Average 2F engine temperature

[Output Shaft]

That pic is not of my truck (don't know who's it is). I don't have a mechanical gauge installed. Only the oem. Inline hose fittings can be found at Autometer.com & other places.

Accessories - Adapters, Fitting & Hose

 

[Shacklewhacker]

That pic is not of my truck (don't know who's it is). I don't have a mechanical gauge installed. Only the oem. Inline hose fittings can be found at Autometer.com & other places.

Accessories - Adapters, Fitting & Hose

Gotcha - thanks. I only use my OEM gauge as well. Happy with it, and I do not have temp issues based on all of my testing/conditions and an infrared thermo. Just thinking, if I ever did want to test via mechanical, this is the least intrusive to the motor.

 

[wngrog]

OS - where did you get that rad hose inline setup?

Steiger Performance

Steiger Performance - your source for a variety of unique automotive and motorcycle products.

www.steigerperformance.com

 

[wngrog]

I installed the in line adapter above in my 40. Post #1155

Project Patina-November 1968 FJ-40

forum.ih8mud.com

Right there my Autometer gauge with factory TStat, fan clutch and new radiator my 40 reads 200-210

I’ve recently added Holly Snipers to two new 2Fs in my 60 and 55. I added the sensor for them in the drain plug location on the drivers side of the block.

On the 60 with AC I will see 225 running hard. Stock temp gauge is barely over 1/2 there it’s sensor is in the stock location.

On the 55 with no AC it’s usually maxed at 220 pushing hard.

All have new cooling systems, green Fluid and proper Toyota gaskets and Tstats

This is 65 mph. Ambient 70* in the 60

 

[HemiAlex]

I see 189* in normal driving, 210* idling at a stand still after 10 mins with the AC on and if I’m really loading it up in 4th and 5th gear up and down hills, it will get close to 200*. All verified with a digital temp gauge.

 

[Willard]

So here is mine on a mechanical gauge.

 

[Willard]

Also for the sender the PO did this crazy pipe fitting. It works great and even with AC running pushing hard uphill in the heat of the summer I never went past 190*
Ya I know the wire job is sketchy...still fixing all of that.

 

[OSS]

pushing hard uphill in the heat of the summer I never went past 190

That's because that funky T fitting is full of air and the sensors aren't submerged in coolant. The reading on the gauge is wrong (cuz sensors aren't submerged in flowing coolant).
There's no way to purge the air in that fitting and eventually small bubbles always circulating in the coolant find their way into that fitting & displace the coolant - leaving the sensors dry.

The cylinder head in all engines creates small bubbles in hotspots at certain locations in the water jacket. These little bubbles eventually find their way to the radiator where they are purged out into the overflow tank when the engine is warmed up from cold... so it's not an issue. But if there is a high spot (like your T fitting) the bubbles will eventually accumulate and create an air pocket that can't be purged.

 

[Willard]

That's because that funky T fitting is full of air and the sensors aren't submerged in coolant. The reading on the gauge is wrong (cuz sensors aren't submerged in flowing coolant).
There's no way to purge the air in that fitting and eventually small bubbles always circulating in the coolant find their way into that fitting & displace the coolant - leaving the sensors dry.

The cylinder head in all engines creates small bubbles in hotspots at certain locations in the water jacket. These little bubbles eventually find their way to the radiator where they are purged out into the overflow tank when the engine is warmed up from cold... so it's not an issue. But if there is a high spot (like your T fitting) the bubbles will eventually accumulate and create an air pocket that can't be purged.

I would argue on that on some points
My engine is not a fair assessment as all components of the cooling and heating (AC to) is new. As well the engine (8K ago) and head (13K) ago) were rebuilt.
The temp sensor for the mechanical gauge should reach into the head (based on the replacement I have).
Heat soaked it reads right where you would expect and doing 65 down the highway exactly where you would expect.
190*-195* up the hills (staying at about 50mph) should be about right as I was not loaded, but pushing hard in 3rd.
If anything the stock gauge is way wrong, and would seem correct on that assessment since it always shows cooler for that I would agree it being off, but then I have a feeling it was installed to keep the gauge working).

