Ok, so I got my water temp gauge to work today (aftermarket digital one) and it reads 275 degrees, then flashes "High". So I shut the car down, and roll to a stop, and chill for a few. The car NEVER ran hotther than halfway between H and C on the stock gauge, and now it seems to be killer hot after my removal and reinstall of the engine!! Any ideas? I am running 50/50 distilled H20 and Prestone as well as 20W-50 oil. I turned on the heater to see if that helped, but to no avail. My buddy (who was in the car at the time) thinks it is the gauge goin wacky. ANy ideas??!?!?!?!?!

 

275? You'd be boiling over long before getting that high. It's a PITA, but you probably should consider taking out the sender, sticking it ina pot of boiling water, and checking the sender to be sure.

PauLC

 

Ok, here is the scoop. The first time I fired it up, it read 96 degrees. THis was adfter the engine was sitting for 12+ hours, and was cold to the touch. I check the coolant everyday since the reinstall, so it was cold/cool. As I am crusising during the day, it peaks to 220 after a brixk 15 minute drive (I hammered it once). As I am leaving the gym, it goes all kinds of crazy high. So I kill it, and it drops immediatly (like in 10 seconds) from 280+ to 190. My guess, some wireing goofy. Any ideas on what else to check?

 

HELP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!! I can't drive my car till I fix this!!! It has never overheated, it sucked all of the coolant back into the rad from the overflow, so I know there is a good vacuum, so it has to be the gauge, but I am still worried!!!

 

Wow. This is the first time I have never gotten any help!!

 

Could it have anything to do with the fact that I broke the Intake Air Temp sensor?

 

Water pump issues perhaps?

 

how bout replacing the oem temp sending unit? to the oem gauge. see if it changes any thing. look at your plugs to see if your running lean.
you also mentioned the "air sensor" that might coincide with a lean mixture causing over heat... my 2 cents

 

thermostat??

 

Could the thermostat go bad just because I removed the engine? The temps were fine till I pulled and reinstalled the engine...

Also, the upper rad hose is hot, so the thermmostat is working. Like Silk said, it should boil over right? It never did. The gauage just shows that it should be doing so!!

 

flush a refill your radiator again. not enough water and too much coolant can cause quick overheat.

or just drain your cooling system, refill with mostly water.

 

Ok, I just ran it for 30 minutes. The gauge reads 230ish. Water boils at 212. I have 30%coolant, 70% h20. I sould boil over at this point. The upper rad hose is hot, so the thermostat is opening, so that works. The overflow tank has mabye 3/4 of an inch of coolant in it, and it is actually quite cool. i have no power loss, or any buzzers. I am going to get a volt reading from the sensor to see if that is the problem. My buddy and I both beleive that it is just the gauge, b/c if the engine was that hot, the overflow tank would be boiling...

 

Rico, do this. It'll confirm whether or not you are actually overheating or if it's just a dud gauge.

 

Anyone got a stock sensor? I pitched mine when I replaced it!!

 

if your radiator cap is faulty and not releasing pressure properly then of your over flow wouldn't boil.

 

Sounds like you answered your own question... Why would it be 96 when you fire up the car?

Test the sender and gauge...

-Matt

 

I checked the cap, good pressure. The h20 pump is cool, cuz if you squeeze the upper rad hose, you can feel it push out, so the pump is cool. I know all is good, I am just a compulsive worrier!! Anyone know what kind of volt reading the sender should put out? I rewired the damn thing, and still no-go. Also, as I was sitting at a light, it was at 235. As I accelerated, it dropped to 218, and when I stopped to park, it dropped to 190 in like 4 seconds. It just goes all over the place. I ******* HATE electronics.....Wish I could afford a carb...

 

Ugh! Don’t go there, whole different set of problems.

It really just sounds like a dud gauge. It reads 96º when the engine’s cool! Just rip it out and send it back!

Actually, if you’ve got some time, pull the sensor out and stick it in a container of water at various temps. Use a separate thermometer to check the readings. Remember you’ll need to earth the body of the sensor to the block or chassis, and only put the tip of the sensor in the water.

 

Thanks Jason. I bought the gauge from SiyahGTU here on the forum, so I don't hold him to fault. I will just try and find a new sensor on the net. Thanks guys for putting up with my over zealous worried!!

 

Water boils at 212. But you're not running with just water. The coolant raises the boiling point, remember?

And leave your mixture where it is. If you run with too much water your cooling sys will start to corrode (I just got reamed out over this last week.

Running at 230F would make me **** a brick! 240F is supposed to be about as high as you can go b4 you roast the engine (from all I've read.)

If you just did a rebuild, who knows what got dinged or otherwise took a hit while things were being moved around. Last winter I crunched my water thermo sensor while adjusting the alternator belt. The car was a bitch to start for over 2 weeks b4 I finally found the broken unit.

Good luck!

 

Well, the gauge never goes below 96. It is like 60 degrees outside, and the gauge still reads 96 when i start the car after sitting for 6 hours. Also, I did notice somethin. The gauge displays either "501" or "SO1", then it says "LO" then it shows the temp. Any ideas?????

 

what brand of gauge?

<edit> Disregard.... Looked at your sig...

-Matt

 

Remember, water boils at 212 degress at sea level with no pressure. Once you pressurize the cooling system, water will boil more along the lines of 220-230 degrees. Add antifreeze and you are moving even higher up. An over heating Rex is easy to hear, the coolant will boil loudly and spew everywhere (assuming the cap is working). My suggestion is to use a coolant additive like "Tow Cool", or "Hyper Lube coolant additive". These things break the surface tension of water and help it move more efficiently. I am not a big fan of adding things to your gas/oil/coolant, but I use the Hyper Lube in my Rex and my truck and it really works. You really need to check your sending unit if your getting high readings and no boiling..

Rat

 

I know. Thanks. All is well. I am getting a new sending unit.

 

Cool, hope it works out!