99 Subaru Legacy outback overheating ONLY when driving

Start be replacing the cooling system cap . Thermostat is also suspect . diag can be tricky if not skilled . an infra red thermometer can assist in determining if t-stat is opening to circulate coolant . Do you smell coolant ? Cooling system pressure test for pinhole of vapor leaks strongly recommended . This is NOT an engine you want to overheat ! Also check water pump drive belt tension could be slipping . If the cooling system has not been filled with a quality coolant mixture the water pump could also be suspect especially if any rust has been obserbved in the radiator . Are there leaves or debris lodged between the radiator and a/c condenser ? Check if so flush out with high pressure water . Good luck !

Hmm, 1999 Legacy with only 66,000 miles? Tell me, how do you know that?? Did you actually purchase this BRAND NEW? And, if you did, which I seriously doubt, you would have known everything about the history of this car! SO, how long have you really owned this car?? And, how many owners had it before you? Finally, how did you acquire it, private party, used car dealer? So, tell us.... By the way, the first person was absolutely correct, you don't want to EVER overheat your car.... results will be VERY EXPENSIVE.

You have probably already blown the head gaskets...a $2000 repair... By the way, if your mechanic seems UNSURE of what's wrong, you have the WRONG MECHANIC.

I have owned the car for 2 years. I live on Martha's Vineyard and the only previous owner was an elderly woman who only used car to drive to grocery store etc. Has never even been on a highway. I don't know very much about cars so I am just trying to figure this out, thank you. My mechanic is a family friend and doesn't usually work on subarus besides for brakes etc. Did not pay very much for the car, so if it is something that is cheap enough will fix because it is a great island car. Thank you Clif for the actual suggestions on how to help.

YES, family friend or not, you really need someone who knows how to work on Subaru's, otherwise, you run the risk of ruining your car...

Cross, on top of replacing the cap, I'd have the coolant checked for cooling capacity and if it's bad, replace it. If you're on an island, are there any parts stores nearby that check little things for potential customers?

Mark's partially correct in that the HGs are blown here, but not because YOU did it! The 95-99 DOHC 2.5H has seriously undersized wall thickness between cylinders and cooling lines, resulting in explosive percolation of the exhaust gases into the coolant, blowing the coolant. It is NOT the rad cap nor t-stat...ever!

Ernie, OK, thanks, by the way, how am I partially correct?? I said earlier that she probably has blown head gaskets. YES, the 1995 to1999 Subaru Outback cars have a genuine archilles heel here, too bad!

Is it even WORTH FIXING???

cross.. does it overheat at lower speeds with minimal throttle? It's pretty much assumed that overheating while driving + subaru = blown head gasket(s).. but I like to see people dig a bit before throwing a 2-3k bill in their face. I'd get it warmed up again and to the point that it's hot and then open (if there is one?) the coolant res (NOT the rad cap -- NOT the rad cap!) and see if bubbles are coming up. If there is, then 100% you have a head gasket issue. You might try to see what the forum goers say about swapping engines to more reliable (at least HG wise) engines and what entails. Wish you luck. By the way, MARK, you shouldn't try to decide for others what is and isn't worth fixing. You've spent 10 fold on maintenance on your one vehicle vs what I'll spend in my lifetime on maintaining a used car. Scratch-- you've probably spent more on one car than I've spent on ALL our used cars, 8+.

walth- well, I don't know, there's a point of diminishing returns on any car and it seems ridiculous for you to tell me that when I had my last car for almost 20 years and yes, I actually understand how used cars can save money.... BUT, there comes a time to upgrade for safety reasons.... a 16 to 17 years old car is definitely not as safe as a newer model.... I came to realize that with my old Honda Accord, which was in fine running condition when I sold it. Blown head gaskets and who knows what else in this situation is a completely different story... Would you recommend that this car be fixed if it needed new head gaskets and a transmission overhaul?? It all depends upon condition..... sorry....

By the way Walth-, I purchased my 2010 Subaru Outback Limited as a certified pre-owned vehicle and outside of some maintenance, the car has not cost me anything substantial.... I've had it 30 months and it's been a great dependable vehicle.... I purchased it four years old to save on depreciation.....plan to keep it for 10 to 12 years and then get a newer model...

When did he say anything about the trans?? Another unnecessary "repair".. My 03 has a trans issue but I still drive it and I would drive it anywhere. And both my foresters weep oil/coolant. Still drive them. Not perfect and don't have deep pockets like you. How many unnecessary repairs did you do on the Honda?

Walth- how many years or miles do you typically keep your cars???

Miles don't mean much compared to fluid maintenance. Haha mr. Don't buy used bought a used car. Smh

walth- I don't make unnecessary repairs... The question about the transmission was a rhetorical question, in other words, I wanted to see how far you would go to advise this person to keep this car... Oh, I see that your 2003 has a transmission issue and you don't want to fix it?? NO, I don't have deep pockets, but, I'm not interested in getting stranded in the middle of nowhere... Look, all I'm saying is that your safety and security are of paramount importance when you are on the road, so, driving a car without modern safety features or worn out components will wind up not ending well.... YES-, I have had many used cars, but. all of them have been fixed completely when they need it to stay on the road or, I've gotten rid of them, period. People who saw my old Honda approached me all the time asking if they could buy my car... finally sold it because it wouldn't properly tow my teardrop trailer. there's nothing less expensive than just driving an older model, but, you have to ask "---how much is your safety worth".

