[huskerredd]

I have a 1998 Subaru Legacy Outback. My daughter was driving last night and it just died on her. She said it was boiling over. I checked it out tonight thinking it was the thermostat. I changed that and filled with coolant let idle for about 10 minutes, the fans came on, so I took it for a spin. No more than got out the driveway and the temp shot up, turned around and popped the hood and the coolant was backing up into the overflow tank. Could it be a bad water pump? Any help will be greatly appreciated, you guys are great.

 

[Durrr]

Bad head gasket is my guess, sounds pretty serious. If your daughter ran it hot for to long she may have warped the heads. This can cause it to over heat quicker. I literally just did a hg replacement on my 98 ob. The hg's on these are notorious for failing.

My symptoms were very similar. Drive around town no problem, go on the freeway no problem but once I get off the freeway (driving on it for ten miles or longer) my temp gauge would spike & my overflow would fill up.

I just signed up on here but I've been a mechanic for years, hope I'm wrong for your sake

 

[RobLog]

the coolant was backing up into the overflow tank

Sorry to write this, but this is a classic symptom of a blown head gasket in our cars.

 

[huskerredd]

How difficult of a job is replacing the head gasket on these?

 

[huskerredd]

Is there a way that I can check to be sure it is the headgasket before I tear into this.

 

[RobLog]

Is there a way that I can check to be sure it is the headgasket before I tear into this.

The most definitive test would be to see if there are exhaust gases in the coolant. There is a test kit for this available at most auto parts stores. Or a shop will charge a $50-100 diagnostic fee to verify or not. If you do this, take it to a shop with experience working on Subarus.

With other cars, a compression test is sometimes recommended. Pass on this test as the DOHC engines found in our cars will likely pass this test even with a blown HG.

How difficult of a job is replacing the head gasket on these?

These links are for SOHC engines, not the DOHC one you have, but the scope of the work is very similar:

http://www.subaruoutback.org/forums/99-do-yourself-illustrated-guides/41500-diy-2001-subaru-cylinder-head-gasket-replacement.html

http://www.subaruoutback.org/forums/99-do-yourself-illustrated-guides/7867-2000-my-obw-car-head-gasket-replacement.html

http://www.subaruoutback.org/forums/99-do-yourself-illustrated-guides/33809-engine-removal-thread.html

 

[huskerredd]

Thanks for the reply, do you recomend going a head and getting a complete head gasket kit? I've seen several options, what kind of timeline am I looking at to do this task. I'm not affraid to takle anything, just a matter of digging in and getting it done as soon as possible so my wife doesn't have to shuttle the kids around as much. I'm guessing that by the responses I have below that it is most likely the head gasket, don't have the extra cash to have a diagnostic run on it. Any other suggestions I would be very grateful.

 

[RobLog]

The Felpro kits are a good buy and have a pretty good rep. I used one in my car and have been happy with the results. I don't believe Subaru has a ready-made kit, so you'd have to buy each piece separately, but the parts are top-notch.

At a minimum, you will need

-head gaskets (2) note: MUST be Multi Layer Steel (MLS) gaskets or don't bother
-valve cover gaskets (including gaskets for 4 spark plugs) (2)
-camshaft gaskets (4) EDIT: should read camshaft seals (4)

highly recommended:
-intake gaskets (2)
-exhaust gaskets (2)

recommended:
-front main seal (1)
-oil pump o-ring (1)
-sealant for oil pump

I know what it means to be short of cash, but if you can swing it:

If the car is over about 150k miles and these items have never been replaced:
-everything that touches the timing belt except the camshaft sprockets and crankshaft sprocket. This would include smooth idler pulleys (2), toothed idler pulley (1), tensioner (1), and water pump (1). If the timing belt has over about 50k miles on it, replace it, too. There are some pretty good TB kits on eBay for a good price ... search the forum for recommendations on kits/sellers.

You also really need to have a machine shop check the heads for flatness and burnt valves and do the work if necessary. This is not not cheap, but is essential for a successful HG repair. If they do valve work, and probably even if they don't, you will need to adjust the valve clearances, as well.

For a first timer, I'd allow a week, including machine shop time.

Oh yeah: don't forget to change the engine oil since it's been overheated. A drain-and fill of the ATF would be a good idea as it has been over heated, too.

 

[Durrr]

I'd be concerned about the heads being warped since the car was over heated. Subaru does sell a complete gasket kit.its over $300 if you plan on keeping the car I would spend the money on all the stuff roblog suggested. Your looking at a considerable difference in cost with subaru parts vs aftermarket. like mentioned use felpro gaskets & gates timing belts if you go aftermarket oreilys sells a felpro gasket kit & a timing belt kit that should cover most wear items. Your gonna spend $800-$1000 if you replace all wear items & get your heads inspected, machined & new valve guides pressed in + new fluids & filters. Adds up quick!

