Oil and Coolant Mixing

[rover67]

We calibrate our fiber optic temperature probes for animal testing using boiling water and a calibrated thermometer for reference but you really dont need the reference for what you are doing honestly. Just do the math for the pressure (or altitude) and be done with it. 203*F like you said.

You can bring your camp stove over so you dont even have to pull anything to apart. Just drop the sender in a pot right there next to the block.

I also wouldnt go throwing parts at it (like a new radiator) that sounds expensive and unnecessary at least at this point.

Nice thing about a check at 203 is if it's going over that particular spot on the gauge you know the cooling system is not keeping up especially with a 180* thermostat AND 203 isn't going to hurt anything so you still have some headroom.

 

[DaveInDenver]

100% agree Marco. The fan clutch was a shot in the dark and when that didn't change anything a dope slap to think more on it. That wasn't all that expensive a test, though. Not radiator kind of money anyway.

I also did the water pump but that's normal preventative I would have done anyway since the bearing felt pretty worn and the mag chloride didn't do the casting any favors.

When I held the two fan clutches they felt about the same at room temp and I did some messing around with a heat gun on the old one. I'll be darned if I really understand how those things work. It sort of felt stiffer but it wasn't *that* much stiffer so maybe the silicone oil does wear out over time. I dunno, maybe that replacement would have eventually happened anyway.

 

[Rzeppa]

I bought one of these when I had to troubleshoot the routing of the lines of the boiler at my home: https://www.homedepot.com/p/Klein-Tools-Digital-Infrared-Thermometer-Dual-Laser-IR5/207004900

 

[DaveInDenver]

Came across this little gem the other day putting Toyota part numbers into auto parts catalogs.

Sankei KW-6T

Cost me $8 (total was $15 shipped and goobermint tribute) ordered through NAPA Online but I suspect any decent parts store could actually order it. The distributor who drop-shipped to me was Worldpac, who you've likely heard of if you worked in auto parts.

I believe Sankei is the Toyota OEM for this part. The 22R and 22R-E used 83420-20020, as did Corolla, Celica, Starlet, Supra, Cressida, Tercel, Camry, Corona, MR2, 4Runner, 40, 60, 70, 80 series, Lexus SC300, etc. Diesels, too.

The 83420-16010 returns a much smaller number of the same models. Looks like the part number changed around 1977 to 1980 for the different models. It's -16010 for 1969-1980 *J40/55 and -20020 after for all models up to 1997 *J80, I assume due to some sort of minor spec change or maybe a change in supplier.

Point would be that if your Toyota had a temp gauge from roughly 1969 to 2000 this was likely the sender.

You may have heard of them as Sankei-555, e.g. they also do our beloved triple five chassis parts.

ETA: Well, trying to find it again is proving unpossible. Guess I stumbled into a momentary wrinkle in the time-space continuum.

 

[Rzeppa]

I don't know what year they changed, but my '71 sender (and dash gauge) is backward from my '76 and up. When open/de-energized, the gauge reads pegged-hot on the early sender/gauge, then when you start the motor it will go down and read cold until it warms up. The form factor for the early and late senders is the same.

Maybe the cutoff was the transition from F to 2F?

 

[DaveInDenver]

@Rzeppa, interesting. I don't know much beyond what the EPC returned for the part number.

Didn't those early FJ40 senders look completely different?



As to operation, I dunno for sure. All I can think is that these things basically are a negative coefficient thermistor (resistance decreases as temperature increases) so how the needle will work depends on how you use it. I noticed that even on the same year truck the gauges didn't work the same way using the same sender.

I'm just basing that on how you diagnose the combination meter on a truck with a tach vs. one without, such as the values you're supposed to see when looking back into the reciever with the sender disconnected. The combo meter with a tach won't even work open circuit while a non-tach meter will measure 25 ohm and show ~4.5V open circuit.

So that implies that a non-tach truck is a bridge while the tach is probably just a divider. For a combination meter with a tach you replace the sender with a lamp and watch that it illuminates to check the gauge.

Some of this is speculation on my part, which is why I bought another sender to tinker with and see if I can figure out just how accurate these things are. Completely useless information in 2024 but just curious. Gauges now are less-and-less directly reading a sender or sensor and rather are driven by the ECU. Not always, so you can sometimes see a discrepency if you read coolant temp from the OBD port and the gauge.

 

[Rzeppa]

No, like I wrote above they have the same form factor. I swapped in a used F shortly after I got the rig and used a sender from a 2F and after I fired it up I noticed the temp gauge was backwards, to the right when cold and to the left when hot. I took the original sender off the original F and put it in and then things started working right. Lots of FJ40 stuff will mix and match, but not everything!

 

[rover67]

So the sender was bad and you got a new one?

