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Discussion Starter #1
Hi All,

I picked up a 66, I6 coupe in Oct. It needed a water pump when I got it. I replaced the water pump, hoses, heater core and thermostat(160 degree). The radiator looks "new", but the car sat a few years before I got it. Seems it was parked, not stored(I had to replace gas tank too). Anyway, I took it out today. The temp guage was reading to the low side of the middle. When I got out of the car, I heard a slight "hissing". Before the winter I noticed a little coolant on the garge floor, and some coolant in the overflow tube after drives. Is this as simple as a bad radiator cap? or do I need to look deeper before the summer rolls around? Also, I did not put a spring in the lower radiator hose. The vendors I checked out, list a radiator hose spring for a small block, does that fit an I 6 too?

Thanks,
George
 

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Coupla things. The engine was designed to run it's best with a 190° thermostat, the 160 will sludge the oil and reduce hp and gas mileage.

The radiator should be filled cold 1" below the seal ring under the radiator cap. Any higher than that, and it will just go out the overflow hose.
 

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I would sure look at the lower radiator hose spring. Mine would suck shut just when I revved the rpms up when I was working on it.
I agree on the higher thermostat.

Good luck
 

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Yeah, you can buy hose springs if yours is missing.
 

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Don't mean to insult you but if its overheating a problem could be that you put your thermostat in backwards. I am sorry to admit that I made this mistake and it almost cost me big time. The spring points into the motor. It's a mistake that once I thought about it should have never been made, but it happened, that's the learning curve in this business haha.
 

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If you fill the radiator up coolant/water will over flow until it reaches that sweet spot, about 2 inches below the top of the radiator , and after that no more overflow. I put on a after market overflow recovery system and run a 180 degree t-stat with no problems.
 

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"Coupla things. The engine was designed to run it's best with a 190° thermostat, the 160 will sludge the oil and reduce hp and gas mileage."

Original Autolite Thermostats in '65-'66 6cyl Mustangs were 192 degrees to be exact....Trucks got the 190 degree thermostats...just some vintage info on I6's...

If you hear "hissing", You have a pressure leak somewhere...Most likely a bad radiator, or a bad radiator cap. Check the whole radiator for "white spot" leaks... If you see an abundance of white...There is your leak. Upper and lower hoses can leak too, so check those as well....All in all, You have a leak somewhere..

PS: Running in NJ, You should be using a 180 degree thermostat year round.. It is more than sufficient.. I would only recommend a 160 thermostat for someone living in Arizona, Death Valley, CA, or Texas.

I'm formerly from NY, and ran a 180 degree for 20+ years with no issues..at all.. 160 is way too cold for NJ....It would take like 20+ minutes for your car to warm up...

I don't think that the I6's ever came with lower radiator hose springs originally. Only the V8's....and not even that is for sure, not that it would ever hurt.

PPS: If you hear hissing, That's actually good. Follow the "hiss" with your ears. It will lead you to your leak, and your problem.


Tony K.
 

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My son and I restored a 66 coupe as a father-son project a couple of years ago. We rebuilt the entire drivetrain, as well. The radiator was replaced, heater rebuilt, new hoses, new thermostat and so on. It is a factory A/C car, as well. It is the 6 cylinder with a 3 speed. It runs hot even with a 180 thermostat. I changed out the factory fan blade and that has helped. But the bottom hose did not have a spring in it, so maybe I need to add one. Where can I buy one of those? Anybody have a part number? The A/C cannot be ran in town or the engine will overheat. If we're going over 40 mph, we're fine with it. If the A/C is not running, it just runs hot in town. I was thinking of adding a bolt on aftermarket electric setup that can be easily removed for the shows.

Al
 

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With A/C, It should originally have had a big bladed "5-Blade" fan originally. Later 200-250 I6's came with a "6-Blade" big blade fan sometime in '68 thru '70 for the I6's. They repro the later fan, I suggest that you pick up the correct Ford "6-blade" fan. You will need it with A/C. They even sell a fan shroud that you can use with the six banger radiators as well. That will also help your situation. *Also try using the CMB aluminum Water Pumps (Part# 125-1290) sold through Jegs and Summit and Ebay. They are high flow for the I6's and run way cooler and have a later high flow impeller design. You also live in Hot Arizona, Try using a high performance 160 Degree thermostat like ones from Robertshaw or Mr. Gasket (They are made by the same company). Do all those things..and you will run as cool as you can.. The very last resort is an aluminum radiator.
Also, If you are running with an original Ford compressor, They have lots of friction and drag, If the problem persists, You may want to think about going with a more modern non-friction, lighter Sanden compressor. They are great, and a workhorse! Those hose springs can be bought at any autoparts store.. Try NAPA as a start.

Can't think of anything else!
 

