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!!

13 Answers

7,035

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

7,035

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

6,140

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 of 1 people found this helpful.
7,035

what is HC? Hydrocarbons?

6,140

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

6,140

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

My 91 Subaru Legacy wagon temp started rising two days ago and it rises close to the H on the dash and then it will drop back down to medium again. Usually that's always a sign of thermostat. USUALLY* lol well I get a thermostat and I jack my subi up go under the car and see my thermostat housing... but it has three bolts and two different hoses, it's like a u shaped metal piping connected to the therm housing, and about 6 inches down its welded to what looks like my muffler or exhaust pipe. I'm so confused. I took the three bolts out and of course couldn't move the housing cover because it's welded to muffler/exhaust pipe! Well I wedged a brick in between the pipe/hose and frame just so I could try to get the old thermostat out and in the two wholes, no thermostats??? I'm so lost any one have any suggestions???

7,035

http://www.fixya.com/cars/t4878193- 1991_legacy_i_cannot_find_the_thermostat

6,140

Are you actually trying to find a t-stat in an exhaust manifold?

7,035

If he hadn't linked a pic, nobody would know.................Tim, I hope you find it and fix it and don't have any more overheating issues. good luck

6,140

Try taking a look under the LEFT side of the motor, where you'll find the lower rad hose emanating from the cast alum t-stat cover. You can remove it and test stove-top, but again I expect you'll find the overheating to be due to a blocked heater hose, radiator, or blown internally head gasket. But maybe you'll get lucky....

I did head gasket test, it came out good. My coolant isn't leaking and my coolant nor does my oil look milky so I don't think it's head gasket. It just started doing this two days ago. I haven't drove it cuz I don't want to worp anything or blow a gasket or screw my water pump up. I think it's either radiator hose, t-stat, or maybe air in my coolant flow?? I've replaced t-stat on a 5.9 dodge 1500 and water pump as well as a chevy cav. I've never had to go under my car to get to a t-stat housing. This is irritating. But thanks guys for the feedback! Much appreciated! I'm in S.C. Hopefully I can get the t-stat replaced today before the hurricane starts hitting us. Hope all you guys are safe if any of you are close to the southern east coast. Thanks again. I'll keep y'all updated

Your Answer

Legacy

Looking for a Used Legacy in your area?

CarGurus has 15,069 nationwide Legacy listings starting at $1,795.

ZIP:

Subaru Legacy Experts

  • #1
    Anthony_60
    Reputation
    1,270
  • #2
    Nick Eidemiller
    Reputation
    740
  • #3
    dandyoun
    Reputation
    730
View All

Related Models For Sale

Used Subaru Impreza
218 Great Deals out of 22,518 listings starting at $1,505
Used Subaru Outback
433 Great Deals out of 35,973 listings starting at $1,000
Used Subaru Forester
413 Great Deals out of 38,570 listings starting at $1,000
Used Honda Accord
1,117 Great Deals out of 73,322 listings starting at $1,100
Used Subaru Impreza WRX
43 Great Deals out of 1,180 listings starting at $1,500
Used Toyota Camry
1,138 Great Deals out of 86,705 listings starting at $800
Used Honda Civic
820 Great Deals out of 60,826 listings starting at $950
Used Subaru Impreza WRX STI
28 Great Deals out of 626 listings starting at $9,490
Used Nissan Altima
1,365 Great Deals out of 77,587 listings starting at $1,695
Used Audi A4
341 Great Deals out of 12,502 listings starting at $1,899
Used BMW 3 Series
1,169 Great Deals out of 32,725 listings starting at $1,200
Used Toyota RAV4
875 Great Deals out of 52,468 listings starting at $1,600

Used Cars For Sale

2018 Subaru Legacy For Sale
8,380 listings starting at $19,672
2017 Subaru Legacy For Sale
28 Great Deals out of 1,489 listings starting at $15,000
2016 Subaru Legacy For Sale
22 Great Deals out of 638 listings starting at $11,495
2015 Subaru Legacy For Sale
78 Great Deals out of 1,547 listings starting at $10,950
2014 Subaru Legacy For Sale
24 Great Deals out of 568 listings starting at $6,999

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.