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420A 2gNT Trying to trace an overheating problem!

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FF_Tinsley

Probationary Member
15
1
Nov 21, 2014
Barboursville, Virginia
Okay all bear with me here as I explain this all and try and make the most sense to help you help me!

I just recently purchased a 1996 Eclipse RS manual, 193xxx miles, only "mod" is a CAI done by the previous owner. I drove it twice before purchasing and it ran really smooth (besides my poor 5 speed driving capabilities). I drove it home that night and all was well, did a few spirited pulls but nothing extreme. I stopped at a stoplight and noticed smoke pouring from the hood at an excessive rate, so I promptly pulled over and determined that a coolant line had burst. I checked it the following morning to find that the hose coming from the thermostat running to the back of the engine (not sure of the technical term) had burst, I replaced that and attempted to drive it again. It overheats while at idle about 3/4 the way up the gauge, doesn't go down much when going about 60 mph.

I have since replaced the coolant temp sensor, thermostat, coolant return line to the overflow, burped the coolant system. I drove it approximately an hour to a neighboring city and at a cruising speed of approximately 70 mph the needle sat just above half on the temp gauge. It never sits perfectly even like any other car I've driven.

I left the town this morning and about 5 miles into my 70 mile drive back home the temperature spiked, the needle couldn't go any further up the gauge if it wanted to. I pulled over promptly, not as much smoke as the first occurrence but it was quite a bit coming from what I believe is the coolant line going into the heater core as its the one that goes into the firewall. I let it cool off and topped of the coolant and off I went. Not even a few miles down the road it got hot again. I pulled into an Autozone and checked the fan relays and topped off the coolant after it cooled down. I drove home about 60 miles and it held up just fine, still sitting at a bit above halfway. I let it sit until earlier today when I had to go to class and 5 minutes into driving the temperature spiked all the way past the danger zone again and coolant seeming to have drained from one of the heater core hoses. I will get those hoses off tomorrow and see if they're damaged but if that is not the issue where should I check next?

That is where I am at now. Sorry its so long but I want to answer any questions that may arise as to what I have done and checked so I can figure this nonsense out and try to enjoy this car!

Also if it means anything the CEL is on and the codes are
P1490 - Low Speed Fan Relay Circuit
P0185 - Oxygen Sensor Heater Bank 1 Sensor 1
 
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If your fan isn't turning on or spinning as fast as it supposed to it can def effect your temps. The leak is all the pressure finding the weakest spot and bursting thru it, or a loose clamp! And most likely you'll need a new front O2 sensor it's got a bad heater, or the wiring is messed up. This will heavily effect mpg if not fixed!!
http://engine-codes.com/p1490_chrysler.html
 
If your fan isn't turning on or spinning as fast as it supposed to it can def effect your temps. The leak is all the pressure finding the weakest spot and bursting thru it, or a loose clamp! And most likely you'll need a new front O2 sensor it's got a bad heater, or the wiring is messed up. This will heavily effect mpg if not fixed!!
http://engine-codes.com/p1490_chrysler.html

I didnt think of it that way, I reckon ill replace the hose and clamps back there. The fans when they do kick on are plenty powerful if you ask me. Ive also been running the A/C fan just for a little extra kicker. It doesnt seem to make a huge difference though.
 
Might have to back flush the radiator. What color is your coolant, nice and green or brownish? A flush wouldn't hurt anything, maybe the flow in the radiator is not as good as it needs to be. Just a suggestion.
 
Ill make the next steps by replacing the hoses going to the heater core, followed by a new radiator and a full coolant system flush. Hopefully that works.
 
Try this, pull the thermostat housing fill cap, turn the car on, do you see the fluid moving? How about when you give it a lot of gas? If it's not flowing great at idle and doesn't over fly with lots of gas, you probably have a bad water pump!
 
Try this, pull the thermostat housing fill cap, turn the car on, do you see the fluid moving? How about when you give it a lot of gas? If it's not flowing great at idle and doesn't over fly with lots of gas, you probably have a bad water pump!
Ive let it run with the rad cap off to watch it, it seems to just rise to the top of the fill hole I turn it off before spills over. It just seems to bubble up, doesnt move anywhere.
 
Don't replace anything yet. Figure out WHY the car is overheating, and then replace faulty components where needed.

The first thing you should to is find any leaks. Driving the car until it overheats and pisses coolant everywhere is a horrible way to diagnose the problem. Go to AutoZone or whatever local parts chan is near you, and rent a coolant system pressure tester. You can rent it free, just throw down a deposit. Here's an example: http://www.autozone.com/test-scan-a...kit/oem-radiator-and-cap-test-kit/391374_0_0/

Once you have the tester, hook it up to the car, charge the cooling system and find any leaks. Repair whatever leaks are found.

