Overheated after a long drive?

BSOD2600 · Post by **BSOD2600** » Mon Oct 02, 2006 1:09 am

I just got back from a 215 mi drive and when I pulled into the gas station (right off the freeway), coolant started to spew out the overflow. Then I continued home and the temp gage was about at 3/4, which is a LOT higher than I've ever seen it. A few minutes later, I get home and coolant is still spewing / bubbling out the overflow.

I just did this 215 mi drive on Friday with zero problems. Any idea why this is happening?

subytech · Post by **subytech** » Mon Oct 02, 2006 1:42 am

check to see that your radiator/condenser arnt pluged up with dust, durt and crap like that. they could have pluged up from the drive. Or it could possibly be some problem with your water pump/ thermostat, look at the underside of your water pump for any coolant seepage. Have you ever replaced the T-stat?

BSOD2600 · Post by **BSOD2600** » Mon Oct 02, 2006 1:55 am

Ok, but why all of a sudden would this problem pop up? I've done several long road trips in the past 2 weeks and never had a problem. I used one of those coolant/antifreeze measuring devices and it's fine. Also, since it's been an hour since I got back, the coolant overflow tank is now dry -- I assume the engine sucked the remainder back in? That mean I should go get some more coolant and add it to the system?

Nope, I've never replaced the thermostat.

subytech · Post by **subytech** » Mon Oct 02, 2006 2:26 am

First off yes you should go get some more coolant and add it to the radiator if it needs some and deffinatly to the over flow bottle. The vacuum created in the cooling system when the coolant cools does suck the coolant from the overflow bottle back into the radiator. By over flow do you mean the hose that comes out the overflow bottle cap? Water pumps can all of a sudden fail, the internal bearings can sieze, also I forgot to ask, do you know if you're cooling fans are functioning proporly? Now that i think about it its probubly not the t-stat that would cause overheating right after start up, It could also be that the junk that builds up in your cooling system over time just started to restrict your radiator or heater core enough to stop effective coolant flow, depends on how well the cooling system has been maintained. Or all the driveing you have been doing has caused a chunk of that build up in your cooling system to come free and plug something up. sorry for the vegue answer, there are just so many possibilities, good luck

BSOD2600 · Post by **BSOD2600** » Mon Oct 02, 2006 11:53 pm

Ok, went and got more coolant and filled it up. Started the car and let it idle until the temp was in the normal range. Started to drive around the block and the temp gage climbed back up till it was overheating.

After I got back home, I felt the top hose that goes into the radiator -- it felt warm. The radiator and the bottom hose that goes into the water pump felt cold. Since I don't have a leak around the water pump nor any odd noises, I guess it's the thermostat thats bad?

Any tips to replacing it?

subytech · Post by **subytech** » Tue Oct 03, 2006 2:04 am

Way to go, thats exactly how they tought me to test for a stuck T-stat at tech school, and I had to pay for that lol. the T-stat is increadibly simple, once you climb under the enging, there will be a plastic houseing that your bottom rad. hose clamps to, that is the t-stat housing, there are 2 bolts conecting it to the water pump, just unbolt those to bolts and be ready for the green waterfall that comes out. Also when you pull out the old T-stat, sence its stuck, there will be coolant behind it so be ready for that as well. once the coolant stops draining, just remove the t-stat from the water pump (you may have to pry it out with a screwdriver or some plyers, be carful not to scratch the sealing surface of the water pump) and replace it with the new one (be sure that the new t-stat is facing the right way and the gasket is on correctly, dont ask why i say this lol.), bolt everything back together and fill the radiator back up, let the car run for a few min with the rad. cap off, and every once and a while squeez the upper rad hose and rev the engine for a few seconds to burp out any air pockets. I usually let the car run untill the fans have come on before I put the rad. cap back on. once thats done drive it and make sure its not overheating or leaking. The only other thing I would recomend is that you use a genuine subaru T-stat, and not just because I'm a tech, cheap aftermarket ones from online and places like Shucks and Napa are mostly piles of crap. The way I look at is, how long did the original last? 12 years?

BSOD2600 · Post by **BSOD2600** » Tue Oct 03, 2006 2:54 am

Well I replaced the thermostat with a OEM subaru part... also got an aftermarket -- damn what a difference!

