My temp gauge keeps teeter totting on the highway I can not use the ac at all now what would cause this to go real high then back down over and over?

Asked by May 19, 2016 at 11:14 PM about the 2004 Subaru Legacy L 35th Anniversary Edition Wagon

Question type: Maintenance & Repair

I have a Subaru Legacy where when I am
on the highway the temp gauge goes real
high and the. Back. Down to normal over
and over and I sure can't use the ac!!

7 Answers

6,145

I wouldn't drive it until you get it fixed. Whether it's a thermostat, water pump, head gasket, leak, or other issue.. just don't drive it and warp the heads (if they aren't already?).. I'm guessing head gasket since the load from the AC is making it worse? Try to get some "ball park" estimates from local places and get a feel for who has the most realistic prices, explanations, best bang for buck. maybe even google maps search (and skim reviews) for mechanics. HTH

6,145

Also read this: https://allwheeldriveauto.com/subaru-head-gaskets- problems-explained-part-ii/

3,670

Search the forum, as I've addressed this in length several times. Quickly: OE t-stats and water pumps are always fine, so ignore unless someone put in an aftermarket one on you; check rad for exterior front surface debris (leaves, mud, dirt); back-flush heater hoses (under windshield). Be sure to purge air fully. Still overheat under load? Sniff expansion tank for HC, indicating exhaust gas percolation. If so, you need HGs ($1600), suggestiing tossing this baker's dozen years Subie. But do the simple stuff first (but it ain't a t-stat nor water pump).

1 out of 1 people think this is helpful.
6,145

what is HC? Hydrocarbons?

3,670

Yup. First gases will bubble up under light throttle; eventually full- time at hot idle, with even violent explosions when revved up. One of the few times I wear eye protection.

55

also your gauge might be going out

3,670

In my 30yrs exp servicing thousands of Subarus I've NEVER seen a faulty temp gauge.

Your Answer

Add photo

Related Questions

Legacy

Looking for a Used Legacy in your area?

CarGurus has 16,456 nationwide Legacy listings starting at $800.

ZIP:

Search Subaru Legacy Questions

Subaru Legacy Experts

#1 Anthony_60
Anthony_60
Reputation 1,210
#2 Nick Eidemiller
Nick Eidemiller
Reputation 690
#3 dandyoun
dandyoun
Reputation 630
View All

Related Models For Sale

Used Subaru Impreza
174 Great Deals out of 15,351 listings starting at $1,695
Used Subaru Outback
318 Great Deals out of 32,542 listings starting at $1,650
Used Subaru Forester
260 Great Deals out of 24,582 listings starting at $995
Used Subaru Impreza WRX
42 Great Deals out of 1,154 listings starting at $1,500
Used Honda Accord
697 Great Deals out of 83,203 listings starting at $500
Used Toyota Camry
854 Great Deals out of 90,790 listings starting at $1,200
Used Subaru Impreza WRX STi
26 Great Deals out of 591 listings starting at $8,991
Used Honda Civic
480 Great Deals out of 81,845 listings starting at $558
Used Nissan Altima
795 Great Deals out of 77,606 listings starting at $2,700
Used Audi A4
198 Great Deals out of 10,847 listings starting at $1,333
Used BMW 3 Series
1,069 Great Deals out of 34,811 listings starting at $900
Used Toyota Corolla
757 Great Deals out of 74,633 listings starting at $1,991
Used Mazda MAZDA6
99 Great Deals out of 16,554 listings starting at $1,750

Used Cars For Sale

2017 Subaru Legacy For Sale
5 Great Deals out of 10,875 listings starting at $19,665
2016 Subaru Legacy For Sale
55 Great Deals out of 857 listings starting at $12,795
2015 Subaru Legacy For Sale
32 Great Deals out of 837 listings starting at $11,500
2014 Subaru Legacy For Sale
40 Great Deals out of 1,180 listings starting at $9,499