Overheating Issue

[Lawsonmh15]

So, a few weeks ago I noticed my temp gauge fluctuating in a way that made no sense. I figured it was time for a new thermostat and flush so I had it taken care of. All seemed fine for a week or so, then the same thing again. The weird thing is that the temp would spike and fall under driving conditions that doesn't make sense. (i.e. I may be nursing it doing 30mph and it spikes, but then getting on the gas going up a hill would drop the temp to normal).

 

I checked the reservoir and noticed it was bone dry so I added water and drove home. It still overheated, but when I checked the reservoir, it was still completely full... I took it to a friend's shop yesterday and they did a pressure check and tested for exhaust and the pressure was fine and there was no exhaust in the coolant. Furthermore, they could not get it to overheat (which seems odd because today it did it about 9 miles in to my drive to work). Nonetheless, they topped off the coolant and I went on my way.

 

As I mentioned, on my way to work, the same thing happened again, however, today I moved my car from the parking spot to another after about 10 minutes and discovered a puddle of coolant on the ground. Popped the hood and I see that there is coolant leaking from the right side and it looked like everything on the right side of the radiator from the fill valve and top of the reservoir, down to the hose had coolant on it, making it difficult to see where the leak is coming from.

 

Is there a particular point of failure I'm not recognizing here? Also, is the heater core in the vicinity by chance?

[Suzam]

Can you give us the year, model and engine size?

 

you should do a search on the board for "Burp" or "Burping". You may have air trapped in the system since the reservoir was empty.

 

Also buy a new radiator cap, the one on there may not be working correctly and needs replacement.

[Rooster2]

It would be helpful to know what year and what model Subie you own. So, please let us know what you got. Certain Subie motors like the 2.5 phase 1 used in 96-99 year Subies are prone to head gasket trouble. The problem starts to present itself like yours with random over heating that gets worse and worse. What happens is that exhaust gas leaks into the cooling system to cause the over heating.

 

However, you may be lucky in that it is just a bad hose or leaky radiator. Suggest you clean up the sprayed out coolant, then look for a source of the leak. Pretty hard to tell much until all the coolant mess is addressed first.

[Ricearu]

he took it to his friend's shop and did a block test on it. no hc's in coolant.

[johnceggleston]

this is a pretty classic symptom of bad head gasket. it is possible it isn't but i'd bet it is .

 

what car and year??

 

2.5L engines 96 - 99 are prone to this problem.

 

re-fill the cooling system and burp it properly (do a search for burp or burping) and the next time it over heats, check for bubbles in the radiator over flow reservoir, NOT THE RADIATOR. bubbles indicate bad head gaskets.

 

good info here:

 

http://www.ultimatesubaru.org/forum/showthread.php?t=104353&highlight=badheadgasket*

[Lawsonmh15]

Can you give us the year, model and engine size?

 

you should do a search on the board for "Burp" or "Burping". You may have air trapped in the system since the reservoir was empty.

 

Also buy a new radiator cap, the one on there may not be working correctly and needs replacement.

 

I wondered about this exact thing since I noticed when his guy did the coolant flush, he didn't pull the valve on the top left side of the radiator. The fact that it fluctuates at odd times also made me think the coolant would almost get stuck, then for whatever reason, begin circulating again.

 

Almost forgot, it's a 99 Legacy SUS. From what we've found, it looks like the engine has been either rebuilt, or replaced.

Edited October 29, 2010 by Lawsonmh15

[GeneralDisorder]

Head gaskets - pretty much a sure bet on that engine. Spiking temp gauge - dissapearing coolant..... yep.

 

GD

[johnceggleston]

Almost forgot, it's a 99 Legacy SUS. From what we've found, it looks like the engine has been either rebuilt, or replaced.

 

how long have you had the car?

any service history available?

how many miles?

 

i didn't really mean to give you hope by suggesting the burp. i just wanted to eliminate possibilities. there is a good chance if you fill and burp it correctly it will not overheat for a month, maybe more maybe less. but if it is bad head gaskets it will come back.

 

the link in my post above will shed a lot of light on how HGs fail. everyone who has been through this has held out hope that it was a bad t-stat or blocked something. almost all were disappointed.

