Head Gasket?

Mikerizer

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Make
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Grand Caravan
Year
2006
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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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Usually when you have a head gasket failure the cylinder(s) that are burning the coolant will generally be free of carbon.
 

Mobile Dan

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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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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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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
 

Mikerizer

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We've been babying this van for over a year; I moved last year, and it's taken me until now to get my shop where I could get the van in. I've torn it down and had the heads checked out. The machine shop immediately identified where exhaust gases were getting into the water jacket. The head was out .005" so he milled them true. A few valves needed work. I'm getting ready to put it back together.

I have a question: what is the bolt size and thread count for the head bolts? I can't seem to find a tap to clear the threads in the block. I though they were M10 x 1.50, but that doesn't feel right. I took a head bolt to Lowe's and used the things they have on the shelves, to try to determine the diameter and thread count. I couldn't find a match - Metric or SAE either one. What size tap do I need? Thanks!
 

Mikerizer

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I found it on Fel-Pro's website! It's 11mm x 1.50

 

NickD

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Around the mid 80's our brilliant congress forced the automotive industry to switch to the metric system, their idiotic reasoning was that the Japanese refused to buy our vehicles. The reason they refused to buy our vehicles because they wanted the steering wheel on the right hand side, so after a huge expense in converting all of our tooling, they still refused to buy our vehicles.

Millimeters are too small of a unit, working on any import car, all the metric sizes were even like 8, 10, 12, 14,16 etc. In the US we used kid engineers to do the conversion, so they just went to the next nearest size that explains that 11 mm odd # size, replaced a 7/16" bolt.

This wasn't changed overnight, even working on 94 and later models, still using so-called SAE bolts, so had to crawl under with both metric and English sockets and make darn sure it was a snug fit.

Ha, last screws to change to metric were interior, guys were searching high and low for a 5.5 mm socket when in reality it was a 7/32" head screw.

If you ever want to meet a huge bunch of idiots take a trip to Washington DC.
 

Mikerizer

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Agreed, NickD! Those smaller sizes can drive you nuts! 7mm, 8mm, 5.5mm, 7/32, etc. It's generally a pain in the rump to work under a dash.
 

NickD

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I purchased complete sets back around in 1983 when taps and dies were still made in the USA. The way they are making crap today cold roll unplated steel in aluminum, electrolysis binds the two metals together. Claim aluminum blocks to save weight, aluminum is the most common metal on this earth, can be poured at 1,100*F, less machining, its a heck of a lot cheaper than cast iron at 2,700*F. Also if you water pump is not spinning, heads will crack. Keep a sharp eye on your cooling system.

Single drive belt system with all limited lubricated ball bearings is just about the dumbest thing the automotive manufacturers did. But hey, you only have one belt to replace! Alternators and AC compressors can over 10 HP that puts quite a load on that little tiny water pump shaft. With multiple belt systems, water pumps lasted well over 200K miles with some over 330K, try more like 60K today.

Four of my kids are driving Caravan's because they gave me more than two grandkids, can only fit two car baby seats in a sedan, but don't get any more tax breaks. Typical life of these things is about 100Kmiles first the AT blows than head gaskets. Don' know if Chrysler is making them better today.

Throwaway vehicles cost more today than a home did a few years ago, so both mom and dad have to go to work. Least a home keeps up with inflation.
 

Mikerizer

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Thanks for the heads-up on the water pump...it was replaced less than 10,000 miles ago, so it should be good.

It's a shame that the Blue Book value on this 2006 is only $2,000 and my 2003 Tacoma was just over $10,000 when I sold it five years ago. The only reason we're keeping it is because it has a lift in the back for my Dad's power chair.
 

Mikerizer

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I hope I didn't mess up. Can you tell me which cylinder head is considered Left and which is Right? The head gaskets are marked L and R. I put the R on the rear head, thinking that if the front of the motor was turned facing forward, that cylinder would be on the right side of the vehicle.
 

billr

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That sounds correct, as long as you consider the "front" of the engine to be the end that does not have the flywheel!
 
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