temp gauge jumping, car overheating?

[a_k]

Lately my car has been running hot, really hot. SOmetimes all the way to the H.
WHen it idles its right in the middle but esspecially when i get on it, it will go up to the L. WHen I am driving down the highway at 75, about 2100 rpms, it will be right in the middle, jump to l, bounce off past the H, the car will start to jerk (just like if you are at 3k in first and give it a little gas then let off) then will go back down to normal right in the middle all in about 4 seconds. I dopnt think there is air in the system, I ran it for a bit without the cap on and held it at 2k for a min. Is this the temp sensor or t-stat? I'm hoping its a cheap fix. Thanks for the help everyone, and the only engine related stuff I have done is full exhaust.

 

[ss93cobra]

Sounds like your t-stat is taking a poop on you. If it was just the temp. sending unit, the engine wouldn't react like it did. Make sure too that you have filled the coolant as well and that the fan is operating correctly.

 

[a_k]

thank you. YTeah it is filled all the way and the fan works fine. Do you know where I could get a new t-stat? I'll probably try napa later.

 

[DMAN302]

Jerking thing is not a good idea..id be a little concearned about that issue, check the oil for coolant, and replace Tstat.

 

[HISSIN50]

what I would do:

get a real gauge.
check the condition of the stat and rad cap. for stats, I like the Mr Gaskets. 10 bucks at local speed shops. 180* should work fine.

i would also give the primary electrical connections a once over. since the gauge moves when the jerk occurs, it could be a bad connection.

good luck with it.

 

[sgarlic]

what I would do:

get a real gauge.
check the condition of the stat and rad cap. for stats, I like the Mr Gaskets. 10 bucks at local speed shops. 180* should work fine.

i would also give the primary electrical connections a once over. since the gauge moves when the jerk occurs, it could be a bad connection.

good luck with it.

I've gone through 3-4 instrument clusters, none of which ever had a temp gauge that was even close. Ditto on the t-stat.. I put a brand new one in, and 2 days later it took a crap.. for no reason.. happens all the time.

 

[a_k]

alright awesome im going to order an autometer temp gauge and get a 180 t-stat. I'll call around and see if i can find the mr. gasket one if not ill order the motorcraft one from 50resto. thanks everyone.

 

[Umby]

You should be able to get a Mr Gasket or Motorcraft stat at NAPA, maybe even Pep Boys

 

[a_k]

what I would do:

get a real gauge.
check the condition of the stat and rad cap. for stats, I like the Mr Gaskets. 10 bucks at local speed shops. 180* should work fine.

i would also give the primary electrical connections a once over. since the gauge moves when the jerk occurs, it could be a bad connection.

good luck with it.

hmm after driving it more today i'm thinking its probably not the thermostat. When i push in the clutch to shift it will drop two letters sometimes. And when sitting in my driveway when I got home if I played with the windows the temp would change.
I'm going to check the ground tommarow and see if thats it. I'm still getting a new gauge though, the Cold NORMAL HOT isn't doing it for me. I just need to find somewhere to put it. I like the a-pillar in my friends wrx but idk how it would look in a stang. i'll prob replace the thermostat anyway its so cheap. Thanks everyone i'll let you know how it goes.

edit- can anyone tell me where the ground is and if i need to take the dash apart?

 

[HISSIN50]

I am not sure where grounds are on an SN. i would want to ensure the motor grounds are up to par (if the sender itself cannot achieve ground through the motor, the resistance sent to the gauge is off).

also if grounds are insufficient, throttle and clutch cables can be recruited for use as grounds (next path of least resistance).

toss some grounds on and see how it does.

good luck.

oh yeah, for gauges, i have a triple pillar in my 94GT. i like it. some guys do clock replacement pods (goes where your clock is on the dash). and Andy has a nice set up here

(I know he has posted pics of his gauges on here before, but I happened to have them saved from The Corral).

good luck.

 

[jruppert]

I had a lot of trouble with the grounds on my 94 gt. There is a ground connected to the side of the timing cover next to the oil filter. I ended up buying autometer mechanical oil and temp gauges.