Coolant temp question

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Stin1
Posts: 1672
Joined: Fri Nov 17, 2017 10:43 pm

Re: Coolant temp question

Post by Stin1 » Wed Jan 12, 2022 10:08 am

After it’s completely warmed up , grab your upper and lower radiator hoses. If there’s a drastic difference in temps that new thermostat may have failed.

SWFL_NSX
Posts: 32
Joined: Tue Sep 07, 2021 2:25 pm

Re: Coolant temp question

Post by SWFL_NSX » Wed Jan 12, 2022 12:46 pm

Sorry if I missed this-was the new thermostat OEM?

If not, consider replacing it with one from Honda. I did some back-to-back testing on D16 thermostats last year and there was a wide variance between OE and aftermarket.

Beyond the thermostat I would start looking at the temperature sensors. Air pockets in the cooling system usually create overheating and/or lumpy idles, not over-cooling.

Lastly, where are the temps falling from, and to? It's possible that your cooling system isn't operating optimally right now because of issue with the fan or radiator, and the system is returning to "normal" when it's coasting down a hill.

Disclaimer: I don't own an ITR yet, but have been playing with Hondas for a while =)

SlowNeal
Posts: 21
Joined: Sat Jan 08, 2022 5:46 pm
Location: US
Badge Number: 98-0857

Re: Coolant temp question

Post by SlowNeal » Wed Jan 12, 2022 4:43 pm

The car acts perfectly normal.... no issues.

Both hoses heat as they should, and everything holds pressure.

I did use a Honda OEM thermo$tat, no change after replacing it.

I'm only using the factory gauge, not looking at the coolant temps directly with a hondata or something similar.

The gauge is falling from "normal" (just to the left of the water on the gauge ~40%) to maybe 20-30% on the gauge. Never all the way to the C line or below.

SWFL_NSX
Posts: 32
Joined: Tue Sep 07, 2021 2:25 pm

Re: Coolant temp question

Post by SWFL_NSX » Sat Jan 15, 2022 10:53 am

Not much to add I'm afraid. The symptoms really do match a t-stat that is sticking open, but it's unlikely a new OE has failed and shows the same symptoms as the previous.

Might want to post to Honda-tech in the GSR section to confirm that this sort of thing isn't normal for that model.

IF it's abnormal then time to break open the FSM to see if it lists a range of operating temps. I don't know if you have an OBD1/OBD2/Chipped ECU, but there may be a way to see what signals the temp sensors (there may be more than one) are sending to the engine. It's possible that the temp is fine but there is a sensor issue or a gage issue. Good luck!

SlowNeal
Posts: 21
Joined: Sat Jan 08, 2022 5:46 pm
Location: US
Badge Number: 98-0857

Re: Coolant temp question

Post by SlowNeal » Sat Mar 26, 2022 4:56 pm

Just wanted to post an update... it turned out to be the temp sending unit. The little one wire deal under the distributor.
After replacing it, the gauge reads normal as it should.

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