flush cooling system- now overheating

bluegt500kr · Nov 29, 2009

I have a 67 Coupe with a 289. Have had few several years and has never even began to overheat. The coolant was looking like dirt so I thought I would flush and replace coolant. Ran the flush through, ran it a while with just water, drained and replaced coolant. Now, it's overheating. When it warms up, with the radiator cap off, the coolant is circulating through so I assume the thermostat is opening. Any suggestions would be greatly appreciated.

2+2GT · Nov 29, 2009

Overheating how? Needle at "H"? Coolant coming out of cap?

bluegt500kr · Nov 29, 2009

gauge going well above top 1/4 of range. doesn't boil over sitting at idle but does come out of overflow after driving. Definitely boiling. I did notice another thread that pointed to a lower radiator hose. When I flushed the system could I have gotten enough crud in the lower hose to restrict flow?

2+2GT · Nov 29, 2009

Nahh. Now the question is, did you get all the air out? When refilling a system, the coolant should be 1" below the seal ring in the cap.

5280/4 · Nov 29, 2009

bluegt500kr said:
I have a 67 Coupe with a 289. Have had few several years and has never even began to overheat. The coolant was looking like dirt so I thought I would flush and replace coolant. Ran the flush through, ran it a while with just water, drained and replaced coolant. Now, it's overheating. When it warms up, with the radiator cap off, the coolant is circulating through so I assume the thermostat is opening. Any suggestions would be greatly appreciated.

it seems possible that rust and other stuff could have blocked some passage ways. Maybe even the radiator. I run a gano filter and collect any junk in my system.

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bluegt500kr · Nov 29, 2009

I believe I got all of the air out. I pulled the upper hose and the water at thermostat housing is still very brown. I do think I will pull the radiator and have it reworked. I have no idea how old it is. I also noticed that the lower hose has no wire in it so I am thinking hoses replaced. There is a layer of rusty plaque on the the inner surfaces of both hoses. Can I pull the thermostat and run fresh water directly into the block to flush?

2+2GT · Nov 29, 2009

Why not just get a new spring?

I'd flush the cooling system any way I could. Have you used a cooling system cleaner in it?

bluegt500kr · Nov 29, 2009

I have used a cleaner. I did realize something that is interesting when I pulled the radiator. I believe my car has a 6 cyl radiator because it has LH lower/RH upper connections and the 289 radiators I have found in the NPD catalog are all RH upper and lower. My water pump is also a LH outlet and I can't find a replacement that is a LH outlet. Also, the fan shroud has both cutouts on the RH side. Not really sure where the P/O found these parts. Not sure what to do at this point. Any thoughts?

tx65coupe · Nov 30, 2009

Are you sure your car has a 289 in it and not a later model 302?

I have a late model roller 302 in my 65 and have an aluminum radiator with hoses on opposite sides like the 6 cylinder radiator to compensate for the reverse rotation water pump.

If you car is overheating now, I bet something is clogged or partially restricted.

2+2GT · Nov 30, 2009

bluegt500kr said:
I have used a cleaner. I did realize something that is interesting when I pulled the radiator. I believe my car has a 6 cyl radiator because it has LH lower/RH upper connections and the 289 radiators I have found in the NPD catalog are all RH upper and lower. My water pump is also a LH outlet and I can't find a replacement that is a LH outlet. Also, the fan shroud has both cutouts on the RH side. Not really sure where the P/O found these parts. Not sure what to do at this point. Any thoughts?

If your lower water pump inlet is on the LH side, too, then you are fine. The actual radiator is the same size for the 200 and 289, only the lower hose location changed. The six actually has a better design, with the hoses on the same side effectiveness is reduced.

bluegt500kr · Nov 30, 2009

? water pump

so if I keep the 6 cyl radiator with the LH lower outlet, and I want to replace the water pump, any suggestions on where to get a pump. All of the 289/302 water pumps are RH inlet.

2+2GT · Nov 30, 2009

bluegt500kr said:
so if I keep the 6 cyl radiator with the LH lower outlet, and I want to replace the water pump, any suggestions on where to get a pump. All of the 289/302 water pumps are RH inlet.