Once you are sure the system is leak free, you need to make sure the system is full and free of air. Fill the radiator at the water neck, and also fill the overflow up to the cold level. Once the system is full, you should be able to put it through a few heat cycles before the system is completely free of air. If you're worried about the system leaking, fill it up with distilled water until you're sure it is free of leaks. This will keep you from wasting a bunch of coolant and save you a few bucks. After it's leak free, drain out half of the water and top the system back off with coolant.

If you suspect a few heat cycles didn't clear the system of all the air, you can also burp it yourself. With the vehicle off, remove the radiator cap and fill the system. Also, fill the overflow up to the appropriate level. With the cap still removed, start the car, and let it warm up until the thermostat opens. You will be able to tell when the T-stat opens by looking into the water neck where the radiator cap goes. You'll see coolant begin to circulate in the system when the T-stat opens. Once coolant is circulating, add coolant as needed. Replace the cap when the system is full, and take the car for a drive. This should remove most, if not all of the air.

Once you've done all of this, the car should no longer be overheating. If the car still runs hot, you probably have something more serious wrong, which will take more diagnosis. The first simple thing to check would be the T-stat and proper operation of the fans. If those are working properly, you could have major component failure such as the water pump, head gasket and so on.

Lastly, if the car is NOT overheating at speed, I doubt it's a problem with the fans. The cooling fan really only does anything at low speeds and idle. If the car is overheating at cruise, the fans aren't the problem.

Here are 2 very informative threads on cooling issues. I would highly reccomend reading each one:
http://www.dsmtuners.com/threads/the-dsm-cooling-system-faq.377985/
http://www.dsmtuners.com/threads/help-im-overheating-heres-how-to-fix-it.200575/
 
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Constant bubbles coming out of the rad cap is a tell take sign of a blown head gasket. Could of warped your head with the first overheat. In either case, check flow from rad to see if pump is good, make sure rad is not clogged, make sure nothing is blocking airflow in front, fully bleed all air, and tighten all hoses.
 
Constant bubbles coming out of the rad cap is a tell take sign of a blown head gasket. Could of warped your head with the first overheat. In either case, check flow from rad to see if pump is good, make sure rad is not clogged, make sure nothing is blocking airflow in front, fully bleed all air, and tighten all hoses.

I let a local shop guy take a brief look at it, hes sure it isnt the HG.
Don't replace anything yet. Figure out WHY the car is overheating, and then replace faulty components where needed.

The first thing you should to is find any leaks. Driving the car until it overheats and pisses coolant everywhere is a horrible way to diagnose the problem. Go to AutoZone or whatever local parts chan is near you, and rent a coolant system pressure tester. You can rent it free, just throw down a deposit. Here's an example: http://www.autozone.com/test-scan-a...kit/oem-radiator-and-cap-test-kit/391374_0_0/

Once you have the tester, hook it up to the car, charge the cooling system and find any leaks. Repair whatever leaks are found.

Once you are sure the system is leak free, you need to make sure the system is full and free of air. Fill the radiator at the water neck, and also fill the overflow up to the cold level. Once the system is full, you should be able to put it through a few heat cycles before the system is completely free of air. If you're worried about the system leaking, fill it up with distilled water until you're sure it is free of leaks. This will keep you from wasting a bunch of coolant and save you a few bucks. After it's leak free, drain out half of the water and top the system back off with coolant.

If you suspect a few heat cycles didn't clear the system of all the air, you can also burp it yourself. With the vehicle off, remove the radiator cap and fill the system. Also, fill the overflow up to the appropriate level. With the cap still removed, start the car, and let it warm up until the thermostat opens. You will be able to tell when the T-stat opens by looking into the water neck where the radiator cap goes. You'll see coolant begin to circulate in the system when the T-stat opens. Once coolant is circulating, add coolant as needed. Replace the cap when the system is full, and take the car for a drive. This should remove most, if not all of the air.

Once you've done all of this, the car should no longer be overheating. If the car still runs hot, you probably have something more serious wrong, which will take more diagnosis. The first simple thing to check would be the T-stat and proper operation of the fans. If those are working properly, you could have major component failure such as the water pump, head gasket and so on.

Lastly, if the car is NOT overheating at speed, I doubt it's a problem with the fans. The cooling fan really only does anything at low speeds and idle. If the car is overheating at cruise, the fans aren't the problem.

