rads84n94camaro

Curious to get some other opinions and or if anyone else has had a similar scenario. I've had my 84 for about 10 years now and have upgraded to a 355, WC T5 with a mechanical fan. My thermostat never worked properly in the car and now I'm starting to weed out any problems. Hopefully within the next year or so I'll be putting the LS1 T56 swap I have sitting in my garage in. In the mean time, I'd like to drive the car while I'm building the LS1. Here's the dilemma. Replaced the temp sensor that's in the drivers side head and all seemed well but now when the car idles for about 20 minutes or I go for a burn the gauge reads like its peeked at 260. Replaced the radiator, upper/ lower hoses, thermostat, and flushed the whole system with new fluid. Jacked up the front end to prevent any air pockets forming in the engine, but it still is doing the same thing. Mechanical fan seems fine and is not spinning freely, and the water pump is relatively new. So I borrowed a coworkers laser infrared thermometer and shot multiple locations for read outs. Here's what I got...

Car idling for about 15 minutes and temp gauge reading over heating

water pump. 124.7 degrees
front engine block 160.5 degrees
temp sensor in head. 220 degrees
thermostat housing 155
intake manifold next to tstat housing. 156

car after holding around 2 thousand rpm for 5 minutes

water pump. 143 degrees
front engine block. 164 degrees
temp sensor in head. 236 degrees
tstat housing. 162 degrees
intake manifold. 166 degrees.

So I'm wondering if either my gauge is reading inaccurate, I should be putting a temp sensor in the housing right about the thermostat, or maybe the sensor in the head is either faulty or is the wrong ohms resistance for our cars. I'm also try to take matters into reutilizing the stock gauge cluster for the LS swap if possible, and the cheapest fix. There's plenty of other bugs I'd like to work out before I make her into a roller. Perhaps just getting mechanical gauge and mounting it somewhere in the car would be the easiest route. Thanks in advance.

deadbird

A search for 'coolant gauge' would probably result in many posts on this subject. Many will conclude that the now 26-36 year old gauges leave much to be desired in the accuracy dept.
I've never personally had an issue in any of my cars but, that's just one case.

rgauder

iTrader: (1)

You didn't put thread sealant on the new temp sender did you?

henryd3

iTrader: (128)

Get a cheap laser gun temp sensor and check at the hose coming out of the thermostat cover and see what it says. That you can probably believe.
Harbor freight has some

rads84n94camaro

I did not put thread sealant on the sensor. All those temperature readings are from shooting it with a laser gun. I've actually made the decision today to go pick up another temp sensor from the parts store and putting one in the coolant neck housing. Easier for me to just put a new one there as opposed to pulling the one out of the side of the block and getting an air pocket in the block. They don't exactly break the bank. I'm thinking there's a very good chance I'm getting more resistance through the wire from my unwrapped headers.