MattFick

First I would like to say ive searched my symptoms on multiple websites before posting,

I have a 95 Trans Am with a fully rebuilt engine (3k ago) and recently I have been noticing my temperature spiking from 210 all the way up to the last line (before the danger zone) within seconds while at stoplights, but what I find interesting is when I drop it into neutral, it cools down. at first I was thinking it may be my fans but they are kicking in when they are supposed to be, i get hot air from my heater once in a while but most of the time its cool air coming through, i have a 160 tstat (new) all 3 sensors are new (d/s head, p/s head, and sensor on the front) new water pump, new radiator and all new hoses. I am not losing coolant, its not smoking nor does my exhaust smell like coolant, my oil is fine and not contaminated neither is the coolant, this has been happening for about a month now, i never let it get all the way up but im getting tired of having to cut the engine off every time i stop at a stop light, but before I start going on a wild goose chase buying parts that may not even fix my problem, I would like to know if anyone has had the same issue and what steps I can take to eliminate possibilities.

Chimera96

are you sure you have bleed the cooling system fully?

MattFick

I bled the system when I put the new radiator cap on because it pushed about half a gallon out through the reservoir. Correctly? Im not sure but I followed all steps on the shoebox website

Injuneer

Do you have the correct LT1 type t'stat?

What sensor do you have in the passenger side head - stock only has a sensor for the gauge in the driver side head and the one in the water pump for the PCM? Has someone possibly installed a separate fan control switch?

To determine if your coolant was contaminated, did you do a hydrocarbon test?

MattFick

The tsat is the correct one, its hyptertech with the oring around it with no gasket, and just by looking at the coolant it looks brand new still. The sensor in the ps head is for the fan switch

Injuneer

What fan switch? The PCM controls the fans using the data from the sensor in the water pump housing. Someone has altered your system from stock. What temp do the fans go on at low speed? What temp do they switch to high speed?

MattFick

I have the jet fan switch 185 195

grabbem88

I take it this is an automatic put it in neutral temp drops?

What's the trans temp?

Restrictions in the cooler lines bent kinked??

MattFick

Not sure of trans temp, havnt plugged in, which will most likely tell me info that will help out, but the hoses are all fine, im leaning towards tstat being stuck shut

artic94

I had this problem back in the summer I back flushed my heater core problem went away