FJ60 Radiator Help

[nakman]

@nakman

Here's the kicker though ... PO installed a thermostat. Looks like he used 1/2 a tube of red RTV on the housing. Before the flush-&-fill I used to find floaties of RTV in the filler neck. Sounds like I should probably peel that apart and see what's happening in there, eh? I'm swapping the head in a few weeks so that would be a good time.

I am guessing you'll probably pull the thermostat housing anyway just to give the head removal a little room? the nice thing I found was the mating surfaces are completely flat... I put 80 grit in the orbital and sanded them down to get rid of the remnants of old gaskets, RTV, etc. It was easy on the 2 thermostat housing parts as I could put them in the bench vice. Took a lot longer on the engine block though as I left that bolted to the truck... and wasn't so easy to access every little nook. but there was a bunch of built up gasketty stuff on the block that was definitely in the way of a nice flat plane. I probably went a little overkill as the new gasket (the one that looks like a 40 bezel) was pretty thick and rubbery, so could absorb a little bit of imperfection. but hey, I don't leak any coolant so there's also that.

 

[Cruisertrash]

I am guessing you'll probably pull the thermostat housing anyway just to give the head removal a little room? the nice thing I found was the mating surfaces are completely flat... I put 80 grit in the orbital and sanded them down to get rid of the remnants of old gaskets, RTV, etc. It was easy on the 2 thermostat housing parts as I could put them in the bench vice. Took a lot longer on the engine block though as I left that bolted to the truck... and wasn't so easy to access every little nook. but there was a bunch of built up gasketty stuff on the block that was definitely in the way of a nice flat plane. I probably went a little overkill as the new gasket (the one that looks like a 40 bezel) was pretty thick and rubbery, so could absorb a little bit of imperfection. but hey, I don't leak any coolant so there's also that.

Yeah, makes sense to pull the thermostat house parts out, doesn't it? More stuff to add to the list. At least I won't use so damn much RTV this time, like the last guy did.

 

[AimCOTaco]

Also I don’t know if a fj60 era 2f has a thermostat with a jiggle valve, I am sure it does.. if it does it needs to be positioned correctly
It can cause weird temp issues

One other thing is Did you burp it when done?

Here is a picture on orientation of the jiggle valve

I know of many different valves and their functions but what does a Jiggle Valve do? Anyone?

 

[simps80]

This is a family forum
I am not sure why you are asking these types of things here tbh.

Ok now that I got that trapped air out of my system…

A jiggle valve allows trapped air in the cooling system to escape back into the radiator to be vented

Thermostat replacement: jiggle pin and bleeder valve

Discover the importance of bleeding the cooling system after thermostat replacement, the function of the thermostat jiggle pin, and more.

www.gatestechzone.com

 

[simps80]

Tbh as discussed previously the thermodynamics of a horizontal aligned thermostat vs a vertical aligned thermostat doesn’t jive in my head on why it would matter the relative position or orientation of the “jiggle pin” in horizontal instances of a thermostat this is where I agree with Bruce and @DaveInDenver can probably explain the science in more clear terms…
Interesting though how sources like above quote a 12 o’clock orientation of the pin regardless of corresponding vertical/horizontal orientation of the tstat…

But overall the concept of the radiator being the highest point in the system does make sense on why a thermostat with a jiggle valve/pin is consequential…

as I wrote previously I have had weird heating/cooling problems as most probably have with air in the system…

And getting that air out of the system has solved those problems…jiggle pin/valve orientation being chief or least chief amongst the contributing factors.

I maintain that regardless of orientation of either tstat vertical/horizontal or corresponding orientation of the “jiggle valve/pin” in relation to the clock….Mr. T tstats have that valve/pin and many aftermarket ones do not…..
And that is likely for a very good reason well beyond my schooling…

 

[DaveInDenver]

Are you asking me about the 12 o'clock jiggle pin orientation? No idea.

But I did get a decent night's sleep, sooooo...

If the t-stat is truly horizontal then I can't see how it would matter either. So I'm left to surmise that it's not *exactly* flat in the way we think.

Which you know to be true, the engine may well be machined such that the housing is flat compared to the block or whatever. But the engine doesn't sit flat relative to the Earth, does it? Air bubbles only care about physics and gravity specifically so probably 12 o'clock has something to do with where air bubbles are expected or observed to find a path that continues ever upward.

The t-stat orientation relative to Earth wouldn't have to tilt much for the position of the pin to matter. Just a small slope, like even 1°, would cause bubbles to prefer floating to one side over the opposite. Ultimately a large enough air bubble would burp if the pin is at the low side but it might take filling the whole top of the cavity with air before it happens and you'd never fully burp.

Which brings up another thought. The recommendation is based on a stock truck, right? If my theory is correct then it's not necessarily an absolute orientation if your truck is squatting in the back or lifted and now sitting stink bug or sits on a sloped driveway. You might want to orient the pin so that it sits in a more suitable orientation in those cases.

And honestly, if I was to guess, I'd bet Toyota engineers would actually tilt the t-stat housing a couple of degrees intentionally just for this reason. It would be almost imperceptible just looking at it. Has anyone put a level on the plane of the housing?

 

[Cruisertrash]

@DaveInDenver Oh, that's an interesting take. Totally plausible too. To take a level to the t-stat housing, you'd need to take a level to the ground first - if you're looking for a potentially VERY small tilt.

@simps80 the jiggle pin (I don't even like saying that phrase) would still function as long as air bubbles are being moved by the coolant flow/water pump, but the hose against the fire wall between the heater tee and the head is the highest point in the 60 cooling system, no?

 

[DaveInDenver]

@simps80 the jiggle pin (I don't even like saying that phrase) would still function as long as air bubbles are being moved by the coolant flow/water pump, but the hose against the fire wall between the heater tee and the head is the highest point in the 60 cooling system, no?

The jiggle pin is there to burp air when the engine isn't running, the air slowly floats up and ends up at the radiator fill neck as the coolant cools and settles.

With the engine running the t-stat is open so air that's trapped (or churned by cavitation) will pass through it fine but since the fluid is being moved it's not going to settle out very well. Imagine taking a Coke and shaking it up. All the fizz is distributed until you let it settle down.

Interesting that you mention the heater hoses. I've found by trial and error that putting a Prestone fill-n-flush "T"s in one of those hoses is actually a pretty sure way to burp air from my cooling system.

 

[Cruisertrash]

@DaveInDenver Thanks for the clarification. I had that exact Prestone burping tee on that hose until the hose developed a leak (at the factory tee above the head) near Gunnison on the road home from SAS last summer. I found a very similar hose at the NAPA there and just swapped the whole thing. It never leaked and was really great for burping. I've thought about trying to find a metal one at some point.