just a simple question, but it may show my ignorance with mechanics. I have a 1978 F150 Ranger with a 351 M in it. My problem is it blows off steam after just about every trip - 1 mile to 50 miles, doesn't matter. I have replaced the thermostat and am about to take the radiator off and have it "superflushed" (ie boiled, etc) at a radiator place. The truck had been sitting idle and used only intermittently for about two years, and though I didnt have any problem initially with the overheating, I figure the radiator may have some corrosion in it. Once I get that back and put it in, along with new hoses, I am hoping it will fix the problem. If it does not does anyone have other suggestions? Also, my temp guage doesnt work on my dash and I was wondering if that has any effect on the overheating?

 

Be sure to put a new cap on.
Dave,
79 F-150 4x4, 390 w/C6, Edelbrock carb, 33X12.50 never will be finished.

 

The thermostat may be sticking, replace it when the radiator is out. The temp. gauge has no effect on the operating temperature.

Barry

 

But put a temp guage on there, fix yours or get one. If you overheat your engine to the point its boiling over, you are possibly doing severe damage.

chris
79 F-150
79 mustang

 

agreed, get a gauge. I have a rebuilt 400(5k miles)tried everything to get a cooler idle, running temp. turns out The carb needed metering. If you have a stock motorcraft, try a kit. check for vaccum leaks that could be leaning engine out and cause expensive damage
you'll get there, keep truckin'

https://www.ford-trucks.com/dcforum/User_files/3a9df0394b631ce6.gif






77'FORD F150 XLT 400

 

 

I have a problem with gauges not working. Any chance someone out there can give us some advice on tracking down and fixing the problem? Water temp gauge especially. Thanks, Jim

 

I waited 2 years replace the sending unit, it was about$4, took five minutes, my gauge has worked ever since

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77'FORD F150 XLT 400

 

The temp. gauge works exactly the same way as the fuel gauge (and oil pressure gauge). Turn the ignition switch to acc. and ground the lead that goes to the temp. sender. The temp. gauge should peg out on the “hot” side.

If you want to check the calibration of the gauge you need to go to Radio Shack and get some resistors. Ford specs. out 10 ohms for “Hot”, 22.8 ohms for “Mid” and 73 ohms for “Cold”. Some of these are not standard values so you have to fudge a little, the gauge won’t know the difference. For the 10 ohm, get Cat. No. 271-080 10 ohm 2 watt wirewound. For the 22.8 ohm get Cat. No. 271-1103 22 ohm ½ watt carbon-film. For the 73 ohm get Cat. No. 271-1106 68 ohm ½ watt carbon-film. Now turn the ignition switch back to acc. and take the lead that goes to the temp. sender and connect it to one side of the 68 ohm resistor. Take the other end of the resistor and ground it to the engine. Give the gauge a little time to respond, the needle should rest close to the tick mark by the “C”. Now do the same thing with the 10 ohm resistor, the needle should now rest close to the tick mark by the “H”. With the 22 ohm resistor the needle should be midrange.

If all your gauges are acting funny you need to back up further and replace the instrument voltage regulator which is screwed onto the back of the instrument cluster. The screw grounds the case for it to work properly. Usual symptoms are no readings or all gauges reading high.

Barry

 

Thanks for the advice. I guess it's time to get under the dash and figure things out. I am encouraged by the apparent ease of the quick fix (replace gauge), and I am greatful to learn the tech side of the fix, too. It's a good feeling to know that there are folks out there willing to help those that are eager to learn.

Thanks again,
Jim

 

yeah, thanks guys. I also appreciate the good advice and will try it out on my temperature guage. I recently got my radiator back and they had boiled it, repaired the core, flow and pressure tested it, repaired a small leak, and soldered on the the mounting bracket for $65 and the guy told me if at anytime within the month I thought the radiator wasn't flowing well I could bring it back and get the $65 towards a new one - which goes for $145. Nice guy -real straightforward. I asked him if there was any indication when a water pump was going and he said only if it were leaking. In twenty years of dealing strictly with cooling systems he had only seen two water pumps not working because of internal problems. They both were due to the truck or car sitting too long (5 or so years) and the pump being corroded to the point of no return. When I asked him about a coolant he said they all were pretty much the same and to just get one that is enviromentally friendly - and he wasnt the type you'd expect to be pitching that.
I went to Autozone and got a 160 and a 180 degree thermostat and will put the 180 degree one in tonight - along with the radiator. I think the one I put in before was a 195 or so. I'm going to go back tonight and get the temp. sending unit, put it all together and pray for the best. Wish me luck! And thanks again for the replys...

 

Put the radiator in last night, with a 180 degree thermostat, new hoses and filled it 50/50 with coolant/water. Ran it for about 10 minutes in idle, about five minutes of that with the cap off. Everything was fine. Then I took it ten miles down the road, parked it and it started overflowing out of the tube. Let it sit for awhile then brought it back, thinking I may have filled the fluid level too high. It didnt overflow or steam when I got back, but the fluid in the radiator still sounding like it was boiling. Went to tinker around it at lunch today and found a small leak from the bottom hose, at the attachment to the water pump. I hadnt tightened the clamp enough, so I did that. Then I ran it again in idle with the cap off, just to see the flow and to see if the thermostat was working. It ran fine, the flow was good, and the fluid didnt get too, too hot. Just have a few questions though:

1) how much fluid should be going through the hoses once the thermostat has opened? I was pressing each hose together with my fingers and it didnt appear as though a whole lot was going through, although some definitely was.

2) i feel ignorant for asking, but I will anyway: What direction should the fan be blowing? Right now it is blowing towards the engine. My roommate say it does that to cool the engine block. I figured it was there to cool the radiator core, so the fan should be switched around.

3) and where exactly would a temparature sending unit mount on a 351M with a manual transmission?

Thanks for your help...

 

pull the thermostat out, began to boil some water and make sure you have a candy thermomitor and place the thermostat in the pot w/ the thermomitor. it should open around 180. if not replace w/ new one. you might also want to disconnect the heater hose and by pass the heater core to see if this helps cuz your core might be clogged a bit and restricting the flow, if you get better flow replace the core. make sure you take the inlet hose off the core and run it to the water pump. hope this helps a little.

 

i should add that if you can't get a better flow you might want to consider replacing the pump as this was sitting for a few years. i don't know if this would work, but to get an idea as to what temp you are running at you can stick the candy thermonitor in the radiator, i have never done this, but i don't know why it would not help.

 

You didn't say if you replaced the radiator cap. If the spring is weak, or it is a low lb cap, this will not let you fill the radiator very full. I would ask the radiator guy if it would be ok to put a 15lb cap on. This will help eliminate the tendency to overflow after you turn the engine off. If he says your radiator is a little too old for a 15lb cap, then the best solution is to run a recovery cap and bottle and you can get by with a cap as low as 7lbs.