. . . So, I've got at least 2 problems going on now. 1. Overheating, which I'm still trying to figure out. And 2, the gauges not consistently working. The car had the problem with the gauges in the past and I forgot about it. . . .

Make sure there is no air in the cooling system. An air bubble can inhibit coolant flow which will lead to an overheating situation. Let the engine idle with the radiator cap removed. When the thermostat opens the coolant will start to circulate through the radiator and any trapped air behind the thermostat will escape. Did you install the thermostat with the proper orientation? The sensing side should point towards the engine head, NOT the radiator.

If you are confident there is no trapped air and you still have overheating, then it is possible that you have a partially plugged radiator. A plugged radiator reduces area for heat exchange and this can lead to engine overheating.

Also a failed head gasket can lead to overheating. Is the engine pushing excessive amounts of coolant into the overflow bottle but the excess is not returning to the radiator after the engine cools to ambient temperature?

There is a 26 way electrical connector behind the instrument cluster that powers all of the bulb, features, gauges, etc on the instrument panel. I suspect that the intermittent gauge operation is being caused by a poor connection between one or more individual electrical pins and respective sockets. Fix for this is to remove the instrument cluster, clean the pins and bend them slightly for a more secure fit in the electrical sockets.

 

Make sure there is no air in the cooling system. An air bubble can inhibit coolant flow which will lead to an overheating situation. Let the engine idle with the radiator cap removed. When the thermostat opens the coolant will start to circulate through the radiator and any trapped air behind the thermostat will escape. Did you install the thermostat with the proper orientation? The sensing side should point towards the engine head, NOT the radiator.

If you are confident there is no trapped air and you still have overheating, then it is possible that you have a partially plugged radiator. A plugged radiator reduces area for heat exchange and this can lead to engine overheating.

Also a failed head gasket can lead to overheating. Is the engine pushing excessive amounts of coolant into the overflow bottle but the excess is not returning to the radiator after the engine cools to ambient temperature?

There is a 26 way electrical connector behind the instrument cluster that powers all of the bulb, features, gauges, etc on the instrument panel. I suspect that the intermittent gauge operation is being caused by a poor connection between one or more individual electrical pins and respective sockets. Fix for this is to remove the instrument cluster, clean the pins and bend them slightly for a more secure fit in the electrical sockets.

I let the car run a while with the radiator cap off before I took it for the drive. The coolant was cycling pretty well. I think I had the air out of the system. I think I put the thermostat in the correct way but I'll take it off and double check. That's an easy thing to do. I think I'm going to try and flush the radiator this evening.

I've had the exact same problem with the gauges. When it was hot in the car they would quit working. As the A/C ran and it cooled, they'd work again. At the time, Neons were common in the junkyard and I replaced the cluster rather than fixing the solder joints.

It has been nasty hot around hear lately.

It's also possible that the water pump has lost its impeller vanes to corrosion, and is not pumping effectively; especially if it's the original.

It is the original water pump as far as I know. We've put the last 100k miles on it. It hasn't been changed since we've had it.

I don't know if the forum Neons.org is still running; from that site I have gleened (since I owned a '99 Neon)

The Instrument cluster was prone to failure from circuit paths burning out on the circuit board. People have fixed it simply by removing the instrument cluster and pulling the plastic back off and finding the burned out circuit trace (they are large, not like tiny ones on the motherboard of a computer) and simply soldering a wire to bridge the burned out section to the copper traces on the circuit board.

Intermittent electrical issues due to corrosion to the ground straps, especially under the dash, i.e. intermittent instrument cluster. Follow the ground strap for all the wiring under the dash, including the radio, several will bolt to the metal safety/crash cage under the dash and it will be very rusty by the bolt to ground.

The 2.0L, both SOHC and DOHC were prone to headgasket failures until a new MLS gasket was used to replace the original Composite Headgasket. Even if the headgasket had been replaced in its life, they might have used a Composite gasket or did a sloppy job installing the MLS gasket and it would fail again eventually. As well, milling heads removes metal and makes the head more likely to warp and enough overheating can cause the head to warp. (This will cause overheating).

The Neon also has an aluminum core, plastic tank crimped on the core type radiator that will NOT last the life the car.

A pressure check of the cooling system will tell if the radiator is bad or if you have a coolant leak somewhere.

A bad pressure cap (they're cheap and don't last) can cause overheating, the system won't hold pressure and be more likely to boil over.

