Cooling system

NORTHERNWOOKIE

MEMBER
SUBARU

1998 Subaru Legacy 2.5L, 140 000 miles, standard transmission. Was recently towing a trailer and engine overheated. Topped up coolant, but problem persisted, even when not towing. Reservoir keeps filling, but rad doesn't draw coolant from reservoir. Coolant in reservoir is cold to touch. Had pressure test done on rad, and head gasket test done also. Both came back negative, only problem was the rad cap was not holding recommended pressure. Replaced cap with USED cap, issue persists. Can drive for a few days without problem, then suddenly overheats. Other than replacing the used cap with a new cap, do you have any suggestions for fixing this issue? Thanks!

1 Reply

RASMATAZ

MECHANIC
75,992 POSTS

Do a cooling system flush, inspect the thermostat, and bleed the system see below

Always bleed air from cooling system after replacing coolant. Set heater for maximum heat. Remove radiator cap. Loosen drain plug and remove drain bolt (if equipped) from engine block. Drain coolant reservoir. Fill coolant reservoir to MAX mark with 50/50 water-coolant mixture. Loosen bleed bolt and fill radiator up to base of filler neck. Close bleed bolt when coolant flows out without bubbles. Tighten bleed bolt. With radiator cap removed, start and operate engine to normal operating temperature. Add coolant if necessary and check for leaks.