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Need suggestion for a mysterious coolant leak

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1 hour ago, Rusty_OToole said:

When you burn gas each gallon produces 1.07 gallons of water.

 

Yeah, but there isn't any UV dye in that water, whereas he's seeing it in the water coming out the exhaust.

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11 hours ago, joe_padavano said:

 

I think that is a reasonable conclusion.  I'd suggest that your problem is either a head gasket or a crack that is closing up as the engine heats up.

So if the coolant is not present in the cylinder chambers, is the head probably cracked that causes the coolant straight going to exhaust passage and being burned?

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9 hours ago, Rusty_OToole said:

If there is coolant or water getting into the combustion chamber the spark plug will be clean. It isn't possible to clean the combustion chamber and not clean the spark plug .

 

When you burn gas each gallon produces 1.07 gallons of water.

The dealer said they checked the spark plugs, but I maybe they didn't checked all of them.

Or the coolant is not leaking into combustion chambers but straight going to the exhaust passage.

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14 hours ago, joe_padavano said:

 

Don't confuse humidity in the air with a real internal engine leak.  The air sucked into the engine always has some humidity in it, and water vapor is a byproduct of combustion. There will always be some water vapor (and often liquid) at the tailpipe when you start the engine until it warms up.  That doesn't mean that there ISN'T a head gasket leak (which may or may not be sealing itself as the engine comes up to temperature and parts expand), but some water is normal.

That is true. I just noticed  the damp smoke (more like steam) from my car is obviously more than many other cars.

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Today there is a bad news, I checked another same model car of my friend, when his engine was warming up, the water drips at the tailpipe is also slightly fluorescent when under uv light, wtf, I got crazy. His car is not losing coolant at all. Lost an important evidence.

But I found there are many things different between his car and my car.

Firstly, his car has much less and thinner damp smoke than mine after cold start, and there is completely no condensation on the underside of oil cap.

Moreover, I felt his engine is running more smoothly when I put my hand on the car.

Besides, a much higher pressure can be built up in his coolant system, the pressure meter on his car showed 8.5 psi after engine was completely hot (thermostat opened). For my car, the pressure just stayed at 4.5 psi after engine was hot and thermostat opened, and then it needed to take 30-40 more minutes to slowly get to 8 psi with engine idling. So I think the low pressure may be caused by a coolant leak during engine warming up. Now these are all the symptoms which seem still not obvious enough for a blown head gasket or engine crack. So confused, maybe have to remove the head?

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6 minutes ago, TerryB said:

Seems like you will need to have the heads removed to see what is going on.  Or make it someone else’s problem.

Yes, or just put a bottle of bars leak to see what will happen. Have got tired with this tricky problem.

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It took 2 yrs of trips to the dealer to get my 2013 Dodge Caravan repaired.  They finally found a service bulletin for defective cyl head issues on the 3.6 engine.  Car had less than 20k miles on it so convincing the service dept a cyl head could be bad was part of the issue.

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Greetings.  May I suggest a youtube channel which might give you a place to check. This person is a former ford dealership tech who has  set up his own repair shop. He seems to be well versed  in fords especially some of the quirks of modern models. You might search his channel for a solution.  The channel is " fordtechmakuloco" .  Or possibly search youtube globally for coolant leak( insert your engine here).  Good luck and happy motoring!  

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17 minutes ago, Studeous said:

Greetings.  May I suggest a youtube channel which might give you a place to check. This person is a former ford dealership tech who has  set up his own repair shop. He seems to be well versed  in fords especially some of the quirks of modern models. You might search his channel for a solution.  The channel is " fordtechmakuloco" .  Or possibly search youtube globally for coolant leak( insert your engine here).  Good luck and happy motoring!  

Thank you. I will visit his channel to have a look.

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Yesterday I started  engine and left immediately for a 10 miles nonstop driving, after engine cold I saw the coolant level didn't drop any!

Last week I started engine and just left it idling for half hours, then after engine cold I saw coolant level dropped 0.5cm.

So it seems that the car is losing coolant only when engine is idling or running at very low rpm, especially in the first half hours after engine starting. What could it be?

 

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It's normal for coolant to expand when hot and contract when cold. This can amount to a lot more than .5cm. I wouldn't be surprised by 20cm between hot and cold. Maybe more. Does the coolant drop enough that you have to add more? How often do you need to add, and how much?

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1 hour ago, Rusty_OToole said:

It's normal for coolant to expand when hot and contract when cold. This can amount to a lot more than .5cm. I wouldn't be surprised by 20cm between hot and cold. Maybe more. Does the coolant drop enough that you have to add more? How often do you need to add, and how much?

I always took a photo of coolant level before I started the cold engine, then started engine and did the test, then took another photo of level after engine is completely stone cold, so it doesn't concern the coolant expanding.

If always city drive every day, coolant recovery tank will be empty after 1 week. If it is a long trip on freeway, it seems losing much less.

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1 hour ago, Spinneyhill said:

2011 vehicle will be a pressure system with a separate reservoir tank. Are you measuring the water level in the reservoir or the top of the radiator?

My car doesn't have a rad cap, only can measure from a recovery tank.

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Without reviewing whole thread, the "jump in cold car, bound down highway=no appreciable loss, while jump in car, tootle around doing errands =loss, does sound like something cracked, or not sealed, when all cold/contracted, that expands, sealing itself up, when mass of engine/head hot/expanded (already included in speculations above) ...

May well require pulling head to find... personally, I'd be inclined ti try stop leak first, in hope will seal during moderate temp periods (cold enough to leak but warm enough for sealer to bond)...

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6 hours ago, Bud Tierney said:

Without reviewing whole thread, the "jump in cold car, bound down highway=no appreciable loss, while jump in car, tootle around doing errands =loss, does sound like something cracked, or not sealed, when all cold/contracted, that expands, sealing itself up, when mass of engine/head hot/expanded (already included in speculations above) ...

May well require pulling head to find... personally, I'd be inclined ti try stop leak first, in hope will seal during moderate temp periods (cold enough to leak but warm enough for sealer to bond)...

Thanks for reply. There are some more important clue, it can pass pressure test no matter engine is cold or hot and running or not, in the first half hours after start engine the coolant system pressure is much lower and building up more slowly than other cars.

It seems coolant is leaking only after engine start and when engine is running at low rpm. Where the crack could be? Exhaust valve?

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If it were leaking into a cylinder, it should leak while sitting, cold, because the crack has opened up with contraction?

 

How do you measure coolant system pressure?

 

If the pressure comes up slowly, I would wonder if it is warming up fast enough, i.e. is the thermostat stuck open?

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3 minutes ago, Spinneyhill said:

If it were leaking into a cylinder, it should leak while sitting, cold, because the crack has opened up with contraction?

 

How do you measure coolant system pressure?

 

If the pressure comes up slowly, I would wonder if it is warming up fast enough, i.e. is the thermostat stuck open?

I bought a pressure tester. When it is sitting and cold, it can hold 18 psi for couple hours. It seems no leak while sitting and cold.

I connect pressure tester to recovery tank and start engine with no pressure. Like other two cars I checked, engine takes 20 minutes to warm up and thermostat opens.

But after thermostat just opens, the pressure read on my car is lower than the other two, and it needs maybe 20 more minutes idling to reach the pressure read on other two cars.

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