ASE Heating and Cooling 4

Question 1

A cooling system holds pressure poorly during a pressure test, but no external leaks can be found. Technician A says the head gasket could be leaking. Technician B says the heater core could be leaking. Who is correct?

Accepted Answer

Both A and B

Answer

A pressure loss with no visible leak can come from an internal head gasket leak or from a heater core leaking into the cabin.

Question 2

Why is a refractometer preferred over a float-type hydrometer for checking coolant?

Accepted Answer

It reads accurately for both ethylene and propylene glycol

Answer

A refractometer gives accurate freeze-point readings for both glycol types, while hydrometers are calibrated for ethylene glycol only.

Question 3

What happens if the coolant mixture is more than about 70% antifreeze?

Accepted Answer

Freeze protection and heat transfer both get worse

Answer

Above about 70% glycol, freeze protection actually gets worse and heat transfer drops, which can lead to overheating.

Question 4

Why does the lower radiator hose often have a coiled wire spring inside it?

Accepted Answer

To keep the hose from collapsing under water pump suction

Answer

The lower hose is on the suction side of the water pump, so the spring keeps it from collapsing at high RPM.

Question 5

What is the typical recommended service interval for long-life OAT coolant?

Accepted Answer

5 years or 150,000 miles

Answer

Extended-life OAT coolants are commonly rated for about 5 years or 150,000 miles; always follow the OEM schedule.

ASE - Automotive Service Excellence Certified Tech Practice Test

ASE - Automotive Service Excellence Certified Tech Practice Test

ASE Heating and Cooling 4