2G Coolant System Issue

[dizily555]

Last issue on this rebuild, my engine is not staying cool and I don't understand why. I am checking coolant temp via my OBD2 scan tool. With the car at idle or driving it will heat up to 223 and maybe more if I let it, the fan doesn't turn on at any point and to fix this I tried replacing the coolant temp sensor, coolant temp switch, and replaced relays, all to no solve the problem and lead me to fixing the fan by directly wiring the fans to the battery. I know the thermostat is good because it opens in boiling water, and I can only believe the water pump is good because it is brand new and is a good brand from O'Reilly's where I work. However with this being said it still gets hot, with the cap off I see no coolant moving which gives me a red flag but I don't know why, the thermostat has to be open at 180 or close to it and the water pump must be moving coolant because the system has pressure and with a funnel used to get air bubbles out, they come out. I flushed the heater core and radiator so they aren't clogged and I completely rebuilt the entire motor nothing can be clogged as I would know. Wondering if anyone can point me in a directed of what to try next, cooling fans need to turn on when the car reaches temp and I need to see coolant rushing past the open cap. I don't know what to try next, please help!

 

[luv2rallye]

Did you replace the 2 wire temp sensor which the ECU uses to control fans? The 1 wire one only runs the dash gauge. Did you burp the system by squeezing the lower hose while running and cap off? New cap? Radiator old and need replacement? You may want this fan override: http://www.dsmtuners.com/threads/cooling-issue-plus-wiring-them-up.273645/#post-151319397

 

[dizily555]

Yes I replaced the temp sensor at the same time as the idiot light/gauge. I did not burp the system because I had the funnel and large pockets of air were coming out. I checked coolant lines at the oil cooler and turbo return line for air pockets and found steady streams of coolant. Yes everything is new because I get everything so cheap, that is how I know the system builds pressure is the safety release on the cap lets off the pressure before removing the cap. The radiator is in good shape, before I installed it I took the garden hose to it and flushed it then let it dry for a few days. I cant see it having any issues. It almost seems as if a coolant line is connected to the wrong spot which is creating a closed system so to speak, cutting off an area on the engine of coolant but everything seems fine and I know everything is put together properly as I've spent the time and money to do so. Very confused, in other posts I hear of water pump problems, I didn't go oem however its a good water pump that should have no issues. But the thermostat doesn't seem to open as it gets to temp, which what do these motors like to run at, letting coolant flow through the system it just runs perfect and gets to 210 and I shut it off.

Also I am going to use your wiring link to fix my fan problem, simple switch from work will do the trick. Could my problem be the fans need to keep the temp around 203-210? My 420a runs consistently at 203 during these warm Minnesota days, which could also be heating up my motor.

 

[luv2rallye]

I thought you have a 2g 4g63 turbo. Do not do my fan override if it's a 420A!

Your post 1 said the thermostat is working but post 3 says it's not - so which is it? It MUST be working to cool the engine. The turbo uses a 180* one.

Even though you used a funnel, still burb the lower hose too.

Something is wrong if the ECU is not turning the fans on (was it rewired? Are they aftermarket fans - not the 4 wire factory?). Here is how the factory fans should operate: http://www.dsmtuners.com/attachments/fan-operating-mode-2g-jpg.86862/.

 

[dizily555]

Yes I have two 2g's, my daily is the 420a and I'm trying to be driving the GSX but it has these issues. Maybe comparing the coolant temps is like comparing apples to oranges but I thought it was something to note. But sorry for the confusion. When I put the thermostat in boiling water I watch it open once it starts to boil, however when I install the thermostat and let it get up to temp the coolant level never goes down the temp goes up until I shut it off. I did just notice this however and I don't know how it is supposed to be, this threaded hole in the thermostat housing. Is there supposed to be a bolt here? Could this need to be blocked off? I will be burping the lower coolant hose from now on, the fans are factory but the previous owner did put a 4 pin trailer harness as the radiator fan so I know it had issues before. As I said though the fans are wiring directly to the battery with a switch so they can be on or off, I will be rewiring them from the ecu as you have given me links for but I don't think that will solve my problem with overheating just that the fans will turn on at the correct time. Here are pictures of the inside of the thermostat housing, what is this supposed to look like and what temp do 4g63's like to run at? Wondering if 207-210 is normal I just need fans to maintain that temp.

