420A 2gNT Trying to trace an overheating problem!

FF_Tinsley · Nov 21, 2014

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

o0GuitarKid0o · Nov 21, 2014

water pump or blown head gasket or faulty thermostat

Calan · Nov 21, 2014

lasthope05 said:
... and its a 420a, Not a dsm.

lasthope05 · Nov 21, 2014

GST with PSI said:
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.

I guess by your reasoning a chrysler sebring and dodge avenger are considered DSM's also correct? Made in the same time period, same plant sharing and sharing similar chassis/unibody. By definition they are DSM's but the majority of members dont consider them that.

Warborg · Nov 21, 2014

lasthope05 said:
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.

Agree with GST with PSI, this is contrary to everything I've read on the subject as well... Regardless of the engine, it's still a DSM... It was a collaboration between Chrysler and Mitsu, so just because it has a Chrysler motor in it doesn't "disqualify" it from being a DSM. Also by your definition, the 2G Spyder wouldn't be DSM either, even though it is a Mitsu motor.

tuurbo junkiiiee · Nov 21, 2014

Thermostat could be stuck open, clogged radiator or radiator hose. Fans could not be pulling hard enough

Dsmkauai · Nov 21, 2014

Omg who gives a crap!! Stick to the issue at hand for the o.p. there probably a huge merged thread for arguing about who's really a dsm LOL

! My 95 has factory dsm stickers all over it and my 98 doesn't says Chrysler!! Lol

FF_Tinsley · Nov 21, 2014

rough said:
I hope you figure it out! N/T 420a's are pretty simple to troubleshoot!

I hope I do also! thank you![DOUBLEPOST=1416614978][/DOUBLEPOST]

Dsmkauai said:
Omg who gives a crap!! Stick to the issue at hand for the o.p. there probably a huge merged thread for arguing about who's really a dsm ! My 95 has factory dsm stickers all over it and my 98 doesn't says Chrysler!! Lol

Yeah interesting arguement but it doesnt help me out! LOL

lasthope05 · Nov 21, 2014

Haha. Yea, sorry bout that.

Post back when you check a few of the things we told you so we could help you narrow it down.

Dsmkauai · Nov 21, 2014

You may be able to pull the radiator and flush it real good. Depending on what comes out and how it looks and flows, you can determine if it should be replaced. Also Check all the small coolant lines going to the turbo and ofh those can clog easy!

FF_Tinsley · Nov 21, 2014

Dsmkauai said:
You may be able to pull the radiator and flush it real good. Depending on what comes out and how it looks and flows, you can determine if it should be replaced. Also Check all the small coolant lines going to the turbo and ofh those can clog easy!

It isn't a turbo! I wish!

Dsmkauai · Nov 21, 2014

Oh ya sorry spaced for a sec LOL

! Still Check all the small lines going to ofh and throttle body!

DSM1G90 · Nov 21, 2014

Looks like the whole system needs to be power flushed, radiator flushed out with gunk and junk that lives in a vehicle with 193K miles on it. After all the flushing, new cap, T-stat and gasket are in order.

Slobonator4G63 · Nov 22, 2014

Some over heat situation are duet air in the system id suggest maybe parking on an incline and with a coolant funnel fill your coolant into the rad cap and make sure your heat is set to full blast and watch for bubbles to surface into the funnel. and maybe give the bottom rad hose line a squeeze and see if this helps.

FF_Tinsley · Nov 23, 2014

DSM1G90 said:
Looks like the whole system needs to be power flushed, radiator flushed out with gunk and junk that lives in a vehicle with 193K miles on it. After all the flushing, new cap, T-stat and gasket are in order.

Ive opted to just buy a new radiator, might as well freshen it up if Im going to have it off anyways. That will be done tomorrow. Ill post back with results.

Fayt · Nov 24, 2014

You shouldn't need a radiator unless your current one is blocked/not flowing.
When the car is at temp, do the top and bottom hoses feel around the same temp? If the bottom is cold while the top one is hot, your radiator is clogged and would need replacing or a good cleaning.
Do you have heat inside? If you don't, the heater core would need cleaning also, fairly easy with CLR/water and an air compressor.

DSM1G90 · Nov 24, 2014

After all of the cleaning and still overheating, and going back to the 193k mile thing, bet the WP needs replacing.