[Suzam]

Granted the symptoms of a possible head gasket are there but a "temp gauge fluctuating" isn't an overheating spike and there has been no boil over.

 

It's possible since there was no exhaust gases detected in the coolant that it's a simpler problem.

 

A $5 radiator cap and a burp of the coolant system might cure the issue before the head gaskets are condemned. As long as the engine doesn't overheat to the point of warping the heads if it is indeed a bad gasket.

[Lawsonmh15]

Well, I just unscrewed the vent and burped it while adding water, then flipped on the ac and put it through the paces for the last 10-15 minutes and the temps stayed where they ought to be. I filled it with water through the radiator cap until water came out of the vent then tightened it and took it for the aforementioned spin. When I got back I sat with it in park for a few minutes to simulate a light and then checked the reservoir. The reservoir now has coolant in it. Nonetheless, the coolant looks weird, as though it has froth on the top. Any ideas on that?

[GeneralDisorder]

Temp gauges spike when the coolant stops flowing. This is due to there being a big air bubble at the top of the engine - the water pump can't circulate coolant past the air bubble.

 

The bubble is either air from a loss of coolant (leak) or it's combustion gasses. It's obviously not leaking out the cap if the reservior is dry so scratch that as a possible leak..... look around. If you don't find a leak then it's probably burning the coolant which is a head gasket failure. *usually* these engines push exhaust gasses into the coolant and displace it into the overflow bottle - but that's not the only way head gaskets fail - sometimes they will drink coolant.

 

GD

[GeneralDisorder]

Nonetheless, the coolant looks weird, as though it has froth on the top. Any ideas on that?

 

Bubbles in the overflow . CLASSIC head gasket symptom on that engine. It will get worse.

 

With EJ's - you pop out the vent plug, fill them till coolant comes out the vent, close everything up and you are done. That's it - no other burping or fussing should be needed. If it overheats then it's either leaking it, burning it - bad head gaskets.

 

GD

[Lawsonmh15]

Bubbles in the overflow . CLASSIC head gasket symptom on that engine. It will get worse.

 

With EJ's - you pop out the vent plug, fill them till coolant comes out the vent, close everything up and you are done. That's it - no other burping or fussing should be needed. If it overheats then it's either leaking it, burning it - bad head gaskets.

 

GD

 

As I mentioned in the original post, I couldn't tell exactly where the leak was coming from, but in my search for a "burping tutorial" I realized it was coming out of the top of the reservoir.

 

Also, when my friend's employee did the swap and t-stat, he did not pull the vent plug so I'm beginning to feel more confident about it having to do with trapped air, however, I'd love to know why you say it may be the HG based on the frothiness look. As I mentioned, yesterday my buddy did a pressure check (pass) and there is no trace of exhaust fumes in the coolant. Also, as I mentioned, the engine was replaced or rebuilt prior to my purchase.

 

Lastly, given that the mechanic did NOT pull the vent when he did the fill on the coolant, could that cause the HG's to go bad?

[GeneralDisorder]

As I mentioned in the original post, I couldn't tell exactly where the leak was coming from, but in my search for a "burping tutorial" I realized it was coming out of the top of the reservoir.

 

If it's being forced out the top of the reservior - that usually indicates an over-pressure condition - either a bad radiator cap or combustion gasses causing the system pressure to increase beyond the set-point of the cap. When the cap opens the coolant is forced into the overflow and that usually is accompanied by a bubble of combustion gasses that stop the flow of coolant and over time (depending on how large the leak is - could take several hours of driving or could take 10 minutes) will cause the temp to suddenly spike.

 

Also, when my friend's employee did the swap and t-stat, he did not pull the vent plug so I'm beginning to feel more confident about it having to do with trapped air, however, I'd love to know why you say it may be the HG based on the frothiness look. As I mentioned, yesterday my buddy did a pressure check (pass) and there is no trace of exhaust fumes in the coolant. Also, as I mentioned, the engine was replaced or rebuilt prior to my purchase.