Nope. 70-up pumps had the inlet on the RH side. You sure that's not a conversion radiator? The 6 had a small hose connector, but you can get them with v8 sized connectors.

bluegt500kr · Dec 1, 2009

the outlets on the radiator are 1-1/2 on top and 1-3/4 on bottom just like a V8 radiator. It does look like there is a metal sleeve in the upper connector like a gano filter but without any kind of screen. Maybe the old screen is what's clogging things.

WORTH · Dec 3, 2009

bluegt500kr said:
I have a 67 Coupe with a 289. Have had few several years and has never even began to overheat. The coolant was looking like dirt so I thought I would flush and replace coolant. Ran the flush through, ran it a while with just water, drained and replaced coolant. Now, it's overheating. When it warms up, with the radiator cap off, the coolant is circulating through so I assume the thermostat is opening. Any suggestions would be greatly appreciated.

Is your lower rad connection on the same side as your waterpump now?

Are you running antifreeze now?

Are you leaving the fluid level down an inch in the radiator?

Where does the temp gauge run at idle?

Where does the temp gauge run at highway speed?

bluegt500kr · Dec 3, 2009

Yes, the lower connection is on the same side now. Yes, I am running anti-freeze now and the water level is about 1 inch below the filler neck. The gauge at idle will move to about halfway after about 5 minutes but moves 3/4 to the right after running, whether on highway or in town for 10 minutes. Before the flushing it never moved to even the halfway point.

tx65coupe · Dec 3, 2009

There may still be air in the system and the hot reading is from a steam pocket. It could also be that the sending unit has an issue with the connection or wiring.

You could try something like this to see how warm it is actually running. I have it an thinks its nice to have.

Micro Temp MT-100 - Spark Industries Micro Temp Digital Infrared Pyrometers - Overview - SummitRacing.com

bluegt500kr · Dec 3, 2009

I will check with infrared thermometer. It's definitely boiling in radiator but I'm not how hot the engine is. What is the best way to get any air out and is there a way to know if all of the air is out of the system?

tx65coupe · Dec 3, 2009

From my experience, usually after driving it a few times, the air in the system will burped, for lack of a better word, out.

WORTH · Dec 4, 2009

I haven't been on the boards in awhile so I'm going to introduce myself just so you don't think I'm your typical Internet nutcase. ( I'm a special nutcase) I'm Eric I retired from my own auto repair shop about 4 years ago, I specialized in radiator, heating and AC, as well as doing general mechanics on the rest of the beast. At present I own a 65 ragtop,a 69 coupe, a 46 pickup and my daily driver is a 65 F-100 that I just put 4wd in.

Now back to your cooling dilemma, Just a couple of routine facts to get you started.
If you have an overheating problem it's because you are producing more BTU's than your cooling system can get rid of.

there are a number of things that can simulate overheating and get you to chase your tail for days.

Make sure the system is tight, any leaks can lower the pressure in the radiator and cause it to boil water.

Do a pressure test on the radiator cap, a cap that leaks pressure will allow the water to boil.

make sure your heater works, a lot of engines need the water to circulate threw the heater to properly circulate threw the engine block, if the heater is clogged it could cause water to boil.

BONUS; temp gauges can not be trusted, if the gauge goes up to a certain point and stop rising there is a very good chance you are not overheating. If you were making more BTU's than you could get rid of the gauge would keep climbing until it pegged itself at the top.

Check those little things and see how you make out.

rsweld · Dec 31, 2009

I had a similar problem,after completing the restoration of my 65 convertible, new water pump, thermostat, radiator and hoses I flushed the block and then the 289 immediately began to over heat. being stubborn I couldn't believe that the brand new radiator would be plugged so I pulled the heads to check for a head gasket problem, everything was fine their. After beating my head for anothe month trying to solve the problem my Wife convinced me to pull the radiator and take it to the radiatorshop to be rodded, guess what the raiator was plugged solid with rust. Apparently after flushing the block, rust deposits continued to break free from the block and plugged the radiator. I now run a Gano Engine Coolant Filter in the retrn hose between the thermostat housing and the radiator. I clean the filter once every 2 months an have solved the overheating problem, infact the temp gage now will only move to the first line no matter how much I drive it and here in south Georgia it gets well over 100 degrees in the summertime.

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