I'm really hoping it's not a head gasket. If it is I may take it to a junk yard and see how much they'd give me for it. I may end up buying a combustion leak tester to see if that is the culprit. I may also get a pressure tester to see if it's another issue.

The instrument cluster sounds like it may be a bit of a project. Is it one of those where I'll need to take the dash out?

Thanks for all the advice.

 

I have seen broken solder joints on the instrument cluster board and that can cause the cluster to fail.
Any AIRBAG light coming on? If the gauges drop to zero when the headlights are turned on, that sounds like an electric current leakage from the instrument cluster illumination circuit into the communication bus circuit.
The 2.5 volt communications bus is very sensitive to over-voltage or under-voltage problems. Any 'leakage' caused by conduction to ground or to +12 volts can knock it out of operation.
Electrical leakage can be caused by a corrosion 'path' at a connector that leaks current between terminals.

 

Another thing to look for is a poor ground related to the headlights. It could be the same grounding screw terminal as the radiator fan?

 

I've had the exact same problem with the gauges. When it was hot in the car they would quit working. As the A/C ran and it cooled, they'd work again. At the time, Neons were common in the junkyard and I replaced the cluster rather than fixing the solder joints.

 

If you replace the cluster, the mechanical odometer can be swapped over to the new cluster to keep your current mileage.
I'm not saying that your problem is definitely in the cluster.

 

To clean the pins and their sockets, you could use electrical spray cleaner or compressed air.

The overheating is probably caused by blockage somewhere. Cleaning the radiator will be more complete if you remove the bottom hose. A complete flushing should also include disconnecting the hoses to the heater core and clearing it out with a garden hose (don't let the water pressure get too high), and removing the plug(s) from the engine block.

 

It's also possible that the water pump has lost its impeller vanes to corrosion, and is not pumping effectively; especially if it's the original.

 

I don't know if the forum Neons.org is still running; from that site I have gleened (since I owned a '99 Neon)

The Instrument cluster was prone to failure from circuit paths burning out on the circuit board. People have fixed it simply by removing the instrument cluster and pulling the plastic back off and finding the burned out circuit trace (they are large, not like tiny ones on the motherboard of a computer) and simply soldering a wire to bridge the burned out section to the copper traces on the circuit board.

Intermittent electrical issues due to corrosion to the ground straps, especially under the dash, i.e. intermittent instrument cluster. Follow the ground strap for all the wiring under the dash, including the radio, several will bolt to the metal safety/crash cage under the dash and it will be very rusty by the bolt to ground.

The 2.0L, both SOHC and DOHC were prone to headgasket failures until a new MLS gasket was used to replace the original Composite Headgasket. Even if the headgasket had been replaced in its life, they might have used a Composite gasket or did a sloppy job installing the MLS gasket and it would fail again eventually. As well, milling heads removes metal and makes the head more likely to warp and enough overheating can cause the head to warp. (This will cause overheating).

The Neon also has an aluminum core, plastic tank crimped on the core type radiator that will NOT last the life the car.

A pressure check of the cooling system will tell if the radiator is bad or if you have a coolant leak somewhere.

A bad pressure cap (they're cheap and don't last) can cause overheating, the system won't hold pressure and be more likely to boil over.

 

No, you don't need to remove the entire dash, its about a 15 minute job to get the instrument cluster out. Maybe a 30min-1hr job to get enough of the dash and things installed in the dash (instrument cluster, radio, hvac controls) out to get enough access under the dash to clean/repair grounding straps.

Are you loosing coolant? If you're NOT loosing coolant, then your overheating is NOT from a leak or bad pressure cap. Coolant circulating well while at idle doesn't tell you much other than the thermostat is opening. You can still have a dozen problems that can cause overheating and it will still show the fluid circulating well at idle.

 

Nope, not loosing coolant.

Well, heck, if you're just going to give up on it, why don't you tell us where you are and put a price on it? You just might find a fellow Allparian that will buy it from you and fix it.

