227 Degrees, 7 Minutes From Start w /Heater Blasting (1 Viewer)

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I'd be afraid that would crack the 25yo fan if the clutch is good...


Naw, you don't 'jam' it in there. Just allow the magazine to 'tick' the edges and IF that breaks any fan blades then your fingers will do so too. Worst case scenario....you discover you need to replace the fan.

Fans DO get brittle over time and should be replaced when/if they don't feel flexible *when at rest* you can't twist them slightly by hand.

They are inexpensive to replace.

Borrowed picture below of a brittle fan that 'quit' and took out the radiator.
Brittle Fan.jpg
 
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Clutch maybe 2yo.

Doubtful. If you haven't done the clutch mod *blue hub* that would be my first move. 15K CST or greater fluid.
 
Doubtful. If you haven't done the clutch mod *blue hub* that would be my first move. 15K CST or greater fluid.
I have. That’s why I’d be astonished. :)
 
This "procedure" doesn't sound even remotely safe.

* I'm told the process is, have someone kill the engine--and grab the fan a half-second later. If you can stop it, the clutch is gone. Sounds like a finger-breaker to me, but I'm told it's not. Is this the correct procedure?

totally fine unless your planning on letting an infant do the diag work, done it plenty of times. its plastic blades and not the old metal finger choppers so your good
 
Thanks for the swift reply. You mean I WASN'T actually at 227? (Is it even possible for the temp to climb that fast?) I'm in Panicville here...

short answer is maybe, if there was an air pocket at the coolant temp sensor then it would be very unlikely that the rest of the cooling system was at that temp. a steam or air pocket will register hotter than the rest of the system.

have you replaced your t-stat, it may not be fully opening and causing an over heating when under load
 
totally fine unless your planning on letting an infant do the diag work, done it plenty of times. its plastic blades and not the old metal finger choppers so your good
Good to know but I'll take a pass. I've seen far too many industrial hand injuries due to line of fire incidents. Typical response is "I've done it this way a hundred times".
 
Good to know but I'll take a pass. I've seen far too many industrial hand injuries due to line of fire incidents. Typical response is "I've done it this way a hundred times".
fair enough, dont want to stick your fingy where you wouldnt stick your dingy. you can always use something else to stop the fan blades like a newspaper or magazine as mentioned above
 
When did you last replace your thermostat? If it isn't opening, it can cause this as coolant won't flow. I found that out the hard way when I replaced the thermostat years ago and accidentally put it in backwards so the spring didn't open :doh:. It heated up very quickly like what you are experiencing - not sure they fail catastrophically like that though when they go - they probably just don't open as well as they age but figured I'd through it out there but @NLXTACY has more experience with overheating so I would trust his opinion more than mine :p
 
Okay, so, cranked 'er up with the usual roar. Starting temp 83F. Idled for 30 min in driveway, settling in around 650rpm and never got above 182. (Took about 15m to hit 180.) Tried to grab the fan a few times with glove held with glove. I can't stop it immediately, maybe 3 or 4 blades go (very) firmly by before I can stop it. I assume that means blue hub clutch is fine?

Replaced water pump with AISIN 2 or 3 years back, but did not change out thermostat. Gonna hafta drive a few miles on Tuesday, will replace thermostat and likely pipe o-rings if problem recurs. Well, even if it doesn't.

Any other thoughts? Will filling rad to brim reduce chance of air pocket? Anything else I can do on that score (other than change rad, which is on the list with oil pump cover/main seal)?
 
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You said,

"Radiator does have a slowish leak, but that's been true for a year"

I would personally address this first and foremost with a new one then go with OEM thermostat and if theres still an issue pull clutch fan and drain and fill with the proper amount of fluid and viscosity
 
Okay, so, cranked 'er up with the usual roar. Starting temp 83F. Idled for 30 min in driveway, settling in around 650rpm and never got above 182. (Took about 15m to hit 180.) Tried to grab the fan a few times with glove held with glove. I can't stop it immediately, maybe 3 or 4 blades go (very) firmly by before I can stop it. I assume that means blue hub clutch is fine?

Replaced water pump with AISIN 2 or 3 years back, but did not change out thermostat. Gonna hafta drive a few miles on Tuesday, will replace thermostat and likely pipe o-rings if problem recurs. Well, even if it doesn't.

Any other thoughts? Will filling rad to brim reduce chance of air pocket? Anything else I can do on that score (other than change rad, which is on the list with oil pump cover/main seal)?

DO fill radiator to 'full', but you'll need to correct any leaks that are not at the highest point in the system.

You might have one of those 'mystery' heat issues that take awhile to diagnose. I'd order and put in a 170°F 'MotoRad Fail-Safe' thermostat in the interim. It might keep the engine from being pushed over the edge until you can investigate further.

 
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DO fill radiator to 'full', but you'll need to correct any leaks that are not at the highest point in the system.

You might have one of those 'mystery' heat issues that awhile to diagnose. I'd order and put in a 170°F 'MotoRad Fail-Safe' thermostat in the interim. It might keep the engine from being pushed over the edge until you can investigate further.

Thanks for the tip. Leak is very high up, around the point where the fins meet the metal hood up top (on the outside). Untended, it will eventually drop the water level below the top of the structure inside. I keep meaning to put the new rad in, but it's nutcrushing expensive and I want to run cleaners etc. through the system for a few weeks to a month before installing. Also want to anodize it. Don't think it's the rad running the temp up, will have to go exploring if problem continues...
 
My $.02, drain, flush and fill with Thermocure and distilled. Run for a day, drain and flush again making sure your block drain pours clean and unobstructed. Install new Rad and T-Stat and be done with it. A new Rad is way cheaper than popping a head gasket or worse.
 
Thanks for the tip. Leak is very high up, around the point where the fins meet the metal hood up top (on the outside). Untended, it will eventually drop the water level below the top of the structure inside. I keep meaning to put the new rad in, but it's nutcrushing expensive and I want to run cleaners etc. through the system for a few weeks to a month before installing. Also want to anodize it. Don't think it's the rad running the temp up, will have to go exploring if problem continues...

You could pressure test the system to determine how bad *and where* the leak(s are. Enough of a leak would not let the system pressurize fully, which dramatically affects the boiling temp of the coolant. Same holds true for a failed or failing radiator cap.

The fail-safe Tstat is cheap insurance against getting overheated before you are able to realize it and react and might solve your issue outright anyway.


.
Pressure Test System.jpg
 
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My $.02, drain, flush and fill with Thermocure and distilled. Run for a day, drain and flush again making sure your block drain pours clean and unobstructed. Install new Rad and T-Stat and be done with it. A new Rad is way cheaper than popping a head gasket or worse.
Depends on the rad. :)
 
You could pressure test the system to determine how bad *and where* the leak(s are. Enough of a leak would not let the system pressurize fully, which dramatically affects the boiling temp of the coolant. Same holds true for a failed or failing radiator cap.

The fail-safe Tstat is cheap insurance against getting overheated before you are able to realize it and react and might solve your issue outright anyway.View attachment 2740558
Clearly, I need more shiny tools. Cap is new oem, replaced 2-3 years back. Chances pressure testing will blow a bigger hole in the radiator, or some heater hose I couldn't reach when I swapped things out? I mean, better it blows in the driveway, but still...
 
TYC1918 from Rockauto is $190... works well in AZ heat.
I guess it must not be very hot in SoCal since you seem to feel comfortable leaving a leaky radiator in the truck.
 
Ron Davis, Death Valley Grade... I gotta scour the system first. As much as that's possible, anyway. Been putting it off; guess it's time.
 
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