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Guest Message by DevFuse

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'01 EZ30D (H6) Cooling problem, 750 miles from home

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21 replies to this topic

#1 nhzero



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Posted 12 July 2013 - 10:27 PM

2001 Outback VDC, 108k total miles. Tricked out, all options.

Had this car about 8 months (from 89k) with no real issues beyond topping up the coolant by about 1/2 quart a few months ago. This week while going over the Grapevine pass, I had the car overheat with large amounts of bubbles coming out into the overflow tank.

I limped into Fresno and replaced the thermostat and all hoses, as well as flushing the coolant. It got to just before Mt. Shasta, where the overflow was bubbling again about 5 minutes before the passenger top hose nipple cracked off the radiator. CHP gave me the "best shop in town," where they swore up and down that they couldn't find any trace of exhaust gas in the coolant and they couldn't in good concience replace my head gaskets because they never go out and there were no indications. They replaced the radiator, thermostat (again, and OEM, again), and put in new coolant, with conditioner. They drove it up the mountain and swore it was strong.

I got halfway over Grayback pass when the coolant smelled again. Lots of bubbles in the overflow, added 2.5 quarts of coolant, and it made it to Oregon Caves. Now it starts to push 3/4 temp any time I head up any kind of hills. I'm seriously close to calling this car a wash, but I know if I try to trade in a car 750 miles from home I'll get bent over. Should I push the head gasket through the I-5 again, try Hwy 101, or just spend a couple days trying to get a different car? Thanks!


#2 grossgary


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Posted 12 July 2013 - 11:25 PM

wow, that is no good.


that is a long ways.  it starts pushing 3/4 up the gauge even when the *radiator* is full?  if it overheats and pushes coolant into the overflow then the rad may need refilled and burped of trapped air again if it doesn't get properly sucked back into the radiator (which i guess it should if it's got all new cooling gear and radiator cap).


make sure it's not trapped air but at this point that hardly sounds like the case.


travely at night (cool), no A/C, heat on, take the least stressful pass and fill it up entirely with whatever keeps it the coolest (all water?).  try two bottles of conditioner, that's a good bet for existing leaks.  keep the a/c OFF and the heat on high when it starts overheating.


pull over, let it cool down, and refill the radiator if you have too.


unfortunate to see that on such a tradiationally good platform, i have two H6's because of how reliable and low maintenance they are.

#3 ShawnW


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Posted 13 July 2013 - 12:31 AM

What about the radiator cap?  I replace them all the time on the 4 cylinder models and fairly often on the 6.  Does it hold pressure on a pressure test?  A failed one would certainly have these symptoms.  

#4 CNY_Dave


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Posted 13 July 2013 - 09:44 AM

I have had a perfectly good cap not hold pressure due to a tiny bit of grit/crud.


Bubbles in the coolant could be exhaust, or if not holding pressure, merely boiling coolant.


I hate to ask if anyone checked the radiator fans.

#5 Hydropneumatic


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Posted 13 July 2013 - 11:15 AM

When I had bubbles in the coolant reservoir, it turned out to be the head gaskets. Here's a thread on another board on the subject of EZ30 head gasket issues:



#6 Fairtax4me



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Posted 13 July 2013 - 11:16 AM

What about the radiator cap? I replace them all the time on the 4 cylinder models and fairly often on the 6. Does it hold pressure on a pressure test? A failed one would certainly have these symptoms.

Same thoughts here. I dont see any mention of that being replaced. Coolant has to be kept under pressure to prevent it from boiling. If the cap is bad it doesn't hold the proper pressure.

#7 johnceggleston


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Posted 13 July 2013 - 12:26 PM

cool it off, fill it up, and drive it with the cap loose.

it can't hurt.

apparently it is going to over heat even if you don't.


so far i have not heard any one try this on an H6.

it works for the H4 96 - 99 ej25 until the leak gets really bad.

it SHOULD let the exhaust gas escape.

that is if there is an internal head gasket leak.


if the system has enough coolant, it should circulate.

if it circulates it will cool.

but once the level drops below the level of the top hose, will it circulate?


if the cap is loose, and there is no HG leak, how much coolant will you lose?

enough to stop the coolant from circulating?

