The spring end ALWAYS goes opposite the radiator hose

 

On a Ford, you're correct, in fact, on every American Designed gas motor I've ever seen, that holds true. Not so for a Number of European Engines, and then you get into some diesels (Detroit Series 50/60 Spring to Mind) where there is no spring on the thermostat at all =]

Nothing like standardisation.

 

well yeah but who has a detroit series 60 in the pick up LOL ...and to anyone thinking of putting a european engine in a ford truck...you will be dead to me LOL

 

Oh, I don't know, I'd consider a 900 Series Mercedes Diesel in an F-250 or bigger. Hell, I might even consider a 904 in a 1/2 Ton....

And Land Rover actually had some real nice V-8's... Of course, they were all just Buick Nailheads, cast in aluminium....

And I'd give my left arm for a Series 60 like diesel that would fit in an F-series. Course, I don't see that happening anytime soon...

 

i work on the mercedes diesels in the sterling trucks that sometimes end up in the peterbilt shop i work at and from those experiences i think mercedes should stick to cars...those diesels suck...and they are a PITA to work on compared to the cummins and older cats

put a cummins diesel in one of these things and thats just plain awesome LOL

 

Well, I flipped my thermostat around on the weekend and no difference. Still reads just below the 'N'. Other than replacing the block temp sensor, what's the best way to determine it's operating properly?

 

the topic is a coolant leak in a 4.9 engine.

come on back down from space.

 

In all seriousness, if swapping the Thermostat out didn't fix things, the next place I would check would be the Water Pump, check the weep hole to make sure it's not leaking from there, but it might have corrosion on the impeller or whatnot, and it's not pumping as much as it should, or the impeller might even be loose (I've seen this happen on 302's now and then).

And it is entirely possible that your Fan Clutch isn't working properly, and running all the time (I believe you said something in your initial post that makes that unlikely, but I can't recall.)

Or maybe even your sender is no good. You can always get an old mechanical gauge (Cheap enough at most parts houses), and there should be a couple of ports up on the intake that you can screw it into, and check when the thermostat opens.

I've got one of those Laser Thermometers I use for things like that, which while not as accurate as hitting the fluid directly with a sensor, is usually within 10-15 degrees, and is good enough for diagnosing bad Senders/Gauges.

As an aside, in my 89 F250 with the 302, and my 92 F250 with the 351W, they rarely get above the O in normal operation. The only time I've seen the 92 do it is when pulling my toy hauler, and that's pretty much only if I spend a whole lot of time in 3rd and 4th gear really pushing the engine, and as soon as I let off the loud pedal, or upshift and bring the RPM's down, it cools right back down.

 

Hmm I'll have to check that out.

I considered that, I picked up a replacement for $4, so even if my truck does just run that cool I'm not out much.

I got a new sender, thermostat, housing, and gasket from napa. I need to check the weep hole on the water pump, but I hadn't noticed any leaks under it so I'm hoping it's good. I was going to put everything in tonight, but the water pump in the wife's car is hemmoraging coolant so that takes priority =/

I'll report back once I get everything swapped out.

 

Lol, nevermind....was gonna say use the obdII to monitor the temp but its a 90 :P

 

if it reads on the N whats the big deal? my 300 never goes above the O, even wheeling...the one time it did i was in the mud and got a chunk of mud or a rock in between the belt and a pulley and the belt came off some how...and it managed to shrink the belt too? either way that was the only time its ever been about the O as far as my memory can go

 

Well mine only goes a hair (literally) past the first bar, no where near the N. It just makes me nervous =/ I want to at least replace the sender to make sure I'm not running hot thinking I'm running cool.

 

the sender on the thermostat is for the computer and the sender for coolant temp is on the side of the motor.

fyi.

 

oh i see...thats a bit low i agree...but theres a good chance its just the sending unit or maybe a wire somewhere is in bad shape causing resistance which would throw the gauge off...

 

Well I got around to replacing the thermostat, after some struggles.

I ended up having to use a hand pump to get the coolant flow started when flushing the radiator. Lots of fun muck at the bottom of the radiator O.o

I put the new thermostat in and gasket on, but after tightening the bolts on the housing i noticed a very slight leak coming from the bottom of the housing. I had used some gasket sealer but I was impatient and it was still tacky when i put the gasket on...

So I let the truck sit overnight, I'm going to check after work to see if the leak stopped. If not I'll have to pony up another $2 for a fresh gasket.

Oh, and thanks for the tips about using a good rust penetrator and tightening the bolts first, worked like a charm!