Vega

Ok guys, been a while. I'd like to start by saying this isn't actually a 3rd gen, or an f-body, or GM for that matter. I'm having trouble with my girlfriends 04 Neon and while Neon boards would be better to post this question on I myself am an F-body purist and have never owned anything but so this is really the only forum I've called home and I can't really bring myself to join a nee forum just for one general question that most likely isn't model specific. So here goes...

The coolant system on this Neon is giving me an aneurysm. I know I know, the first mistake was buying a neon haha. Well here's what's going on. Earlier this year the car started leaking coolant. Took it back to the dealer and they replaced the heater core. It still leaked so I replaced the water pump (PITA by the way). She had mostly water in it and now it got very cold, froze, and popped a freeze plug. I replaced the plug and put new coolant in, now it's overheating but it overheats when you drive and cools down when you let it idle. I decided to replace the thermostat and after that didn't work I replaced the radiator which helped a good bit but didn't fix the problem, it still overheats on the highway. Also there's absolutely no heat whatsoever no matter how hot, cold, high, or low the settings are and no matter how hot or cold the motor is (even in the red there's mostly no heat). And one really strange symptom is when I turn hard to the right the motor cools down to normal in a matter of seconds, then slowly climbs back up. Doesn't do this during hard acceleration, braking, or left hand turns just right hand turns. Also I'm 99% sure positive its not a head gasket or anything like that, the car runs super smooth and gets great mileage, also I replaced the spark plugs and there's no sign of coolant or any foul play there. I'm thinking maybe the block/heater core coolant passages are blocked?

Any help would be greatly appreciated, I'm about at my wits end here. thanks

Vega

By the way my replacing the water pump fixed the leak and all was perfect until the freeze plug popped. I've checked the other freeze plugs they seem fine and there's no leaks anywhere. The only possibility there is if any of the freeze plugs had a pinhole that was leaking air in rather than coolant out but I'm pretty sure that's not happening as the system still holds pressure and that wouldn't really explain the weird behavior during right hand turns

Edwardgp

Now that is a real head scratch-er, have to think about that.

FRMULA88

transverse mounted engine... right hand turns sloshes coolant from the radiator..

Check the t-stat it's probably going bad or is bad and coolant is not circulating as it should. Remove and test it or simply replace with new..

Check the cooling fan(s), with the A/C turned on the cooling fan(s) should run, if not you have wore out cooling fan(s) or the fan senor switches are not connected.

Check to make sure heater control valve is installed and properly connected with vacuum line... if this is not hooked up or missing you will not have heat...

not to sound negative BUT dealers are notorious for making thing look broken so you have to come back for more work...

Check the heating and cooling system components carefully and make sure the cooling system is properly filled and not "air bound"

you may want to invest in the service manual for this car as there may be model specific items to check..

Confuzed1

iTrader: (4)

If you popped a freeze plug....that itself puts a lot of stress on things. Always a great idea to do a antifreeze check if you know a cold snap is coming.

Wonder if it's possible that your heater core is still frozen solid? As said above, check your heater control valve....then again it might not I have one since a lot of the newer cars circulate coolant through the heater core all the time and simply shift vent doors to allow heat in.

You're sure it's not the head gasket? Neons are well known to blow head gaskets. How's the oil look? Other than that check cooling fans, coolant flow etc.

Vega

Hey no worries man, I would completely suspect this shady little buy here pay here place to just rig something up so it works for a few weeks and call it fixed. I'm very skeptical that they actually replaced the heater core. Also I had suspected the control valve but haven't checked it, this just reinforces that suspicion and makes me want to check it more

Other than that the cooling fans kick on every time at the normal temp and work perfectly. Also the old thermostat was bad so I replaced it but when I swapped the radiator I checked it again and, yep, this new ones bad already too (it's a fail-open model though) but after that I pulled it and ran the car without a thermostat just to see if it would change anything and it didn't. Just made it take longer to warm up, naturally. I had suspected air lock and have run it with the radiator cap off a lot trying to get all the air out. Would let it run for an hour, shut it down, let it cool, run it again, did it 5 or 6 times, not sure if that's enough or not as I've never bled air from a coolant system

Thanks for all the input I really appreciate it. You see why I had to post this issue, I feel like I've gone step by step through just about every typical test procedure a decent mechanic would go through and I'm pretty stumped to the point where I think it has to be blockage in the block

I'm not ruling out that the new water pump may be going bad but I'm skeptical of it cause the car does fine and actually cools down during idle. The water pump runs off the timing belt which I replaced while I was in there so I'm sure it's not slipping

Vega

I'm not 100% sure its not the head gasket but I'm a good 90%. I haven't found any coolant on the spark plugs, no smell of coolant in the exhaust during idle, idles extremely smooth and just overall seems like a very healthy motor, no real loss of power (as if there ever was any in that 2.0 to begin with haha). I mean I can't for sure say it's not cause I honestly don't know but every indication says the gasket seems fine

Another thing I'd like to mention is there was a lot of water run in the car last year, almost exclusively water with no coolant and I'm pretty sure it was run with water before we got it too. The old radiator had an abnormal amount of built up rust and sludge at the top inlet. Bottom was decently clean. Which is what's making me think there's something in the block blocking the passages, along with the right hand turn deal, thinking hard turns force more coolant through the blockage or dislodge the blockage until, a few seconds later, either the coolant gets choked down again or the blockage flows back to the choke point

Again, I appreciate all of your input everyone. Don't worry about hurting my feelings with any suggestions at this point I'm open to anything

FRMULA88

Go to a radiator shop have the cooling system power flushed. be prepared to replace the radiator again. if they can't de-scale it.

Aluminum block & tap water = big problem waiting to happen.. After the system is cleaned always run a 50/50 mix. (anti-freeze & distilled wate or buy premixed Anti-freeze ) besides doing what it says anti-freeze also has corrosion inhibiters.

FRMULA88

Go to a radiator shop have the engine / cooling system power flushed. be prepared to replace the radiator again if they can't de-scale it.
Straight water boils at 212 but it is corrosive.. it also freezes at 32 so this is big problem waiting to happen.

After the system is cleaned always run a 50/50 mix. (anti-freeze & distilled water or buy premixed Anti-freeze ) besides doing what it says anti-freeze has corrosion inhibiters.

Did you test the radiator cap to also make sure it holds the rated pressure?

cars that run straight water you should add a corrossion inhibitor like water watter, or other brand but still need to be flushed at least annually.
and in zones with winter weather anti-freeze should be added to give adequate protection during those months... if you want the extra work have at it otherwise run 50/50 mix year round and be done with it.