1968 over heating issue

[retroman99]

So now that I got it running seems it runs hot.
I have 3 row radiator
rebuilt FOMOCO water pump
4 blade stock fan
160degree thermostat
it starts out ok temp gauge gradually moves from cold to hot but pegs all the way to hot
coolant flows out past the cap into overflow the hose and onto the ground
i have a 13# cap
I checked the temp gauge with a 10ohm resistor it does what it is supposed to do
i checked the temp with an infrared thermometer at the thermostat and temp gauge seems ok. made sure it was well grounded. no Teflon tape
i tried to run the engine with the cap off to see if the thermostat released when it was supposed to. well right at 160 degrees water flowed very violently. actually overflowed and made quite a mess. i had read on-line that you could do this not sure what happened.
seems strange if the temp was still below 212 why it gushed like old faithful
i was running 50/50 mixture and have ordered an overflow tank and 6 blade fan but seems something else is going on. any ideas?

 

[p51]

The things I would first check:
(1) No air in the cooling system
(2) No leaks in the cooling system

EricTheCarGuy on tracking down overheating problems...
https://www.youtube.com/watch?v=hUzOTnsWImI

 

[p51]

The things I would first check:
(1) No air in the cooling system
(2) No leaks in the cooling system

EricTheCarGuy on tracking down overheating problems...
https://www.youtube.com/watch?v=hUzOTnsWImI

Oh, and a third thing...
(3) Make sure the thermostat is not installed backwards

 

[green56]

over heating

I had the samething over heating did the samething you did what i found out that my Dist in side you have the plate that moves well that moved to far and get the timing way off and that over heated car put a new dist and it works fine I also put a fan in Tom From WI

 

[rvrtrash]

i tried to run the engine with the cap off to see if the thermostat released when it was supposed to. well right at 160 degrees water flowed very violently. actually overflowed and made quite a mess. i had read on-line that you could do this not sure what happened.
seems strange if the temp was still below 212 why it gushed like old faithful
QUOTE]

If you have air trapped in the system, the water could well be over 212 degrees, but the thermostat stays closed because it's not in contact with it. It will also compress the air as the water heats up, resulting in an immediate "boil-over" when the thermostat does release. Couple of things. I generally recommend a higher temp thermostat, because it's better for the engine. I also either buy a thermostat with an air bleed already in it, or drill a small hole to let the trapped air get by. Checking to make sure the thermostat was installed correctly, as mentioned, is a good idea. Finally, was the water flowing from the top hose side (right side) of your radiator? Newer 302's have the water pump vanes reversed, and it's possible you got the wrong water pump or one that had been rebuilt incorrectly.

Steve

 

[robert campbell]

The old "install the head gaskets backwards" trick has caused many an overheat, but ensure you try all of the above before you go there.

Tom is right on with the advance of the distributor. I run all stock engines at 12 degrees BTDC initial as a start point. Get a timing light and also ensure the vacuum advance also works and the diaphragm holds vacuum. You should see the timing bump up immediately as you crack the throttle. This tells you that the vacuum advance is working.

Now to check total advance. You should see timing in the range of 38 total with the vacuum hose removed from the distributor. You can do this by pulling it off and then cracking the throttle slowly open to get engine to around 2,500 or 3,00 rpm.

Many people do not realize if you check this with the vacuum connect do to the lack of a load you also get 10 to 15 degrees of vacuum advance as it is all in. so seeing timing above 38 degrees will always happen in the no load check at 3,000 rpm.

Rob

 

[BigJim]

Running too lean can cause overheating issues too.

