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View Full Version : Mysterious Overheating - Head Gasket?


phoenix96
12-07-2004, 07:45 PM
Hi everyone.

For the last year and a half I've been having some periodic heat problems in my SVX. For some history of the car:

It is a 1992 SVX LS-L, now up to 145,000 miles. It's on the original transmission (a transmission cooler was added sometime prior to 114,000 miles when I acquired the car). The radiator, water pump, steering rack, and timing belt were replaced at 125,000 miles (the radiator was cracked and no longer held pressure, the water pump bearing was showing signs of going out, and the steering rack was leaking). Other than both rear wheel bearings being replaced and the front right CV joint being replaced, that's pretty much the extent of the mechanical work that's been done (beyond normal maintenance). The only performance modification is the ECUTune Stage 1 chip, which was installed in August of this year.

The car drives perfectly most of the time. In normal operation, the needle in my temperature gauge stays just below the halfway point. My A/C compressor is not functional (it doesn't even have a belt on it right now) so it is never run, although a lot of the time I will have the climate control system set to "Vent". I've seen no signs of oil leaks anywhere.

Here's a chronology of the problems I've had:

August 2003: After 4 hours of highway driving in 100 degree weather, I reached a mountainous area and was driving uphill. I decided to stop to get a bite to eat, and as I pulled onto the offramp and slowed down, the needle in the temperature gauge started to rise. I found the nearest parking lot and stopped the car before the needle hit the red. After letting it cool off for half an hour and checking the coolant level (which was fine at that point) I hit the road again. I drove another two hours with no problems (it was evening by this time so it wasn't quite as hot out).

September 2003: Driving hard up a 7% grade in 100 degree weather, the needle in the temperature gauge began to rise. It hit around the 3/4 point (halfway between the thermostat icon and the red) before I slowed down and dropped the RPMs to ~2500, and the temperature began to drop again. It returned to normal once I was over the hill and didn't rise again.

September 2004: Driving up that same 7% grade mentioned above, in similar weather, the needle began to rise again. I kept the RPMs between 2500 and 3000 and made it over the hill.

At this point, I was convinced that the problem was because of a combination of high ambient temperature and heavy load on the engine (going uphill). The next time I had a problem changed that idea though:

November 2004: I got an oil change (at which time my radiator cap was also replaced - I checked the new cap, it is rated at the proper pressure level for the SVX) and immediately afterwards set out on a driving trip. After four hours of highway driving (the weather being in the mid-60s most of the time), I reached a city. After a bit of city traffic, I was stopped at a red light. When the light turned green and I began to accelerate, the needle in the temperature gauge quickly started to rise. I increased my speed up to the speed limit (~35) and the temperature returned to normal again. I had no more problems that day.
The next morning, I did about 20 minutes of city driving and found that I was having a constant heat problem. Every time I started to accelerate from a stop, the temperature would rise. Once I had reached around 30mph, it would return to normal again. I set out for home again, and had no trouble during the four hours of highway driving. About a half mile from my house, going up a very slight incline on a residential street, I had to make a complete stop for some deer crossing the road. When I gave the car some gas to get moving again, the temperature quickly shot up all the way to the red. I pulled off the road and stopped the car as quickly as I could. After about 15 minutes with the hood open (with the engine not running), the temperature had returned to normal and I started the car again. At idle it didn't seem to have any problems, so I accelerated and quickly got back up to 35mph, and thereafter had no troubles.

Since that last incident, I've made several 100 mile round trips with some city driving in between and had no temperature problems.
It has made me very wary of driving the car when I don't have to, however, and I'd really like to get this issue resolved. I've begun to become concerned that it may be a head gasket issue.

If anyone has any insight, I'd be very grateful.

Edit: For a bit more information, I've never lost coolant. I've never seen steam come out from under the hood or anything like that either.

msvx95
12-08-2004, 04:01 AM
Even though I'm not a pro at this.......I did have a similar problem with my 90 legacy.....The temp. needle acted funny like yours does and mine started to be consistent, but to the point of me only being able to drive the car for about 5 minutes before reaching red zone in the temp gage.......It turned out to be head gasket....I didn't see smoke but, everynow and then the coolant would microscopically hit the exhaust.....I never saw any coolant on the ground though.......But the good folks at Subaru fixed it for 1000.......No problems now though......