Here are 2 very informative threads on cooling issues. I would highly reccomend reading each one:
http://www.dsmtuners.com/threads/the-dsm-cooling-system-faq.377985/
http://www.dsmtuners.com/threads/help-im-overheating-heres-how-to-fix-it.200575/

Thanks for the awesome information! I did attempt the pressure tester from Autozone, however the adapter for the cap doesnt fit properly. I may have worded it wrong about the bubbling, when I fill it up with coolant after it has leaked I was told by a local guy to squeeze the radiator hoses, dont recall the reason but the engine is off and cool when the bubbling happens from me squeezing it. When I fill it up and leave the cap off, the coolant flows up to the fill neck, I turn off the engine before it spills over.
 
You need to have the car running and up to temp with the thermostat open and the cap off to bleed the system and check for bubbles. Turning the car off before it spills doesnt tell you anything.
 
If the coolant isn't moving, that's your overheating problem, water pump! While your doing the water pump, time for a timing belt job! Lot's of good answers here so far, but since OP stated there is no flow "which there is even with t-stat closed" something is severely blocked or water pump is gone! Even with air and junk in your system, it will not cause it to over heat to the degree OP is experiencing.
 
You need to have the car running and up to temp with the thermostat open and the cap off to bleed the system and check for bubbles. Turning the car off before it spills doesnt tell you anything.
Ok thanks i'll give it a shot.
 
No spill funnel fill with coolant turn car on. Fan speed on and heat on in the car. Air can become trapped in the heater core there are also 2 temp sensors 1 1 pin. Temp sensor this runs the gauge 1 2 pin sensor is for the ecm. A scan tool data list will show what the actual temp is coolant temp sensors will not read air tem. For these sensors to work correctly the must be submerged air pockets will throw readings off best way to test a system is with scan tool data. It u have a 185° t stat u should see on a data list temp go to around 190-195. Then the t state will open and temps will drop a needle on ur stock guage with no numerical #s is not a actually way to tell the engine is over heating. Temp sensor to the gauge could be wrong. Gauge could be wrong system could have air locked.
 
Lot's of good answers here so far, but since OP stated there is no flow "which there is even with t-stat closed" something is severely blocked or water pump is gone!

Agreed, there is flow even with the T-stat closed, but it wouldn't be visible at the water neck. Since looking into the water neck with the radiator cap removed is the only easy visual way to check for flow, it will only happen if the T-stat opens. If the T-stat never opens, you'll never see coolant flowing through the system. So, the water pump is probably fine, and it's more likely the T-stat isn't opening.

In addition, the symptoms described don't indicate a bad water pump IMO. Water pumps don't go bad overnight. The impeller will typically erode slowly over time and lose its ability to circulate coolant effectively. The OP should have noticed the car running hot when he initially purchased it if this were the case. It's more likely whatever is leaking caused an issue, and possibly created other issues after the OP ran the car hot.

OP, when's the last time the T-stat was replaced? How about the last timing belt job? Has the car had any maintenance done? Timing belt, water pump, hoses, belts, plugs, etc?

You just bought a DSM. If these things haven't been done, they should be first up on your to-do list. Also, you better get handy with a wrench. If not, your life is about to get exponentially harder.
 
He said its a brand new t-stat in his first post and its a 420a, Not a dsm.
 
Not of the time at the shop I'm at when a customer replaces coolant for whatever reason. It's Done incorrectly and air is trapped in the system 2nd to that they drive it hot and it knocks out the temp sensor to the gauge or the t stat gets burnt up and not operating correct given the car had no problems before it lost coolant and now it dose start with the easy stuff see what the ecm is reading for coolant temp this tells u if the gauge is correct or not it it is there's a problem. If the gauge reads hot and the scanner says it isn't now u have narrow ur search down. A water pump not flowing could cause the problem but as stated about they don't go bad over night the impeller on ur pumps r metal and do not break away from the shaft like cheap gm pumps with plastic impellers
 
Agreed, there is flow even with the T-stat closed, but it wouldn't be visible at the water neck. Since looking into the water neck with the radiator cap removed is the only easy visual way to check for flow, it will only happen if the T-stat opens. If the T-stat never opens, you'll never see coolant flowing through the system. So, the water pump is probably fine, and it's more likely the T-stat isn't opening.

In addition, the symptoms described don't indicate a bad water pump IMO. Water pumps don't go bad overnight. The impeller will typically erode slowly over time and lose its ability to circulate coolant effectively. The OP should have noticed the car running hot when he initially purchased it if this were the case. It's more likely whatever is leaking caused an issue, and possibly created other issues after the OP ran the car hot.