Aftermarket on the left and OEM on the right:

Anyways after getting the new one installed, I left the car idle for 5 minutes. After a while the fans kicked on but I still didn't feel the upper radiator hose getting warm. A few minutes later the temperature gage crept up past the 'normal' mark and sure enough the car was overheating again! Oddly enough this time the engine didn't suck/blow any coolant from the overflow.

Guess my water pump went bad? A new one from Subaru is $114, plus who knows how much for labor. The subaru dealer is 3.1 miles away from my house, think I should risk driving it there or get it towed? Also, I plan on having them do the hydrocarbon sniff test, just in case the engine is on its way out.

subytech · Post by **subytech** » Tue Oct 03, 2006 4:25 am

if you live that close then i would worry to much about driving it, but it sounds to me like you have a bubble in the upper rad hose still. the turbo models are hard to get all the air out of, especially when you drain it as thuroghly as you do when you do a t-stat, cus you dont fill the system at the radiator, and you have to rely on all those little hoses comming of the coolant tank to fill the system. the best way is to take the little coolant line right above the upper radiator hose off and see if theres coolant at the radiator there, if theres air in there add coolant and sqeeze the radiator hoses until coolant starts comming out the radiator. At work we have "spill free funnels" that belmouth at one end and attatch to the coolant bottle at the other using fittings that come with the funnel, we fill the funnel up and run the engine making sure the funnel always has coolant in it so the highest point in the system is well above the radiator so the coolant is always trying to push out any air. you might be able to find one of these funnels at napa or other quality parts store if not just make sure that you do everything possible to get all the air out of the system, reve the engine to say 3k rpm and hold it for like 5-10 sec, to get the water pump spinning faster, squeez the hoses, make sure there is plenty of coolant in the overflow bottle. I don't think its the water pump because you said it wasn't leaking or making any funny noises, the fins on the pump could be damaged, but they would have to practicly be missing to cause the symptoms you described.

subytech · Post by **subytech** » Tue Oct 03, 2006 4:28 am

It was the upper hose that was cool this time right?

BSOD2600 · Post by **BSOD2600** » Tue Oct 03, 2006 5:22 am

subytech wrote:It was the upper hose that was cool this time right?

Correct. Even after the fans turned on, the upper coolant hose wasn't really warm at all.

Alright, I'll check/fill the radiator with more fluid. Should I also be leaving off the coolant cap while trying to get the air out?

Manarius · Post by **Manarius** » Tue Oct 03, 2006 5:45 am

I think you have a block in the radiator. That upper pipe should be pretty darn hot at operating temp.

subytech · Post by **subytech** » Tue Oct 03, 2006 6:55 am

yes you need to have the cap off or the air wont leave the system, dont replace the cap until you're sure all the air is out.

subytech · Post by **subytech** » Tue Oct 03, 2006 7:02 am

Manarius wrote:I think you have a block in the radiator. That upper pipe should be pretty darn hot at operating temp.

quite possible but if theres an air pocket in that hose it wont warm up.

BSOD2600 · Post by **BSOD2600** » Tue Oct 03, 2006 7:29 pm

Went out this morning and removed the coolant cap and heard a sucking sound. Noticed the coolant level dropped so I added more... a lot. Kept massaging the upper radiator hose and adding more coolant to the tank. Then started the car and let it run with the cap off. The level slowly went down. Eventually when the engine reached the normal operating temperature, coolant started to continuously come out. I decided to then put the cap back on. Sure enough, more slowly this time, the temperature crept up back to overheating. This time though, the upper radiator hose was hot, while the lower was still cold.

Turned the car off and then took off the smaller hose that goes from the coolant tank to the upper radiator area (right above the large radiator hose). Soon as I took it off, a lot of air/steam came out. Let the car cool down for 10 min and then put coolant in that small tube. It didn't take much before it wouldn't really drain down any more water.

I left the small tube disconnected and up in the air. Turned the car back on and let it warm up. Steam kept coming out the smaller tube. Once again the car slowly got to the overheating temp and I turned it back off.

I've got a CEL that I need to find out. Also once it cools down, I plan on taking off the large upper radiator hose and see if there is any coolant in the radiator -- if not, filling it up. If all of that doesn't work, then I guess it's off to Subaru I go... *sigh*.