Edited by johnceggleston, 13 July 2013 - 12:29 PM.

#8 nhzero



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Posted 14 July 2013 - 11:03 PM

Replaced the radiator cap with the flush in Fresno and again in Mt. Shasta. Both OEM. I'm now in the Bay Area. I ended up doing very well until the high spot at Willits on Hwy 101. I then had it climb uncontrollably even with max heat and fan, so I stopped for an hour and added about 3 quarts of water. It has done very well on everything other than hills, especially with A/C

Fans are fine. If anything, they are turning on too soon as they start within 30 seconds of starting the engine warm.

The mechanic in Mt. Shasta told me it held a pressure test, but then later it sounded like he only did a chemical test for exhaust, which he said came out negative.

Coolant does NOT gets sucked back in properly on cooling.

Here's what I've come up with:

a) coolant looses about 2.5 quarts per 4 hours of driving, all out the overflow
B) no coolant in the oil
c) no white smoke that I can see
d) A/C makes it worse
e) runs okay briefly after filling up the radiator, but it doesn't take an hour before I have to turn off the A/C on hills
f) temps over 80F make things much worse, which may be why I never noticed this problem driving at ~50mph on surface streets of Ventura County.

#9 Fairtax4me



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Posted 15 July 2013 - 12:33 AM

Coolant not returning to the system from the overflow means the system is filling with air, and can't create the vacuum necessary to pull the coolant back in. Usually this is because of a leak.

The only other thing that makes logical sense is an obstruction preventing proper airflow through the radiator. That or one of the shields that is supposed to direct air to the radiator is missing. This would lead to boiling of the coolant going up long grades.

Otherwise it does sound like a bad head gasket, which is practically unheard of on the H6, though its certainly possible.

These engines almost never mix coolant and oil. Any failure is an external leak or a breach of the fire ring into the combustion chamber.

#10 Pgh_Scoob


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Posted 15 July 2013 - 09:29 AM

I am not familiar with the h6's at all but from what I just read it sounds like a head gasket issue... Even though all of the test and checks have come out fine this is what I suspect to be happening. This is coming from a coworker (55 yr old tech) who had this exact issue with is daughters forester.

It is a very small internal laek that is only allowing small bits of combustion gas though but when it does get through the gases get caught in the t-stat housing ( if this is under the timing cover like the forest and other 2.5's)

All of his block tests and everything never showed anything and he eventually just pulled the heads I believe.

There is also a video explanation about this on youtube that I came across a few months back. The guy described the exact symptoms of my coworkes car and had the same results.

I hope this helps,


#11 johnceggleston


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Posted 15 July 2013 - 11:55 AM

bad head gasket, which is practically unheard of on the H6,

as nipper has said repeatedly , ''any aluminum head can blow a head gasket''.

and it does happen in the H6.

a quick search on subaruoutback.org will confirm this.


the bubbles in the over flow makes it sound like an internal leak, like the 96 - 99 ej25.

but it also acts like a low coolant problem.

so maybe it is an external leak and over heats once it loses enough coolant.


either way, driving with a non-pressurize system, lose cap, should reduce the problem.

(unless it burps out so much coolant that it will not circulate.)

for an external leak, less pressure means less force pushing coolant out thru the leak.

for an internal leak, less pressure MAY allow exhaust gases to escape, reducing the loss of coolant.


crawl under the car and look for wet, oily stains where the heads meet the block.

my guess is you will find one side very oily and/ or wet.


also if you drive with the cap loose,

you can stop every hour or (30 - 45 minutes) and add coolant to the system, or water, before it overheats.

this is not ideal.

but unless you plan on paying a shop to make repairs, 750 miles from home, it may get you home.

#12 nhzero



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Posted 16 July 2013 - 05:15 PM

I got home late last night due to the blessing of mild temperatures and few hills on Hwy 101 South. This is particularly providential as the King City area is not known for mild July temps.

I lost around 4 gallons of coolant via the overflow weep hole from SF to Ventura County. On steep hills I had a surging alternator (headlights would go bright with brake/battery trouble lights flickering) when the coolant was low, but beyond that, if I kept coolant levels up it did pretty well, although it did get progressively worse. Still no oil loss, white smoke, or coolant in the oil.

