2004 NA Z. I'm sure I have had air in my cooling system for some time now as my heat only worked when moving. It probably stemmed form when I did a spacer install years ago. Other than the heat issue, it was not a problem. A few days ago I noticed my temp at idle rose to about 1/4" below the Hot marker. Once I started moving, it would go away.


About this time, I got a Service Engine light with an Error code of "507" which refers to "Idle Speed Control System." Possibly unrelated, but notable as I have had 0 major engine issues in 4 years of ownership. Fast forward to tonight- I decided to add coolant to the system and when I did so with the engine idling for about 8 minutes, it did not seem like the coolant level dropped down as if the thermostat opened. The engine temp did not rise past normal. either.

If anything the level seemed to rise and lower in the radiator fill neck until it almost wanted to boil over. There was a decent amount of air bubbles coming out and I just kept slowly adding coolant until it stayed about full. The overflow bottle was a bit above the return line the whole time.

On my way home from work, I stopped at a store and noticed a medium amount of white smoke from under the hood. The antifreeze appeared to be leaking from around the fill neck on the radiator. I refilled the system (revving to 3K RPM for 10 sec at each top off with the heat on high) and the smoke seemed to be getting worse. I looked under the car and there seemed to be what looked like a 8 " diameter pool of antifreeze around the middle of the engine. I topped the system off (while making sure the res bottle was half full and limped it home.

Mind you, during this whole episode, the engine temp never left the normal area. Not once did it even move toward hot. I drove for about 10 minutes with no issue. There was no fluid under the car at all and the smoke was minimal (probably just residual spillage burning off). I checked the levels in the res bottle and at the radiator and everything looked fine. I drove the remaining 20 minutes home with the same scenario.

If it were not for the antifreeze on the ground and the CEL, I would think it was ok. BTW, after I did the accelerator pedal process to determine the code it was gone except for when I let off of the gas for a second while drive and it would pop up for a second. When I stopped at the store the first time, it was on solid after that.

Am I looking at potential head gasket replacement very soon? I have donne 3 head jobs on FWD cars before, so I am hoping I have the skill to do it myself if necessary. Is there anything I can do to troubleshoot other than doing a full purge the proper way?

Sorry for the huge post, but I wanted to make sure I covered all the symptoms and everything I did.

-T

 

https://my350z.com/forum/forced-indu...nightmare.html
https://my350z.com/forum/forced-indu...heating-2.html
http://www.amazon.com/gp/product/B00...9649753&sr=1-1

could be your thremostat starting to stick randomly

 

When I did my spacer install I did a coolant flush as well, and my thermostat wasn't opening, overheated at idle and heater didn't work. You may need to bleed the system using the bleeder valve located near in the engine bay near the battery. Let me see if I can find a picture for you. I wasn't able to bleed the system the way I normally do other cars, by letting it run with the radiator cap off, revving etc. You need to do it with the bleeder open.
here's the picture

 

Thanks bro. I did search and I saw numerous threads referencing the bleeder valve by the batt, but I could not find it when I was under the hood at the store. I will try bleeding it that way. Still itching about the visible coolant under the car though.

 

This is from the second thread. I would feel relieved, but there was coolant on the ground under the engine at one point.

 

I bleed my car from one of the TP water lines. I think they are the highest points in the system

 

You're supposed to jack the front end of the car up when bleeding to allow the air to bubble up to the "high point"

 

I had coolant on teh ground 2

 

And it was fine after bleeding it? Where the heck would the coolant be coming from though? Coolant had to be leaking from somewhere, right? Unless there is a pressure release valve somewhere around the middle of the motor that lets go when it the system is overfilled, but even then, my cap was off shen I was seeing fluid. Im really really hoping it's not a head gasket on it's way out. Weird thing is it never overheated once, unless my temp sensor is faulty.

 

Curious, do you have aftermarket hoses?

I was chasing a leak forever, I would see a puddle like you, and I could smell it but could never pinpoint the location, I started thinking it was HG too.

Until I saw a drip on my charge piping, which I followed all the way up, finally figuring out where the leak was coming from.

I had to double clamp the top hose connection (water bypass hose) to the hard pipe on the left side of the motor.

Seen here;

 

I've ner touched my hoses, but thanks for the diagram. Keep in mind the car was fine yesterday before I went to add coolant-other than the occasional heating up at idle.

 

Do they sell those funnel kits at auto zone or do you have to get it online? Can I make my own?

 

You did say that the coolant escape seemed to be coming from around the radiator neck when you stopped at the store. I don’t know all that much about cars, but I know that there is a pressure valve in the radiator cap to let coolant travel back and forth between the radiator and the overfill tank. Also there is a gasket that seals between the cap and the radiator fill neck.

Since one of the things you did when filling the system previous to having the leak, was to remove and replace the cap. Shouldn’t you be checking the operation and sealing of the cap before worrying about exotic things like head gaskets?

 

How would coolant make it from the cap all the way to the back of the engine and dripping off the oil pan to the ground at idle then? I guess it could have been blowing back when I was driving, but there was a consistent drip.

UPdate: problem seems to have disappeared, other than a slight smell of antifreeze at idle. Could just be residual coolant burning off. Drove 35 min with no issues and no leaks. I think I probably let enough air out to get it back to where it was before the symptoms.