 

Pressure check is meaningless because the leak could only open when the engine is hot - I've seen engines that would run fine indefinately without a thermostat in place but would overheat when run to proper operating temp. The exhaust gas check is usually a better test but there's any number of reasons it could have failed that.

 

The bubbles in the coolant are an indication of exhaust gasses pressureizing the cooling system. That is seen on almost 100% of these engines when then HG's let go.

 

Lastly, given that the mechanic did NOT pull the vent when he did the fill on the coolant, could that cause the HG's to go bad?

 

An air bubble will cause the coolant to stop circulating and could cause a blown head gasket, yes. The fact that the engine was rebuilt does not make any real difference and depending on what parts were used and how the work was done could make it MORE likely to have blown a gasket. Anything but the OEM gaskets from the dealer are prone to failure unfortunately.

 

GD

[Lawsonmh15]

Just did another quick but hard drive no issues. I have to wonder if I saw frothiness or not the last time, as this time, before driving I checked the reservoir and there was no coolant in the reservoir and when I got back I left in drive w the parking brake on and checked the reservoir and there was coolant in there but no froth look, making me wonder if what I saw the first time was actually, nothing but an empty reservoir. I did note there were bubbles bubbles coming up while it was running, but they didn't sit at the surface. I suppose if it's the HG... then it's the HG and I get it cleaned up and trade it in, but really I guess the only thing I care about is that it doesn't overheat and remains reliable.

 

The more I read about the HG issue, I guess I'm not sold. Perhaps you can chalk it up to "ignorance is bliss", but everything I've read talks about the HG's going out between 60-130,000 and I bought it with 80k and it now has 170K.

 

This all started after an oil change using the new Mobile One 0W-30... Nothing but problems from there (albeit they "guarantee" warranty protection up to 15W 30...

 

Lesson learned. It used that 0 weight quick too so I made a change to the 20W-50, hoping it will start with the impending cold weather.

[GeneralDisorder]

20w50 is a bad choice - stick with an SAE 30 oil. Thicker oil like that is for engines with higher bearing pressures like diesels. It will not help with anything on a Subaru. The manual says 10w30 for a reason and that should not be deviated from for any reason EVER over the life of the car. That stuff will increase startup wear and you don't want that.

 

I just did an exhaust valve job on a '97 OBW with the original head gaskets that never blew out. It currently has 169k on it. It's very possible that you have OEM head gaskets that are just now failing. Especially since the engine was replaced a long time ago and now has at least 90k on it. It could have been rebuilt using the old (flawed) head gaskets. It wouldn't surprise me at all.

 

GD

Edited October 29, 2010 by GeneralDisorder

[Rooster2]

20w50 is a bad choice - stick with an SAE 30 oil. Thicker oil like that is for engines with higher bearing pressures like diesels. It will not help with anything on a Subaru. The manual says 10w30 for a reason and that should not be deviated from for any reason EVER over the life of the car. That stuff will increase startup wear and you don't want that.

 

+1 on 20w50 as a bad oil choice. Subie engines don't like thick oil. Stick with the manual's recommendation. 10W30 is the way to go.

[Lawsonmh15]

Alright, drove for about 1:45 minutes in rush hour traffic in weather that was about 20 degrees warmer than the past few days and had no issues. Since this began I haven't had a drive that didnt result in overheating so I feel pretty good about it being air in the system. Oil was 5W-20. Feel better about that too. thanks for the input.

[johnceggleston]

Alright, drove for about 1:45 minutes in rush hour traffic in weather that was about 20 degrees warmer than the past few days and had no issues. Since this began I haven't had a drive that didnt result in overheating so I feel pretty good about it being air in the system. Oil was 5W-20. Feel better about that too. thanks for the input.

 

the internal head gasket leak works like this: exhaust gas leaks into the coolant, displaces coolant into the overflow, and beyond, (adding gunk to it) and eventually causing an "air" pocket in the cooling system and over heating. over heating can be cause by loss of coolant or from an "air" lock in the system.

 

when the leak is new, just beginning, it will only leak a little and can cause an occasional overheat. this is usually addressed by flushing the cooling system and maybe replacing the t-stat. (when buying a car if you see service receipts for either, or they mention either in the car ad, look harder at the car). depending on the car, the driver and the leak, it could be weeks or months before it overheats again. as the leak gets worse, it will happen more often.

