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I'm pretty sure of the problem, just lloking for confirmation.



2002 Dodge Neon SRT. First thought was the thermostat. I just finished replacing it and no dice, still overheating. Tried blowing the heat to cool it off on the ride home, heat blows cold.



All the fresh coolant I put in the resevoir after changing is still in there, doesn't seem to have moved any fluid at all.



I'm pretty sure it's the water pump.



I won't be changing a water pump, the Neon's water pump runs off the timing belt. I hate this car enough without going through dropping the motor out to replace a water pump. Plus I just don't have the tools here.



Is there something I may have missed? I'm not happy about the thought of paying to have this thing fixed but it's my wife's transportation so I have to.

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According to a mechanic I know,the Neon is the easiest car made to work on.

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Well I think it's ok now. I ended up calling a buddy about it. He said he's seen something on Dodge's like this before. Apparently they are really picky about air in the system. I went out and popped the cap again and sure enough it started bubbling. Topped off the coolant again and gave it a test drive. Heat blows hot and temp gauge stayed normal. Hopefully that solved it.



This had me realy confused because I tested the old thermostat in a pot of boiling water and it didn't budge. I was sure it was the therm and then it still overheated with it out. I'll drive it to work a few times next week to be sure but hopefully it's g2g now.

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Thermostats are required for proper coolant flow in most engines.  The thermostat is constantly adjusting itself to the engine load, most of the time they are just barely open.  As engine load increases, the flow area increases.  

Running an engine without a thermostat can cause trapped air pockets due to turbulence.

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Is it due to this being on of the great designs where the radiator cap is the overflow that you ignored my question?  Because that was what I was getting at.  Burping the vehicle is one of the more time consuming parts of the job if you dont wish to spend 250 on a vacuum bleeder for the cooling system.  

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Thermostats are required for proper coolant flow in most engines.  The thermostat is constantly adjusting itself to the engine load, most of the time they are just barely open.  As engine load increases, the flow area increases.  

Running an engine without a thermostat can cause trapped air pockets due to turbulence.

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You probably just had an air pocket trapped in the system after swapping the bad T-stat.

Always run them with the cap off, long enough for the T-stat to heat-up and open, letting all the air purge from the cooling system.

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Kick him in the balls for me.

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No.



Thermostats don't adjust to "load" they adjust due to the coolant temp.



All thermostats are slightly open, thats so the coolant flows, so it is always moving over "hot spots". It would also be very hard on the water pump to pump coolant, into the engine, if no coolant was leaving the engine.



Coolant for the heater, is often set up to "bypass" through the pump, again so that a certain amount of coolant is always moving.



Finally, if there was no thermostat, water wouldn't stay in the radiator long enough to be cooled down, before going back into the engine. This would eventually cause overheating too.

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It's not a good idea to argue with Keith, on things like this.

 

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It is when I 'm right.

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Well I think it's ok now. I ended up calling a buddy about it. He said he's seen something on Dodge's like this before. Apparently they are really picky about air in the system. I went out and popped the cap again and sure enough it started bubbling. Topped off the coolant again and gave it a test drive. Heat blows hot and temp gauge stayed normal. Hopefully that solved it.

This had me realy confused because I tested the old thermostat in a pot of boiling water and it didn't budge. I was sure it was the therm and then it still overheated with it out. I'll drive it to work a few times next week to be sure but hopefully it's g2g now.

Quoted:







No.



Thermostats don't adjust to "load" they adjust due to the coolant temp.



All thermostats are slightly open, thats so the coolant flows, so it is always moving over "hot spots". It would also be very hard on the water pump to pump coolant, into the engine, if no coolant was leaving the engine.



Coolant for the heater, is often set up to "bypass" through the pump, again so that a certain amount of coolant is always moving.



Finally, if there was no thermostat, water wouldn't stay in the radiator long enough to be cooled down, before going back into the engine. This would eventually cause overheating too.

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This. I had a 2000, and while it was probably the most reliable car I've ever owned (and I treated it like dogshit), replacing the timing belt and water pump was a bitch.

I'm sure it's no big deal for somebody who does them every day, but I was kicking myself for not paying somebody to do it. I saved a bunch of money, but I was miserable for the better part of a perfectly good Saturday.

There ain't shit around that motor that's easy to get to. And God help you if you need to replace freeze plugs, or replace the exhaust manifold. Thank God I never needed to, because I would have junked he car before I tried that.
 

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Sorry, wasn't trying to ignore it. Fluid was pretty bad. Really dark. Thought it may have had oil in at first it but it hasn't separated into layers, probably rust. I've got it in a bucket just to make sure. Neon's had a lot of head gasket trouble in models prior to 2001. No evidence of it on this one.



The cooling system is pretty whacked on this car, as is most everything else. The "radiator" cap isn't even on the radiator. The top hose from the radiator runs back to the front upper corner of the block on the passenger side. The thermostat is right there between the block and this short hard plastic tube that the hose connects to. The cap is on that tube. The overflow tank is in the back of the engine bay behind the motor, it has an upside down "J" shaped tube molded in to it to allow excess that won't fit in the system out ETA: you can see i tin the pic below on the right side of the tank, it's the rounded part sticking up above and behind the yellow cap.. To check the fluid in it you either have to use a stick or get a flashlight back there to shine through the tank.



When I drained the coolant I looked everywhere for the drain. Culdn't find it. Found plenty of exploded diagrams on google of where it should be. No luck still. Finally found it and realized why I couldn't before and why there are no actual pictures of it on google on the car. There is no possible way to drain it without removing some supports under there. It's right behind one of them. I found it by running my hand behind there. I just drained using the return hose on the bottom.



If this doesn't get it going right it's going to a shop. I looked again to see how bad the water pump would be. I don't think I'd have to drop the motor but it would be hard anyway. Here's a picture of one that looks close to what I'm dealing with. This is a 2005 but it's near enough for you to get an idea. You can't see any of the belts here, they're on the left side under the torque strut, behind the power steering reservior. The timing belt is then behind the accessory belts under a housing. I may be able to peel the inner fender and get at it that way. You can also see the cap, center left, and the coolant reservoir upper middle right also, not to mention miles of hose and wire randmoly scattered around.



http://www.allpar.com/neon/images/neon-sxt-engine.jpg



Had a problem with this car a few years ago, was giving an error code for the evap system. Checked gas cap, no problem there. Looked far and wide under the hood for the leaky hose, couldn't find it. Couldn't find the charcoal canister either. Finally crawled underneath and found the evap purge solenoid, charcoal canister, and the leak. All in the back passenger side wheel well.



Whenever I touch this car I feel less like I need a diagram and more like I need a map. And my wife wonders why I prefer cars and trucks from before the 80s.

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The water temperature is a function of the load.  When the engine is idling, the thermostat is nearly closed.  Even when on the highway, the thermostat is only partly opened.  

The reason this is HIGHLY IMPORTANT is a thermostat can be sluggish, allowing the water temperature to spike but only when the engine load is at the maximum.  This can cause problems like pinging under load since this is where cylinder head heating is greatest.  And at full load, manifold pressure is highest, meaning preignition is most likely to occur.  Since many vehicles lack a water temperature gauge and those that have gauges can have the sending unit on the water pump inlet, such transient overheating conditions will escape view.

When testing a thermostat, note the valve orifice diameter of the thermostat.  At full opening temperature, the valve must open a distance of 1/2 the diameter, otherwise it is sluggish and could cause transient overheating.  This happens over time as the coupling grease which forces the valve open leaks out of the piston seal and into the coolant.  Or you could just replace the thermostat every 50k miles or 4 years.