2.5 Liter, Coolant Issues

[Studdog]

I recently purchased a 1998 Legacy Outback with a 2.5 & automatic. I got the car very cheap. The car had no heat and would only get to 1/4 on tempature gage. I was sure there was no Thermostat, and it was obvious that the car had overheated in the past, due to looks of engine compartment.

 

I was correct there was no thermostat. I put in a new thermostat and had system flushed. I could let the car idle for 45 minutes and it would not overheat, and had great heat. When I took the car for a test run (after 5 minutes of driving) it would completely lose the heat at low RPM and the gage would show engine was starting to overheat. If I revved the engine to 3000-4000 RPM the heat would come back and the temerature gage would quickly show a drop back to 1/2 point.

 

I then replaced the waterpump and timing belt. This time the heat was even better and car ran at 1/2 point on temp gage. After about ten minutes of driving the heat was gone and engine was overheating. Revving the engine would have no effect as it did with old pump. I have tried three new thermostats with the same results.

 

Here's the confusing part: If I put in a thermostat with a 3/8" inch hole in it, the car will run for days at several hours at a time and never overheat. The bad thing is that it then takes 3 times as long to warm up and has luke warm heat. The temp gage will then only reach 1/8 and less. I tried the thermostat with the hole in it many times during the above senarios and it would always give these results.

 

Thermostat is in the correct direction. Upon refilling coolant after working on, I warm engine and shut off. Wait for a back suction (Thermostat Opens?) and quickly fill when this happens. Am I not doing something correctly? Any ideas? I've been working on this for over a month.

 

I have never used a forum before, I hope I am doing this correctly. If not, I apologize for my ignorance.

 

To further elaborate: the coolant markings in the engine compartment appear to have come from the radiator cap area.

 

One more item I forgot to mention; when I first got the car and inspected the cooling system, I found the fans did not work and immediately fixed the issue. I assumed this was the reason for overheating in the past, but I guess I was wrong.

 

I think the first thing I am going to try is replacing the radiator and the cap. I will post the outcome of this.

 

After this I will look into replacing the head gaskets. I realize head gaskets could be the issue, but am stumped as to why a thermostat with a 3/8" hole drilled in it will cause the car to never run hot and the oil looks good, the overflow never bubbles, and the exhaust shows no burning coolant.

 

Also, what is the trick to not getting air trapped in the coolant system when refilling? This seems to be a pain in the butt. If you have the knowledge please explain in detail? All the literature states that these cars are known for trapped air, but does not explain how to remove. Maybe it's common knowledge, but I have never heard it explained.

 

Why is the thermostat placed at such a low level?

[seattlelegacy]

First of all, welcome. That's the good news.

 

The bad news is that you might have a wonderful 2.5 litre headgasket issue, which would explain why you got the car so cheap. Check the oil to see if there is coolant in it (may look milky), and after running the car, check to see if there are bubbles in the coolant overflow. Get back to us. You also mentioned that the compartment appeared to have coolant in it. I'm guessing that coolant spray is due to headgasket issues. Did the person who sold it to you give you anymore details. If you're good with wrenching, you can replace the headgaskets yourself. You may want to remove the engine to do it, or you might be able to do it with the engine in the compartment. It sounds like the car has overheated enough that you're going to need the heads machined too if it is indeed a headgasket issue. Search the board for "headgasket", and you'll have plenty of reading for a few days. With any luck at all, its something else, but it sounds like you've done all you can with the thermostat issue. Good luck.....

 

Jordan:-\

[Studdog]

Thanks for the welcome and reply!

 

Here's the update: The oil looked fairly fresh when I got the car, but as always, I made an immediate oil and filter change. I always do an immediate tune-up to a new-to-me used car. I checked the current oil and it looks as good as new. I am not finding any bubbles in the coolant overflow. Spark plugs looked like normal slightly used plugs when I changed them and new ones still look good. There is no coolant in the exhaust fumes.