 

some of these cars with bad head gaskets can be driven around town "forever" and show no sign of over heating, some will over heat after 20 - 30 minutes of any type of driving, and some only after 30 minutes of hiway driving. so "test drive" the car.

 

in a normal car, the coolant level will vary in the overflow depending on the conditions and type of driving. usually when the cars heats up it will push more coolant into the overflow, then when it cools down it will suck that coolant back into the radiator. this is a normal process, but the cold level should be the same from one day to the next. in other words, it is not loosing any coolant.

 

if the car pukes coolant out of the over flow it's bad news. if there are little bubbles in the coolant in the overflow bottle after the test drive, this is bad. if the coolant level when cold before you drive it and the coolant level when cold after you drive it (cold, hours later) is not the same, i would think this is a bad sign. if there is any gunk in the coolant, this is bad. if the coolant is brand new, i would ask why and look harder at the car.

 

typically, cooling system pressure testing does not "catch" bad gaskets in the early stages, maybe never since the exhaust is leaking into the system, not coolant leaking out. there is a test which will look for exhaust gases in the coolant, but if the leak is small, and the coolant just changed it may not catch it.

Edited October 30, 2010 by johnceggleston

[Tahoe Subaru]

Subaru's are famous for HG problems. Sometimes they overheat for the normal reasons. leaks. The last 3 cars brought to me for HG's, 2 were water pumps, seems like no one changes them at the first timing belt change. One was a hose at the throttle body. All were overheating which can cause the head gaskets to blow.

Just food for thought.

[Lawsonmh15]

As much as I hate to say this... It overheated on the way to work today. Not feeling inclined to pay $1500 to have them replaced, so I suppose it may be time to trade this sad, sad subie in...

[Lawsonmh15]

As much as I hate to say this... It overheated on the way to work today. Not feeling inclined to pay $1500 to have them replaced, so I suppose it may be time to trade this sad, sad subie in...

 

The reality of the situation is that I have a month old daughter and lady to support and $1500 seems ridiculous for an 11 year old car. If there's someone out there in the Denver area who can do it for much less, let me know. Also, is the machining of the heads the most costly part of this, or the labor?

[johnceggleston]

trading it in may be you best choice as far as price, but it is always hard to know how much you got on your trade in when they are adjusting the sale price of your purchase, and vise versa.

 

on the other hand you can have a 2.2L engine put in for less than repair, probably.

 

at 170k and you have had it for 90k, i'd fix it and drive it. the repair or replace will be way cheaper than the monthly price of almost any other car.

 

check with 'lmdew', larry is in colorado springs i think and a member here. he may be able to fix it for a fair price or maybe buy it out right.

[Lawsonmh15]

trading it in may be you best choice as far as price, but it is always hard to know how much you got on your trade in when they are adjusting the sale price of your purchase, and vise versa.

 

on the other hand you can have a 2.2L engine put in for less than repair, probably.

 

at 170k and you have had it for 90k, i'd fix it and drive it. the repair or replace will be way cheaper than the monthly price of almost any other car.

 

check with 'lmdew', larry is in colorado springs i think and a member here. he may be able to fix it for a fair price or maybe buy it out right.

 

Thanks for the heads up. I really hate the idea of having to part with it, at the same time, the last payment was made about a month before this all went down. I just wonder when the next repair would be coming and at the same time, I have to think it's no coincidence that this all started happening after the oil change with the 0W-30 Mobile one.

[johnceggleston]

Thanks for the heads up. I really hate the idea of having to part with it, at the same time, the last payment was made about a month before this all went down. I just wonder when the next repair would be coming and at the same time, I have to think it's no coincidence that this all started happening after the oil change with the 0W-30 Mobile one.

 

generally speaking the only thing anyone can / could do to that engine to contribute to a head gasket failure iis to overheat it. drive it with out enough coolant or when it is running HOT and you can kill the gaskets. so i doubt the oil change had anything to do with it. it just doesn't make sense.