My car was overheating a few weeks ago. I pulled out the Thermostat and it was trashed. I gave the system a fairly thourough flush with my water hose, and replaced my thermostat with a 160 deg unit. Well, after I did that, my coolant temp hardly ever rose above 160, only after hard driving then getting stuck in traffic. It usually stayed around 130-140, which I thought was odd. Yesterday I replaced my 160 with a stock 195 deg. unit. Now my temp gets to around 160-170, never up to 195. When I shut the car off, my overflow tank is usually bubbling now, which it WAS NOT doing with the 160 stat. Anyone know what the heck it going on? One thing that is weird is that my fan does come on, althought I'm not sure exactly when it does come on. Anyone know what my problem could be?

 

The CTS or coolant temp sensor provides temperature information to the ECM. The temperature sending unit is the sending unit for the guage.

They are not all that accurate. Try hooking up a seperate, electric guage with a different sending unit to be sure. Try to have both hooked up to tell the difference.

The overflow tank is supposed to be there for expanding coolant (which it does when it heats up). It may puke out now because it actually is getting too warm.

Is this a carb or TPI application?

 

TBI. Is the sending unit the one next to the thermostat housing?

 

The sender for the guage is usually in the drivers cylinder head.

I don't own a TBI unit...so I don't know for sure...

 

I just got done replacing mine on my 305 TBI...

This thread should help...

https://www.thirdgen.org/techbb2/sho...hreadid=101135

the link in the thread shows a picture of what it looks like, on mine, its like in the middle 2 cyclinders on the passanger side...right above the wires that connect to the starter...

 

Hey bud, I think the one on the passenger side is for the cooling fan relay. The temp. ga. sensing unit is in the head on the drivers side.

 

It should be the same for TBI or TPI...that deal stretches back a way into the early 70's anyway...the temp sending unit (guage) has been in the driver's head for at least that long...

 

Well, my car is still overheating, and I dont know why. My fan seems to be working just fine (comes on around 220, cools it down to about 170-180, shuts off). I think I have a water leak somewhere. I was low on water the other day, and I had filled it up when I replaced the T-stat. I'm going to have to run the car for a while when I get a chance and look for the problem.

 

Check for a coolant leak and consider just replacing the rad cap...if the system isn't fully pressurizing due to a bad cap, then the water will boil at 212F...see the problem?


Good luck