 

I got the car from someone that bought it at an auction and only bought it to sell, so not much to find from the history. The reason I think it has had overheating in the past is because of the finish on items in engine copartment has the whitish gray look and the underhood insulation has the same markings.

 

I was thinking it did not sound like a headgasket issue, but will take your advise and look into it further. If there are any other ideas, please let me know.

[Studdog]

To further elaborate: the coolant markings in the engine compartment appear to have come from the radiator cap area.

[cookie]

Now you know how to sell a Subaru with a blown head gasket. Take the thermostat out. The sooner you fix it the better off you will be.

[Studdog]

One more item I forgot to mention; when I first got the car and inspected the cooling system, I found the fans did not work and immediately fixed the issue. I assumed this was the reason for overheating in the past, but I guess I was wrong.

[WAWalker]

Yep, headgaskets. They will not leak coolant into the oil or exhaust. Combustion gas leaks into cooling system.

[straz]

I'm in a similar situation. Head gasket blew in November on my '97 Outback. Had it repaired as well as a new theromostat installed. Ran fine for a couple months, but now is exhibiting similar symptoms to your vehicle. Overheating and at times, the gauge will spike and then return to more normal levels. Very inconsistant. I had a compression test done at a garage and it passed. So now, I'm suspicous that the radiator may be bad and there could be corrosion that is ihibiting the flow of fluid.

 

Perhaps getting a compression test could help you isolate the issue. I'm in the market for a radiator, so if people know where a good source for one may be... Let me know.

 

Tim

[Suzam]

A compression test will not be a positive test for a blown headgasket. The Phase I 2.5 can have a good compression test with a bad head gasket. That's why the overheating can seem to be an intermittent problem, like at highway speeds but fine at idle. Unless you see sludge in the overflow and it smells like exhaust, you can only tell with a hydrocarbon test of the coolant which will tell you if there is a leaking head gasket.

 

As I read your post I wonder if you have tried replacing the radiator cap with a new one?

[idosubaru]

head gasket, your situation isn't as weird as you think. there are numerous threads about "undetectable" overheating....which always ends up being head gaskets on these motors....okay, almost always!

 

you can pick up a 2.2 liter motor for a couple hundred and swap it in, it's nearly a direct swap and 2.2 motors are easy to find. and they don't have the head gasket issues the 2.5 has.

 

if you choose to fix it, the newer head gasket is an updated version and solves the leaky head gasket issues assuming the block isn't toasted. many have successfully replaced the head gaskets in 2.5's.

[Studdog]

I think the first thing I am going to try is replacing the radiator and the cap. I will post the outcome of this.

 

After this I will look into replacing the head gaskets. I realize head gaskets could be the issue, but am stumped as to why a thermostat with a 3/8" hole drilled in it will cause the car to never run hot and the oil looks good, the overflow never bubbles, and the exhaust shows no burning coolant.

 

Also, what is the trick to not getting air trapped in the coolant system when refilling? This seems to be a pain in the butt. If you have the knowledge please explain in detail? All the literature states that these cars are known for trapped air, but does not explain how to remove. Maybe it's common knowledge, but I have never heard it explained.

 

Why is the thermostat placed at such a low level?

[Subarian]

Not so fast with the head gasket. There are a couple of clues here people are missing. 1) The car's heater goes cold at low RPMs and the temp gauge goes up; speeding up the RPMs puts everything back to normal. 2) The condition doesn't occur with a 3/8 hole drilled in the thermostat.

 

My diagnosis: Trapped air in the cooling system. When you have air in the cooling system, it tends to congregate in the upper parts of the system, especially at low RPMs. Since the coolant temp sensor and the heater core are rather high in the system, you get no coolant around the sensor and none running through the core. Once you speed the engine up, coolant is forced through those places.

 

The solution is actually really simple. You need to purge the air out of your coolant system. To do that, park the car with the nose uphill. Take off the radiator cap, and fill the radiator. Squeeze the top hose to force out any air bubbles, and refill. Keep doing that until you can't get any more air out. Now start the engine and let it warm up to normal operating temp (fans come on). Refill the radiator as necessary. Also make sure the overflow bottle has coolant in it, as it will refill the radiator when the engine cools down.

