coolant reservoir not going down?

Hello all,

I've been trying to chase down a coolant issue. I think there's a blockage somewhere but I wanted to pick the brain trust and see if I'm missing anything.

First things first:
Had some engine hesitation and cylinder misfire. cleaned the maf sensor and put in better gas and it seemed to go away. While I was testing my fixes out (doing some driving around the local highway), saw my engine was overheating. immediately went home and turned it off. saw it spike up to 230F.

So I looked through everything and noticed my reservoir was overflowing and was actually spewing coolant out of the overflow. I replaced my radiator cap. easy enough, that seemed to work for a little bit. then the engine starting overheating again. Heat would rise when engine RPM's were low and woudl kinda stabilize to acceptable numbers when the RPM's were higher. So the drive home was stressful. Also noticed no heat coming from the heater core an could hear water sloshing in the heater core behind my dash. air in the system!

So I replaced the thermostat and had to add a ton more coolant using the special funnels. Everything seemed fine when I did this. I let the engine idle for a while and it kept the temperatures pretty good. Reservoir didn't fill up in my 1.5 hour test. highest temps I saw in a 45 min idle was 212f. Drove around, everything seemed fine. Temperatures were all acceptable after a little drive. No air in the system that I could detect.

Then earlier today, I went for a drive and the temperatures all seemed fine but I noticed my coolant reservoir was a little high. Okay, maybe it's becuase it's hot. that's normal. But I checked it when the engine was as cold as can be and the reservoir has not lowered. not one bit. I looked in the radiator cap and it was bone dry in that area when previously it was definitely full to that point. I drove home because it was a short drive and the reservoir in fact, went up and started overflowing again. I could hear my serpentine squealing halfway home. Also noticed air in the heater core as there is sloshing behidn the dash.

What does the brain trust think? The only other thing I can think is maybe the radiator has a blockage and the nuclear option is to replace it entirely but I want to see if there's anything I'm missing. Is there a blockage in the reservoir? is there a leak somewhere I'm not detecting?

TL;DR:
engine coolant reservoir is not going down. suspect blockage but not sure. engine temperatures SEEM fine for now but there's air in the system when previously there wasn't.

here's a few photos. This is the coolant as of now:

You can also see that it definitely spewed out, that little bit of wet spot on the hose is coolant. I suspect that this has been spewing out and caking the front of my engine for a bit as there's a ton of grime and dirt there.

I should note: 122k on a 2017

 

check the radiator for restrictions such as dirt/mud or any other debris that may be stuck in between the fins before you rule out the radiator as being bad. Did the misfire condition happen before the motor overheated, or during? And how long did the misfire occur?

 

debris between the fins being more than the normal simple bug stuck in there? I didn't do a dedicated search but didn't see anything that would catch my eye. I can check later tomorrow when I get a chance.

the misfire happened before the motor overheated. it happened once and then the engine went into limp mode. I pulled off the freeway, and turned off the engine, looked around and smelled around, nothing. then I started it up and it started up just fine. I had to take care of a few errands so I gingerly drove around and could feel some engine hesitation. After cleaning the maf sensor and putting different fuel in, the engine seems much happier. no hesitation.

 

how did you bleed the coolant system? did you use a funnel attached to the radiator and climate control with Heat on?

Two questions, the misfire and possibly the hesitation should have have set the engine light on. Did you retrieve any trouble codes? Second question is, why did the motor overheat the first time?
I guess one more question, do you have a scanner/code reader available?

 

Yes. Used the funnel attached and ran the heat on high. Watched the bubbles come out of the system.

Yes. The engine light came on. P0302. Cylinder 2 misfire. I pulled the code immediately because I have a reader on me at all times. After i restarted the engine after the misfire and limp mode, the cel was not lit and the next day, when I went to get some parts (i suspected plug and boot at this point), i tried to read the code again and it was gone entirely.

The first overheat event, I'm not sure exactly what happened. I noticed it as I was testing my maf cleaning. The reservoir was overflowing and the temps were climbing.

 

A realy boogered up MAF sensor could effect both banks only, not just one cylinder on a bank.

Bank 1 passenger side Cylinders 1-3-5
Bank 2 driver side Cylinders 2-4-6

Are there any abnormal noises or leaks from the water pump? Any leaks at the rear of the block? Gotta find the cause of the overheating concern.

One thing maybe look for is a misfire at first startup after been sitting for a few hours. The misfire may only last for a few seconds and won't set a MIL.

If you have a suitable scanner/code reader that has Mode 6 data, you can check for prior misfire(s) and present misfire(s) in the current drive cycle. Mode 6 data is actually pretty useful for diagnosing drivability concerns. Mode 6 will capture events that don't set a MIL/CEL

Here's a screen shot of my Mode 6 Data from the Fusion App from a few weeks ago..

You can see that I had some misfires at Cyl#4


Another example of Mode 6 Data.. I also had a Pending Code P0430. looking at Mode 6 Data I got a pretty good idea of whats going on as to why I had that pending code..

 

Now if you looked at the obvious. What about the coolant line in the back of the engine? It should spray on the tranny. Also if you changed the thermostat maybe the water pump??? Interested in solution for the old memory bank

 

I would perform a compression test (at a minimum on #2) and coolant system pressure test. If air is getting in the system and you have a random misfire, it is possible you may have pushed a head gasket. This is a free test you can do by renting the tools if you don't have them.

 

How is the fan? Is it cycling on and off? Is it running while you over heat?

 

This is why I suggested to watch for a misfire at first startup, most often in this situation the misfire lasts for just a few seconds as the coolant inside the cylinder burns off and is easily not noticed.

edited:

 

disconnect the hose between rad and overflow and verify no blockage with air

Verify new radiator cap is the correct one and operates as it should

Verify fan is properly working

Verify the rear coolant fitting that some have reported cracking isn't an issue

Pressure test the system to verfiy no leaks. Tools can be rented at parts house.

 

pull the plug. if it looks really clean like steam cleaned you have a HG issue or worse a crack somewhere. no tool rental necessary

 

First thing I would do is to replace the radiator cap. Cheap, easy, and an integral part of your cooling system. That is the key to your over flow functioning properly. I would start by watching one of the hundreds of videos on the YouTube about how your cap works. Then start looking further from there if that doesn't fix it. No need to get complicated thinking you have a serious issue until you eliminate the simple things.

 

OP has already done that. Right in the first post.

 

guys radiator caps dont cause misfires. dont waste money on nonsense parts.

 

Did you ever "burp" it?

Is there coolant in the oil?

Have you started it cold, with the radiator cap off, and are there bubbles coming up especially at high RPMs? If so... bad head gasket.

 

If your reservoir is filling up, you are pulling fluid from your engine without replacing it from the radiator due to blockage. Dropping level in the radiator sounds like it is flashing off in the engine because of the blockage. I believe you are way beyond simple fixes, coolant issues seem to build up slowly into major issues. I agree with others pull your #2 spark plug. Have a compression test ran along with a coolant system pressure test. In my opinion your cylinder miss is being caused by blown head gasket, or head issue caused by blockage or a bad water pump.

 

If you have unexplained air coming into the cooling system, you need to be looking at a head gasket issue.

 

Also, a leaky HG on the exhaust side can potentially cause an overpreasure condition within the coolant system. Which can sometimes explain why the coolant bottle is overfilling and spilling over without a present overheating condition.