overheating car
March 28, 2013 10:41 PM   Subscribe

98 Subaru Forester started seriously overheating after a 1 1/2 hr drive. Overheated only while driving, not while idling. Oil level is fine. Coolant a bit low; added some. Still overheating. Tried turning on heat to cool engine; no heat - the heat was working earlier in the drive. It's @ 40F, so it's not the weather. Stranded in a quaint town, would like to get home to the trusty repair shop.
posted by theora55 to Travel & Transportation (30 answers total) 1 user marked this as a favorite
 
Water pump is probably the problem.
posted by empath at 10:45 PM on March 28, 2013 [1 favorite]


If it's the water pump, any garage should be able to do this job. I'm not familiar with the cooling in your car, but it might instead be the thermostat. Again, straightforward to diagnose and repair.
posted by zippy at 10:54 PM on March 28, 2013


Those also have a serious problem with the head gaskets failing, which is especially suspect if you're mysteriously losing coolant.

My parents have a 99 forester, and this exact situation happened and lead to having to replace the majority of the engine(short block) when the previous owner tried to drive it to the shop. Tow it to a shop, don't try and limp it there.
posted by emptythought at 11:07 PM on March 28, 2013 [1 favorite]


This will sound ridiculous, but replace the radiator cap and go from there.
posted by notyou at 11:08 PM on March 28, 2013


This happened to my car recently. It turned out to be some weird electrical problem causing the fans not to run. Three days and $80 later, they fixed it.

I have no idea if this is helpful to you or not.
posted by Sara C. at 11:11 PM on March 28, 2013


No heat + overheating usually means bad water pump. But it could also be a bad head gasket blowing bubbles into the coolant, causing it to overflow and then go low.
posted by gjc at 11:56 PM on March 28, 2013


If its the head casket, you can often (but not always) tell by looking in the oil filler cap. If the oil looks like a whiteish emulsion, that's the trouble. However, no heat from the heater (which is normally run of the same cooling system as the radiator etc) would suggest water pump to me.
posted by prentiz at 1:52 AM on March 29, 2013


Overheating is the most common way engines get destroyed, so take emptythought's suggestion to have it towed seriously.

I suspect the thermostat is shot. Thermostats are cheap, easy and quick to replace but the overheating their failure leads to can wreck the engine just as fast as any other cause of overheating. Don't push your luck.
posted by jon1270 at 2:02 AM on March 29, 2013


Seconding bad thermostat...in this case stuck shut not allowing the coolant to circulate to heater core or radiator
posted by carlsdad at 3:38 AM on March 29, 2013


This happened to my car and it was a hole in the radiator. I let it cool down, filled it up with water again, limped home which was luckily nearby then had it towed to the mechanics where they confirmed it and told me if I'd kept driving it with no water circulating, I'd have blown the head - costing thousands. So there's that. If I were you, I would get it towed. New engines are expensive. Radiators or water pumps are much cheaper.
posted by Jubey at 3:48 AM on March 29, 2013


I had a 98 Forester that I had hoped to have for the rest of my life. I didn't know that certain years were prone to head gasket problems. I had a friend who went through the same thing with an Outback, he had always had his car serviced at the dealer and they covered the cost of fixing it. I did not and had a local mechanic replace the radiator (which was thoroughly compromised with oily gluck) before I got it properly diagnosed as a head gasket problem.
posted by InkaLomax at 3:59 AM on March 29, 2013 [3 favorites]


Exact thing happened to my 2000 Forester two weeks ago, including the no heat issue (which normally would have helped lower the needle on the engine temp gauge). My leaking head gasket finally failed at 301K miles (I had known it was coming). I had it towed (flat bed, naturally) to my repair place--a dealer, but they have always treated me fairly--confirmed it.

I'm sorry this happened to you. I ended up getting a 2014 Forester as cost to repair would have been in the 5K to 6K range.
posted by apartment dweller at 5:28 AM on March 29, 2013


After replacing the radiator cap, think thermostat first, as it's cheap and easy, and then waterpump, and then head gasket.
posted by Slap*Happy at 5:34 AM on March 29, 2013 [1 favorite]


Just had exactly the same thing happen to my 2002 Malibu (overheating engine while in use, low coolant even when topped up, no heat in cabin). Turns out it was a pump malfunctioning. Brought it in this week and it's back on the road running perfectly now!
posted by Meagan at 5:37 AM on March 29, 2013


Those also have a serious problem with the head gaskets failing, which is especially suspect if you're mysteriously losing coolant.

Was going to say this. I used to have a 99 Forester; exact thing happened.
posted by Miko at 5:44 AM on March 29, 2013 [1 favorite]


The coolant still flows through the heater core regardless of whether the thermostat is open or closed. A car with just a broken thermostat will blow hot air when overheating.
posted by gjc at 5:49 AM on March 29, 2013 [2 favorites]


Subaru Forresters are well known for their head gasket problems. I have the same problem with my 2002 model. The mechanic put a gallon of antifreeze in it to see how long it will last without replacing them.
posted by candasartan at 5:55 AM on March 29, 2013


If it were the head gasket you'd see white steam from the exhaust, and you'd be losing fluid but you may not be over heating provided there's enough coolant to circulate properly. Nthing either a bad waterpump or a stuck thermostat.
posted by Gungho at 6:47 AM on March 29, 2013 [1 favorite]