 

Enjoy driving your Subaru.

[WAWalker]

As I said coolant WILL NOT leak into the oil passages or into the cylinders. Combustion gas is being pushed into the cooling system when engine is hot and under load. There for your oil will look good and the engine will not be burning coolant.

 

The Combustion gas being forced into the cooling system will either cause an air lock or push coolant out of the system, which every you are going to loose heat. A thermostat with a 3/8" hole in it works because it allows coolant to circulate all the time preventing an air lock. When the head gaskets start leaking bad enough pressure will build and push coolant out regarless. Assuming that you have a thermostat that lets the engine get to full operating temp. Believe it or not when these head gaskets start leaking they only leak at full operating temp. and seal back up at lower temps. Part of the reason they are so hard to diagnoise.

 

To bleed the air out of the cooling system when filling all you need to do is take the bleeder screw out of the radiator and fill. Test dirve to get car to operating temp, let cool, and top off radiator. And yes be sure to put coolant in recovery bottle.

[cookie]

WA,

 

Nice job of stating this problem. I have also come to the conclusion that they seal nicely until full operating temp. I chased this on a Ford truck years ago and it nearly drove me nuts.

[WAWalker]

Cylinder leak down test with engine hot is about the only way to really nail the leak down. But I don't usually bother unless someone really wants to spend the extra money for me to pull the spark plugs on a smoking hot DOHC and perform a leak down so I can tell them again, yes your head gasket are leaking.

 

All of these engines will need the original head gaskets replaced. Weather the new gaskets fix the problem, we won't know till we see enough of them @ 200,000+ with the new gasket.

[cookie]

But if you figure most of them are near 100,000 miles now the actual useful life of the average car is only another 100,000 miles. There are always cars that beat the average and there are a lot of them on this board, but most will be dead in another 100,000. I think this means that the gaskets should last long enough.

[nipper]

I recently purchased a 1998 Legacy Outback with a 2.5 & automatic. I got the car very cheap. The car had no heat and would only get to 1/4 on tempature gage. I was sure there was no Thermostat, and it was obvious that the car had overheated in the past, due to looks of engine compartment.

 

I was correct there was no thermostat. I put in a new thermostat and had system flushed. I could let the car idle for 45 minutes and it would not overheat, and had great heat. When I took the car for a test run (after 5 minutes of driving) it would completely lose the heat at low RPM and the gage would show engine was starting to overheat. If I revved the engine to 3000-4000 RPM the heat would come back and the temerature gage would quickly show a drop back to 1/2 point.

 

I then replaced the waterpump and timing belt. This time the heat was even better and car ran at 1/2 point on temp gage. After about ten minutes of driving the heat was gone and engine was overheating. Revving the engine would have no effect as it did with old pump. I have tried three new thermostats with the same results.

 

Here's the confusing part: If I put in a thermostat with a 3/8" inch hole in it, the car will run for days at several hours at a time and never overheat. The bad thing is that it then takes 3 times as long to warm up and has luke warm heat. The temp gage will then only reach 1/8 and less. I tried the thermostat with the hole in it many times during the above senarios and it would always give these results.

 

Thermostat is in the correct direction. Upon refilling coolant after working on, I warm engine and shut off. Wait for a back suction (Thermostat Opens?) and quickly fill when this happens. Am I not doing something correctly? Any ideas? I've been working on this for over a month.

 

I have never used a forum before, I hope I am doing this correctly. If not, I apologize for my ignorance.

 

To further elaborate: the coolant markings in the engine compartment appear to have come from the radiator cap area.

 

One more item I forgot to mention; when I first got the car and inspected the cooling system, I found the fans did not work and immediately fixed the issue. I assumed this was the reason for overheating in the past, but I guess I was wrong.

 

I think the first thing I am going to try is replacing the radiator and the cap. I will post the outcome of this.

