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Old 07-27-2017, 03:14 PM   #1 (permalink)
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Default MASSIVE coolant leak...

2008 Tribeca 6cyl here. I had just filled the coolant at the dealership when I had them work on squealing brakes and do inspection. A few weeks later I'm sitting in the drive-thru at taco bell and I notice that my engine is beginning to overheat. I pull over and notice my coolant reservoir is empty. Luckily I'm only a few blocks from my house, so I get it home quickly and park it then go on vacation. I come back, I fill the radiator as much as I can without overflow, and I fill the reservoir to the max fill line and I wait. Everything seems fine for about two weeks until a hot day with a lot of traffic where work meant driving half the day, then when I'm stopped in line for food again after driving all day, I hear the cooler kick into high gear and see my thermals start going up again. Get it home and once again the reservoir is empty not even two weeks later. Today I made sure it was full, put a piece of cardboard under the car, ran it until the cooler kicked on, and then noticed that there was a very significant volume of coolant soaking the cardboard. Most likely I had not noticed this leaking because it was happening on the road and not when I was parked in my garage, and it only began once the fan goes into overdrive.

I'm not a mechanic, but it seems to me that the most likely culprit is either going to be a damaged radiator or a cracked hose or loose fitting given the sheer volume of liquid coming out. Are there any non-obvious things I should be looking for in diagnosing this problem? I'd like to get it done right the first time. While I'm not a mechanic, I am pretty mechanically inclined and an engineer by trade so I should be able to take care of this ideally without having to pay someone else hundreds of dollars in labor over what it costs in parts when I have 3 days to get it done.

This thread will document my successes and failures toward that end. If you have any feedback or tips, it would be greatly appreciated.
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Old 07-27-2017, 03:36 PM   #2 (permalink)
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Um, seems very odd that it survived two weeks after the refil and then on a "hot day" decided to... "discharge" shall we say.

What happened during two weeks?
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Old 07-27-2017, 04:22 PM   #3 (permalink)
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Most of my driving during that time was shorter trips that didn't involve sitting in one place. It wasn't until I was stuck in a 5 minute line at the drive thru that the thermostat went over 50%, at which point panic set in and I was just desperate to get it home without it exploding or whatever.
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Old 07-27-2017, 04:38 PM   #4 (permalink)
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Just to clarify:

-Had engine inspected and filled with fluid by the dealership in April.
-Noticed issue with thermals in June while sitting idle at drive thru. Pulled over and noticed reservoir was empty. Went on vacation because flight was shortly after. Did not fill but it sat in garage.
-Got back from vacation. Filled reservoir and radiator. Waited.
-Two weeks pass without incident and I check the first 4 days dilligently without seeing a difference in reservoir. Then today when standing still again my thermals escalate and I pull off to notice empty reservoir. Luckily I am only a few blocks from home again and I take it back home about 1 mile. I then fill the reservoir and do the cardboard thing and it's dry until the fan kicks up when it goes above the 50% mark on the thermometer and then I notice not 5 minutes later that the carboard is soaked. There's still a medium amount of coolant in the reservoir because it only went on for about a minute while I tried to get an eye on where the coolant was coming from, but I couldn't do that without removing the bottom cover etc.

Maybe the increased pressure trying to cool the engine on less coolant is making a normally slow leak worse? Maybe there's a rupture in the hose that only is bad enough when the cooler is at 100%? Maybe I don't know what the hell I'm talking about?
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Old 07-28-2017, 04:08 AM   #5 (permalink)
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Start with pressure testing the system and the cap. You will need the small bayonet adapter for the Asian models.

Probably your radiator needs replacement if the coolant hasn't been changed every few years but a pressure test will pinpoint the issue.

Easy job. You might loose a pint of tranny fluid and you 'should' flush out the system and run the long life coolant. If you don't flush, use the normal blue coolant and add the $3 bottle of conditioner.


