My 1998 Sub Legacy Outback Overheats

Asked by Jan 17, 2017 at 06:38 PM about the 1998 Subaru Legacy 4 Dr Outback AWD Wagon

Question type: Maintenance & Repair

I put in a new waterpump,new belts,radiator,thermostat.I added Bars Leak
Gasket Repair.Problem went away for about a year.Made the mistake of
adding more Bars Leak.Water would not circulate and it started to overheat
again.There was no water in the oil,the heater worked fine and I found no
leaks.I took it to a shop to have it Back flushed.He told me he did a blue dye
test and the test showed that the head gasket was good.I drove it home and
it overheated.I would like to know what this blue dye test is supposed to
show,if I have a bad head gasket or possibly an air lock or something.

3 Answers

96,055

It can't hurt to purge the air out of the system but if that does not work then back flush it again as the radiator is probably plugged up. Next time use Subaru's anti-leak or Alumaseal.

2 of 2 people found this helpful.

Thank you for your response.I would still like to know what a blue dye test is and what is it suppose to show.Also,what is the best way to purge the air from the system.

6,910

I'd posted a thorough procedure for purging and explaining early DOHC 2.5i motors HG issues here. Just search for it.... Note Bar's Leak NEVER helps to seal the DOHC 2.5i's infamous internal head gsaket high pressure percolation. A smaller t-stat, while not blocking flow, WILL cause overheating as its flow rate is lower. Check that t-stat was OEM. Rear heater hoses can clog...especially with a sealer. So it's important to back-flush THROUGH THE HEATER CORE; otherwise flow is too little. THEN: to purge quickly: raise FRONT of car with jacks or on curb; remove rad cap and install tight-fitting funnel in place to create a larger surface to view if possible. Start and warm up car. Add coolant mix to rad/funnel until nearly full, squeezing top hose to purge its air pockets up the funnel. Because the funnel level may be unstable it helps to turn the ac/defrost on so that the fans operate continuously, providing a measure of isothermality. Keep watching the now-stable liquid "lake" in the funnel as you twist the throttle-body to rev up and down. Be careful to not get splashed if hot coolant shoots up toward you! Either you will become satisfied that the coolant level stays stable, with NO air bubbles percolating up the funnel, or you'll see constant tiny bubbles all the time...increasing with throttle..., or you'll be satisfied that you're fully purged. If the latter, dump the funnel excess into the outer expansion bottle, cap[ the radiator, and go for a drive. IF the heater core and hoses are clear, AND the new T-stat is OE, and you still blow air (and coolant) out the radiator (and/or expansion tank), the odds are overwhelming that you need a pricey full head gasket service. Given your chariot's age, I'd toss it. But I'd only do so after ruling out the little stuff. I once "saved" a DOHC 2.5i by back-flushing coolant hoses, and a few times by returning to the proper OEM t-stat...and only a couple of times by changing out a clogged radiator, but 90+% chance your motor's percolating, and should NOT be rebuilt, as the subsequent failure rate from having overheated the block results in rod damage soonafter. Subie used this motor for only 5 years for these thermal sensitivities, simplifying things with the "new" SOHC 2.5i in 2000...which through 2009 has "external" (atmospheric...not high pressure percolation) HG leakage that although endemic, don't usually harm the sturdier block, and are just a more predictable repair. So again: flush this thing well, assure you've the right t-stat, purge, check for overheating. If so, dump the motor.

Your Answer

Legacy

Looking for a Used Legacy in your area?

CarGurus has 338 nationwide Legacy listings starting at $4,499.

Postal Code:

Subaru Legacy Experts

  • #1
    Anthony_60
    Reputation
    1,310
  • #2
    dandyoun
    Reputation
    760
  • #3
    Nick Eidemiller
    Reputation
    740
View All

Related Models For Sale

Used Subaru Impreza
35 Great Deals out of 708 listings starting at $2,995
Used Subaru Forester
50 Great Deals out of 934 listings starting at $1,095
Used Honda Accord
46 Great Deals out of 1,212 listings starting at $1,795
Used Toyota Camry
51 Great Deals out of 2,123 listings starting at $2,750
Used Honda Civic
278 Great Deals out of 4,709 listings starting at $2,287
Used Honda CR-V
41 Great Deals out of 2,695 listings starting at $300
Used BMW 3 Series
147 Great Deals out of 2,221 listings starting at $2,200
Used Toyota Corolla
146 Great Deals out of 3,479 listings starting at $2,495
Used Nissan Altima
62 Great Deals out of 1,248 listings starting at $999

Used Cars For Sale

2018 Subaru Legacy For Sale
23 listings starting at $26,760
2017 Subaru Legacy For Sale
72 listings starting at $22,680
2016 Subaru Legacy For Sale
22 listings starting at $15,990
2015 Subaru Legacy For Sale
4 Great Deals out of 74 listings starting at $13,900
2014 Subaru Legacy For Sale
30 listings starting at $12,990

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.