The cheapest I've paid in parts to get a poor man back on the road is under $200 & that was only hg',s intake & exhaust gaskets, timing belt, oil filter, oil & coolant. This is not advised just an example

The machine shop should charge less than $100 to resurface your heads, possibly install new guides under $100 total as well. Get your gasket kit first, the new valve guides in most kits are included, that way you can bring them with you to the machine shop.

subaru built these cars with the mechanic in mind, subaru mechanics can do a head job in 10 hours. The tear down is straight forward. If you have any knowledge and experience with a decent set of automotive tools then do your research & have at it. my first time took two days. Btw this job can be done with the motor in the car, but I highly advise pulling ten more bolts (automatic)& pulling it out. I've read the write ups on doing the job in the car & it seems like it would be very tedious on a DOHC motor & would kill your back!

 

[kellio]

I recently bought a 2000 Outback with related issues. The person I bought it from told me it was using coolant but I'm unable to duplicate the problem. I've driven it for around an hour under normal conditions without the temp gauge going above normal however the main sensor light is on on the dash.
He also told me that 2 mechanics had told him it had a cracked head but
there are no bubbles in the radiator indicating a blown HG and I've also dropped the headers off the heads to see if there is water coming from the exhaust ports but there isn't.
While this maybe a "If it's not broken, don't fix it" scenario, the guy is hardly likely to sell me a cheap car because of overheating problems if there aren't any and I'm concerned about taking it on a long trip only to find it playing up after a hundred or so miles. It also seems "doughy" at the bottom end in that the revs need to up fairly high when starting on a hill before releasing the clutch and it tends to lug or ping if the revs are too low.
A local mechanic quoted me $75 just to plug it in to his diagnostic machine but I'm wondering if there's an easier and cheaper way in which to diagnose the problem.
I'm fairly handy with tools etc and have worked on lots of conventional engines in the past and replaced many head gasgets among other things and indeed heads and engines but this one has me stumped.

 

[subiesailor]

Plugged up bad radiator - fans that are not running etc all reasons why a car might run hot or overheat other than just HG failure. Pick your item from the list and start checking

 

[kellio]

Plugged up bad radiator - fans that are not running etc all reasons why a car might run hot or overheat other than just HG failure. Pick your item from the list and start checking

Thanks but it has a new radiator, water pump and timing belt and the fans are running fine.

 

[subiesailor]

Thanks but it has a new radiator, water pump and timing belt and the fans are running fine.

Any idea if the thermostat is a stock subaru part or if they went with a cheaper off brand thermostat? This is always an issue for the subaru engines the off brand thermostats never work correctly with the subaru's. very well known issue

 

[kellio]

Any idea if the thermostat is a stock subaru part or if they went with a cheaper off brand thermostat? This is always an issue for the subaru engines the off brand thermostats never work correctly with the subaru's. very well known issue

No. They'd actually removed the thermostat and was running the car without it. I tested it yesterday by placing it in hot water and it was working fine, so I put it back in the car and took it for a run. Nothing changed.

 

[subiesailor]

No. They'd actually removed the thermostat and was running the car without it. I tested it yesterday by placing it in hot water and it was working fine, so I put it back in the car and took it for a run. Nothing changed.

Still doesn't answer if its a subaru tstat or a knock off. Yes there is a big difference

 

[kellio]

Still doesn't answer if its a subaru tstat or a knock off. Yes there is a big difference

I really don't know. I can't tell the difference by looking at it because I have nothing to compare it with but since the problem is not evident and the one I put in hasn't changed anything, I don't think the thermo is the problem.

In anycase, having the wrong thermo in or indeed not having one in at all is not likely to cause the general warning light to appear on the dash and certainly would not cause the car to be sluggish.

 

[cardoc]

Without a thermostat, any vehicle is going to run hot. Its called heat soak. The coolant moves too fast to cool down in the radiator and boils. The thermostat serves two purposes in this regard: control engine temperature and flow.

Why was it removed in the first place? Any idea?

If the overheating issue is gone with the thermostat installed, just keep an eye on the temperature gauge and coolant level.

Even on old hot rods, we at least install a restrictor plate in place of the thermostat.

 

[kellio]

Without a thermostat, any vehicle is going to run hot. Its called heat soak. The coolant moves too fast to cool down in the radiator and boils. The thermostat serves two purposes in this regard: control engine temperature and flow.

Why was it removed in the first place? Any idea?

If the overheating issue is gone with the thermostat installed, just keep an eye on the temperature gauge and coolant level.

Even on old hot rods, we at least install a restrictor plate in place of the thermostat.

I have no idea why the thermo was removed in the first place but it's my guess that whoever removed it may have thought it was faulty and was responsible for lack of coolant flow resulting in overheating.
On a hunch I took a look at the timing belt which I'd been told had been replaced recently. I ended up refitting it because it appeared to be a tooth out on one of the cams. Whoever had done the job had done it in the traditional way by lining up the timing marks on the respective geared pulleys with the marks on the crank case and heads etc and had ignored the timing marks on the belt itself.
What they hadn't taken into consideration was that once the tensioner pressure had been released back onto the belt, it would pull the closest pully back toward the tensioner as much as 1 tooth.
This being the case it occurred to me that the knock sensor could be getting a wrong signal and in turn delivering a wrong signal to the computer to make it change the ignition timing by retarding at higher revs too much to cause the overheating problem.
After doing this I took it for a test drive and found it to be far more responsive down low without the pinging experienced before.
I'm yet to take for a long drive to check the temperature problem but so far what I've done seems to have addressed at least one of the problems and possibly all.
I'll post back here with an update after carrying out more tests.