 

After this I will look into replacing the head gaskets. I realize head gaskets could be the issue, but am stumped as to why a thermostat with a 3/8" hole drilled in it will cause the car to never run hot and the oil looks good, the overflow never bubbles, and the exhaust shows no burning coolant.

 

Also, what is the trick to not getting air trapped in the coolant system when refilling? This seems to be a pain in the butt. If you have the knowledge please explain in detail? All the literature states that these cars are known for trapped air, but does not explain how to remove. Maybe it's common knowledge, but I have never heard it explained.

 

Why is the thermostat placed at such a low level?

 

alot of cars now use a reverse flow radiator due to emissions. It keeps the engine temp more even. I think subaru does it because thats the only place where there is room to put it and make it easily serviceable.

i agree with air traped in the system. Blown headgaskets would make bubblesin the radiator. Bad news is that you may need HG anyway soon depending upon how hot the car got in the past. Also in any car that overheats repeatedly or gets cooked with an aluminum engine, its important to change the oil. The oil takes a beating in these newer engines and begins to break down.

 

nipper

[Subarian]

But if you figure most of them are near 100,000 miles now the actual useful life of the average car is only another 100,000 miles. There are always cars that beat the average and there are a lot of them on this board, but most will be dead in another 100,000. I think this means that the gaskets should last long enough.

 

I hope the Subarus haven't descended to the level of being an average car. Two of my three GLs have over 250,000 on them.

[WAWalker]

But if you figure most of them are near 100,000 miles now the actual useful life of the average car is only another 100,000 miles. There are always cars that beat the average and there are a lot of them on this board, but most will be dead in another 100,000. I think this means that the gaskets should last long enough.

 

Well you can keep them going as long as parts can be had, unless you are in the rust belt. But then your looking at engine replacments, transmissions, big dollar items. Most people would rather buy somthing new.

This is why I haven't really jumped on the bandwagon for replacing the 2.5L with a 2.2L because (1) I did two and was not completly happy with the performance, customers seem to be happy, but if I'm not happy I don't try and sell it. (2) For the price of doing head gaskets another 100,000 is good service, when compaired to a new car payment, and by that time they probably won't have the car anyway.

 

I think the biggest problem with this head gasket issue is that the people who know are dumping the cars on those who don't. Nothing worse than to buy a new to you car to find out it need head gaskets.

[Subarian]

WAWalker, I agree with your last statement. It's unethical (and to me, at least, unthinkable) to sell someone ANYTHING if you know it has a problem and you don't disclose it.

[cookie]

When I was a kid I had more time than money. I bought cars when they needed engines and trannies. At this point in my life I have more money than time and I buy a car and run it until it needs major work. After I retire I will be back to the first system.

When I sold my last Mercedes it needed a heater core but I had rebuilt engine, tranny, and changed the rear end. The mechanic who bought it was thrilled.

With this car I expect I'll trade when the first major part goes. That should be around 200,000 I expect.

[WAWalker]

So your saying the 200k+ cars are for the young and retired? LOL

[pheasbo]

I have a '98 Outback with 74K, bubbles in overflow bottle, AF blown out overflow bottle on belt drives. Classic internal HG leak on the Phase 1 2.5; but at 74k? WTF? Towing insurance rules.

 

Was told to "snip top and bottom of thermostat". Haven't tried, but can see the reasoning behind the theory.

 

Also have replaced cam seals, (twice, second under warranty) oil pump seal, valve cover gaskets (all at 58K). Power steering pump leaked at 50K. Been adding Lucas, seems to work.

 

Sell it (full disclosure) or fix it for $1,200?

 

People in my area are selling similiar mileage rigs for $10k with average askings on higher mileage rigs, i.e. >110k, between $7k-8.5k.

[ballitch]

like already stated, air in the system. dont get too hastey with the phase I HG issue just yet. there is a bleed screw on the EJ radiators. loosen it and do all that mumbo-jumbo. if that doesnt work then you might want to buy this part. 11044AA610, its the new 4-layer HG. that is a subaru part number, look on nasioc.com for the proper head bolt torqueing ritual, and follow it to the "T".

 

~Josh~