a restricted transmission cooler caused the issue with this 1997 Chevrolet pickup.
Vehicle
1997 Chevrolet Pickup K3500 6.5L Diesel
Title
Engine Surges, Flushed Automatic Transmission Fluid Cooler
Complaint
The customer states the engine surges.
Cause
Confirmed the customer’s complaint and found the engine surged.Upon further inspection, found the automatic transmission slipped intermittently, which gave the sensation of the engine surging. Performed a visual inspection of the automatic transmission fluid and found it was at the proper level. Connected an oil pressure gauge to the line pressure test port, used the scan tool to command the automatic transmission pressure control solenoid to increase line pressure and found the actual line pressure reading on the oil pressure gauge did not match the commanded pressure intermittently. Removed the transmission pan to perform a visual inspection and found there was no excessive metal and clutch material in the pan. Connected an automatic transmission fluid cooler flow tester to the automatic transmission fluid cooler and found the fluid flow was below specification, which indicated it was restricted.
Correction
Flushed the automatic transmission fluid cooler and verified the vehicle operated properly. The customer’s concern did not return.