Just did a water pump on a M104 merc...green coolant eats aluminum.
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Old 07-28-2017, 06:20 AM   #6 (permalink)
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Quote:
Originally Posted by Thomasmryan View Post
Probably your radiator needs replacement if the coolant hasn't been changed every few years n't flush, use the normal blue coolant and add the $3 bottle of conditioner.
not true subaru coolant is specd for 10 years. so no need to change if there are no issues.

wash off the residue, let it dry, and start the car, see where it is coming from.
external leaks are relatively easy to find.
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Old 08-01-2017, 11:22 AM   #7 (permalink)
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2008 was a cusp year. Mine has green and thus 30k change interval.
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Old 08-01-2017, 11:51 AM   #8 (permalink)
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Just a reminder that there are two bleed valves as shown in the manual. Doubtful that any mechanic would be doing it by the book.

Last edited by avk; 08-06-2017 at 05:03 AM.
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Old 08-04-2017, 10:26 PM   #9 (permalink)
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Wow! This isn't a complete nightmare or anything!

So, first hurdle to overcome was funding. FINALLY, that was taken care of as of today.

As I waited for the funds to clear, I spent a significant amount of time struggling with a stripped bolt holding up the underside splash cover (rounded and the philips head was obliterated) and in the end, despite all my best efforts, I couldn't get it via conventional means. I actually had to melt the shielding off around that last bolt using a propane torch. So I'll need to buy a new shield I guess. Also, those plastic push tabs that hold all the plastic bits in place are in pretty sad shape in general so I'll probably need about 50 new of those lol.

Tomorrow I'm going to hit it hard and start posting pictures.
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Old 08-05-2017, 05:33 AM   #10 (permalink)
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no bleed valves in 08
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Old 08-05-2017, 09:02 AM   #11 (permalink)
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Coolant(s)
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Old 08-05-2017, 10:01 AM   #12 (permalink)
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Quote:
Originally Posted by tdelker View Post
no bleed valves in 08
are you sure?!

Last week I've replaced coolant in my Tribeca, I used Prestone. I did everything according to manual, so far all good.
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Old 08-05-2017, 01:16 PM   #13 (permalink)
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Today I filled the coolant and got under the car while it was running to see if I could trace where the coolant was coming from. For the first few minutes the car was running, there was no dripping. As soon as it started dripping I got under there with safety glasses and looked to see if I could trace the source. Whatever it is seems to be toward the top of the engine rather than the bottom. It then trickles down and pools up in small amounts in a hidden spot between steel plates on the undercarriage then seeps out through the holes that I assume are there to drain water that builds up under the radiator.

I noticed that for only a short while a pretty steady but small stream of drops was coming down from the top of the passenger side radiator along this hose and traced it back to this area of the engine.




You can see that it even pooled up inside a crevice right around where I believe the source of the leak is. Unfortunately, as I was laying under the car the stream of droplets slowed back down again and by the time I had got up to see where it was coming from on top it was not there anymore and it seemed like the steady drip had stopped. I could still see evidence that there was some liquid escaping from places where it shouldn't be though. The hose right in front of the fan had something wet splattered on it. The fans push air outward, so it couldn't have come from the radiator.

My first thought is maybe the hose is fractured in a way I can't see and when the cooling system actually engages or has to work hard that fracture begins to leak at an accelerated rate. Is that a reasonable conclusion? Or is this a sympton of something larger that only a professional would be able to discern?

Thanks again for the help and feedback!
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Last edited by Rambo; 08-05-2017 at 01:21 PM.
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Old 08-05-2017, 05:57 PM   #14 (permalink)
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Okay so I unseated the radiator and wiggled it around SLIGHTLY in order to see if I had all the bolts undone. I figured now that I have everything stripped down as far as I can get it without emptying the cooling system I'd see if I could replicate whatever caused that splatter. I ran it for about an hour and strangely there was no leaking on the cardboard during the entire time. Thinking that perhaps I was a secret genius who had accidentally fixed it, I decided the ultimate test was the drive thru, so I went to get some food (yes I eat a lot of fast food okay?). I got back and when I pulled over the cardboard the leak was in full swing again but this time it was coming from the front passenger side of the radiator. You could see the stream of droplets if you look in right next to the front license plate.