Tempting. The car hasn't been driven much since 2011. I live at work, and have 3 other vehicles that I enjoy driving more. It's been cheap to insure and I'd let coworkers borrow it on occasion when they would have car troubles. It's had its issues over the years and I know it pretty well. I'm pretty effecient with some of its fixes, but it hasn't had a problem over heating before and my mechanical knowledge is fairly basic. I figure I'm going to sell it, the Ram, and Durango get the wife a newer minivan. The family has grown since we've gotten all of them. They all probably have more miles behind them than ahead of them. I'm going to miss the old Ram, kinda sorta my first car and I've had it for a while. It doesn't have enough seat belts in it for the family and I've got a newer Ram that can haul everyone now. But I'm still going to miss it. The Neon is going to be cheap. I guess if a fellow Allparian were interested they could contact me.

 

Well, heck, if you're just going to give up on it, why don't you tell us where you are and put a price on it? You just might find a fellow Allparian that will buy it from you and fix it.

 

Once again, man, just let us know your location. Personally, I'm in Lake Wales, Florida.

 

While I understand the temptation to just dump it for whatever you can get, it will make an easier sale if it's running properly with fewer problems. If the fixes aren't costly, I'd say perform them first, then list it before driving it any more. But if the repairs go into 3 figures, you might set your asking price at 3 figures, and be honest about it needing some work.

If you're not losing coolant, that rules out an expensive head gasket repair (or a time-consuming one, if you do it yourself). A full flush, including the bottom radiator hose, heater core, and the drain plug(s) in the engine block, might solve your problem. If Bob's right about the water pump needing replacement, you're still under 3 figures (unless you have a shop do it). And if you don't have to make a junkyard run, the gauge problem should cost you nothing more than some time, which you could also treat as a learning experience.

 

A 1999 Neon probably has the MLS gasket from the factory. They are much less likely to fail.
It's possible you have air getting in somewhere. Borrow or rent a coolant pressure tester and see if you can find any problems. be sure to test the cap too.

Sadly, used Neons have very little resale so it's easy to spend more than you'll get in return. The time and cost to change the water pump (plus timing belt and ancillary items) is high. Parts alone will run over $100.

 

Make sure the fans are coming on. If you have a ground issue, they won't and the car will overheat. The gauges coming in and out are most likely due to the solder joints on the gauge cluster. If there is a ground issue, the temp gauge on this car will peg the hot side of the temp gauge and move up and down. I bought a scan gauge to make sure I knew what the temp was coming from the computer. The alarm will usually sound. Check your grounds and your battery. I had to sadly let go of my Neon this year when the windshield rusted through. As they get older, they get harder to take care of. These are not low maintenance cars. Another thing that can go is the wiring harness which has been known to melt together.

 

If the cooling system has not been periodically flushed and fresh antifreeze used, the coolant additives get depleted, corrosion starts and the radiator and/or heater core get restricted. Then overheating occurs. Sometimes the only solution is to replace radiator and heater core. Getting access to the heater core in the dash is labor intensive so that adds to the cost.

The 2.0 liter 4 cylinder engine is very durable and will last a long time if proper, preventative maintenance is performed in a timely fashion. I have a 2003 Neon with 288,500 miles and it is reliable and has no issues that affect running. You are on borrowed time on that engine if the timing belt and water pump have not been replaced. If the timing belt breaks or strips the teeth on the cogged belt, a valve(s) and piston(s) will clash and that forces an expensive engine repair.

You cannot look at the current resale value and use that as a determination if you should spend money in repairs. Very few vehicles bring more resale value after spending dollars on repairs. You have to view the cost of repairs against the replacement cost for a similar vehicle in age and odometer miles. If the remainder of the vehicle is in good shape, then it might be worthwhile to spend money on repairs and have an additional, reliable vehicle to drive in certain situations. Only the owner can make that decision.

 

He wants to get rid of the car. He doesn't want to keep it. He might try donating it. That is what I did with mine. The biggest issue with me is rust. Rust killed my Satellite, an 86 Charger that I owned, and now my 99 RT. I would have continued fixing it, but a rusted out windshield frame and roof is a major safety hazard and big $$$ to repair.

 

I've been packed with with several work assignments and juggling at least three projects at home the last few days. Changing the spark plugs on the Ram 2500 with a Hemi turned into quite a chore.
Good news. The Neon is not over heating any more. I flushed the radiator and put a new cap on it. Drove it about 50 miles this evening and it did well.
Gauges are the next project, but they'll have to wait a couple weeks. We're heading out for vacation tomorrow. I was hoping to have the Neon going before we left but I just ran out of time.
I do appreciate all of your advice, tips, and help. I'm going to pull this back up when I get back to turning the wrench on the Neon.