1976 Dart Overheating and other issues

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As stated many times here, "One change at a time" that way you know if it was good, or bad. If bad, revert back to original & try something else on the list.
 
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Thanks for all the feedback, I look forward to tinkering with the car this weekend and report back here.
 
Well, I decided to get outside and work on the car. I flushed the radiator and flushed the block best I could till it ran out clean water. Lots of crud and sand in there. Here is what the thermostat housing looks like. I’ll leave it soaking in wd40 overnight probably and clean it out tomorrow with simple green. I hope the car runs cooler once all is said and done. I also picked up new Continental upper end lower rad hoses and stant 195 thermostat. Scraping the old gasket off now.
Does the felpro thermostat gasket require sealant?

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Good job.

Gaskets generally don't get sealant.
Sometimes a dressing is used to help hold in place during assembly. Indian Head Shellac, Hi-tack, and similar named products.
However...
If the sealing surfaces are badly corroded, then gasket can't conform. So then it may be neccessary to use a form a gasket or similar RTV.
Hopefully you don't have to go there.

Tip: With copper radiators and relatively open coolant systems (the recovery tank is still open to atmosphere), the best coolant is 'conventional' green. Theadvantages are that the corrosion inhibitors in the 'conventional' green work right away, and they protect solder and copper reasonably well. Universal coolants, regardless of color, are hybrid organic anticorrosion technology. They require time to build up and become effective, and even then are not usually great in protecting solder an copper.
 
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From the look of the thermostat housing, the radiator is certainly plugged. The water pump impeller may also be gummed up.
I would do a general overhaul on the complete cooling system:
New or recored radiator
New thermostat
New-replacement thermostat housing
New upper-lower-bypas-heater hoses
New water pump
If you plan to use the heater, new heater core
 
A ton of great advice offered here. heres something i learned a while back, its on a newer jeep but very similar.
Overheating on warm days at about 20 or 30 miles driving.
Thermostat, fan clutch, water pump and flushed multiple times. same issue. Rad was plugged. Like totally blocked.

The telltale,was when it was getting way up on the gauge, the air passing through rad should be extremely hot. Its wasnt. by placing my hand (away from any moving parts) in the wind that the fan generated it was unusually cool for such a hot engine. After solving the problem, i cut the rad open.
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I need to add, you will need to do a more aggressive cleaning.
Heavy duty rad flush, and lots of flushing.
 
Lots of good advice here. I too see that thermostat housing and would think that the radiator is plugged. Radiator shops are few around here and expensive. Probably cheaper to just buy a new one (bought larger 22" Air conditioning one for mine for 180). That said, I wound not replace it or have it rodded until I was sure all that crud was out of the block. Might be best to pull the water pump to do part of this. I've read of people using vinegar or dishwasher soap to clean cooling system. Might look into that. I'd also rig up a strainer (try McMasterCarr)on the the input hose until it is clean. Dont want to plug a rodded or new radiator.

Another non cooling system issue not mentioned yet could be the heat riser.
 
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dunno if its been said but if you still have problems after flushing, the radiator may be clogged. the fins clog with rust and sludge. either replace or find a shop that will recore. if you wanna get crazy have then put triple core in it. those lines between the fins are small, they clog,and back in the day when they leaked they were eliminated by ctutting them off and soldering sht at the tank etc. i agree the radiator looks at the least old and rusty. do all of the other stuff first if it still runs hot go after checking the rad out good.
 
Yuck! That t-stat housing says a lot!

Imagine that through the whole cooling system including the passages in the block and head. Without getting too much into it, I'd drain and flush then drive for a few days with some radiator flush.
Then, your rad is definitely restricted and needs to be rebuilt or replaced.

New water pump, hoses (formed, not those cheesy convoluted universal ones) 50/50 mix of green Prestone (unless you go with a new aluminum radiator) and you'll be good for a long time.
 
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Really really great advice for a newbie, thanks to you all.

Here is where I’m at. After posting the pictures last night and letting everything soak in degreaser, I cleaned all the gasket material and a wire brush to clean out the thermostat housing. I added pictures of the result. I think it came out good. (Image 1-3)

Fast forward to now, I purchased Continental molded hoses, superstar 195 thermostat, a felpro gasket, Ideal SS hose clamps. I’m working on a real tight budget. So my goal is to see what I can work with before ripping things out and replacing.

I idled the car and topped off the radiator once the t-stat opened. All looked well and I went for a drive, which turned into a one hour drive! I’m very happy. The needle sat just below the middle mark the entire time. (image 3). About an hour after driving I pulled over and let the engine idle 10 minutes to see if the temp would rise it didn’t move from just below middle. Drove back home and all well!! No leaks or overheating at all.

However, once I shut down the engine l and let the car sit, since the is no airflow, the temp gauge went quite high in my opinion (Image 4). Please see picture below. When I start up it will drop right back down to just below middle.

So overall I am pleased I can at least use the car. I’ll be saving up now for a new radiator and water pump. Hopefully those will be in by March/April.

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This is probably dumb, but what about filling it with evaporust then letting it set for a few days?
 
Yes its normal for the temperature to rise after shutdown.
Or don't believe. Go get a '76 owners manual and see what it says.
This from page 10 of the 1975 Plymouth Valiant Owners Manual.
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PS. Look carefully if using Prestone. Last I checked they are not selling an IAT but a HOAT.
 
Update: ok well think the radiator bit the dust. Car runs cool so I think the flush and new thermostat made a huge improvement, but now the radiator is leaking. So I’m looking for a new radiator and will also put in a new water pump.
Don’t need anything like those BeCool($800??). My car is stock slant six. Just need it to be dependable.

Read up some positive reviews on Champion radiators and their American Eagle line. Considering this brand. Only problem is can’t figure out how I know what radiator is in my 1976 dart. 19” or 22” is what the manual says. Does anyone know? I only see Champion providing a 26”. I’ll have to call them. Also, there looks to be a transmission line running into the radiator at the bottom. Is this what is referred to as a tanscooler?

As for the water pump, any recommendations? I read a thread about no need for a high volume pump (flowkool). Any quality brand recommendations?

as stated before I’m just working with basic tools and don’t want to modify anything. Just replace and make the car very reliable.
If anyone has any other recommendations for something solid on a tight budget I’d love to hear them. Thank you.
 
Check with Cold Case also, they are a vendor on the site.
 
Do yourself a favour and get some heavy duty rad flush and do it before you replace rad. You may want to prepare yourself for heater core replacement in the future. Its likely not much better than the rad.
From what i see in your photos i can only assume it had water in it for some length of time.
 
This is probably dumb, but what about filling it with evaporust then letting it set for a few days?
White vinegar, drain the radiator and top off with vinegar, start it up just enough to warm up the radiator to the touch.
Let is set for a week or so, drain and flush out with clean water.
Be warned the last one I done like this, dislodged some stop leak.
So the radiator went to the shop anyways, but it was really clean on the inside.
 
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