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Old 04-18-2015, 09:14 PM   #1
Layvon
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Default Overheating at Idle, or Bad sensor?

I am having issues with overheating at idle, new build, idles fine, nice and smooth, stead idle at 1000-1050. 14.0-.2 AFR, not that it matters for this, other than its stable. I have tried burping the system 2-3 times, letting it run, heat on, heat off, squeezing upper and lower radiator hoses, pulled thermostat, verified functionality, running out of ideas. My plumbing is like this on paper.



I rotated the turbo feed line straight up, and feed through the AOS from the bottom to the top, then go down to the Heater Core, then go back down to the WP. Here it is in Real life.



I am using a Link G4 ECU, and the base map came preloaded with the sensor, BOSCH STD NTC. I wanted to verify, so I took a spare coolant sensor at ambient air temp ( 16.7 * C )according to my temp gun, measured resistance ( 2,890 Ohms ) Which is on par with what the chart below says it should be



After yet another attempt where the car pushes past 100* C I have shot the coolant cross over tube / brass sensor body directly with a laser temp gun that proved to be pretty accurate above, and it seems to match more closely with the BOSCH 280 130 017. This was not verified with a multimeter, it was based on what the computer was telling me ( Measured temp, 53* C on the body, 280 sensor 57* C, the STD NTC sensor says 72* C ) With that said, the STD NTC would make it seem like it was getting hotter than it actually was. Here is a data log showing how fast it went from 75 to 104*C. I chose to data log this one after estimating 60-70 seconds the last time.




Do these temp sensors go bad over time / after sitting out for a while? I've been known to use brake clean on things, but I dont think that this would have much effect on this sensor. I'm open for ideas. Even willing to try to change out sensors since I have a spare if they fail often enough to give it a try.


Finally, here is a graph showing me switching back and forth between the two sensors that I think it could be.




Any help / advice MUCH appreciated. Want to start driving and not working on silly crap any more.
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Old 04-18-2015, 09:41 PM   #2
subydude
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Are the fans coming on at any point with the sensor that could be bad?
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Old 04-18-2015, 09:48 PM   #3
Layvon
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Yep fans come on when instructed. (85* currently)

I have put an air mover fan in front and it didn't seem to make much of a difference.

Layvon
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Old 04-18-2015, 10:02 PM   #4
subydude
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And the bottom radiator hose is hot as well? I know you've pulled the thermostat already to check, but maybe try drilling a hole in it (1/8 or so) if it doesn't already have one. Overheating like that is usually a flow restriction or a fan issue.
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Old 04-18-2015, 10:09 PM   #5
Layvon
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Yeah it has one of those little nipply check valve things in it. I orientated it towards the top.

Short man on here text me and said when he deleted his res that it took a week of heating up... Cooling down, topping off. Heating up cooling down. Etc. I guess it could be that, I've just never had issues like this before.

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Old 04-18-2015, 10:11 PM   #6
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Wierd. So I am assuming that ECT are engine coolant temps?
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Old 04-18-2015, 10:15 PM   #7
subydude
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Does it overheat while driving?

My lemons car (old mark 3 golf) hates to bleed coolant standing still. In the end you have to take it for a drive and let it get stonking hot before it'll circulate coolant all around. After that it's just fine. Different platform, but if your car is fine driving around but only over heats sitting still I would think it's something other than a coolant reservoir that's causing the issue.

If it is just the reservoir, then driving it some should help bleed it quicker.
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Old 04-18-2015, 10:16 PM   #8
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So the only thing you have done different is the res delete? I think that may have something to do with it.
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Old 04-18-2015, 10:18 PM   #9
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Have you taken it for a Drive?
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Old 04-18-2015, 10:29 PM   #10
Layvon
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Well there is a little bit more than just that Rob, but my last setup had it deleted also and it was bubble free like instantly.

I have driven it 1/2 mile. I'll try driving tomorrow some more and see what I can come up with

Layvon

Last edited by Layvon; 04-18-2015 at 10:40 PM.
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Old 04-18-2015, 11:10 PM   #11
seanathanq83
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Yea I don't think it has anything to do with deleting things, I have the coolant tank thing deleted, and the oil cooler/heater thing deletes, so basically one hole on each side of the water pump tapped and plugged. And I never had any over heating issues. Only thing different with me is my cross over turbo has a pipe that I return the coolant too and I don't run it through a catch can.

Have you tried taking that out and seeing how it goes? As now you are pumping though the heater core the. Down to the bottom of the block and into the radiator, not falling through the engine line stock
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Old 04-29-2015, 09:46 AM   #12
Layvon
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Little update, I took the thermostat out and swapped sensors at the same time. Now the car doesn't stay up to temp, which is a good thing. All air bubbles were out of the car in about 2 minutes of idling, which is what my experience was before.

I believe it was a bad sensor because I know the thermostat was working since I checked it the first time in pot of water. The coolant crossover tube used was a tube with no line heading back to the heater core, no i didn't delete it, there simply wasn't one; which is why I used it because it was a very clean look and I had other plans as shown to get the water into the core. The other option is that it came off a car with a different calibration for the water sensor than what my computer was reading giving it a false reading. This is what I think it was personally.

I will be firing car back up today and seeing what it does with thermostat re installed.

Last edited by Layvon; 04-29-2015 at 09:51 AM.
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Old 05-11-2015, 07:36 PM   #13
Layvon
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Just a follow up for helping people in future. It was a bad sensor, never even got coolant hot enough to open thermostat.
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