It's in the shop now; I'll let you know how it turns out.

#13 Cougar


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Posted 16 July 2013 - 05:48 PM

Unfortunately I think you have a head gasket problem. The flickering lights may mean the alternator has a regulator problem. It might be happening while getting over heated and something is breaking down.

#14 kingbobdole


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Posted 16 July 2013 - 09:21 PM

Sounds like a bad/wrong rad cap to me. High altitudes + weak cap = no party

#15 nhzero



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Posted 16 July 2013 - 09:22 PM

Replaced cap twice - both OEM & same issues. I don't think it's the cap.

#16 nhzero



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Posted 20 July 2013 - 01:25 PM

My normal shop (excellent shop, by the way, won't do work until they see positive proof the car needs it!) triple checked it for hydrocarbons with the chemical check in the coolant: zero hydrocarbons.


They also rolled the dice and used the California smog machine: zero issues.


It now fills the overflow tank and has 1/4" bubbles rolling out of the overflow line at the rate of about 1 per second within 10 minutes of starting the car. The mechanic has seen the bubbles, but won't pull the engine to do the head gasket because he says he doesn't have any indication of a head gasket leak. The car still has great power, especially when the coolant is full, but when it gets low, there is some minor roughness, and the alternator problem show up.


He wants me to continue driving it and mark down how often I add coolant, even though I gave him a good log of the 4 gallons I added previously. Should I just clean the engine and pawn it off to a dealer? I hate to do this to someone else...

#17 Gloyale


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Posted 20 July 2013 - 01:29 PM

Absolutely classic symptoms of Subaru Headgasket failure.


Take it somewhere reputable, that will do the work.  This guy just doesn't want to deal with it probably because he's unfamiliar with the internals of the "that crazy 6 cyl boxer with the chain"

#18 johnceggleston


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Posted 20 July 2013 - 07:04 PM

i read a post about one guy who put a battery operated household carbon monoxide detector inside a plastic bag and used a rubber band to attach it to the top of the rad where the cap fits.


sure enough it ''smelled'' the exhaust.


as often as you have been adding coolant, perhaps the concentration is not high enough to show positive in the test.?

just a thought.

#19 Fairtax4me



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Posted 20 July 2013 - 09:15 PM

You have to take it to someone who knows these engines.
The H6 has something like 100 bolts just holding the timing cover on. Most mechanics would lose track of that many bolts.

#20 nhzero



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Posted 22 December 2013 - 03:07 PM

FYI, it has now degenerated to the point that the bubbles are coming into the overflow within 30 second of starting the car, and the alternator heats up and starts having voltage regulator breakdown (headlights surge bright and battery lights on dash flicker) within 5-10 minutes of starting. If I drive 30-60 mph with low revs, I can get it to drive around 60 miles before the temp starts climbing.

The reason I'm updating is that I've now had it in three shops, and all don't want to change the head gasket since they can't find coolant in the oil or see white smoke in the exhaust. Can't trade it in since it smells like a glycol factory, but can't afford another one outright. I'm a little stuck. Anyone know a shop in NW Los Angeles or Ventura County that will actually DO the work, preferably for a reasonable cost, but after 6 months of this, just doing the work at all would be nice...

#21 Fairtax4me



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Posted 22 December 2013 - 04:49 PM

Hard to believe with an area of that population that there isn't a shop nearby willing to work on that engine (or that even knows how to diagnose a bad head gasket). All they need to do is put a leak down tester on it with the radiator cap open.

Might start a new thread asking for suggestions to get more attention.
Otherwise, pick up the phone book and start calling around.

Edited by Fairtax4me, 22 December 2013 - 04:50 PM.

#22 johnceggleston


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Posted 23 December 2013 - 09:33 AM

i would probably be hesitant to ask this of a shop that does not want to do the head gaskets,

but my next question would be ,

how about an engine swap, would you do that work?


buy a JDM import engine and just swap it in.

it probably will cost about the same,

but it might be a faster turn around.

but regardless,

it is another solution.

Edited by johnceggleston, 23 December 2013 - 09:34 AM.

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