lovemyseven

iTrader: (2)

Just installed a digital water temp gauge, that is tapped into the throttle body coolant line. Also just installed the miata thermo switch as well. Tonight while driving around normally, in about 75 degree weather with the a/c off, the temp gauge showed temps in the 180's and lower 190's while cruising on the interstate. Once I exited the highway, at a stop light it slowly climbed to 210, then down a little to about 208. After a short mile drive to a parking lot, just before killing it, it climbed to about 228. Got back in about an hour later, it was at 190, then 231 at another red light, then back down to about 207 on the interstate back home. Slow through the hood, killed it to open garage, cranked it back up to pull in, gauge was blinking 260 after sitting for a minute after driving.
Sorry for the long explanation, but I figure give you guys the most info possible. Seems to be running a little hot, but I may just be paranoid. My only modifications are a downpipe a modified air box, and an M2 ecu.

Thank you,
Jason

rynberg

OMG! That is WAY too hot!

The Miata thermosensor should be kicking your fans on at 207F, you really shouldn't be seeing temps much above that at all.

I also think your gauge must be faulty, because 260F would have completely boiled over.

You need to verify everything is working correctly -- thermosensor, tstat, your gauge, the fans. Also make sure to burp the system thoroughly.

lovemyseven

iTrader: (2)

how do I verify everything is working correctly. This car only has 13k miles on it. also these readings are in Fareheit

lovemyseven

iTrader: (2)

I mean how to I test the thermo sensor. The T-stat could be bad I assume because the previous owner didn't drive it enough. Maybe it has dried out some, nothing else seems to have dried out though.

4Fun

iTrader: (8)

Or here is a thought, there might be air in the coolant lines, do you have a gurgling sound under the hood when you park it? If so it needs to be burbed. just a thought

turbojeff

iTrader: (30)

If you didn't have the Miata t-sensor that sounds about right to me. The 260 reading is really hot but just shutting it down and starting it up a couple minutes later usually shows quite a bit hotter temps, 260F is really hot though. I'd replace the T-stat if you haven't, otherwise keep an eye on the temps. Cruising my car in stop and go traffic gives similar temps to yours IF I don't have the parking lights on.

I'd put the temp sensor in the water neck instead of the TB coolant line FYI.

lovemyseven

iTrader: (2)

I read a thread that went back and forth forever about where the best place to put the sensor is. It said the filler neck will only show temps when the thermostat opens, and that the throttle body coolant line is better because it shows temps of the coolant actually flowing through the engine itself. Which is the best?
I do need to burp the system I believe. Isnt' the best way to do so, to leave the cap off, let it run and keep refilling until it does nothing but overflow?

adam c

iTrader: (2)

To get the air out of the system: Slightly jack up the front drivers side of the car. Disconnect the throttle body coolant line. Fill the AST, and cap it. Then fill thru the filler neck. Keep an eye on the open TB fitting. If coolant starts coming out, reconnect it. Fill the filler neck, and cap it. Replace the TB line if you have not dont so already. Drive the car. Check the levels again after it has cooled completely.

KevinK2

burp sys and test/replace tstat and caps.

in some FD cases, the maita switch is not effective, since the 221F low fan speed trip must 1st occur for that switch (normally 226F) to be effective. test by grounding the switch with ign on, engine cold ... fans should come on. if not, could link both relays to the miata switch, similar to method in this link.

http://rx7.voodoobox.net/howto/fanswitch/fanswitch.html

ptrhahn

iTrader: (9)

I got some really wacky readings from my aftermarket guage... especially right on hot start up... and it seemed to fluctuate w/ electrical load. I even tried suplimental grounding. I pretty much wrote it off as a christmas-light, removed it, and rely on the PFC temp reading... that thing was gonna give me a stroke!

r1dreamer

iTrader: (4)

wow i have a cyberdyne digital water temp gauge that is tapped into the water pump housing. with my FMIC and on a 90 degree day i dont see temps above 210. something is definatly wrong.

lovemyseven

iTrader: (2)

I don't want to tap into the water pump housing, so is it better to install the sensor in one of the threaded filler neck holes that are filled with hex plugs or leave it i the throttle body line?

adam c

iTrader: (2)

I didn't want to tap the housing either. I bought a greddy radiator hose adapter. It's a nice aluminum piece that splices into the radiator hose. I believe the size is 38mm. I recommend that you replace the hose if it has not been replaced lately. Pretty easy installation too. Any Greddy dealer can get one for you. I think it was $28.

lovemyseven

iTrader: (2)

what about the hex screw locations on the filler neck?

r1dreamer

iTrader: (4)

the hex bolt will not see a temp until the thermistat is open and the system is pressurized. therefor you wont get a reading until the engine is around 200

RonKMiller

Before you do anything, replace the T-stat and caps (2)with new OEM, then start screwing around with everything else. Make sure you clean off the filler necks before installing with a light dressing of 1,000 grit emory cloth, not common sand paper.

Unless you are leaking or burning coolant, these are the roots of most cooling system evils.

skunks

you should have put it in the water filler neck man, the throttle body line is the worst place you can put it. I cant believe only one person mentioned this! do a search for more info.

lovemyseven

iTrader: (2)

first of all, no one has yet to give a good reason why the throttle body line is a bad place to put a sensor. It contains the coolant that is actually running through the engine at all times.
I just replaced the thermostat with a unit from autozone that opened up more and slightly faster. I also realized, though I simply just haven't noticed before, that the filler neck cap was a piece of ****. The car only has 13k miles on it, so I believed the only other owner never replaced it. It has japanese text on it, but no spring whatsoever. I got a sixteen pound relacement as well.

maxcooper

Check that the sender body is grounded. With the sender in the TB coolant line, it seems likely that it wouldn't be. That may give erratic readings. Use a wire to ground it.

-Max

lovemyseven

iTrader: (2)

i grounded it to the throttle body itself, how is that?

jeff48

Maybe I missed this but is your OEM gauge still functioning? and if so, what is it reading when you show >230F on the cyberdyne. If it is over the halfway point you will have eliminated the question about the aftermarket gauge. Also the TB placement for the sensor is inaccurate for any number of reasons so that may contribute to the problem.

BTW you can get an aftermarket Tstat that is full open at 80C and change to the Miata Tsensor for fan control. Otherwise try the fan mod and use the switch as needed.

lovemyseven

iTrader: (2)

I don't remember what the stock gauge was reading, probably right about halfway. Still no one has answered WHY the TB placement for the sensor is inaccurate. Why would it be better in the filler neck where it won't read any significant temp until the thermostat opens. Does the TB line get a different rate of flow? Does it carry more heat than normal?