Coolant issues

rusty ol ranger · Jun 2, 2018

87 2.9 Ranger/5sp.

Ive had issues for a while with cooling, that i thought untill a few days ago was just the gauge. It never actually overheated, but would run hotter then it really should....

The other day it was like 90*+, everything was dandy, temp gauge reading a bit below halfway. Stopped at store, came out, started it, temp gauge was at top of normal, but cooled down pretty quick after i took off, down to just above 1/2 (its only 1/2 mi at 30mph home)

Now. Next day i noticed the thing taking longer to heat up, it has a 180* failsafe, so im assuming that hot day locked it up.

Today i popped the hood, now, before this went on the coolant tank was maybe, 1/2 or a bit lower when hot, radiator was always full when cold.

Today, the tank, when warm, is damn near totally full...

Im wondering wtf? I havent added coolant...was it possible that (new) tstat was stuck paritially closed and then when it got hot enough to "fail" it allowed a bunch of coolant out of the block?

Now the truck still gets into normal range, just takes a while, but never goes over 1/2 way.

BTW, oil and filler is clean.

RonD · Jun 2, 2018

All liquids expand in volume when heated, so a gallon of coolant at 70degF might be 1.25gallons at 200degF
Which is why there is an Overflow tank(or air space left in Degas system)

The amount of expansion is directly related to temperature of the fluid.
On an overflow system there is a pressure rated radiator cap.
Usually 14-16psi, the expansion of the coolant causes this pressure at the cap
Cap's spring holds this pressure until its above the rating, say 17psi then it allows some coolant to flow to overflow tank until pressure is below 16psi.
This pressure in the system raises the boiling point of coolant from 230degF to 260degF, which is why pressure is used at all, just safer.

If your rad caps spring is going bad so opening at 5psi then more coolant would flow out to overflow tank.
Yes, if coolant was over 230degF then more coolant would show in overflow tank because of the extra expansion.

When you shut off a warmed up engine the fan and water pump stop, so coolant just sits in HOT heads, no circulation to carry heat away, so if you turn the key back on after a minute or two temp gauge should be higher, but that also depends on WHERE the temp SENDER is located on the engine.
Overflow can also get more coolant after shut down, as temp of un-circulated coolant in heads gets hotter it expands

I have to climb a longer grade on my way home, I generally let the engine idle for a minute or two, even run it at 1,500rpm, no load, before shutting it off, so I can get rid of the extra heat from the climb up the hill, especially in the summer, lol.

Feel upper rad hose after starting cold engine
Let engine idle for 2 minutes then feel it again, should still be stone cold, compare it to heater hose temp, heater hose SHOULD BE warming up, upper rad hose shouldn't be warming up, if it is then yes t-stat is stuck open

rusty ol ranger · Jun 2, 2018

Its weird though because the tank got full...AFTER it quit getting so hot....

I know the Tstat is stuck, but im just trying to figure out wtf is going on before i crack a head.

RonD · Jun 2, 2018

Maybe Rad cap is/was not holding 16psi pressure, that would push extra coolant to the overflow tank
Or rad cap return valve/overflow hose was blocked

rusty ol ranger · Jun 2, 2018

If the radiator cap was bad, could it also possibly cause it to run hotter then normal?

As i read that i remember i pulled the cap off rusty #1 and stuck in it to replace the one that was on there that was shot. Supposed to be a temp fix, but it was the original one off rusty 1 from 87

EDIT

I forgot till about 10 min ago that the same hot ass day i pulled the hood open and played with some wires, most notably the sender wire (pulled it off and squeezed the plug tighter for a better connection) and the little black secondary ground wire that goes from the main battery ground to the core support.

After i did this i noticed all my gauges behaving much better, no more fuel or oil gauge spikes, or random drops.

Does that little black wire effect that stuff? Or am i crazy?

Reason im wondering now is because it was a bit chilly this morning, 53 or 54*, and i still had decent vent heat within 2 or 3 miles.

Coolant issues

rusty ol ranger

2.9 Mafia-Don

RonD

Official TRS AI

rusty ol ranger

2.9 Mafia-Don

RonD

Official TRS AI

rusty ol ranger

2.9 Mafia-Don

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