 

[DaveInDenver]

So the sender was bad and you got a new one?

Dunno yet, the new lower temp turdstat just showed up today. I bought that sender mainly just cause, it was too cheap to pass up. Figured it was worth stockpiling parts like that when I find them. With my track record the old one will twist off in the intake if I didn't have one handy.

 

[DaveInDenver]

Alright, put in the 180F thermostat.

Also pulled the sender and tried a few tests on it. It seemed to match the new one at room temp (around 1.2k ohms) but when I dropped them both into boiling water the old one was giving odd readings. The new one fell right to about 81 ohms. They're expected to be about 25 ohms at 239F which I can't really test. So I just put the new one in.

I don't know for a fact that the old sender was bad but it seemed suspect. I was working outside and the rain clouds were starting to build and I didn't really feel like testing the old one, draining and filling coolant again to maybe just replace it anyway.

Sitting idling for 15 minutes it sits right where I'd expect.



The mark I put on was as close as I could get to a reading since I couldn't fit my camp stove under the hood in a place where it didn't seem like a serious risk to melt through a fuel line. So this is is the spot in time where the needle came to rest and how much my water had cooled (the temp is accurate, based on a Fluke DMM/thermocouple adapter arrangement). Close enough.

It's hard to really see but the view from the driver seat the needle is about one thickness below this line pointed down and with a 180F t-stat it seems reasonable. I didn't note it but the needle moves off the lower line at around 100F and 195F is basically flat.

So if this spot is about 10ish degrees below 195F (give it a generous +/- 5 degrees from 180F) I was running an indicated something like 205-210F (very approx) when it concerned me, although with a suspect sender. It was essentially mirrored vertically, needling sloping up to the left. It probably wasn't really that near to overheating, although with summer yet to really hit who knows.

 

[rover67]

so...... time to drive the thing?

 

[DaveInDenver]

so...... time to drive the thing?

Yup.

I have been driving it, here and there, but now for real.

There is one thing I'm still trying to figure out. A weird sound, a tick, tap, squeak sort of sound that isn't exactly RPM dependent but does seem to be throttle dependent. By that I mean if I'm driving along and push the throttle to the floor it gets louder. It'll also do it at a particular RPM engine braking without any throttle.

I'm fairly certain it's not internals, a rod knock, piston slap or something like that. At idle it sounds good and sitting still I can't really get it to make the noise. If I rev the engine it sort of makes it for a second but doesn't sustain like it does moving.


View: https://youtu.be/qxSEK9bkmlI


So I'm thinking there's still an exhaust leak somewhere or maybe the EGR valve is making noise or something's just loose. Point being I'm pretty sure it's not serious. Maybe it's the valvetrain or something clutch or flywheel related, but that's not my impression trying to locate it. It does it with the air suction both connected or disconnected. Seems to be under the intake somewhere but can't really figure it.

It sure sounds bad. Can hear it with the windows down echoing off medians and other cars in traffic. It's loud inside the cab. Sounds like it's right under the glove box.

 

[wesintl]

that's what i generally see with my bj70 on the toyota guage. 190 is slightly below center, center is usually 200. 220 is usually the white line below red....

 

[DaveInDenver]

that's what i generally see with my bj70 on the toyota guage. 190 is slightly below center, center is usually 200. 220 is usually the white line below red....

Yup, this is what I expected to see, it's like what the needle did on Imelda.

 

[DaveInDenver]

Drove around about 40 miles the last couple of days. Temp needle is holding fast at that happy spot. I'm finding myself watching it less and less, so I think it's safe to move on from that.

The only downside is now my mind has wandered to really wondering what's that whistle-squeak is all about. Doesn't seem to make any performance difference but sure is irritating me.

One quick pump of the pedal and it starts with just a few cranks and the rest of the day it starts almost immediately. Idles nice, pulls into 55 MPH traffic with completely acceptable power. No kidding, it has the sensation of actual accelerating.

So I'm just going on the assumption there's an emission path to figure out. Maybe a bolt I'm still overlooking that's loose, a gasket that got nicked or something.

 

[RicardoJM]

Excellent work Dave! Drive it and enjoy it!

 

[wesintl]

Nice work Dave, Forget about it for now and enjoy. Come back to it in a few weeks. There might be more clarity to the noise or not

 

[DaveInDenver]

Nice work Dave, Forget about it for now and enjoy. Come back to it in a few weeks. There might be more clarity to the noise or not

It's a casual annoyance that I'll poke at. It's got me curious but not *too* concerned. I have a laundry list of things to get done before it gets taken much on Interstate (front axle, for example). I get stopped for a chat almost every time I drive it, which is cool.

 

[Rzeppa]

I get stopped for a chat almost every time I drive it, which is cool.

You can probably imagine the chats I get stopped for when I'm in the FJ45.