hey Guys,
new to the board. first post! anyway I recently purchased a '65 dodge dart four door in pretty good condition. I'm having a problem though. whenever I take it for long drives ( more than a half hour) it starts to overheat and the radiator fluid boils over and steams out of my radiator tube that connects near the cap. I thought it was the thermostat so I replaced it with a new one and still same problem. Simeon suggested to drain it and run a water hose from the engine to get rust and debris out. anyone else have this problem? thanks!

Where exactly does the steam come out of? I believe if there is any steam it should only come out of the pressure valve on the radiator cap.

Overheating is usually caused by low fluid level or a restriction in the system.

Check the oil level, low oil can cause the system to overheat.

Check the lower hose to see if it has been crushed. If it has, then replace and install a spring inside the hose to prevent it from collapsing.

Check for air leaks in the upper and lower hoses. The cooling system needs to be pressurized to do its job, if you have a leak it won't be able to pressurize and that could be causing the boiling.

Check the water pump by observing the fan, if it wiggles more than 5-10 (I'm not 100% on the 5-10, it could be slightly more) degrees than it means the pump is on its way out.

Did you boil the thermostat to ensure it is opening at the correct temperature? If not you may consider taking it out and trying that. You can also test the thermostat while its on the vehicle by running the engine with the radiator cap off and watching the coolant. Be very careful when removing the cap while it is still warm.

Also there is a block plug on the passenger side near the distributor. You may want to drain the coolant from there to see if anything comes out. If nothing comes out jam a screwdriver in there until you get liquid.

Let us know how many of these things you've checked. Also a history of the car and service that you know of may help.

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'66 Dodge Dart

well on the physical radiator there is a hole on the fill neck and a tube is connected to that hole and it goes along and down the right side of radiator which I believe is an overflow. at first it will be pure liquid coming out of this tube and then it turns to steam. I don't really know anything about the history of the car. oil level is fine and I just did an oil change last week.

Oh the overflow, I thought you meant the upper radiator hose.

As far as I know, it is relatively normal for some coolant to spill over out the overflow tube and its not (as far as I know) any indication that the engine is overheated. What does your temp gauge read when this happens? Also, what other things do you notice that may be a symtom of overheating?

As for the overflow tube, you can connect the other end to an overflow tank and then you won't drip it all over the place and it will get drawn back into the system when more coolant is needed.

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'66 Dodge Dart

pretty much looks like an old Stanley steam car when it over heats. hahah like a few quarts boiling over. curently doing an engine flush. I took out the brand new thermostat I had put in and tested it at 180 degrees which is its temp and the bastard didn't open! probably because of all the gunk in my engine clogging it so hopefully this flush will take car of that. will get back when I'm done.

Hehe, sounds like an interesting sight

Most thermostats (especially the cheaper ones) don't open exactly at their rated temp, its just a best guess. Also some open faster than others. So you may want to let it sit in some boiling water for a few seconds. Or if you have a generic one, maybe spend the $8 and get a Stant SuperStat 180F, you can get them at Pep Boys and possibly Napa. Also, others have had success with other thermostats, but I can't remember which ones, however I'm sure they'll chime in sooner or later.

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'66 Dodge Dart

Josh is pretty much right on with everything. Fasten some type of closed container down along side the radiator and put the end of the hose in there so it will be drawn back into the system as it cools.

I think you have to install the right type of cap to do that because I don't think all caps are bi-directional. Not sure on that part but I'm sure someone will correct me if I'm wrong.

You get pretty much what you pay for in a thermostat. Even if you get a good one, put it in a pan and boil it before putting it in to test it. I know sounds silly but which is easier? Boiling a pan of water or draining the system and pulling the thermostat again. I've seen a lot of crappy thermostats.

Another thing. Does your gauge or light actually indicate that it is overheated?

Dennis

Just a note about the coolant overflow tank. You can normally find tanks in junk yards (or possibly new from Chrysler?) that have a hole and hose barb thing in the bottom that your overflow tube will fit nicely. And as far as I know there is nothing special about the cap.

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'66 Dodge Dart

Actually, valiant, you are correct. The old original cap on cars not equipped with a "puke" tank only work one way. They cannot draw fluid back into the system after they "puke". You can recognize them because they only have one gasket on them and the cars with tanks have two gaskets.

The newer caps will work on both systems.

That being said, you might want to check the radiator cap and make sure it is good. It is an important part of the system too. The cap pressure actually raises the boiling point of the coolant by 45 degrees F. so if it is not doing it's job, you could boil over prematurely.

this radiator is still giving me the same problems even after the flush and new thermostat. in debating just taking the thermostat out and not replacing it. I don't know what to do!

If your using a 180 stat, what pound cap?
Is it a new style double rubber gasket type so it will draw water back out of your coolant tank to eliminate any air in the radiator......hopefully you have retrofitted your system with tank and cap to run a 180 stat.....
I believe the original 60's engine thermostats were 160 degrees for the open systems.

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Aggressive Ted

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74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

Does the car overheat at low speed "around town" driving or at higher freeway speeds?
The radiator is likely partially plugged-up and may need servicing.
DD

i was also thinking that I could have a faulty cap. it overhears on longer drives like 20 or so minutes down the freeway or about 45 minutes in extreme temperatures. I did do an engine flush and a lot of gunk came out.

(I can't resist)

Are you sure it's actually boiling and overheating? If you are topping up the coolant right up to the brim each and every time, you are seeing nothing more than the normal burpout of coolant. The old systems do not get maintained brim-full, they get maintained to about an inch and a half below the filler neck, so there's room for the coolant to expand once it heats up. Once its proper level has been attained, it will stop spilling out the overflow.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

I'm glad you can't! Good to see you weigh in. Dennis