BSOD2600 · Post by **BSOD2600** » Tue Oct 03, 2006 10:57 pm

More news...

An hour after my last post, I went out and started messing around again. Right away I noticed the coolant overflow tank was dry! Yay, that means the engine sucked all the coolant in there up. I started up the car again with the coolant cap off and let it warm up. Once it reached the normal temp range, coolant started to come out the coolant tank on top. I capped it and let it idle for a while longer. Temps seemed to be ok. Went for a drive around a few blocks and the temp stayed normal. YAY!

Drove back home and let it idle some more in the driveway. Then the temp started to climb back up to the overheating point. Turned it off and let it sit for 2 hours. Came back and put more coolant into the top coolant tank and did an errand on the way to school -- the temp stayed normal.

So I guess, there was a giant amount of air in the system which caused the coolant not to flow properly? I plan on checking the coolant levels every day the rest of the week to continue to get rid of all the air.

Brat4by4 · Post by **Brat4by4** » Tue Oct 03, 2006 11:44 pm

Either you have an inexhaustable amount of air in your coolant system or there is an inner coolant circuit leak, which I have suspected all along.

Keep the thread updated.

Richard · Post by **Richard** » Wed Oct 04, 2006 2:47 am

After draining the system burping the engine of all its air is quite a fun process. I've developed a technique I call squeeze and fill. I fill the system as much as I can cold. I leave a little room in the resivoir and squeeze the top hose until coolant almost comes out and then I seal the cap. I let go of the hose and I can hear a woosh sound. I open the cap and wow!!! There's a lot less coolant in the rez. So I add a little more and repeat, making sure to top off the overflow rez when needed. After I feel I can't get anymore in I start the engine with the cap off and top it until it starts to pour out. I cap it and give it a brisk drive to get the temp up (hot enough for the fans to kick in) and bring it back. Then I pop the hood and add coolant to the overflow so it's 3/4 full. Then I go inside and wait until everything's cool. When it's pretty much cool, I do the squeeze and fill again. Usually this is enough to do the job, however I check it before I drive it every day for the next week and top it off if it needs it. Same for the overflow rez.

One thing to look for, and I got screwed by this recently even though I know better, is to make sure you have the right coolant/water mix. I thought the stuff I gaffled from work was the pre-mixed stuff. I ended up having 100% coolant to 0% water. This made things real bad.

And distilled water is recommended because it doesn't have additives like tap water does. I think R O water is good too. If you're not sure what your mixture is, get a tester from the parts store. They're usually less than 20 bucks and you should test your mix from time to time anyway.

I hope this helps.

subytech · Post by **subytech** » Wed Oct 04, 2006 3:08 am

Brat4by4 wrote:Either you have an inexhaustable amount of air in your coolant system or there is an inner coolant circuit leak, which I have suspected all along.

Keep the thread updated.

If there was an internal leak big enough to cause these symptoms there would be alot of white smoke comming out the tail pipe.

subytech · Post by **subytech** » Wed Oct 04, 2006 3:11 am

I'm glad to hear your working it all out, like you said just keep checking the coolant level, things should get better. This (air pockets in the coolant system) is probubly one of the most frustrating things about these and any other turbo surbaru engine.

Richard · Post by **Richard** » Fri Oct 06, 2006 4:26 am

Top 5 at least. If they only put a damn bleeder in the system. Everything else seems to have had thought put into it. Why not this?

subytech · Post by **subytech** » Sat Oct 07, 2006 6:07 am

I dont even think its that they have put thought into everything else its just that they have been using the same design for SOO long that they found out whats wrong through trial and error lol. I guess they just haven't really thoght about the cooling system alot, i mean look at all the head gasket problems we've been having with the newer 2.5L blocks, thats all coolant related.

BSOD2600 · Post by **BSOD2600** » Sat Oct 07, 2006 5:34 pm

I'm glad to say that I haven't had any more overheating issues and I think I've gotten all the air out. Sadly, thats not the end of the problems though.

Probably something wrong with my AT: http://bbs.legacycentral.org/viewtopic.php?t=28691

and some smoke the other day: http://bbs.legacycentral.org/viewtopic.php?t=28715

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Overheated after a long drive?

Overheated after a long drive?