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Yep...had that 5 blade fan with the shroud. Will that 6 blade fit the 66? I'll check out some of the Mustang supply shops. I'll get the water pump, as well. BUT I live in NORTHERN Arizona at 7,000 feet...high desert. Right now, I have 12" of snow on the ground and it is 8 degrees outside. During the summer, we average around 75 to 80 degrees but can get to 100 a few weeks out of the year. I can definitely tell the difference in horsepower driving the 200 miles to Phoenix which is at 2,000 feet. Much more get up and go down there than up here! Much hotter, as well! Thanks for the suggestions. I'll get it all done over the winter while she is in storage!

Al
 

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PS: Don't forget, If you are changing your water pump, Don't forget to remove the Hex headed threaded rod that goes in the top of the pump. I can't even begin to tell you how many people throw out the old water pump without removing this small hex headed pipe, only to realize that later on they are screwed without it, You need it for the new water pump...You just transfer the pipe outlet from the old pump to the new one. *Also, If your old pump has original date codes/part numbers stamped into it, You may want to save the old water pump for a rebuild someday also.
 

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Good advice about the heater hose pipe Tony..

I just wanted to add that I've never used a spring on my radiator hoses. I'm not saying it isn't good advice, it's just that I've never had the need.

I run a 180-deg thermostat in my cars.
 

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Discussion Starter #13
Thanks

Thanks for all the great advice, I'll have a look when I get a chance. I did mistype one thing, I put in a 180 degree thermostat, not a 160. So, it's not what it called for, but closer than 160.

Since it sat for a while before I got it, I'm going to change the coolant again in the spring. Then I'll add the lower radiator hose spring, and probably change to the 190 thermostat. Will not fill it up so high on the coolant either. The radiator "looks new", I see no leaks or white stains on it.

Thanks again, this forum is #1.
George

PS. to 22gt, I keep trying to get out to the place your always recommending to pick up a leaf spring kit. "Stuff" keeps preventing me from making the trip. Guess, I'll have to phone in an order.
 

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Discussion Starter #14
i6 rad hose spring ?

Hello again,

Last night I emailed a Mustang parts place about the rad hose spring for the i6, here's what they said...
"The EG-4761 lower radiator hose spring will not work for the 6cyl hose because of the size of the hose vs. the spring. Our manufacturer tells us that the material that the new hoses are made out of these days will be able to hold up to the pressure. Currently no one makes the spring for the 6cyl"
 

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Hello again,

Last night I emailed a Mustang parts place about the rad hose spring for the i6, here's what they said...
"The EG-4761 lower radiator hose spring will not work for the 6cyl hose because of the size of the hose vs. the spring. Our manufacturer tells us that the material that the new hoses are made out of these days will be able to hold up to the pressure. Currently no one makes the spring for the 6cyl"
The 6 lower hose is smaller than the 8, but it should be possible to get it in there, with a little effort.
 

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"Currently no one makes the spring for the 6cyl"

..That's BS.

*Also, That Repro Ford 6 blade fan will bolt right onto your fan blade assembly. The mount holes are the same as your old 5 bladed fan. They used the 6 bladed fan on various 200 and 250 cid engines from '68 to '70...not just A/C cars only..
 

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Discussion Starter #17
Hey Tony,
What can I say, that's what they emailed me. I'll look around for the rad hose spring.
I see you were from Long Island, where about? I was too. I lived in Bellmore, (Nassau County) for about 5 years, before moving to NJ for a job.

Thanks again,
George
 

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I lived in the Babylon/West Islip area. I graduated from West Islip High School in 1988.. Those were the days... Drag racing over Robert Moses Causeway Bridge doing near Nascar speeds...routinely with my buddies back in '87/'88. I was out of my mind back then. I guess all 17 year olds think they're invincible...lol.... One Blow out, and I would have been done for... I do remember buying decent tires though...lol.. I remember one time, I was dragging my '69 Falcon 2door hdtp with a 302..against a friend's '85 IROC-Z, .and I was going so fast and I had the windows open, and air caught under the headliner and blew it up like a balloon, Boy was I surprised.. I just kept on driving.....and laughed about it later...The headliner bows went back in place and did'nt even ruin the headliner...I was shocked. Man could that thing move...!! I remember slowing down was always a problem...All drum brakes...lol...

I'm a lot slower these days.. If I hit 100mph.. I'm on top of the world!

Stay safe....Drive slower....of course unless you really get the urge to Drive fast! Do it in a safe environment.. That's all I mean... Make sure it's a dead road with noone around for miles.... except that cop hiding in the bushes of course...lol...!!!!!!!

Today, I'm lucky if my Speedometer hits 85 on I-95.....Ahhh, Getting slower with age I guess..lol..
 

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Discussion Starter #19
LOL, looks like I have a few years on you... I went to SUNY Old Westbury, graduated in 1986. By that time my first car, 66 springtime yellow sprint Mustang was gone(it was a 16yr old car when I was 17. lol). Had a 76 Cutlass S. I used to drive down the Wantaugh parkway to Jones beach(in the winter), scouting for troopers, then on the way back north open it up to 100+. As you, I wouldn't think of doing those things today....

Thanks again for the tips. This wasn't the first time you've answered a post of mine.
 
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