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[PlanZero]

A few years ago, I had problems with my cooling fan on my 420a. Long story short, even though I replaced the coolant temp sensor, and there was no CEL, the pigtail for the sensor was fried. When I replaced that my fan started working perfectly. Just a thought.
Also, not sure if you still have the a/c fan, but as i m sure you know that fan kicks on when you hit the a/c button. If your car still overheats with both fans on, you either have air in the system, not enough coolant or the thermostat is bad. I would just get a new thermostat to rule that out. Make sure the little bleeder valve is facing up. And no, there's nothing that goes in that threaded hole (at least on the one I'm looking at doesn't). Does the coolant flow without the thermostat in? Someone correct me if I'm wrong, but I believe if you remove the thermostat and still have no flow, it's most likely your water pump.

 

[dizily555]

After my last post I rolled the car outside and ran a hose to flush the system and try to force out any air bubbles, this resulted in me driving it for about 7 miles and filling it with gas. Note the thermostat was not in and the temp never got over 174 even with the fans off. I am now draining the water down putting in the thermostat that was brand new when I installed it, remember I work at O'reillys so getting good parts is not a problem. The thermostat should be good, as I tested it by boiling it and watching it open, and I am currently thinking I had a huge air pocket in the system. As far as the fans go once I know it will run cool with manually turning the fans on I will either fix them the way they should be or use luv2rallye's thread and connect the fans straight to the ECU with the switch. Ill post again after the thermostat is in and I see how everything is looking.

 

[dizily555]

As I said I put the thermostat back in and filled it up with coolant, backing out of my garage the temp was at 207-210 and staying there. Pressing on the temp would rise to 214-223 when under boost. It seems to be running fine and I don't have an over heating light but that still seems to hot on my OBD2 scanner. Note both fans were running the entire time. Any further suggestions? My logic points to the thermostat not opening but as I've said countless times the thermostat opens in boiling water and I have the bleeder valve facing up. Otherwise my only other idea is that when I drained some coolant out to put the thermostat back in I created the same air pocket. Any further suggestions?

 

[guseclipse]

I had a similar issue and ended up replacing the radiator with an all aluminum one. I then took my stock radiator apart and found some of the tubes had crap that was blocking them. I would also do a pressure Test on the cooling system. There could be a small leak somewhere and it's letting air in the system.

After pressure test new radiator and cap I don't have anymore overheating issues.

 

[dizily555]

I'm absolutely positive that it did not have any leaks, I ran into another issue with seals in my turbo so I'm starting from square one after a turbo rebuild. I am going to be checking the radiator and getting the fans working also make sure that wiring from the coolant temp sensor, and coolant temp switch have good connections.

 

[Galipso]

just throwing out an idea: One thing that ive ran into for increase temps is my coolant overflow catch can line was disconnected one time and caused my motor temps to go high. Fixed after i reconnected the it. Also; ive ran into excess RTV clogging my turbo cooling line at the banjo bolt. This caused my turbo to overheat but not my motor

 

[Mauispyder]

I just replaced my water pump, thermostat , and some of the housing. That weird eccentric bolt hole is normal. I held up my repair to wait for a Mitsubishi thermostat and found that it now keeps the temp rock stable on the factory gauge. My fans work normally as far as I can tell. My open port 2 temp reading stays about 205-212 and the car seems to like this.
Are you losing any coolant? After I changed all of the above stuff, I found my overheating and coolant loss was from one of the small hoses on the front of the engine.

 

[dizily555]

Not losing any coolant, coming off of a fresh rebuild so the water pump is brand new. Waiting for a OE thermostat and see if that opens at the correct point and I can see coolant rush once it opens. I need to check the wiring to my coolant sensors because they are new and should be working however I still have a fan issue and see hotter temps when my gauge is reading right in the middle, not sure which to trust.

 

[Phantom DSM]

From what i recall, when you install the thermostat, the jiggle valve on top of it has to be at the 12'oclock position. Burp the system, coolant overflow line submerged in coolant in bottle, and test it out. It is possible your thermostat was opening too late. Hopefully the OE will help. Use distilled water with green ethylene glycol coolant. Or the pre mixed 50/50. Ive had good luck with the PEAK green coolant. Dont use tap water .
The 2 wire connector has to be working if the fans eventually turn on, check for wiring regardless though.

 

[jimsgsx]

Did you replace the 2 wire temp sensor which the ECU uses to control fans? The 1 wire one only runs the dash gauge. Did you burp the system by squeezing the lower hose while running and cap off? New cap? Radiator old and need replacement? You may want this fan override: http://www.dsmtuners.com/threads/cooling-issue-plus-wiring-them-up.273645/#post-151319397

Thanks man i was just trying to figure out what that 1 wire one was earlier today.

 

[dizily555]

Wondering if anyone has access to a pdf of the factory service manual that goes through troubleshooting for issues like I'm having. There is no reason for my fans to not work the way they are supposed to so I would like to fix them so they work properly.

