Hey all, I finally finished the lion share of the work to get my 67 truck back on the road and while driving back from the muffler shop I saw the temp gauge was on H and not moving down. Fortunately it was really close to home so I made it back without actually overheating.

My first thought was the radiator wasn't working, I had removed it during the rebuild but didn't take it to a shop to be flushed. My friend thought maybe the thermostat wasn't working, I did replace it before reinstalling the pump...although the part is probably from china so who knows. When I removed the pump originally there was a metal on metal sound so I opened up the back of it, rusty blades and back plate. I cleaned them as best I could and closed it back up and reinstalled it.

I let the truck cool down and then opened the radiator cap to check the water level...full. I opened the valve on the bottom of the radiator to drain it down a bit to see the ports on the top of the rad looking for any major obstruction...none found. Should I be encouraged that water actually drained out the bottom??? Then I filled it back up and left the cap off and started the truck and let it warm up, I checked the temp gauge regularly and it continued to climb back to H. The hose coming off the thermostat to the radiator was hot, when I rev the engine there appears to be a small flow of water in the radiator from the view I can see without the cap on. The return hose on the bottom of the radiator was cool...I squeezed the hose and felt a slight pulse as the truck was revved but it never warmed up as I would expect it to.

I shut down the engine, loosened the alternator and removed the belt and free spun the fan. There is a slight raspy noise like some metal on metal, maybe bearings? I read online about water pumps failing and how to tell but there was also a gurgle sound as the fan spun, does that mean its working???

FYI...its a FE352. If anyone has any ideas I would greatly appreciate the feedback. Thanks

 

The bottom radiator hose should be cool(er).. it's the inlet of the engine or conversely, the output of the radiator.

I prefer drill 1/8-inch hole on the thermostat's flange to allow any trapped air to escape. Orient the thermostat so the hole is on top upon installation.

OEM gauges and sensors are notoriously inaccurate and suggest an aftermarket gauge set (oil pressure, water temp, and voltmeter) to provide real information instead of the Kentucky windage of "L" and "H" because it doesn't relate to any meaningful numbers.

 

Likely the bottom of the radiator is clogged(the finned area) and not doing its job. Typical.

Could also be the impeller from the water pump is rotted enough that it is not moving enough water. Haven't seen that happen enough to say it is more common.

I'd pull the radiator and have a shop flush it. Or at least start the truck cold and feel the finned area and see if it stays cool in the bottom(no water movement).

 

Rebuild? Stuff gets loose in the water jackets if they popped the freeze plugs and dunked the block. The stuff flows out of the block and stops on the top of the radiator tubes.
My guess is a partially plugged radiator, common after rebuilds.
And you should have replaced the water pump.
Pull and tank the radiator and put one of those crud filters on the top line from the thermostat.

 

I also think it's MAINLY the water pump but I suggest you do all the above. Right down to Hio's 1/8" hole clocked to the top. All good advise.

 

Okay gentleman,
I pulled the Radiator and took it to the shop to get flushed, I flushed the block through the manifold as directed by the rad guy, I replaced the old water pump with a new one with new gaskets, I drilled the hole in the flange and oriented it on the top and replaced the gasket. I drove it around the block and the gauge is on H again...classic, it was probably just the gauge after all that!!! At least thats what I'm hoping. The lower return hose was warm this time so at least I know the rad is working and the pump is as well unlike before. Next stop...new gauge. I promised my wife its the end of the spending... Just thought you might like the recap.

 

I like to actually check the temperature with a thermometer if the gauge is reading hot and it's not boiling over (you know it's hot then). I have never really trusted electrical gauges.

 

Replace the sender first. Cheap, much easier. Go from there.
We are sorry we sent you around the block on a snipe hunt but we did the best that we knew.

Semper Fi

 

Oh man, I wasn't trying to gripe about the work I appreciate everyones input and it was sound advice...truth be told I wanted to do the water pump but cheaped out after already spending way more than I hoped on ALL the other stuff and I didn't even think about the rad needing a flush which it turns out there where two small leaks and debris. You guys gave me the push I needed to do the right thing. Now I know the main two cooling system parts are operating at 100%, leaving the electrical. I will try the sender first and steal from my donor second for the gauge.

 

Soooo confused still. Did I mention I wasn't a knowledgeable wrencher...as if I need to state the obvious, right? I may actually have to take my truck to a shop to figure this out, I replaced the temp sender unit and ran the truck...still going past the H. The next day I stole the gauge from my donor and hooked that up to see what would happen. Unfortunately the gauge still went over H, I checked the top hose-hot, the lower section of the rad-warm, the hose going to the pump-warm, I felt around the intake manifold and it was just warm.

I didn't continue to run it, maybe I need to drive it to get air flowing through the rad I just don't want to do something to damage the engine after all the work. One of you guys mentioned using a thermometer, where the heck do you put it? I saw some radiator caps with gauges on them???

I'm starting to wonder if there is an issue with the wiring...its all been replaced with a new harness and I checked they were correct but what the heck!!! I flushed the engine and the rad, replaced the water pump with a new one, replaced the temp sender unit with a new one, checked the hoses, changed the gauge to the donor gauge, crossed my fingers and still it shows HOT. WTF, I must be missing something or the truck gods hate me

I've been trying to do all the work myself and this forum has helped a ton...a ton. But I can't figure out what is happening...there's an old guy at the shop a few blocks away who has a 1970 F250 as his daily driver and he did some brake work for me and I'm thinking its time to concede and go to him with my tail between my legs. Does anyone have any other last thoughts on the truck that runs on H after all the work done before I go spend more money? Thanks all!

 

Keep the radiator cap off and stick a thermometer in there to see if it's really getting Hot. While you got the cap off do you see any bubbles? I've heard in the past if heads not torqued correctly a leaky head gasket can cause compression pressure to go in the cooling passages causing the engine to run hot. This is rare but has happened.

 

Man, this is a head scratcher. You have not made any mistakes that I can see.
You know that the engine is hot because you have substituted sender and gauge. You don't know for sure if the radiator is hot.
I agree with Jefa. Stick a thermometer in the top tank to check radiator temperature.
What do you know about the thermostat? Do you have the box that it came in? China? If the radiator temp shows cool the thermostat is the only think that is left.
Bad-out-of-the-box is a common phenomenon here.
Not to insult you but are you certain that the thermostat is not in backwards?
Semper Fi

 

Thats funny CougarJohn because I wondered the same thing after I took it all apart couldn't remember how it was when I took it out and no I'm insulted. I went online to confirm what I believed was the correct direction...good news it was the direction I thought.

I'll try the thermometer and let you all know. I didn't do anything with the heads so hopefully thats not it.

 

The cheap Charlie next step is to pull the thermostat and replace it wit a top quality 180 degree new unit or even the used one from your donor. Or just take the thermostat out completely.
We are befuddled.

 

you can check a thermostat in a pan of water heated on a stove, a thermometer in the water will tell at what temperature the thermostat opens, if it opens at all. I have an ifrared thermometer I use to check surface temperatures of things, it wasn't costly and I bought it at a local big chain hardware store. (around 40 bucks) Many people have these now, maybe you could borrow one from a friend if you don't want to buy one.