Damn that was weird, heat spike?

Rerun

Founding Member
Mar 31, 2002
312
0
16
South Bay, California
Just got done cleaning my car and was going to take the girlfriend out to eat. I'm not hauling ass or anything and I look over and my autometer water temp guage was acting weird. Spiked up to 240 then shot down to 220 then back up to 230 then to 180. This all happened very fast, and finally settled down to it's normal running temp of 200. After dinner drove it for about an hour and everything was fine.

Was thinking maybe a malfunction but the guage is mechanical, so I don't know. Was thinking maybe the t-stat got stuck for a bit or something. Any thoughts?
 
i would just keep an eye on it. do you have other temps gauges in the car? unless it jumped around with no apparent rhyme or reason (or would have been impossible to have actually jumped like it did), i would keep an eye on the thermostat, esp if it is a bit old.

good luck.
 
The first thing i would do before you drive it again is check the coolant level. When the air pokets leave the system coolant has to fill that hole so the level goes down. Make sure level is good and top it off. Run your car for a while at idle with the rad. cap off. This will allow air bubbles to escape. (air bubble well only escape one the thermostat is open.) You may have no more air pockets since you drove it long enough the air probably bleed out through the overflow.
 
Alright just an update.

It appears to happen when the car hasn't been driven or is cold. I haden't driven the car all day and it happened again. I fired it up, everything was great, haden't been but maybe 3 minutes, car started heating up again, got to around 230 so I pulled over and turned off the engine. I checked to see if my electric fan was working and it was. I also put my hand on the engine and it was cold to the touch. :shrug: So I started the car up again, was gonna take it home; all the sudden it dropped to 185. I drove it for 2 hours straight and the car was fine at normal operating temperatures 200 and below, never above 200 though which is normal for me. I made a few stops, car had been sitting for 45 minutes or so each time and never happened again.

I was trying to think back if anything had happened or if I've installed anything that's made this happened and I remember, the first day that it happened, this had happened to the car:

http://forums.stangnet.com/showthread.php?t=461154

I'm going to burp the car tommorrow and see if that's the problem. The first time it had happened, the car had been sitting for a few hours after what was described in the above thread so it was cold for sure. Any other thoughts? Again, I appreciate all your help.
 
So I took off the radiator cap now that the car is cold and I can see half way down the radiator before I see coolant. I'm new to the game of doing my own **** to my car so excuse the ignorance. This mean that the coolant is extremely low and I need to add more? If so I always hear about this 50/50 mix, what's the process of properly adding coolant and burping the system?

If it's normal to see half way down the radiator before you see coolant than I won't add any.
 
in my experience, it is not normal to have the level so low. add 50/50 +/- 10% (i.e. 40/60)...remember that water is what cools. coolant provides the boil over protection, rust protection and lubrication. i run 40/60 coolant to water, respectively, but it should not matter too much for you. i would add a 50/50 mix of coolant and distilled water. dont use tap water. it is best to mix it first - they make premixed stuff which should be good.

add the mix and jack up the driver side front. start the car up with the rad cap still off. let it warm up. when your stat opens, you should see coolant flow from the pass side toward the drivers side. let it get nice and warm...you should get most of the air out of the system.

this would be a great time (before you fill it) to stick a new thermostat in, if that is something you want to do. i would not go colder than 180 (and i like Mr Gasket thermostats).

good luck.
 
no you need to fill it up completely. the 50/50 mix is glycol/water any antifreeze except dexcool will work fine. Just get a jug of antifreeze poor in 2 quarts/litres into an empty container and add the same amount of water. Fill as necesary. As for burping it I bet it is already done if the coolant is that low. What I do is fill it let it run for a few mins with the cap off. Put the cap on drive it around for a while (kinda hard, to get the temp up) afterwards let the car cool down remove the cap if its down any just fill it up put the cap back on and voila your done.
 
start the car with the radiator cap off so it doesn't build pressure. the air bubble should rise. i did this in my "beater" mobile and i had a ton of air. thank you pepboys...anyways, when the air comes up, put more coolant in the radiator to fill it back up to the top. rev it a little, maybe up to 1500 then wait a little while watching it. if no more air bubbles, put the cap back on and you should be all set.
 
Ok, so I bought some 50/50 mix by prestone and some distilled water. I pre-mixed 2 quarts, which was about exactly how low I was. I started the car and let it sit until it warmed up in the meantime gently squeezing the upper radiator hose every so often. I noticed a bubble about the size of a pea every 15-20 seconds. Once it got really warm the coolant overflowed and I just let it happen, then I guess the thermostat opened up and it went down. When it was overflowing I was looking at the coolant and it looks green no milkshake or rainbow. I put the cap on it, and drove it pretty hard for 15 minutes and the temp was the best it's ever been around 185-190. Then eventually it went back up to it's normal operating temps of 200, but never went over that. I'm gonig to let the car cool for a couple of hours then go top it off and burp it again for awhile.

Still, appreciate every ones help, thanks fellas.
 
Welp, after driving it for awhile, the car wasn't overheating but I had to make a few stops and when I did turn off the car, after a few seconds coolant would slowly come out of the cap. So I was thinking maybe I overfilled the radiator or something so I just drove it since it wasn't overheating and appears to be getting less and less each time. Also, there's a bit of 'gurgling' if you will in the upper radiator hose when the car is off.

I called my mechanic and he said that it's probably a bad radiator cap (which I picked up already). If the radiator cap doesn't fix it i'm bringing it to his ass on thursday.
 
Coolant is always overflowing to my overflow bottle but once my fan kicks in it get sucked right back in. It's a repeating cycle while I drive. Your radiator should be full and you should have some coolant in the overflow bottle.
 
your temps dont sound too bad if you have a stock temp t-stat. even if you have a 180, but it is warm where you are, that is not bad.

get a new cap. if the cap is not sealing, it is likely not holding pressure. the pressure (~16 pounds) helps to raise the boiling point. so you could be boiling water off, and running the system inefficiently.

nice work on it so far.