 

[retroman99]

i tried to run the engine with the cap off to see if the thermostat released when it was supposed to. well right at 160 degrees water flowed very violently. actually overflowed and made quite a mess. i had read on-line that you could do this not sure what happened.
seems strange if the temp was still below 212 why it gushed like old faithful
QUOTE]

If you have air trapped in the system, the water could well be over 212 degrees, but the thermostat stays closed because it's not in contact with it. It will also compress the air as the water heats up, resulting in an immediate "boil-over" when the thermostat does release. Couple of things. I generally recommend a higher temp thermostat, because it's better for the engine. I also either buy a thermostat with an air bleed already in it, or drill a small hole to let the trapped air get by. Checking to make sure the thermostat was installed correctly, as mentioned, is a good idea. Finally, was the water flowing from the top hose side (right side) of your radiator? Newer 302's have the water pump vanes reversed, and it's possible you got the wrong water pump or one that had been rebuilt incorrectly.

Steve

thank you the water seemed to come from the upper hose on the passenger side radiator. I verified the thermostat was installed correct side facing the radiator. it sure acted like air in the system and it was burping. I'm removed the thermostat and plan on replacing it with a 180-190 degree. the one I removed did have a small bypass hole as well. ive heard drilling a few more holes in it is also an option. the water pump was from a 68. how can I determine if the pump is working properly. I thought about running with no thermostat to see the water flow.

 

[rvrtrash]

If the water from the engine is coming from the top hose, you're ok.

 

[robert campbell]

If you remove the heater hose on top on the intake manifold when filling it will ensure that 99 percent of the air is out of the system. Fill slowly until the fluid comes out of the intake manifold connection. Stop, and put it on and tighten. Continue to fill until 1 inch below the filler neck of the top tank. You must leave room for expansion of the water in the top tank or it will some will come out the overflow.

Not to disagree with Steve, but until you resolve the issue I would stay with the 160 thermostat. One think to do is put the thermostat in a pan on the stove and use a candy thermometer to see at what temp it truly opens. I worked in a radiator shop for 2 years in the early 70's. Every so often we would have a brand new one that would not open. I never install one without testing it.

If you drive a lot in the winter or store in an unheated garage, you can try the 195 after you get this sorted out, but I seldom go above 180. The 195 was used in these cars when they were required to be a daily driver in cold weather extremes.

Also, I always use pure water during a new engine break in. Water is a lot easier to clean up and a lot less expensive to blow out on the road. There is little heat exchanging characteristics difference on a 50/50 mix vice pure water.

Rob

 

[p51]

If you remove the heater hose on top on the intake manifold when filling it will ensure that 99 percent of the air is out of the system. Fill slowly until the fluid comes out of the intake manifold connection. Stop, and put it on and tighten. Continue to fill until 1 inch below the filler neck of the top tank. You must leave room for expansion of the water in the top tank or it will some will come out the overflow...

Rob

Rob

Question on this technique to remove air from the cooling system... I assume that this is being done when the engine is cold. If so, the thermostat would be closed so how would you make sure that the coolant is topping off? Are you assuming a thermostat with a "weep hole" in it?

Thanks
James

Also, just another note. I've also heard of people parking their car on a slight incline (front of the car higher than back) when filling the coolant to help with getting air out of the system.

And one more final, final note... make sure that the heater is turned on (fan off) when filling coolant to ensure that you get all the air out of the heat exchanger under the dash.

 

[franklinair]

If the thermostat is closed, it doesn't matter. When filling through the radiator the water/coolant goes down through the radiator core, into the lower radiator hose, and backfills the engine.
Another method of letting any air out of the coolant system is to remove the temp sensor while filling. When the coolant gets up to that level, simply screw the sensor back in. (I have NEVER had to 'burp' the coolant system.)

Neil

 

[p51]

If the thermostat is closed, it doesn't matter. When filling through the radiator the water/coolant goes down through the radiator core, into the lower radiator hose, and backfills the engine...

I wasn't concerned that you couldn't fill the system... what I was getting at was how do you *observe* that the coolant has filled to the top if the thermostat is closed...

I like your idea of unscrewing the temp sensor.