OP, when's the last time the T-stat was replaced? How about the last timing belt job? Has the car had any maintenance done? Timing belt, water pump, hoses, belts, plugs, etc?

You just bought a DSM. If these things haven't been done, they should be first up on your to-do list. Also, you better get handy with a wrench. If not, your life is about to get exponentially harder.

Its odd that I didnt notice it when I drove it before purchase, not sure how I didnt. However he did have a power wire going from the battery to the fan relays I reckon in order to have them going at all times, didnt realize this till after I purchased it.

I have replaced the thermostat 2 days ago, new timing belt before I bought it along with the water pump. Didnt say much about the belts but they are very new looking, little to no wear. Im not the best mechanic but I can figure it out with the plentiful instrustions here, I just need to know what to do.[DOUBLEPOST=1416590557][/DOUBLEPOST]
Not of the time at the shop I'm at when a customer replaces coolant for whatever reason. It's Done incorrectly and air is trapped in the system 2nd to that they drive it hot and it knocks out the temp sensor to the gauge or the t stat gets burnt up and not operating correct given the car had no problems before it lost coolant and now it dose start with the easy stuff see what the ecm is reading for coolant temp this tells u if the gauge is correct or not it it is there's a problem. If the gauge reads hot and the scanner says it isn't now u have narrow ur search down. A water pump not flowing could cause the problem but as stated about they don't go bad over night the impeller on ur pumps r metal and do not break away from the shaft like cheap gm pumps with plastic impellers

There are 2 sensors on teh Tstat housing I replaced the larger one, which was labeled coolant temp sensor. The smaller one is controlling what? How would I tell what the ECM is reading (probably a dumb question) but this is my first one so Im not familiar.
 
its a 420a, Not a dsm.
Oh, it's not? Was it not collectively designed and built by Diamond Star Motors and shit out of a factory in Normal, Illinois during the mid 90's?

Sounds like a DSM to me.

OP, try the pressure tester kit again. I know the autoparts store has one that will work. The cap is a pretty standard size. Maybe you can drive the car there, and make sure you get the correct adapter. I would bet there's still a leak in the system somewhere.
 
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Thats what I was thinking of doing. Im probably gonna go with a new rad just for the hell of it and the shop owner is certain thats the issue. Also ill replace the hose and clamps that run to the heater core since thats where it seems to come out of once it is overheated and pressurized.
 
Oh, it's not? Was it not collectively designed and built by Diamond Star Motors and sh** out of a factory in Normal, Illinois during the mid 90's?

Sounds like a DSM to me.

OP, try the pressure tester kit again. I know the autoparts store has one that will work. The cap is a pretty standard size. Maybe you can drive the car there, and make sure you get the correct adapter. I would bet there's still a leak in the system somewhere.

No, it is not. Just because it came out of the same factory doesnt make it a DSM. IT is collectively know that a DSM is a 4g63 car from either a 1g, 2g or galant vr4. Same way an a CSM is a 4g swapped colt/summit/mirage.
 
No, it is not. Just because it came out of the same factory doesnt make it a DSM. IT is collectively know that a DSM is a 4g63 car from either a 1g, 2g or galant vr4. Same way an a CSM is a 4g swapped colt/summit/mirage.

Actually, it's collectively known that the Galant VR4 is definitely NOT a DSM. It was designed and manufactured by Mitsubishi Motors. The Galant VR4 was produced in Japan, and imported to the U.S. to the tune of 3,000 cars. This is why the data plate on the Galant VR4 doesn't say DSM on it.

A DSM is a car that was designed and manufactured by Diamond Star Motors; hence the acronym. This would include the Mitsubishi Eclipse RS equipped with a 420A, making it just like every other DSM that rolled out of the factory located in Normal, Illinois in the mid 90's. I'm sorry if you don't agree, but that's a fact. What you consider to be a DSM based on your own set of qualifications is opinion.
 
Psi is correct. The vr4 is technically not a dsm as well as the late 2gb eclipse. Mitsubishi had broke away from Chrysler with good reason. The 420a was junk this is y when Chrysler acquired mitsubishi stock it was under the terms the turbo model would be a strictly mitsubishi product. Engine trans and everything along with the spyder. This is why na spyders have the 2.4L. Mitsubishi didn't want there performance line junked up. With the inferior made 420A after the disbanding Chrysler tried to copy mitsubishi with the srt4 neon in which they had never previously produced. hmmm a 2.4l turbocharged intercooled engine???? Sound familiar? ?? Sounds a lot like a 2.4 na spyder block turbocharged which in my personal opinion was a mistake
 
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