And if so, that's a belt job right there to be done also.

good luck - DSM

FF_Tinsley · Nov 25, 2014

Fayt said:
You shouldn't need a radiator unless your current one is blocked/not flowing.
When the car is at temp, do the top and bottom hoses feel around the same temp? If the bottom is cold while the top one is hot, your radiator is clogged and would need replacing or a good cleaning.
Do you have heat inside? If you don't, the heater core would need cleaning also, fairly easy with CLR/water and an air compressor.

I did replace the radiator simply in efforts to freshen up the whole car. It seems to have helped a tad bit but none thel less overheated not even a few minutes of driving after letting it reach operating temperature at idle. I pulled up to a car wash and noticed a pool of coolant coming from the hoses leading to the WP. Ill attempt to replace those hoses next.

dgdsm · Nov 25, 2014

One thing I see you haven't done is the cylinder block test. It's an Autozone loaner tool, no cost to you. I had a concern about HG leak in my overheating episode about 1+ month ago, but the cylinder block was negative both with a cold and a warmed up engine.

FF_Tinsley · Nov 30, 2014

For all that have been helping me out and following my trial and error process involved in fixing my overheating problem here's an update.

So far the parts I've replaced include..
Radiator
Thermostat
Countless hoses
Coolant Temp Sensor

None of these have yielded any real results, car warms up fine then the temperature spikes, either in idle or up to speed. Almost as if its picking when it does. If that makes sense. Last night I attempted to replace the heater hoses going directly into the heater core and that is a pita to do so I just bypassed the heating system as a whole and ran a hose to the lower radiator. (pictured below C to D) That seemed to help a bit, I took it out and got hard on it but it still seems to get fairly hot but it didn't reach what I consider the danger zone. The only things I haven't attempted to replace are the other sensor that is mounted in the thermostat housing.. no idea what its called, and the water pump.

I'm at the point now where its going to have to get sold. If anyone has any ideas Ill take whatever advice I can get.

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2gmitsueclipse · Nov 30, 2014

Radiator cap may not be working correctly to vent built up pressure. You would hear a bubbling sound if pressure was not being vented. It can also cause hoses to burst from added pressure. This is easily overlooked. I would only OEM for the cap.

FF_Tinsley · Nov 30, 2014

My cap looks to be in reasonable condition. But I guess it couldnt hurt to spend a few bucks to replace it.

2gmitsueclipse said:
Radiator cap may not be working correctly to vent built up pressure. You would hear a bubbling sound if pressure was not being vented. It can also cause hoses to burst from added pressure. This is easily overlooked. I would only OEM for the cap.

2gmitsueclipse · Nov 30, 2014

Tall tell sign it is in sad shape is the condition of the rubber seal underneath or have buildup under the cap.

dgdsm · Nov 30, 2014

FF_Tinsley said:
The only things I haven't attempted to replace are the other sensor that is mounted in the thermostat housing..

The other sensor at the thermostat besides the ECT sensor is the temperature gauge sensor, but probably isn't the problem. Instead of trial and error and never finding out where the problem is, maybe some systematic diagnosis is needed. If you do the cylinder block test, you'll know for sure if it's a blown HG or no. Doesn't seem to make sense to give up on it without knowing that. Also, another thing to keep in mind is that in 2Gs the fans are controlled by the ECU.

Wayne · Nov 30, 2014

The fact that the fans had a" jumper wire" connected to them is a huge RED flag and denotes that the previous owner had overheating issues prior to you buying the car. (I've seen this type of hack/patch job before) unfortunately based on this and what you have seen/ experienced I'd be willing to bet that the head gasket is blown. if there are no visible external coolant leaks then perform a cylinder leakdown test (pressurizing each cylinder at top dead center) and look in the cap or better yet use the no spill funnel halfway full and look for bubbles in the coolant. this is a pretty simple test and will determine without a doubt the condition of the head gasket.

lasthope05 · Nov 30, 2014

You need to stop buying and replacing parts. Find the root cause of the issue by elimination. Pressure testing the system for possible leaks would of saved you money from replacing hoses. Sensors dont play a huge part in cooling system operation besides triggering the fan and since you are seeing overheating issues at speed it rules it out.

Radiator was replaced and heater core is bypassed so no clogs. You could test your thermostat in a pot of water to see if it opens, but thats new, so it seems like its down to the water pump.

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