Thanks
James

 

[franklinair]

James;
When you fill through the radiator neck the water/coolant follows 2 paths:
1.) Through the radiator core, through the lower hose, backfilling the block & intake manifold to the rear side of the thermostat. (That's why I remove the Temp Sensor- to let any air out of the engine.)
2.) When the radiator fills up, through the upper hose to the front of the thermostat. Any air in that path vents out to & through the radiator tank fill point.

Neil

 

[robert campbell]

Neil is right on as usual. Temp sender or intake heater hose. Either will allow complete filling of the engine block and heads. When you top it off after this procedure you are filling the top tank and upper radiator hose.

I too have never burped an engine using this procedure. Always use clear water. Watched a concurs level 65 GT Fastback blow off the upper heater hose and factory Ford clamp at about 15 minutes of the 20 minute break in at 2,000 rpm.... Antifreeze everywhere! Yuk!!!

Rob

 

[p51]

Neil, Rob,

Got it! I went out and actually *looked* at the engine and now see how it fills up even with the thermostat closed. Doh!

I learn something new every day... and sometimes I learn the same thing twice in one day :wink:

Thanks guys!

James

 

[rvrtrash]

James, Rob is talking about the 5/8" (IIRC)heater hose that connects to the fitting on the intake manifold. You're thinking of the upper radiator hose that has the thermostat under it.

Rob, my shorthand got in the way again. I would agree on the thermostat, since he already has the 160. My observation was just that it was colder than I run, but then I've been known to drive around in 30 degree weather, providing there isn't snow or ice on the roads. You guys in the rain forest don't get those temps. I too have boiled my thermostats and checked with a candy thermometer. I didn't bring it up this time since he said it opened at 160.

I also agree on breaking in with no antifreeze. I had one boil over on me during break in a long time ago, and it dulled the new paint in the engine compartment. I never did get it looking like I wanted again.

Steve

 

[Joeymiami]

I had the same problem and found out it was the head gaskets. Sent the heads to the machine shop, new gasket and that solved the running hot issue. A note that my temps were fine at first and one day it started running hot......

 

[retroman99]

I had the same problem and found out it was the head gaskets. Sent the heads to the machine shop, new gasket and that solved the running hot issue. A note that my temps were fine at first and one day it started running hot......

I sure hope it isn't the head gaskets. just had the engine rebuilt. they appear to be installed correctly as they have the little tag sticking out proud of the heads on the forward end both sides. I'm going to try this weekend to fill it as mentioned I was also thinking of a spot where I could let air escape was thinking right where Neil was with the temp sensor. so when the 6 blade fan arrives this week. I already have the radiator and fan out ready for it along with the overflow tank. I will fill it with good ole H2O as I have had enough antifreeze on the garage floor and engine compartment.

 

[retroman99]

If you remove the heater hose on top on the intake manifold when filling it will ensure that 99 percent of the air is out of the system. Fill slowly until the fluid comes out of the intake manifold connection. Stop, and put it on and tighten. Continue to fill until 1 inch below the filler neck of the top tank. You must leave room for expansion of the water in the top tank or it will some will come out the overflow.

Not to disagree with Steve, but until you resolve the issue I would stay with the 160 thermostat. One think to do is put the thermostat in a pan on the stove and use a candy thermometer to see at what temp it truly opens. I worked in a radiator shop for 2 years in the early 70's. Every so often we would have a brand new one that would not open. I never install one without testing it.

If you drive a lot in the winter or store in an unheated garage, you can try the 195 after you get this sorted out, but I seldom go above 180. The 195 was used in these cars when they were required to be a daily driver in cold weather extremes.

Also, I always use pure water during a new engine break in. Water is a lot easier to clean up and a lot less expensive to blow out on the road. There is little heat exchanging characteristics difference on a 50/50 mix vice pure water.

Rob

thanks Rob
here in So Cal I have read some good things also about only running 80/20 mixture and then add some Water Wetter. I will follow your advice pure water until I figure out what is going on. don't have to worry about freezing down here.