: overheating!!!



dyess1133
09-30-04, 06:32 PM
:confused: my 68 472 has had a problem w/ over heating. i put a new thurmostat in it and a new radiator( the old one was realy messed up!) but the engine temp. gauge still reads all the way to the hot end! when i shift the gauge moves back a little but it still reads pretty high. i can see a little coolent leak coming from behind the water pump pully i dont know what could be leaking there but it's not a real heavy leak. when i took off the old lower rad hose it had some sort of temp sensor slpiced into the center of the hose with 2 wires coming out. but they were snipped off and i dont know where they were saposed to go to. where is the coolent temp sensor saposed to be?after putting in the new radiator i started the car up and run it for about 30 seconds or so, and when i shut it off coolent was shooting out the overflow tube and i took off the cap and a bunch of coolent shoot out! it looked like it was boiling but it didn't feel that hot.

if anyone can help my figure this out it would be great! i have to have it running by this weekend!

lux hauler
09-30-04, 07:17 PM
these cars take a certain type of thermostat.....one with a metal cup on the bottom......you need that.
make sure you have the correct radiator cap....one that is not designed for your specific cooling system can cause problems. a 16# cap is what you'll need.
check to make sure that the entire cooling system is full......and no air locks. if it's over filled it will run out the overflow as it starts to heat and build pressure.

dyess1133
09-30-04, 07:39 PM
thanks but how can i tell if there is air in the system or not? butr do u know where the temp sensor is at? my new radiator is a double core or somthing like that it has a thicker core. i was told that that was better for it but would i have to change any thing else?

JTraik
09-30-04, 08:00 PM
these cars take a certain type of thermostat.....one with a metal cup on the bottom......you need that.
make sure you have the correct radiator cap....one that is not designed for your specific cooling system can cause problems. a 16# cap is what you'll need.
check to make sure that the entire cooling system is full......and no air locks. if it's over filled it will run out the overflow as it starts to heat and build pressure.

Hmmmm im not quite sure what you mean by this specific thermostat, can you show me a picture?

lux hauler
09-30-04, 09:48 PM
Hmmmm im not quite sure what you mean by this specific thermostat, can you show me a picture?
The part circled in red is the cup part I'm talking about. There is a "cup type thing" in the block that the cup on the thermostat mated to. I was told it was used as a bypass to get warm water to the heater core sooner so the heater would warm up faster.
About the air....if you have what you call "boiling" after 30 seconds of run time and the water isn't hot, chances are you have air in the system......let it run a while. Alot of the air will work it's way out. Just make sure that you keep it full and watch that you don't let it get too hot.
The switch in the hose......there was a temperature sending unit and a TVS (Thermal Vacuum Switch?). They were both located at the top, front of the block in threaded holes. I've heard two different stories on what the tvs did.....one is that it advanced the timing at a certain temperature to help the engine run cooler. The other story was that it retarded the timing to help the engine warm up faster. :hmm: At any rate.....there shouldn't be any switches/sensors in the lower hose.
Is your radiator a 2 core radiator? If so, how thick are the cores (how thick is it from front to back)? Is it aluminum? What kind of fan are you using?

barge master
10-01-04, 06:06 AM
Stant #13459 is the right t-stat. If there's a leak behind the pulley, your pump is on the outs. It's rare, but I've seen the impellers rotted off the pumps on cars before. The pulley's turning, but nothing's moving the coolant.

Sasquatch
10-02-04, 02:44 PM
Also check your vacuum advance in the distributor. If this is not functioning properly it can definetely cause boil over and over heating.

dyess1133
10-02-04, 03:46 PM
how do u check the vacuum advance?

Sasquatch
10-03-04, 07:14 AM
Find the vacuum hose coming from your distributor to the carb. Disconect it at the carb and put to your mouth and begin drawing air through it. (sucking) You should feel it getting harder and harder to draw air throught it. This is causing the points plate to shift with in the dist. If you can keep sucking and sucking and nothing happens then the vaccume advance is bad and needs replacing. $8.00 part at most part stores

dyess1133
10-04-04, 01:19 PM
i'm pretty sure the vacuum advance is ok but i cant say the same thing for routing of the hoses. i'm not sure if the hoses are all going to the right places cuase i dont even have a hose going from the carb to the vac advance. the hose from the vacume advance goes down behind the dist. toa little round cylinder with three hose connections on it. the three connections are labled "c" "d" and "mt". the hos from the carb is connected to "c", the hose from vac adv is connected to "d", and the "mt" connection is empty. if this is right than let me know cause i couldn't find and vacume diagrams in my book, and i'm sure if this is wrong it's not helping matters any.

DaveSmed
10-04-04, 01:48 PM
That dopey thing.... its a thermostatic switch that transferred the vacuum advance source from the carb to the manifold if the car starts to overheat. pull the line going from the carb off and run it directly tot he advance. If that other hose is not there, odds are you have a vacuum leak somewhere. I think that line ran to a Tee fitting in the vacuum line going to the dashpot on the side of the carb. (or was that to the air pump?) See if theres anything conencted to it, and follow where it goes.

dyess1133
10-04-04, 02:03 PM
i didn't see any other missing vacuum lines anywhere. i'm not quite sure what u mean about,

" think that line ran to a Tee fitting in the vacuum line going to the dashpot on the side of the carb."

i dont know what a dashpot is

Sasquatch
10-05-04, 06:20 AM
I can tell you this if that vac advance is not working properly or hooked up right you WILL have run on dieseling after you shut the car down and you WILL have overheating with boil over. I know because it happened to me with my 472. I replaced the carb (needed it anyway) and still had problems. Had an old cadillac mechanic clue me in on the vac advance. Checked it and sure enough it was bad. Replaced it and it was the cherry on cake. Never had another problem with dieseling or overheating. If the vac advance is fine perhaps it's that three way switch that is bad. I'd lose that thing and direct vac line everything. What carb you got on it? The original Q-Jet?

mastertech
10-06-04, 10:28 AM
Barge Master has the right idea...you would do well to throw a new water pump on there!