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Discussion Starter #1
Ok...I'll try to keep this short. Also, please keep in mind that this started all of a sudden with no changes or anything done to the car. I posted once before about my car blowing water out of the overflow. Alot of you gave me alot of helpful advice such as moving the fan closer to the radiator, installing a fan shroud, and installing an overflow tank, all of which sounds great and I will do. However, my car never overheated before and the fan spacing and everything else is still the same. The thermostat is only a few months old, and I even tried a new radiator cap. We went on a trip yesterday. It was only about 85. We were going about 70 mph and the darn temp guage was between half way and 3/4! In the past, it never hardly went past the first line (unless sitting in traffic), much less going half way....now it's up there at 70 and it's blowing water out! It's driving me NUTS!!!!! This is my only theory: The water seems to circulate VERY fast. So I think that the water pump is a high performance or something and too much for the stock 289. Either that or the impeller is slipping on the shaft at higher speeds. But still...it never did this before! Also, the car runs better than new...it's very smooth and very powerful (for a regular 289). There's no water in the oil or anything at all to suggest a cracked head. PLEASE HELP!
 

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Check & see if the thermostat is accidentally installed upside down.......that i'll do it! Also check the lower radiator hose, when they get warm, sometimes they will collapse causing a flow restriction.
 

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I agree with the lower hose theory. I had that on my 351C.
When the hoses get old they get soft and at Highway speeds can restrict the flow of water which will heat it up and cause it to puke. If you have a spring in the hose it is not a problem. But try to find a lower radiator hose with a spring in them now adays. I have yet to find one.
 

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I had the same problem a few months ago. The car would run fine at low speed, yet at highway speed I was overheating. It all started after I replaced the water pump. I have a stock 289 also.

I replaced the new thermostat with a 180 degree, hoses...even though they were new, distilled water and prestone at a 50/50 mix with water wetter....and still no improvement.

Finally I took the radiator out and had it cleaned by a good shop; and installed a Gano filter. The problem was FIXED! My car is now running cool again.

Also...today in Central Texas it's about 99 degrees +, and I just got back from a drive through the country (about 100 miles) WITH the AC on the whole trip...and it never got past the E on the stock gauge.

I'd suggest you have the radiator cleaned well, and put a filter in it. You'd be amazed at the amount of crap that old motors have in the cooling system.

Good luck,
 

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I to would check the radiator. I recently had about the same thing happen with my son's Jeep. It would not get hot in town but if you got out on the interstate before long the temp would creep up to the 240 range. I replaced thermostat, water pump, checked all the hoses, and even flushed the radiator. Nothing worked. I had discounted it being the radiator because when we flushed in there wasn't any rust or debris come out. Finally had a friend suggest putting a new radiator in which I did. Has not gotten over 190 since and that is with it parked in the driveway with the a/c on for over 30 min.
 

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Discussion Starter #7
That's just it...the radiator is new. Well, it's about a year or less old. It circulates great when idling...I mean it circulates really fast. That's what I can't figure out. Also, I have a spring in my lower radiator hose. I don't have one in the top, however. Think it could be collapsing restricting the hot water coming out of the motor? (See why this is so frustrating?) BTW, thanks so much for your responses...keep em coming...we'll figure this out eventually.
 

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Is it a constant problem or intermittent? Freeway only?

Have you made any timing adjustments recently?

Try a new sending unit for the gauge, no teflon tape on the threads.

What is the poundage of your radiator cap? Should be at least 13lbs.
 

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Sometimes your block will release a good sized chunk of a mixture of hardened water and oxidation and clog your radiator cause the coolant circulation to back up and cause overflows and overheating at higher speeds......

I had the same problem with my Bronco....only did it at higher speeds and uphills

I got a new radiator and bam!!!! nice and cool again!!!

DO run distilled water and coolant.....no solids in distilled water
 
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