Now I'm thinking it's probably the radiator again. Maybe when I jiggled it the slightly different positioning put pressure on the hole that caused the coolant to go a different way? But then where the hell did all that extra coolant come from in that crevice on the engine?
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Old 08-05-2017, 08:22 PM   #15 (permalink)
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Quote:
Originally Posted by lutek34 View Post
are you sure?!

Last week I've replaced coolant in my Tribeca, I used Prestone. I did everything according to manual, so far all good.
Yup. 3.0 in 06 and 07 had the bleeder. Not in my 3.6L 08 though.
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Old 08-06-2017, 02:08 AM   #16 (permalink)
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Quote:
Originally Posted by tdelker View Post
Yup. 3.0 in 06 and 07 had the bleeder. Not in my 3.6L 08 though.
I got '08 Tribeca with 3.6 and I have bleeder exactly where shows FSM for 2009 Tribeca
Maybe in your case, somebody got rid off this bleeder?
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Old 08-06-2017, 05:07 AM   #17 (permalink)
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Looks like the bleeder on the radiator (right side) was deleted for 2008. That one is hidden under the plastic shroud, which needs to be removed to gain access.
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Old 08-06-2017, 08:25 AM   #18 (permalink)
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Pressure testing is quick and easy. No jousting at windmills.
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Old 08-09-2017, 09:27 AM   #19 (permalink)
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I'm nearly 100% convinced that every overheating/head gasket/cooling system on the EZ30 can be traced to a single, pinhole leak in a radiator hose.

Peruse this forum and the H6 forums on Legacy and Outback, and you'll find scores of phantom tales about escaping coolant.

Cooling systems are closed and sealed, and only a minuscule amount is lost to evaporation. So where is it going?

In my opinion, the problem is with the upper hoses from the heads to the radiator. Of course, radiator hoses will eventually fail over time, it's inevitable. But I think the issue here is that the hoses are failing without observable symptoms, i.e. a microscopic leak will develop in one of the hoses but it will only leak at a certain temperature/pressure. Of course, rubber expands when heated which might be just enough to open the pinhole for coolant to leak out while the car is driving; however, when RPM's (i.e. pressure) and temp drops, the rubber contracts just enough for the pinhole to close. In other words, the hoses are - for lack of a better term - self-sealing once temp/pressure drops. Since these hoses are coming directly from the chamber jackets, going from 2000 RPMs to idle can cause both a significant and immediate drop in temperature in these hoses, so even if you drove for 30 minutes, stopped & put the engine in neutral, popped the hood, and jumped out immediately to look under the hood, you might not see the leak. And depending on where the coolant was spraying, you're definitely not going to see any wetness on the hoses, and wherever it sprayed might have evaporated already. The only way to see it would be to rev the engine to the correct RPM's and hope for a stream... even then, since the radiator isn't exchanging heat very well when stopped, the t-stat will be wide open, which might relieve enough pressure in the radiator to prevent any leak in the upper hose from manifesting.

Even a pressure test might return a false negative because the hose is self-sealing so well at ambient temperatures.

Moral of story... change your upper radiator hoses if you suspect you're losing coolant, even if they look to be in good shape with no visible failures/damage.
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Last edited by psygnal11; 08-09-2017 at 09:32 AM.
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Old 08-10-2017, 07:54 AM   #20 (permalink)
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Ours was leaking from a crack in the plastic tank on the side of the passenger side of the radiator. FYI if you need a new one advance auto can get a lifetime warranty radiator for a decent price and shipping speed. I believe I got ours the next day. Not cheap but it got done. We never had overheating just coolant loss.
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