[MN.Nice.507]

Over the past few days I have noticed some chugging/hesitation while accelerating. It wasn't horrible until today when a few times driving at highway speeds it chugged so hard that I thought it was going to stall. It only seems to do this either when first accelerating from a stop, or once I get over 30mph. Checked my codes using the key turn sequence and it flags a code 21 and no other codes. Idling isn't too rough though.

Along with this, I've noticed that my engine temps will get reasonably high compared to normal (reading at about 3/4 full on the gauge) then it will drop down to below half suddenly and climb back up, & repeat. The car does heat up quite quickly while parked, especially for how cold its been here lately (~30f). When I shut the car off, I do hear what sounds to be coolant gurgling and rushing out of somewhere, louder than i've ever heard it before. There are no leaks anywhere that I can see on the ground at all, and my coolant levels haven't dropped at all.

Is there any way these issues are connected, as they both popped up around the same time over the past 3ish days?

 

[ka9yhd]

When is the last time the coolant system has been serviced? Observe the coolant level in the overflow container. Does it remain at a constant level or does it fill the overflow container then empty it? This could indicate a bad head gasket.

 

[MN.Nice.507]

When is the last time the coolant system has been serviced? Observe the coolant level in the overflow container. Does it remain at a constant level or does it fill the overflow container then empty it? This could indicate a bad head gasket.

I assume its been a while since the cooling system was serviced. Its definitely due for a flush at least, which I plan to get done, tomorrow to see if it helps any. But the coolant in the overflow tank stays constant, does not raise or lower, and haven't had any issues with needing to top it up either. Starting to assume a flaky thermostat.

 

[MN.Nice.507]

**The car was gifted to me this spring, so I'm not sure of its maintenance records. The coolant is still green, but somewhat dirty. I do get some bubbling in the overflow tank AFTER I shut the car off.

 

[ImperialCrown]

Before flushing, have the shop take a sample of the old coolant and test it for the presence of CO2 gases. This would indicate that combustion gases are entering the water jacket from the combustion chamber (i.e. - likely head gasket leak).
How to Test for Exhaust Gases in Coolant (at https://itstillruns.com/test-exhaust-gases-coolant-7885485.html )

 

[Bob Lincoln]

Very likely a head gasket. This happened to me a few days before mine went.

 

[valiant67]

The O2 sensor can be contaminated by coolant in the exhaust.

 

[MN.Nice.507]

Well, just got back from the shop. Turns out my engine temp issues were due to a failed heater valve. The part was replaced, and I no longer have engine temp issues, at least for now. I actually completely lost heat to the cabin on my way up there, now it blows hotter than ever.

They also cleared the "21" code for the o2 sensor, to see if that would clear up the bucking/hesitation issue, its not as bad, but still hangs around when I get between 30-40mph. I have to go back in sometime this week for an alignment anyways, so I will see if another 21 pops up in the mean time.

 

[ka9yhd]

When you flush the cooling system make sure to flush out the heater core real good. There could be some debris in there clogging up the heater core causing it to blow cold air. Also replace the thermostat.

And I agree with IC in checking the coolant for CO2

 

[MN.Nice.507]

Well, the person who last had this vehicle decided it would be a good idea to put some gimmicky E3 spark plugs in it shortly before I got it. Popped some NGK plugs in today and its running smoother than ever. No sign of any unusual contaminants on the old plugs, but I've heard they are notorious for causing misfires months down the line, so don't run them in anything you care about.

 

[Doug D]

I strongly recommend whatever plugs is listed in the owner's manual. In this case regular Champion copper plugs.

 

[ka9yhd]

For Chrysler I stick with the OEM plugs which are Champion

 

[85lebaront2]

For Chrysler I stick with the OEM plugs which are Champion

I completely agree with that. I used to own a carburetor and tune up shop and I stocked the OEM recommended plugs and points (it was that long ago) for all the common vehicles in the area. If you really want to see plug induced issues, try Bosch platinum in a Ford EFI engine, random misfire and atrocious fuel economy.

 

[ImperialCrown]

The Champion Copper Plus RN14YC (Stk # 405) is the recommended spark plug for this.
Premium store brand a/filter, cap, rotor and wires too if it needs it.