2007 H6 problem

[Starlite]

Hello i have some coolant problem on my legacy 3.0.

When I drive and do a kickdown I will see a big white cloud behind my car.

Driving normal and there's no smoke.

Today a noticed the coolant expansion was empty.

There is no water in the oil or oil in the coolant.

 

So night it be a bad headgasket or something else?

Is this a common problem on the h6?

[Caboobaroo]

Have you had any roughness on cold start up? I've had to replace a few heads on the newer EZ30 due to cracks between the valves. Typically dumps some coolant into the cylinder when cold and then starts to seal the crack when it warms up. Eventually they can start pumping exhaust hades into the cooling system and have an overheat.

[Starlite]

Once what i remember.

There is no bubbles in the coolant what i can see, so it might be a crack in the top. 

[1 Lucky Texan]

wonder if that smoke smells sweet like coolant?

 

def. check inside the radiator for coolant level. I have also put a small clamp (actually, 2 zip ties) on the small hose going to the overflow at the radiator neck.

 

caboobaru - would the plug look different in a cylinder with a crack as you describe? Would that cylinder get wet with coolant during a cooling system pressure test?

[Starlite]

I had a leak on my older subaru from 1989, This was a major leak on the head gasket.

Bubbles ang smoke visible in the overflow bin.

And sparkplug was wet.

 

This problem is not that obvious. i dont smell like coolant but once i did a kickdown in front of a friend and she told me it smell discusting, and not sweet like coolant.

[Starlite]

And i have noticed some missfire when starting the engine,

Its like only 5 of 6 cylinders starts sometimes.

[1 Lucky Texan]

if all 6 plugs look the same, but are black with carbon, might be an issue with the PCV system.

[Caboobaroo]

After the engine has been ran, there wasn't much evidence on the plug to show it was consuming coolant. I will usually get the car to operating temp, drive it for 10 miles on the freeway, pull over and have someone hold RPMS up at about 3,000 and look for bubbles in the overflow bottle.

[Starlite]

Done that, no bubbles visible, bight see if i  check for bubbles in the radiator?

[idosubaru]

1.  refill the radiator and expansion tank - how quickly before it shows a decrease in level?

2.  is there any oil loss between oil changes?

3.  any oil or coolant leaks exist?

4.  pressurize the cooling system

5.  has the engine ever had major work done before?

[Caboobaroo]

Only other thing I would do to check for a possible cracked head. With the vehicle cold, usually sitting overnight, I would put a cooling system pressure tester on the radiator, apply 16psi of pressure and watch to see if it drops. Let it sit for a half hour with pressure on it, and see if it's dropped. If it has, remove the pressure tester, install the radiator cap and start it up. If it had roughness for a few seconds, chances are it has cracked.

[Bushwick]

This problem is not that obvious. i dont smell like coolant but once i did a kickdown in front of a friend and she told me it smell discusting, and not sweet like coolant.

 

Carbon getting burnt out (from spirited acceleration at wide open throttle) kinda stinks. Oil getting burnt definitely stinks. Burning oil + diesel is disgusting. Coolant getting burnt produces thick, white clouds that do not disperse immediately and tend to linger a 5-10 seconds, vs. carbon that disappears almost right away.

 

I had a Taurus SHO that belched out a dark gray smoke almost any time I tried pulling away in 2nd gear, at full throttle, and seemed to be a little excessive, but never figured out what was causing it (could have been the clutch, but never was able to detect the smell).

 

You might have two different issues that are appearing at the same time. Could have a minor coolant leak (pin hole in radiator hose, loose clamp, etc.) that's causing the level to drop, and the pu-f-f of smoke could be carbon build up getting burnt off.

 

I'd try and see if you can get the car to repeat the smoking every time or not. If need be, get someone else to accelerate quickly from a stop, to say 50kph then stop, while you are standing outside the car and try and run up and see if you can smell it and describe the scent better.

 

Also, does your car have a manual transmission? A slipping clutch, a leaky rear main or even leaky valve covers can sometimes drip enough oil to get the clutch wet, and it'll slip slightly, and THAT smell is noxious. Dragging brakes stink just about as bad.

Edited February 7, 2016 by Bushwick

[Fairtax4me]

Combination of coolant and sulfur from heavy acceleration does smell absolutely awful.

 

Could be a failed head gasket or cracked head as said before.

Misfiring at startup could be indicative of coolant in one or more cylinders. Typically the spark plugs in a cylinder burning coolant will have some hard crusty ash buildup or blue-greenish/yellowish crud on the ground electrode. If the CEL has come on for a misfire pull the plug for that cylinder and see how it looks.

A leakdown test will tell for sure, but sounds like the heads need to come off.

[Starlite]

Had the car to a local car workshop and had the coolant system tested for leak.

If there was a leak the test gauge should get yellow. He only saw a tiny minimal amount of yellow on the tester.

He was not sure if there was a headgasket or krack in the head.

 

What else could be leaking?

I have tried to watch from wich side of the exhaust pipe it smokes from and it comes from both of them.

[Fairtax4me]

He did a combustion gas test on the radiator?

Those almost never show anything on Subarus.

 

Need to pull the spark plugs out of it after it cools down. The plugs will tell you which cylinder has coolant leaking into it.

A leakdown test on that cylinder will confirm.

[Starlite]

Ok must check the plugs.

Is there any other places in might leak?

The intake , throttle or

something like that?

Edited April 12, 2016 by Starlite

[idosubaru]

it sounds like headgasket.  replace the radiator cap with a Subaru cap. 

 

Ok must check the plugs.
Is there any other places in might leak?
 

 

In general yes, but in your case, probably not. 

 

*external* leaks are leaks from a hose, radiator, etc, that drip to the ground.  

check radiator hoses, heater core hoses, oil cooler hoses, and if you live in a rusty area check the hard metal line that runs across the bottom of the engine or the hard metal line that runs under the drivers side head.  look for antifreeze/wetness.  those are all the components exposed to the elements and prone to issues (though rare on something this new). 

 

*internal* leaks are leaks that end up in the combustion chamber and get burned internally - thereby creating a cloud of smoke behind you. 

 

you described a cloud of smoke and possible engine symptoms (rough idling).  this is indicative of an internal leak, not an external leak. 

if we assume the cloud of of smoke and rough idling are symptoms of coolant loss - then it's an internal leak. 

 

this rules out most hoses and external leaks and suggests an internal issue, which is almost always headgasket.

 

refill the coolant in the radiator and overflow and take note:

1.  how long it takes to deplete?

2.  look for bubbles in the overflow tank

3.  if, after driving, the radiator stays low on coolant and does not draw water from the overflow tank.  dont' check this now though - make sure the system is properly filled and driven first. 

[Starlite]

rough idling only shows sometimes on startup mostly when warm . never when idling.