[shawn e.]

Car got hot last night at the local cruise in slow hot traffic. Boiled over my overflow reservoir. Let the car cool down and hit the highway. When I got home all the coolant in the reservoir was gone. Did it suck back into the radiator when the car cooled down on the highway? This morning was checking the timing and broke a hood hinge closing the hood for a test drive, but that's another story! Any ways..........found out while fiddling with the car that the nipple on the vacuum advance is cracked. Could this cause my overheating? Pulled the thermostat just for kicks it is a 180 degree stat. I only have a dummy light no temp gauge so I don't know how hot, dummy light did not come on. Kind of pissing in the wind right now. Will get a new vacuum advance put the distributor back together and check the timing this week. Should I replace the t stat with a 190 degree stat?

Drove the car over 500 miles last week at Nationals with no probs. Just last night after 45 minutes or so of really slow creeping stop and go.

Sorry for the rambling!

Thanks Shawn

[GT182]

Shawn, I`d say yes on the cracked nipple is the cause. You need the vacuum advance working. After replacing mine it did the trick.... it`s not overheating anymore.

You get yours changed out and you`ll be ok.

BTW... answering form Belview Ontario, as I ain`t home. I`m up here to pick up a CF-5 jet and truck it back home to New Castle. I`ll check to see how you make out when I get back home Tuesday.

[GOAT8U2]

Higher than base/initial timing = Lower EGT

You'll see a massive improvement and be sure to run Manifold Vacuum and don't be afraid of low to mid 20's timing at idle and mid to upper 40's while cruising.

[72LuxuryLeMansLa.]

Originally Posted by shawn e.

Car got hot last night at the local cruise in slow hot traffic. Boiled over my overflow reservoir. Let the car cool down and hit the highway. When I got home all the coolant in the reservoir was gone. Did it suck back into the radiator when the car cooled down on the highway? This morning was checking the timing and broke a hood hinge closing the hood for a test drive, but that's another story! Any ways..........found out while fiddling with the car that the nipple on the vacuum advance is cracked. Could this cause my overheating? Pulled the thermostat just for kicks it is a 180 degree stat. I only have a dummy light no temp gauge so I don't know how hot, dummy light did not come on. Kind of pissing in the wind right now. Will get a new vacuum advance put the distributor back together and check the timing this week. Should I replace the t stat with a 190 degree stat?

Drove the car over 500 miles last week at Nationals with no probs. Just last night after 45 minutes or so of really slow creeping stop and go.

Sorry for the rambling!

Thanks Shawn

Shawn,

I don't know about your car but my '72 came stock with a 195* stat and that is what I run. The only difference would be that your car should run at or near 180* and my car will run near 195*.
The overflow bottle did what it should do. If your pressure overcomes the spring in the radiator cap(replace yours with a new 15lb. Stant brand cap) it will send coolant into the overflow bottle. Most modern systems will then suck the coolant back into the radiator when the pressure is reversed. My car has no overflow bottle. Again I don't know anything about your car(model, year, etc.) but if you buy a Pontiac Service Manual for your year and it should give you all the information you could want.

Karl

[67 Lamnas]

Originally Posted by 72LuxuryLeMansLa.

Shawn,

I don't know about your car but my '72 came stock with a 195* stat and that is what I run. The only difference would be that your car should run at or near 180* and my car will run near 195*.
The overflow bottle did what it should do. If your pressure overcomes the spring in the radiator cap(replace yours with a new 15lb. Stant brand cap) it will send coolant into the overflow bottle. Most modern systems will then suck the coolant back into the radiator when the pressure is reversed. My car has no overflow bottle. Again I don't know anything about your car(model, year, etc.) but if you buy a Pontiac Service Manual for your year and it should give you all the information you could want.

Karl

This will ONLY occur if you're running a closed system radiator cap and have the overflow bottle mounted at the correct height.

[Formulabruce]

Originally Posted by shawn e.

Car got hot last night at the local cruise in slow hot traffic. Boiled over my overflow reservoir. Let the car cool down and hit the highway. When I got home all the coolant in the reservoir was gone. Did it suck back into the radiator when the car cooled down on the highway? This morning was checking the timing and broke a hood hinge closing the hood for a test drive, but that's another story! Any ways..........found out while fiddling with the car that the nipple on the vacuum advance is cracked. Could this cause my overheating? Pulled the thermostat just for kicks it is a 180 degree stat. I only have a dummy light no temp gauge so I don't know how hot, dummy light did not come on. Kind of pissing in the wind right now. Will get a new vacuum advance put the distributor back together and check the timing this week. Should I replace the t stat with a 190 degree stat?

Drove the car over 500 miles last week at Nationals with no probs. Just last night after 45 minutes or so of really slow creeping stop and go.

Sorry for the rambling!

Thanks Shawn

DO NOT put a 190 T stat in your car! The T stat rating is a STATIC rating, its the temp it STARTS to open at. A 190 wont be full open ( DYNAMIC RATING) till around 205 depending on the cooling system capacity and pump.
I recommend a 160 T stat with gas with ANY Alcohol in it as alcohol makes the engine work harder for the same power, and a 160 runs about 175-180 in a pretty normal Pontiac 400 with a 4 core.
Yes a vacuum leak can make it run lean... and hotter..

[shawn e.]

Thanks everyone put a 180 back in. Will pick up the vacuum advance in the morning. Then get the timing dialed in while the hood off the car. I have a nice Innova timing light with voltage and dwell just need to get more proficient with it.

Shawn

[Formulabruce]

Originally Posted by 72LuxuryLeMansLa.

Shawn,

I don't know about your car but my '72 came stock with a 195* stat and that is what I run. The only difference would be that your car should run at or near 180* and my car will run near 195*.
The overflow bottle did what it should do. If your pressure overcomes the spring in the radiator cap(replace yours with a new 15lb. Stant brand cap) it will send coolant into the overflow bottle. Most modern systems will then suck the coolant back into the radiator when the pressure is reversed. My car has no overflow bottle. Again I don't know anything about your car(model, year, etc.) but if you buy a Pontiac Service Manual for your year and it should give you all the information you could want.

Karl

in 72 there was still LEAD in the gas and there were trying to burn up hydrocarbons the old way, with more heat. a 195 T stat will run around 210-215 in a Lemans with today's Alcohol gas with a normal cooling system.
Once your automatic tranny gets over 200 it starts to "cook"...... good luck.
Replaced alot of trannys under warranty in the late 70s for this..

[72LuxuryLeMansLa.]

Originally Posted by Formulabruce

in 72 there was still LEAD in the gas and there were trying to burn up hydrocarbons the old way, with more heat. a 195 T stat will run around 210-215 in a Lemans with today's Alcohol gas with a normal cooling system.
Once your automatic tranny gets over 200 it starts to "cook"...... good luck.
Replaced alot of trannys under warranty in the late 70s for this..

This car gets driven a bunch so I guess my luck is pretty good.

Karl