This is exactly how my 98 Forester announced that its engine was toast. Unfortunately, unlike other model years, which just leaked coolant to the outside of the engine block, this model year's DOHC engine leaked internally, mixing coolant and oil, putting bubbles into a closed cooling system, etc. Not good.
posted by M.C. Lo-Carb! at 6:52 AM on March 29, 2013


I'm going with water pump as the most likely culprit. Not sure about Subaru, but I know BMW uses a plastic impeller in some models that can break up and cause problems later even after the replacement. Might want to make sure the flush the radiator as part of the replacement of that's the case with your car.
posted by empty vessel at 7:44 AM on March 29, 2013


If it turns out to be a water pump, and your timing belt is close to its change mileage, I would consider biting the bullet and getting it changed also. It is pretty much in the same area, and will save labor $$$ compared to doing both simultaneously.
posted by Danf at 8:01 AM on March 29, 2013


The coolant still flows through the heater core regardless of whether the thermostat is open or closed.

Just want to second this.
posted by ssg at 8:27 AM on March 29, 2013


OH just remembered. How they diagnosed my blown headgasket in my 80's Subaru Loyale, was starting it with the radiator cap off. The cascade of coolant out of there was pretty much the smoking gun.
posted by Danf at 9:29 AM on March 29, 2013


No heat + overheating usually means bad water pump.

Or an air lock. If the water was low, try filling it and running it to temperature with the cap off while topping it off.

It is NOT a thermostat if the heater doesn't work - the water always flows through the heater core regardless of thermostat position.

Three options as I see it:

1: There is either not enough water in the system, even though it looks like there is (because there is an air bubble in it somewhere). Follow the water filling process in the manual (or search for it)

2: The water is not flowing (either through the pump not working or through the same air bubble).

3: The head gasket is pooched. Although I'd be surprised if the heater didn't work through a head gasket issue. Coolant loss may be the ultimate cause of your issue through a head gasket failure, but the lack of heat makes me suspect that one of the first two is happening right now. If it happens again after making this better with the fixes (ie coolant loss continues) then it may well be head gasket.

What I'd do:
1: replace the radiator cap (see 4 first) - the system is not able to process as much heat rejection if it can't pressurise. A system that can't pressurise will also have less water volume in it after one heat cycle.

2: Follow the bleed procedure in the manual to refill it.

3: Shine a flashlight in the top of the radiator (if you can) and see if the water looks like it is flowing at all when the car is idling - do the hoses look full, that sort of thing.

4: If the hoses feel to hard to squeeze more than about 10% when the car is hot (use a rag or glove), then the system has pressure. if you can still compress them relatively easily in a hot engine with the cap on, then the system is not maintaining pressure through a bad rad cap or other leak in the engine.

If the system pressurises and you are sure that there is no air bubble (as much as you can be) it is likely the water pump, I think.
posted by Brockles at 9:59 AM on March 29, 2013 [3 favorites]


If it were the head gasket you'd see white steam from the exhaust

This is not a reliable metric for disproving the head gasket. It is proof that it is, but lack of white steam is not proof that it isn't.
posted by Brockles at 10:00 AM on March 29, 2013 [2 favorites]


This year Forester is well known for eating head gaskets; really if you own one you should consider the head gasket as a wear item and have plans to change it when not if it fails.

All the indicators that have been posted (white steam, creamy oil, air in the coolant, etc.) are strong YMMV and depend on exactly where, how, and to what degree the gasket has failed. Even a coolant to exhaust leak can be small enough to not show white smoke while still building exhaust pressure in the coolant system. Many cars exhibit none of these symptoms though loss of coolant (which is often masked by the content of the reservoir) and overheating are usually universal.

Once it has overheated once it can be very time consuming to bleed the coolant system of air.
posted by Mitheral at 10:02 AM on March 29, 2013


If it were the head gasket you'd see white steam from the exhaust

This is not a reliable metric for disproving the head gasket. It is proof that it is, but lack of white steam is not proof that it isn't.


Yes. The head gasket seals multiple systems, and can fail in multiple ways.
posted by gjc at 10:51 AM on March 29, 2013 [1 favorite]


I did not have white steam, just as a data point, when my head gasket went south.
posted by Miko at 10:55 AM on March 29, 2013 [1 favorite]


cost to repair would have been in the 5K to 6K range.

I'd like to note, if you saw this theora55 and went "AWWW CRAP" that an entire engine rebuild ended up costing that much on my parents car. Just the gasket on these is under 2k, and at a local shop might only be $1400 or something like that. I had a friend unload a perfectly good legacy of this same year range because it needed a head gasket and he didn't want to pay that, but i would have paid it instantly.

If it has under 200k miles and is in decent shape, i'd jump at that repair. I'd probably even consider it if it had more. I was just driving that forester i mentioned, which has 198k miles on it, and it felt new.

It's not like you can get a very good car used for under 2k anymore, especially one from around 2000. This is definitely not an "end of car" repair unless you try to limp it and cause more(and more than likely, severe) damage, as i mentioned.

This is a serious problem, but fortunately not a seriously expensive one. and if you're extremely lucky and it is just a failed water pump then it could even be cheap.
posted by emptythought at 5:28 PM on March 29, 2013


It was(is) the radiator. What helped - adding water & coolant, and 'burping' the radiator line to get rid of bubbles. We were able to get home (80 mi) by stopping often to cool the engine & add water. lots of water. Thanks for the help.
posted by theora55 at 9:45 AM on March 30, 2013


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