Remove the thermostat, filled with water, and drove it 300 miles when i first bought it. It still got hot going uphill.

Fast forward to today. I have replaced the thermostat with a motorcraft one, flushed the system with prestone flush for like two weeks, and removed the radiator for a 9 hour vinegar soak. I then flushed the radiator with baking soda and distilled water, backflushed it with a garden hose, and reinstalled it.

The radiator was able to flow all of the water my garden hose could provide without any pressure, so I figured it was still okay. Although the radiator shop told me it was junk based off of age and the white corrosion visible beneath the cap.

I have also replaced the cap.

The temperature (stock gauge) will go to center and then slowly but surely climb up from there. It doesn't matter how I drive it, she will climb and then stop at like 7/8 of the gauge sweep. The check engine light will flicker on and off. Does the check engine light run off of a different sender/switch? because that means I really do have an overheating issue.

Thanks
-Matt

 

The check gauges light is a seperate sender yes. Is there still noticable buildup in the radiator? If the fan is locking in and the bottom of the radiator is hot your radiator is fubar.

 

I don't know about the fan, but seeing as it gets hot at highway speeds, I'm pretty certain the fan is not the issue.

Earlier today I noted that once the engine got hot, the upper hose was warm (not hot) and very, very stiff. Trying to squeeze it was like squeezing a rock. The lower hose was cold to the touch.

Given that the upper hose wasn't hot, but it was pressurized, I'm guessing that the radiator isn't flowing adequately. Which is odd, because it flowed the garden hose just fine.

It may have clogged back up once i put it back in the truck.

 

Get a hold of a non-contact IR thermometer. Get the whole thing (engine, radiator) up to temperature, and "map" out the temperature of the radiator. If large ares of the radiator are cold, and some areas are hot...well, you get the idea.

Often a plugged radiator will show when your on-the-road temp drops a bit when you turn the heater on.

I the radiator checks out, I would pop the water pump and look at the impeller.

BTW, you need a new radiator guy.

Roy

 

If the top hose isnt HOT then youve got water pump or t-stat issues. But before throwing more parts at it, i would check to see how hot the engine is actually getting. Doesnt sound that likely being pressurized like youre saying, but make sure the lower radiator hose isnt sucking shut.

 

Ya What he said^...Check the lower hose for a spring...should have one...

 

My '91 F350 has a flickering temp gauge that says it runs overheated, and check engine flickers when the gauge flickers.....I know the engine isn't overheating at all. Just a ground issue somewhere.


Put a real gauge on it first, to make sure, never trust the dash gauge in these trucks, their garbage.

 

Sounds like a suck t-stat. Could be the impeller but not to likely. Also the radiator should of been rod-d out to clear all the tubes correctly. But I don't think that would cause a cold bottom hose and only warm top hose.

 

Of the two radiator shops I spoke to locally, one said they don't rod out radiators anymore (they only re-core), and the other said that with the amount of corrosion and the age of the radiator, it wasn't worth rodding out. The second guy recommended a re-core ($775).

But I can get a "Spectra Premium" radiator through Autozone w/ lifetime warranty for $300 w/tax. Then scrap my old one for the $50 or whatever. Not a bad deal, but I don't want to replace the radiator and still have an issue.

The lower hose is not collapsing. The thermostat is likely not the problem, because as I said before, this rig still got hot going uphill when I had deleted the thermostat for the cross-state trip.

I also have done a cooling system pressure test. It lost 1-2psi in one hour. So I don't believe it's a bad head gasket.

I think the plan going forward is to order the Autozone radiator as well as a new pump, and tear the cooling system apart in the mean time. Strip out the thermostat (boil and test), remove the water pump (visually inspect), flush out the block as good as I can and see if I find any smoking guns. If not, I'll just install the new radiator and pump and be on my merry way. I can return the radiator and water pump if I don't end up installing them.

I have no reason to suspect the gauge, and I can't find someone who will let me borrow an IR gun (cheapest I can find to buy is $60!). The behavior it exhibits is perfectly in line with an engine that slowly gets warmer. Also, the gauge and the check engine light are in agreement once the engine gets hot, and it's not an obvious electrical fault.

Thanks guys, we're going to put a cork in this.
-Matt

 

Maybe Radiator, but I would check my water pump, sounds like the water pump is not circulating the antifreeze adequately into you engine. GOOD LUCK !!!

 

the truck running hot without a t-stat and full of water is normal because the water will not cool as good as coolant, and with no thermostat the water will just fly rite through the radiator without properly shedding it's heat.

 

+1

WP check costs nothing, doesn't take long.

Amazon has a Pyle for 30 bucks:




I also agree, results obtained while running w/o thermostat are hard to interpret.

Roy

 

No t-stat will overheat. Water will boil over at normal operating temp without a cap. I would check out the champion 3 row aluminum on ebay. Cheap and looks good.Ford 1983 1994 F250 Pickup Truck 3 Row Aluminum Champion Radiator | eBay

 

All evidence points to a bad water pump.

 

^count me in on starting here 1st.learn what the water temp really is,is the only logical place to start.
start with trusting old gauges (ball park idiot lights on a needle) that had very little meaning when brand new is a poor foundation.