Temp guage question

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Nope. No shorts to ground, by virtue of both visual and continuity checks with the VOM.

And you're right . . . I also thought the later sender units wouldn't be pegging the needle all the way left because of the higher resistance.

And yep, I already tried pulling the power lead (which is also daisy-chained with the power leads to the other gauges) and I'm getting the same resistance reading.

Ya think maybe the gauge itself is shot? And/or maybe it needs to be replaced with a comparable year gauge to that of the sender?

You think that your head is hurting?
Yikes!! :mad: :confused: :crybaby:
 
Just for s***s and grins, if I hooked up a cheapo (generic) auto temp gauge to my two incoming leads that nornally go to my stock gauge, wouldn't that tell me if my gauge is the culprit or not??
 
Only if that gauge just happened to have the bimetal setup necessary to work with the sender. The gauge can be adjusted.........and can also ruined......might be time to find an autoelectric / gauge shop. :frown:
 
Status report:

Borrowed the temp sender off my '78 FJ40 F2 engine, and stuck it on my late '60s model F engine that sits in my '59 FJ25. (Any known compatibility problems here?)

After starting, the needle still swings all the way left of COLD and just sits there even after 15-20 minutes of idling.

However, this time when I turn off the warm engine and turn the key back on (without actually starting it), the needle does creep up and parks itself about halfway between COLD and the middle hash mark on the gauge.

That tells me that my new aftermarket NAPA sender may not have been doing its job right from the start, but how come no reading on the gauge when the engine is running??

What's going on here. :confused:



Hey Jim, what happened to the new avatar you were trying out last night?? :frown: Bring it back (and zoom in more on the grill)!!
 
Last edited:
Landcruisersteve said:
Hey Jim, what happened to the new avatar you were trying out last night?? :frown: Bring it back (and zoom in more on the grill)!!
Click to expand...

Caught me testing avatars eh? My bib was white, and then olive drab for a bit also. ;p

If you weren't confused before, try this.....
The post '73? sending unit that you have (the one that works with the plug-in gauge cluster w/ the circuit looking board behind it) is different yet again. I believe it works in the opposite direction.......ie. resistance goes down with a rise in temp......I think. I don't have one to check. In other words it would start at the H side and go down as the engine warmed up.

Still sounds like a short to me.......did you have the gauge out? I can't remember but aren't there little insulating washers behind the nuts?
 
Cruiser_Nerd said:
If you weren't confused before, try this.....
The post '73? sending unit that you have (the one that works with the plug-in gauge cluster w/ the circuit looking board behind it) is different yet again.
Click to expand...

Great. Any idea if the 40's temp gauge is removable from the cluster so that it can be stuck in the 25? At least I'll be able to drive the 25 without worrying about the engine overheating (and I'll worry about the 40 later).
 
A gauge from a '72 or earlier cluster will fit in with a little fussing, it will look different. But you'll have to get the matching sending unit. You can't steal it out of your '78.

I would go down to the parts store and get a cheap ($10 -$15) mechanical temp gauge and stick that in there until you figure out the original one.
 
So, it looks like what I needed to begin with, was a new replacement FJ25 sending unit to match to my FJ25 temp gauge? Rather than the new one I bought for my later F engine that's likey matched to a late 60s/early 70s gauge. Correct?
 
Landcruisersteve said:
By the way, your new avatar is barely readable . .
Click to expand...

Yeah, the guy who needs to see it hasn't stopped in yet..... :rolleyes:

Yep, you just need a new FJ25 sender..............notice it's not in the parts number thread. :frown:
 
Cruiser_Nerd said:
Yep, you just need a new FJ25 sender..............notice it's not in the parts number thread. :frown:
Click to expand...

Is that a nice way of saying I'm up the creek without a paddle? :frown:


(Hurry back to the grill shot for your avatar. That was kinda cool. :) )
 
Cruiser_Nerd said:
I would go down to the parts store and get a cheap ($10 -$15) mechanical temp gauge and stick that in there until you figure out the original one.
Click to expand...

That looks like what I'm going to do for the time being.
So, where would the sender on a mechanical temp gauge tap into on the engine? The original sender port with some sort of a NPT adapter?
 
foxfab said:
OH, you bastid!!!
Click to expand...

OK, I can get back to work now. :D

Steve, the block will accept 1/2" NPT. You may have to get a short nipple, coupler ro reducing bush, depends on what comes in the kit. Just make sure the temperature probe clears the bottom and gets down into the coolant stream.
 
Okay. Got a $18 Sunpro mechanical temp gauge. Screwed in the sender with its standard stock fitting, and it surprizingly screwed right into the port. (I thought there'd be a metric size difference I would have to deal with or something. Anyway, it doesn't leak, even after the engine gets warm.)

Temp reading rises to @ 170 after about 15-20 minutes of idling. And dropped down to @ 160 when I hopped in and drove it around the block a couple of times. After shutting down the engine, the temp rose to around 190 and progressively cooled down from there.

Are these readings about right, considering the above ritual??
 
Sounds good Steve, that's about what mine does now. :cool:
 
Cruiser_Nerd said:
Steve, the block will accept 1/2" NPT. Just make sure the temperature probe clears the bottom and gets down into the coolant stream.
Click to expand...


(I just sent my above post after you must've sent yours.)


So, the port is 1/2", ay? (I kinda figured it would've been metric.) I guess that's why it fit without an adapter.

And the probe appears to be definitely down into the coolant stream.

BTW, there's a second port right next to this one that's currently plugged and not used. (Looks identical in size.) Would that allow me to run two senders to two different gauges once I got the OEM gauge problem resolved? (Just as a redundant backup and cross-reference.)


Glad to see your other avatar back. Now zoom in tighter on that gorgeous grill.

-Steve
 
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