Head Gasket?

Mikerizer

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#1
Make
Dodge
Model
Grand Caravan
Year
2006
Miles
86,000
Engine
3.3
2006 Dodge Grand Caravan, 3.3L, Auto 86k miles

The van has been gradually losing coolant and running hot. I replaced the radiator in November because it had a leak. It's still losing coolant. I saw a bubble stream coming up the radiator, and tested it for hydrocarbons with the liquid that turns from blue to yellow when exposed to exhaust gasses. That test proved negative...the color didn't change. However, other symptoms made me suspect a head gasket or head problem. It stumbles upon cranking, then smoothes out. I pulled the CEL codes...P300 general misfire, and P301 misfire on cylinder #1. I pulled the plug, and it looked different from the #6 plug. I rented a bore scope...not much there, except the piston has an abnormal amount of carbon. The engine was cold and hadn't been cranked for several days. Frankly, I was expecting to see coolant in it.

My brother held a paper towel over the spark plug hole, and I pulled the fuel pump relay, and cranked the motor over. About a teaspoon or less of liquid saturated the paper towel. I do not have a sense of smell, but am told it smells oily with perhaps a scent of antifreeze. To me, it FEELS like antifreeze...you know, that oily at first, then kind of sticky/grimy feel.

So, I'm thinking it's a head gasket or head problem. All that to ask this...is this a common problem on this engine, or is there something else to look for, such as upper intake plenum, or other cause?

Thanks for reading, and thanks for your thoughts.
 

grcauto

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#2
Usually when you have a head gasket failure the cylinder(s) that are burning the coolant will generally be free of carbon.
 
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#3
I've seen no head gasket problems on that engine, and multiple failed intake gaskets, but my best guess would still be head gasket with the symptoms you describe. The location of the coolant passages is not very close to the intake ports on the heads, and so it seems extremely unlikely that coolant would ever leak into the cylinder that way.
 

Mikerizer

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#4
Great thoughts, guys...I should have mentioned the following:
  • there is no sign of oil in the coolant
  • there is no sign of coolant in the oil
  • the van stumbles when you first start the motor, but then smoothes out
  • the van doesn't seem to be burning coolant...no smoke/steam coming out of the exhaust
  • the van does stumble on heavy acceleration
 

billr

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#5
I would suggest pressurizing the cylinder like in a "leak down" test. Leave the pressure on for many minutes and see if bubbles appear in the (cold) coolant. It would be best if you could remove valve rocker arms on that cylinder so you could apply 100 psi or more and have it hold, even if that drives the piston to BDC; but whatever you can get it to hold on TDC with valves operating may still give a good clue