over heating

[spider11]

Hi everyone,
Can anyone help me? I'm over heating. How do I tell if it's the thermostat or if I need a new coolant cap? I"ve been over heating for a couple of days so I've been driving with my heat on and that keeps the temp right at 90 degrees where it's supposed to be but yesterday driving home from work( it was a hot day and traffic was stop and go) it started to rise in temp. when I got home the instament panel was very hot to the touch and when I removed the key I could'nt touch the metal part because it was also too hot. I opened my hood and the coolant cap had blown off. If it't the thermostat, how the heck do I get at it? Can't afford to take to a pro.
Thanks for any help!

[rixGAphx]

*Cliff's Notes* Replace the cap, fill with 50-50 water-AF.

First, get a new cap for the reservoir, it's a pressure cap that is crucial to the cooling system.
About $12US at Checker/AutoZone/PepBoys.

Second, drain out some water from the coolant system, and replace with fresh AntiFreeze.
Old-fashioned green stuff, new-fangled orange stuff (DexCool), enviro-friendly Sierra stuff: Whatever tickles your fancy will work just fine.
Be sure your mixture is 50% AF / 50% water.

Do NOT overfill the plastic reservoir!!
The coolant level should be about 1/4" (6 mm) deep right below the filler neck.
That leaves about 1-1/2" (37 mm) of air. This air space is critical, since the coolant needs space to expand into as it heats.

Finally, do NOT overtighten the cap as you put it on the reservoir!!
Tighten only as tight as an average adult woman can easily tighten with one hand.
If you overtighten, you will distort/slice/nick the washer that seals the cap to the reservoir.

When you fill the system, air that is in the engine block will be trapped at the highest point.
This point is the two-piece 'bleeder screw', at the top of a 4" (100 mm) metal tube on the back of the waterpump.
So, as you fill the bottle to the 1/4" deep mark, open that bleeder and let the trapped air escape. When a little liquid starts to dribble out, you are full.

Heating systems on GA's are a PITA.

Good luck.
-Rick

PS: I think the above will solve your problem.
In any case, all that work is necessary, and it doesn't cost much.
Let us know if your still running hot.
And check the 'search' for overheating, there's a lot of good info there that can help with other hints.

PPS: Don't worry about the t'stat or the ignition key for now.
Though they may be problems, 1) neither is critical at this time IMO, 2) postponing them won't hurt, 3) both are time-consuming to correct, 4) the ignition switch is kinda expensive (~$60US), and 5) your cap MUST be replaced before you can do any further analysis.

[spider11]

Thanks rixgaphx!
I will go out and buy a new cap right away( I'm ready to boot the crap out my car!!!!) when you say fill the system do you mean the coolant surge tank? Also I've had to fill it three time already and have never 'bled' the air out. How critical is this and should the car be running? Sorry as you can tell I'm a complete novice!!

Thank you very much for help! I love my car and it would break my heart to kick the crap out it!!! LOL!

Spider

[spider11]

Any chance it could be the fans?

[tenspeed]

Maybe while you're replacing the cap, check your oil. Sometimes engines will overheat and lose coolant if the head gasket is blown. See if your oil looks dark brown or like coffee with cream.

[rixGAphx]

No chance his current problems are the fans.
They only come on (for pre '99's, at least) when 1) AC is 'on' AND coolant temp is ~215*F or more.
Even in Phoenix, at 112*F and AC 'on' in stop'n'go traffic, I wasn't getting that hot last week.

He *might* have a problem with the fans, the sensors, the t'stat, a blown head gasket (rather rare in the 60* V-6's, tho), or other coolant-related components.
But, we need a functioning system before proceeding with further analysis, and there is definitely a problem with that cap.

Finally, that is NOT a 'surge tank'!!
It's a reservoir, and there is a BIG difference.

Skipping the first half of the 20th century :roll2: , old-fashioned cooling systems from the mid-60's to early '90's (and still used) had a radiator with a metal pressure cap on the neck of the radiator tank.
* You filled the radiator tank to the top, and tightened the cap.
* When the coolant warmed and expanded, it surged passed the pressure-gasket in the cap, flowed thru the tube, and was causght in a plastic surge tank.
* When the car was parked and the engine/coolant cooled, the coolant shrank and created suction. The pressure-gasket in the radiator cap was a one-way valve that allowed the coolant to be sucked, like a straw, from the surge tank.
* As long as you kept an inch or two of coolant in the bottom of the surge tank, all was OK.
BUT, this system ^^^ relied on the filler neck being as high as the highest part of the engine.

When car hoods became very low (for aerodynamics, like our GA's), manufacturers started using cross-flow radiators with side tanks.
* With the top of the engine (heads, intake manifolds) higher than the top of the tank, you couldn't fill the cooling system from a filler neck in the top of the side tank. There would always be air in the top of the engine.
* So, the current system as used in GA's was invented:

Look at your hoses: There's a goofy 'Y' fitting on one of the radiator hoses, that goes to the reservoir.
* You 'fill' the reservoir (only 1/4" deep at the opening), and it fills up the rad, hoses, block, and head by gravity balancing the level of the coolant.
* But if you don't relieve the air bubble in the system (which is about 1 GALLON / 4 L's!!), that air bubble will be stuck at the top of the engine FOREVER unless it is bled.
* Even the waterpump is above this level!! Guess what: if there's no liquid at the pump, it's not a waterpump.
It's an air pump, and it just spins and spins without moving anything.
* The system MUST be filled to the proper level, AND BLED OF AIR ('burped').
* As the coolant expands with heat, it remains inside this 'closed system'. It never 'surges' out.

So, a properly-functioning pressure cap on the coolant reservoir is critical, as is proper filling of the reservoir including 'burping' the air from the engine.

-Rick

[tenspeed]

Rick, have you or do you save these replies? You could write a DIY book or a newspaper column.

I enjoy read your responces, they are always factual. You speak from experience and one can tell that you enjoy helping people.

Thanks for being here, I've learned a quite a few things from your answers.

[spider11]

Hey Rick,
I followed your advice(replaced cap, refilled resevour,burbed the line)still over heating. Know of anything else I can try? Any advice would be greatly appreciated!!
Tenspeed the oil looks dark brown.
Thanks guys
Spider

[4kQuad]

The temp gauage should drop if you turn the heat on Full. The heater core looks just like a raditor, and with the heat on does the same thing. Wind blows by the fins and the heat moves away from the core.

Once a stat is open they stay open till the motor cools down. It takes about 3 to 5 minutes for the stat to open.

On a hot day in traffic it is some what normal for the temp gauage to read a letter or two higher. But it should never reach the red. Are you getting into the red? Or is it staying in the normal running bracket?

Is the Serp. belt tight, if it's slipping a little the pump might not be working as well as it could.

Look for a wet spot on the top of the water pump.

Are any of the hoses getting hot and soft allowing them to bend a little shutting off the flow of water. Like a garden hose when you crimp it.

???

[spider11]

Hey 4kQuad,
My temp guage reads(Canadian car) 40 to 130 degrees celcuis. the needle should stay at 90. It now runs between 2 to 3 lines past 90 which not alot but is enough to boil the coolant. I have never reached the red YET. The hoses are good, there is no wet spot on top of the water pump and the serp belt is tight. I'm thinking of changing the t'stat, don't know what else to do!!!!
Thank for the input. Any other ideas?

Spider