But also check to see if your thermostadt is bad or.......maybe this is a remote possibility......Are your electric fans kicking on or cutting out?......Kinda hard to know that when you are driving though........

I'm curious to know the answer too!

phoenix96
12-08-2004, 04:37 AM
Originally posted by msvx95
Even though I'm not a pro at this.......I did have a similar problem with my 90 legacy.....The temp. needle acted funny like yours does and mine started to be consistent, but to the point of me only being able to drive the car for about 5 minutes before reaching red zone in the temp gage.......It turned out to be head gasket....I didn't see smoke but, everynow and then the coolant would microscopically hit the exhaust.....I never saw any coolant on the ground though.......But the good folks at Subaru fixed it for 1000.......No problems now though......

But also check to see if your thermostadt is bad or.......maybe this is a remote possibility......Are your electric fans kicking on or cutting out?......Kinda hard to know that when you are driving though........

I'm curious to know the answer too!

The head gasket is what I'm afraid of.

The thermostat has not, to my knowledge, been replaced yet. Somehow it doesn't sound like a thermostat sticking to me, but then I'm not an expert on that either.

The fans do run sometimes at least- after overheating, the fans were running after I stopped the engine (with the key still on On), and they seem to run properly at idle. It's difficult to know whether they're cutting out occasionally though.

SilverSpear
12-08-2004, 05:33 AM
Originally posted by msvx95
Even though I'm not a pro at this.......I did have a similar problem with my 90 legacy.....The temp. needle acted funny like yours does and mine started to be consistent, but to the point of me only being able to drive the car for about 5 minutes before reaching red zone in the temp gage.......It turned out to be head gasket....I didn't see smoke but, everynow and then the coolant would microscopically hit the exhaust.....I never saw any coolant on the ground though.......But the good folks at Subaru fixed it for 1000.......No problems now though......

But also check to see if your thermostadt is bad or.......maybe this is a remote possibility......Are your electric fans kicking on or cutting out?......Kinda hard to know that when you are driving though........

I'm curious to know the answer too!

hehe, I am (proudly) the expert concerning this issue.
first of all check out the termostat (that should be changed each 30000 miles).
second check if the fans are working properly when the cars heats up. their heating sensor should give the order for them to work,
third check if all the hoses in which water flows are not having any air instead of water (sorry for the way I am putting it).
fourth check if your radiator is plugged with sand or...,
fifth check if a malfunction in your tranny is affecting the engine to work harder thus overheating (a long shot... but it happens), sixth check if there isn't any water leak of some kind from any hose/engine.
seventh, check all the different levels of oil in your car, maybe you are running on an empty engine. also a probability that any one of your exhausts is plugged, it can overheat the engine. and finally I diagnose your problem with the gaskets syndrome.

as a resume, your problem mostly lies with either the fans, or the thermostat, or the gaskets and or radiator...

I hope I helped in any possible way, but i wish the problem is just with the termostat.

PS: changing gaskets for the legacy is $1000 in the states??? Man!! over here is just $100 including their cost !!

Keep us updated !!

Earthworm
12-08-2004, 02:46 PM
I would check to ensure nothing is blocking the radiator preventing it from cooling.

Check the rad hoses, the top one should be very hot (indicating the water pump/thermostat is functional)

Have the antifreeze checked for the existance of hydrocarbons (indicating either a cracked head/faulty headgasket)

TomsSVX
12-08-2004, 02:56 PM
Ok i just did a headgasket on my SVX and it is not too hard.
Also, the thermostat was probobly replaced w/ the water pump. BUT you should go out and get a new one anyway. Once you have the new thermostat, drain and flush your radiator. Then pop the thermostat housing and replace it with the new one. once you have everything hooked back up, refill while the car is running. Wait until the car reaches running temp then add if needed. Fill the resevior to proper amount. Drive the car around and see if the problem is still there. If it is, bring it to a shop and ask them to diagnose if the head gasket is shot.
OR if you can do it, go to NAPA or some autp store and pick up a block tester. This little device is awsome and i used it to check my work when doing my headgasket. It is a glass tube w/ rubber ends. also includes a ball w/ a check valve. This comes w/ blue liquid that checks the air in the rad. THis will require you to syphon some fluid from the rad, and pull the overflow hose.
Once the fluid level is down and the overflow hose is off, plug the overflow nipple on the rad. Then follow instructions to test the air in the radiator. If there is exhaust in the coolant(which means ur headgasket is shot) it will turn the blue liquid green or yellow. If there is not (headgasket is ok) it will remain blue. easy to check and will save a lot of money if a new gasket isn't needed. Well good luck but i suggest flushing radiator and replacing thermostat first.

msvx95
12-09-2004, 03:25 AM
I cringed when I saw the labor rate at my local subaru dealership....... a whopping $90.00/hr....... Seems its better to buy a service manual and do it yourself at times.

