Pegged temp gauge briefly (1 Viewer)

[fred]

Recently, had a cold snap in these parts. A bit below freezing for a few days, snow & freezing rain.
Chose to drive the Cruiser, due to conditions.
Wasn't worried about the temps, as I knew I had ample antifreeze.
Drive slowly over big hill near start of my commute.
On the downhill, notice wisps of white streaming from edges of good.
Look at temp gauge and it's pegged.
I've been driving less than five minutes.
Turn it off, and pull to shoulder at bottom of hill.
Green fluid on the ground, confirming my views on antifreeze.

Get it flat-bedded home (love AAA Premier!).
Terrified the cause is corroded freeze plugs (which I'd read up on - it is an '82 FJj60, and I have no idea how good the POs were about changing fluids), because I just wasn't feeling like that level of takedown right now.

Finally got to check it yesterday.
Filled the system with water to check (still very green, so antifreeze still present), and, lo and behold, water gushes out!

But not from freeze plugs.
From the easiest dampened hose on the rig, right on top, in front.
Hose from thermostat housing to oil cooler pipe (15777C).

Ordered one. Then went and found an almost dead match at local NAPA shop.

Started her up, runs great.

Anything I should be on the lookout for?
As I said, had been running for no more than five minutes when gauge pegged. Ran fine the last time I'd driven it.

Oil shows no sign of coolant involvement (no "milkshake").
No smoke in exhaust.
Nothing proofing around the head gasket.
I'm hoping the cast-iron head & block saved the day.

 

[NeverGiveUpYota]

Temp and gas by any chance? Does your fuel gauge work? If not then its probably the contacts on the fuel gauge. Temp is connected to it and when the contact gets corroded it causes a spike. Its happened to probably all of us so lots of threads on it.

 

[Ming89FJ62]

don't think it was the VR in the gauge cluster - he had antifreeze boil over

 

[NeverGiveUpYota]

Gotcha. So it was just that one spike when the hose popped. My oops. Sorry.

 

[Output Shaft]

When the coolant level drops enough in the head to create air pockets at the top of the head, the temperature sender will no longer be submerged in coolant and will then get heated directly by the metal fitting... which will now be way hotter than the coolant (or what's left of it). It'll peg in the red, though the engine will very likely not be 265°F.

Once the cooling system loses just a little coolant after it has heated up, it is no longer pressurized. It only pressurizes the first couple minutes after the engine has started.

If the coolant isn't pressurized (because of a leak) 50/50 coolant will boil at 225°F (which isn't really that hot) instead of 265°.
But the head has hot spots in it, so although the overall coolant may be under 225°F, there will be areas on the head that will still boil.

Once the coolant starts to boil, then it's a downward spiral of overheating. The boiling displaces more coolant (and steam) either out the leaking location or the overflow bottle and the water jacket gets filled with more and more air.

Steam blowing out of the engine compartment could be only the result of 225°F unpressurized coolant boiling.

But to answer your question: The engine is probably fine. Don't worry about it. There's nothing you can do at the moment anyway.

 

[cruiserfj45]

Cast iron block and head will take a lot of abuse. Its those aluminum heads you need to watch out for.

 

[LAMBCRUSHER]

there's a reason some of us drive these slow old pigs...

 

[micruz60]

I will suggest, if you do not know the age of the rest of the hoses, to replace all of them at the same time "while you're in there".
Still waiting for my gauges to go weird, spike, and give me shortness of breath.

 

[Rainercar]

Your overheating may have been caused by a stuck fan clutch element.
When I bought my Land Cruiser a few months ago, it was overheating (among other things)
After an engine rebuild, with a new water pump etc, it was still running hot.
I found, that the fan clutch was not working. When the spring (element) on the outside, front of the fan clutch gets rusty, stuck, it will not allow to rotate, when the heat from the radiator increases, therefor the fan will not "lock", when hot.
The best way to check it is, to let the car warm-up and watch the fan. It should start to turn faster, when temp is high. When turned off, it should not free-spin, when hot.
When the car is hot, turn of the engine, the fan should continue to turn only. If it continous spinning right after turning the engine off, thre clutch is not working. Check the spring element and move it a few times, it may free-up if it was stuck. If it does not it, new fluid in the fan clutch may be needed.
It cured my overheating, needle is now in the lower 1/3rd of the scale...

 

[Malleus]

Or, you can reach in and grab it while it's spinning. If you lose a finger, the clutch is still good

I'd consider hosing that residual coolant off the engine bay.