overheating troubles

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Jul 14, 2008 | 06:48 PM

76EconolineND

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overheating troubles

Hello. Ok here goes. I was driving my 74 f100 2wd with a 302 home the other day, cruising at 65-70. I always watch the temp gauge, habit, and for a while it was dead center of the gauge. All of a sudden the gauge pegged out and I pulled over. The overflow hose was spraying like a damn pressure washer. but it looked like it had oil in it. so I let it cool off and limped it home. Drained engine oil, looked totally normal. Checked tranny fluid, looked a little burnt and almost watery but not milky either. i also pulled the spark plugs and they looked great. What could have caused the sudden over heat? Could a tranny line have cracked in the radiator or something? What should I check for? I don't know where to go from here. Any tips will be appreciated. Thank you

Jul 14, 2008 | 07:15 PM

BrentNewland

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Not sure if your radiator has a transmission cooler inside or not, but it's possible. I believe the proper steps here would be to pressure test your coolant system and radiator cap. If your cap was bad it could cause the coolant to boil which would raise the temp; if your (possible) tranny cooler broke then I could see the same thing happening.

But a pressure test should narrow it down.

P.S.: you might want to put your truck in your signature so you don't have to repeat yourself each time you post a new topic - saves some time for you.

Jul 14, 2008 | 09:02 PM

76EconolineND

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First thanks for the advice on the sig, never thought of that. And it does have the trans cooler built into the radiator. Is it possible that the trans cooler cracked and leaked into the actual radiator? I put a new water pump, t-stat, and radiator cap about two and a half months ago. Also Where can I get a rad for less than $200? Thanks again

Jul 15, 2008 | 12:03 AM

BrentNewland

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Definitely possible; a failure (besides destroying the transmission) would let the antifreeze depressurize through the transmission (the transmission doesn't have a pressure triggered cap, but I believe has an open hole for the dipstick). If it started to depressurize, it would lower the boiling point, which would make the coolant overboil, which would overheat the car.

A pressure test, again, should confirm.

*oops, forgot about the issue at hand*

I say install an aftermarket if you don't mind the non-stock look.
http://www.performancebodies.com/sto...sp?dept_id=530
not bad prices.

You can see a pic of an aftermarket here: https://www.ford-trucks.com/user_gal...=16901&width=0

Jul 15, 2008 | 06:02 PM

73f100shortbed

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Joined: Oct 2005

Posts: 3,034

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From: NJ

I got my rad. for my 73 302 at Autozone for under $200

Jul 15, 2008 | 06:38 PM

Thunderjet4x4

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Joined: Apr 2003

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If nothing obvious shows up, you may have to check your Thermostat, even although it is new-they can still fail.
1-A tip from an old mechanic friend said to "cycle" a new thermostat by pressing it open with you fingers-just once! That way they are less prone to stick the first time after sitting in a box for who knows how long.
2-Another thing I usually do, if there is no bypass hole in the thermostat(some don't have one) is drill a 1/16" hole in the flat part/side for air bubbles to remove themselves.
3-I even boil mine on the stove, and check the opening rate/temperature with an old candy thermometer to make sure the little buggers work.

I've had some odd overheating problems before, and this may seem overkill, but I have used those 3 steps since, and have had no problems for a long time-provided the rest of the system is good. knock on wood!

I have used the more expensive stainless steel versions, and they did not seem any better. Now I just replace it every few years.
Good luck-let us know what you find!