 

[1990TSIAWDTALON]

Don't know if this will help but I read on here somewhere about drilling a hole in the thermostat to bleed air under it off. Just putting that out there and seen where without the thermostat your car ran very cool so maybe the coolant just isn't touching the thermostat so it gets hot and opens.

 

[dizily555]

I'm still having this problem but it stopped and has now came back in a little different form. Starting the car when its cold it idles great until once it gets to temp and the fans kick on. When they turn on the coolant temp on my scanner reads a very high reading of 295 to 311, it starts to run terrible with a low surging idle and runs rich. However if I disconnect both fans the car will idle around 210 and idle great. I have replaced all the sensors and have no reason to believe they are the problem. I'm wondering if anyone would know what volt reading I would get from the temp sensor and switch wires so I can test to see if they are getting the correct signal. I'm stumped on this and don't know what else to test.

 

[Mello]

If I am not going OEM the only other place that I've had good luck with part has been NAPA. All the brand new stuff I've gotten from the other places (including O'reillys) has been crap. Even right out of the box. Get a new radiator cap while your at it.

 

[dizily555]

I'm expecting my 2.5" mishimoto tomorrow. Tested ohm load on all the sensors I've tried and they are all the same.

 

[Lou98GSX]

295 to 311 and it idles great at 210 . something isn't right with your numbers .

 

[luv2rallye]

I'm wondering if anyone would know what volt reading I would get from the temp sensor and switch wires so I can test to see if they are getting the correct signal. I'm stumped on this and don't know what else to test.

2 wire ECT voltage: http://www.dsmtuners.com/threads/ra...onnect-the-temp-sensor.475221/#post-153390671.

2 wire ECT resistance: http://www.dsmtuners.com/threads/bucking-for-a-couple-of-minutes-after-start.385461/#post-152374418.

Here's when the 2g stock fans turn on: http://www.dsmtuners.com/attachments/fan-operating-mode-2g-jpg.86862/.

Here's how the 2g stock fans are wired and work (note: it's not straight forward): http://www.dsmtuners.com/threads/cooling-issue-plus-wiring-them-up.273645/#post-151311484.

Here's how to connect 2 wire after market fans to factory harness: http://www.dsmtuners.com/threads/fans-running-all-the-time.261629/#post-151198132.

Make sure your fan shrouds are in place (also with after market fans) or you won't get proper air flow.

I still think your thermostat is not opening at 180*F. Checking that it opens at boiling water just says it is open at 212*. You need to heat it in water with a thermometer to see if it opens at 180*. Here's what the 2g turbo thermostat should look like:

Note: You could also short the 2 ECT wire harness pins together (with key on) to see if fan comes on in a couple minutes.

 

[dizily555]

The 400 miles that I put on I did not have a thermostat in because it ran at the right temp with it out. Something isn't right with that but it worked so I could move on to other issues. I did however pay $30 for a OEM thermostat put it in and it ran hot. The first thing I did was make sure the thermostats "the few I tried from O'Reillys and OEM" opened at 180, they all do. I'm looking into the wiring to the CTS today to see if I have a problem there with the temp jumping up. The fans seem to be turning on at the correct time, when the CTS is reading 210. But to make sure I am going to rewire them as if they are aftermarket 2 wire.

 

[dizily555]

CTS connector shows 5 volts with ignition turned on. Fans turn on when the CTS reads 210 however the actual coolant temp is not 210 when they turn on, with cap off and a probe in the system it reads 170 along with my autometer gauge that reads 170 as well. The coolant temp sensor ohms out correctly with dipping in into hot water. Why would it be reading 40 degrees hotter than the actual temp is?

 

[luv2rallye]

CTS connector shows 5 volts with ignition turned on. Fans turn on when the CTS reads 210 however the actual coolant temp is not 210 when they turn on, with cap off and a probe in the system it reads 170 along with my autometer gauge that reads 170 as well. The coolant temp sensor ohms out correctly with dipping in into hot water. Why would it be reading 40 degrees hotter than the actual temp is?

With CTS unplugged and key on, harness should read 5v (black/white wire). But it should drop when connected and CTS warms up (http://www.dsmtuners.com/threads/ra...onnect-the-temp-sensor.475221/#post-153390671.). If it doesn't, you may have a bad ECU (circuitry on pin 83).

Check also that the ground side of CTS (black wire) gets grounded ONLY through ECU pin 92 which is a special sensor ground. It must not be connected to chassis ground through any sensor. ECU pin 92 grounds it internally (see "Important Note" here for reason: http://www.dsmtuners.com/threads/oxygen-sensor-wiring.244376/). You can check this by unplugging the ECU and CTS black wire should now have no continuity to chassis ground.