Parts for your 1998 Subaru Forester-Radiator

1998 Subaru Forester Radiator — What It Does and How to Look After It

Per the Subaru Forester (SF, MY1997–2002) Factory Service Manual — Cooling System, Subaru’s Technical Information System, and common workshop references such as the Haynes Legacy/Forester manual, the 1998 Forester absolutely uses a liquid‑cooled aluminium radiator. It’s a cross‑flow unit with twin electric fans, and on automatic models there’s an integrated transmission fluid cooler inside the left tank. So yes — a radiator is very much relevant to a 1998 Subaru Forester.

The radiator’s job is simple but vital: carry engine heat away via coolant, shed that heat through the core and fins, and keep the flat‑four running at a stable temperature. The cap (typically 1.1 bar spec) maintains system pressure so the coolant doesn’t boil, while the thermostat and fans help control temperature under all sorts of Aussie and Kiwi driving conditions — from slow city crawls to long climbs with the A/C blasting.

As part of routine servicing, the radiator and cooling system deserve regular checks. Use Subaru‑approved ethylene glycol coolant, mixed 50/50 with demineralised water unless you’re using a pre‑mix. Top up the overflow bottle to the marks and keep an eye out for leaks at plastic tank seams, crusty deposits around the cap, or damp spots under the bonnet after a drive. If the coolant looks rusty, oily, or full of debris, it’s time for a flush.

• Service interval: inspect every service, flush and renew coolant about every 2 years/40,000 km (or per the coolant’s long‑life label if applicable).
• Air bleeding: Subarus don’t love air pockets. Park nose‑up, set the heater to hot, run the engine with a spill‑free funnel on the filler, squeeze the upper hose to burp bubbles, then cap it once the fans cycle.
• Fans: both should kick in when hot or with A/C on. A lazy fan will send temps north in traffic.

When replacing the radiator, choose an OEM‑style plastic‑tank/aluminium‑core unit with the correct fittings. For automatics, cap or manage the transmission cooler lines so ATF stays out of the coolant — and vice versa. New hoses, clamps, thermostat and a fresh cap are cheap insurance. Dispose of old coolant responsibly, it’s toxic to pets and waterways.

Stay on top of it, and the EJ‑series engine will thank you with stable temps and fewer head‑gasket scares.

Popular questions about the 1998 Subaru Forester radiator

What coolant should be used, and how much does it take?
Use a Subaru‑approved ethylene glycol coolant suitable for aluminium engines, ideally mixed 50/50 with demineralised water (or a reputable pre‑mix). Capacity varies slightly by engine and transmission, but owners can expect roughly six to seven litres across the system. Always check the level in both the radiator and the overflow bottle after bleeding air.

Do automatic 1998 Foresters have a transmission cooler in the radiator?
Yes. Automatic models route ATF through an internal cooler inside the radiator tank. When changing the radiator, those two small ATF lines must be reconnected carefully and kept clean. Don’t mix ATF and coolant — if there’s cross‑contamination, both systems need to be serviced immediately.

How does one properly bleed the cooling system on this model?
Park the vehicle nose‑up, set the heater to full hot, and fill the radiator using a spill‑free funnel. Start the engine, let it reach operating temperature, and gently squeeze the upper hose to purge air. Once the fans cycle and no more bubbles appear, fit the cap and top the overflow to the correct mark. Recheck levels after the next drive.