SilverSpear
12-09-2004, 04:31 AM
Originally posted by msvx95
I cringed when I saw the labor rate at my local subaru dealership....... a whopping $90.00/hr....... Seems its better to buy a service manual and do it yourself at times.

over here labor is for work done and never for hr rate !!! over here they dismantle the engine out and put it back for $50...

TomsSVX
12-10-2004, 12:01 PM
Originally posted by SilverSpear


over here labor is for work done and never for hr rate !!! over here they dismantle the engine out and put it back for $50...

In that cae why don't i spend 2grand for shipping ill ship my car over there and have my engine rebuilt. and then ship it back!!;)

Im only joking but thats pretty cool if they do work for cheap but in America, its a dog eat dog world. and you pay out the *ss for hands on things. Thats why i keep myself in the trades so i save myself a lot of money. And i do mean A LOT!!!

Clydesvx
12-11-2004, 05:07 AM
I had the same problem mentioned in the first posting. I had the head gasket replaced and the problem returned abot 50,000 miles later. I ran a long while by notching the gasket on the radiator cap. That allowed the exhaust gas to blow off before it had a chance to overheat the coolant and fill the overflow tank. I opted for a junkyard engine instead of another gasket replacement. That worked well. If it happens to this engine I'll let Subaru do the work.

immortal_suby
12-11-2004, 06:53 AM
Sounds just like my car's symptoms. Already replaced thermostat, fans work fine, water pump fine, and radiator was new. It is awaiting an engine transplant now.

TomsSVX
12-11-2004, 01:23 PM
i say check it like i said earlier with the block tester first. This could save you a lot of money and time.

SilverSpear
12-13-2004, 01:26 AM
Originally posted by tomssvx


In that cae why don't i spend 2grand for shipping ill ship my car over there and have my engine rebuilt. and then ship it back!!;)

Im only joking but thats pretty cool if they do work for cheap but in America, its a dog eat dog world. and you pay out the *ss for hands on things. Thats why i keep myself in the trades so i save myself a lot of money. And i do mean A LOT!!!

why not shipping your engine alone!!! why the entire car ? believe me doing the entire engine (I mean cranks, pistons,....)over here costs $150 tops as labor alone (not considering parts)

TorG0d
12-13-2004, 01:28 AM
My car started to overheat a couple times last summer while at an idle on the (packed) freeway. Think I posted about it . . . anyway, I pressure tested the cooling system (it held pressure for something like 20 minutes before I took the pump off, if memory serves me correctly), but I still keep losing coolant from the reservoir. The thermostat was taken out and checked (I'm a cheap bastard, what can I say), and the radiator stays full, so I don't worry too much about it. Replaced the radiator cap, though.

As to your problem, good luck. Hope it's not your head gasket, though it does look easy to do.

Clydesvx
12-13-2004, 03:18 AM
My symptoms didn't show up until the engine was hot. A pressure test was done at operating temperature and didn't show any problems. When I got lucky and rolled her in when it was happening they found an exhaust leak at the water jacket. I have only seen a few of these problems posted. I guess we are the "LUCKY" ones.

TomsSVX
12-13-2004, 10:17 AM
Originally posted by TorG0d


As to your problem, good luck. Hope it's not your head gasket, though it does look easy to do.

Its not hard to replace and should anly be a day or two job for someone that knows what they are doing.

As long as they don't break a camshaft!!!

phoenix96
02-24-2005, 11:39 PM
Well, finally got around to taking the car in a few weeks ago. Tests found a small amount of exhaust in the coolant. The engine is right now being put back in after having both head gaskets replaced (got the wheel bearings and hubs replaced at the same time). Not an inexpensive job, but I'm looking forward to driving the SVX again after several months.

TomsSVX
02-24-2005, 11:41 PM
awsome, I hope they torqued everything down correctly when placing the heads back on. Have fun with the car!

Tom