+ a thermo reading of the system (did this after I rebuilt the coolant system) shows about on par, +/- 5* . The Gauge funny enough was put in by a shop in Rhode Island (I actually have that receipt).
It was put in to solve what the PO though was a bad gauge and be more accurate to to overheating. Turned out it did not, and the engine was actually toast already.
We will see as once I install the EFI the temp sensor should read more accurate.

 

[OSS]

For some reference (not argument), the coolant temperature at the back of the long 2F where the temperature sensor screws into (very rear of the cylinder head) is normally a lot hotter during operation than the coolant flowing into the thermostat housing in the front. If the thermostat outlet temperature is around 190°-195° when the engine is loafing or idling, the actual coolant temp at the temperature sender location will be several degrees hotter. I don't recall the exact increase, but it was more than 6°F. I discovered this while calibrating the sensor (with completely overhauled head & new sensor).

So whatever temperature is measured flowing out of the thermostat, the coolant flowing past the rear of the cylinder head will be a lot hotter. If a temperature gauge installed back there displays 190°-195°, it's reading low.

 

[wngrog]

For some reference (not argument), the coolant temperature at the back of the long 2F where the temperature sensor screws into (very rear of the cylinder head) is normally a lot hotter during operation than the coolant flowing into the thermostat housing in the front. If the thermostat outlet temperature is around 190°-195° when the engine is loafing or idling, the actual coolant temp at the temperature sender location will be several degrees hotter. I don't recall the exact increase, but it was more than 6°F. I discovered this while calibrating the sensor (with completely overhauled head & new sensor).

So whatever temperature is measured flowing out of the thermostat, the coolant flowing past the rear of the cylinder head will be a lot hotter. If a temperature gauge installed back there displays 190°-195°, it's reading low.

View attachment 2072345

So, the place I have my 2 sensors for my Snipers in the block drain will be the hottest place on the truck to measure coolant according to this graph.

Am I correct?

 

[FJ40Jim]

That graphic has been made up by somebody who is ignorant of 2F coolant flow.

The giant colored arrows do not represent flow through the engine. The WP shoves coolant into the front of the block. It moves through the block, to the rear, where it goes up through the large openings in the HG, then travels forward through the head. The hottest coolant is at the front t-stat outlet on the head.

 

[John McVicker]

^^^
Wow, very interesting Jim...the hottest coolant is at the T-Stat outlet at the head. Great info.

 

[MrMcgoo]

My stock gauge sometimes reads half when driving down the road and than in slow moving with or without the A/C will hit close to the red, it is also is around 110 here lately. I check the temps yesterday and the Radiator read 155, the top hose was reading at 190, and the head was between 190-200 each time I would check it. I didn’t really what to have to install a secondary gauge but this isn’t reliable to just assume it will remain the same every time.

 

[HemiAlex]

I used a koso motorcycle temp gauge on mine. Non invasive and tells me what’s going on reliably.

 

[Beehanger]

Yup - exactly ... Mine will occasionally creep up to 195 after a hard run, and it's warm outside, but otherwise right at 190 w/ 88* C t'stat and autometer gauge.

Is this coolant temp?

 

[Spike Strip]

Yes. Mechanical gauge, sender in upper Radiator hose. Sometimes goes a little above 200*

 

[Beehanger]

Yes. Mechanical gauge, sender in upper Radiator hose. Sometimes goes a little above 200*

My rebuilt engine's block hit 245F for 2 minutes before I caught it---- have a small pit in my stomach over it

 

[Beehanger]

My rebuilt engine's block hit 245F for 2 minutes before I caught it---- have a small pit in my stomach over it

 

[Spike Strip]

Is that with an IR gun?