Focused, alert, defensive driving is worth far more than any electrical bs shenanigans.

walth --- YES, I agree with you 100 percent on this, but, you also need modern safety features like vehicle stability control, ABS, etc. These are not trivial things.... That is WHY they're installed on newer models as standard equipment.... Every year new things are added to the list....The largest percentage of fatal traffic accidents occurred in older cars without these modern safety features..

Cross, keep us posted. lol. Mark, mmm too vague. Did you inspect every car involved in a fatal accident? how do you know what the issues were? Were you the owner of said cars?

I actually read......see these facts..... I don't make this up..... https://www.google.com/search? q=majority+of+fatal+accidents+%2B+older+cars&oq=majority+of+fa tal+accidents+%2B+older+cars&aqs=chrome..69i57.19769j0j4&clien t=tablet-android-google&sourceid=chrome-mobile&ie=UTF-8

Just in case the previous link didn't work..... https://crashstats.nhtsa.dot.gov › Public

walth. --- download the PDF file and read the report yourself...

An excerpt from the article,. The analysis shows that conditional on being involved in a fatal crash, the driver of an older vehicle is more likely to be fatally injured as compared to the driver of a newer vehicle. In fact, the model estimates that the driver of a vehicle that was 18+ years old at the time of the crash was 71 percent more likely to be fatally injured than the driver of a vehicle that was 3 years old or less. The model also produces an estimate for the driver of a vehicle 4 to 7 years old, being 10 percent more likely to be fatally injured than the driver of a vehicle that was 3 years old or newer; a driver of a vehicle 8 to 11 years old (19% more likely); a driver of a vehicle 12 to 14 years old (32% more likely); a driver of a vehicle 15 to 17 years old (50% more likely); and a driver of a vehicle 18 or older (71% more likely). Each estimate represents a comparison to the baseline vehicle age category of 3 years old or newer.

Guess you better buy a new car

Again, with a blown head gaskets issue and who knows what else, this 17 to 18 years old car should really be retired... I'm sorry to say this, BUT, there's a point where spending good money after bad is just fruitless, and IF you're concerned about your overall SAFETY and WELFARE , you'll get a later model.... I'm not saying that you need to get a brand new car.... I purchased a car that was four years old, it was a certified pre-owned vehicle and I had a great experience. No problems at all and 30 months later it runs fine.. Listen, no matter what anyone tells you, YOU CANNOT PUT A PRICE ON SAFETY. If you are gone, it doesn't matter at all that you saved a few bucks...

People don't come to CG to fear death Mar.. people come here for help fixing their car. Stop making this your mission on CG.

and by the way.. "guess you better buy a new car" was directed at you Mar.. not Cross. I think Cross will fix his car and be happy with it.. maybe we'll find out, maybe not.

walth- OK, well, the point still stands that "newer cars" are safer than older ones, you cannot dispute facts.

walth- Here's one final thought and I'm done with this, Car Gurus is YES, about getting advice to get your car FIXED, but, it's also about EDUCATION.... part of that is learning what is and what is NOT sound decisions to either fix your particular car or replace it. SO, it's just my opinion in this case, that the car is too old and has too many years on it to keep it. I actually should have never kept my Honda Accord for almost 20 years either. But, I realize that people love "no car payments" and get very emotional about their cars. I don't care if you want to drive your car for 50 years and keep fixing it, but, I can definitely tell you it would not be safe to do that. Yeah, maybe if this person on the island just uses it to go a few miles back and forth to the market, but, the average person needs more safety and reliability than that. Good luck to you....

Mar K, you're delusional, self absorbed, and ridiculous. You are not the end all with the car market. You are not the one "everyone's been waiting for" to fix their car problem.. by telling them to just buy a new stinkin car. You wound up on a site for dealers to sell USED cars that also has a popular questions section. I'm all for educating people on what their options/troubles are, but It's not up to me to tell them they have one specific option. One that I feel is the most important because my opinion IS. I get sick of you telling people that they have one choice, to scrap their car and buy new in the name of "safe". Nobody cares about your old Honda and how you had a line of people wanting to kick your tires. It would do you good to get away from CG and talk to some people, you know, in real life. Maybe become a greeter at WallyWorld.. so you can watch your car from the front door, ya know. You need to accept that other people have different lives from you.. in many ways, but financially, especially. If someone has a potential head gasket flaw, FINE, tell them they do and that it might cost them 1500- 3000 bucks. Unless you start paying for people's cars or repairs, stop telling them what to do. Stop with the "same ol' Mar" and either help people troubleshoot their problem or don't.

I'm a bit afraid that Walth is correct, here, Mark, in that you have almost absolutely NO expertise to hgelp others with their predicaments. Your meager experience with a couple of vehicles simply precludes you from having any expertise...mechanically, wrt safety, buying and servicing decisions, and nearly every aspect re motoring. Yet your diligent, prosaic style could be useful in some other outlet where an eager beaver would be appreciated. At CG you're simply a poseur...and somewhat dangerous at that. Sorry. I mean well, and wish you well.

look for the bubbles in the overflow when idling and check for heat from the heater to determine if the head needs to be addressed..if so ,find a safe used or new car,a few thousands dollars won't make the car new again,still an old out of date used car!