Stock Temp Gauge Jumping Around after 3k RPMs

[SupraMario]

Ok, So I've got a 1987 2jzgte swapped, the motor swap has probably 60k miles on it. The Stock Temp gauge will jump from less than 1/2 (where it always was) to a little above 1/2 and it's not a slow climb, it's a sudden jump and then back down. Only when I'm going up a hill or above 3k RPM in 5th.

I've ordered a new T-stat as it's the cheapest option, and plan on doing a flush on the system tomorrow. I run a 80/20 mix (water/coolant) right now as it's now 90+ outside now. No coolant is lost, it's all there after I park the car. It also stays cool when I'm sitting or just rolling in traffic, it seems to only do this when I'm on the highway.

Is my sender screwed up? Anyone else ever have this issue?

 

[honeydew]

I think that's normal as I recall. Don't quote me cause I haven't driven my Supra in 2 years but I seem to recall a slight but quick jump when it's under load. As long as it's not continuously climbing past 3/4 you should be totally fine.

If you are really worried, Flush and Fill with Red toyota coolant and/or get a numerical temp gauge or just check your cluster connections. I really think it's a normal reaction to load.

Edited: Do you have a link to your build? Just want to check it out, sounds awesome.

 

[IBoughtASupra]

Cooling mods? What sender? Was it ever changed?

 

[SupraMario]

I think that's normal as I recall. Don't quote me cause I haven't driven my Supra in 2 years but I seem to recall a slight but quick jump when it's under load. As long as it's not continuously climbing past 3/4 you should be totally fine.

If you are really worried, Flush and Fill with Red toyota coolant and/or get a numerical temp gauge or just check your cluster connections. I really think it's a normal reaction to load.

Edited: Do you have a link to your build? Just want to check it out, sounds awesome.

I'm on my tablet, but just search my started threads. The issue with it is that I've been dding the car since 08, and this is the first time its done this. I am going to flush and clean it all up.

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[SupraMario]

Cooling mods? What sender? Was it ever changed?

Stock rad. And stock tt clutch fan setup, the sender is stock.

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[IJ.]

There is a really vague zone in the middle of the gauge that covers a huge temp range... what may appear not too bad is really damn hot...

 

[Poodles]

There is a really vague zone in the middle of the gauge that covers a huge temp range... what may appear not too bad is really damn hot...

This. It goes from half, to overheating and then really overheating.

 

[SupraMario]

There is a really vague zone in the middle of the gauge that covers a huge temp range... what may appear not too bad is really damn hot...

Thing is there is no boiling sounds or gurgling. Its just a little quick rise and then it drops off. It's never hit into the red.

 

[IJ.]

Get a real guage in there and see what it's actually doing, might just be an electrical gremlin Mario.

 

[SupraMario]

Get a real guage in there and see what it's actually doing, might just be an electrical gremlin Mario.

I really hope that this is it. Do you think I could just grab one from a auto parts store? Or are they not trust worthy?

 

[Canuckrz]

Not sure if this helps or not but something similar happened to my 7m after I installed my Trust 20g kit, only happened at highway speed at a similar rpm. The issue was that how the kit eliminated the water lines it caused an air pocket in the T-stat housing, which caused the T-stat to open and close causing the temp gauge to jump around. I replaced the upper coolant line I had capped off to a bleeder valve to remedy it.

 

[SupraMario]

Not sure if this helps or not but something similar happened to my 7m after I installed my Trust 20g kit, only happened at highway speed at a similar rpm. The issue was that how the kit eliminated the water lines it caused an air pocket in the T-stat housing, which caused the T-stat to open and close causing the temp gauge to jump around. I replaced the upper coolant line I had capped off to a bleeder valve to remedy it.

I'm really just hoping there is just a little air in the system. This morning woke up checked coolant, completely full still...but both hoses where kinda tight...im wondering now if my t-stat is stuck closed....

 

[te72]

I'd suspect the elusive electrical gremlin. Have someone watch your gauge when the car is warmed up. Wiggle the sender and wiring to it, and have them yell if anything changes.

 

[SupraMario]

I'd suspect the elusive electrical gremlin. Have someone watch your gauge when the car is warmed up. Wiggle the sender and wiring to it, and have them yell if anything changes.

I really hope it is, ill try the electrical thing tonight after I burp the system.

 

[SupraMario]

Ok so I burped the car, a few decent size bubbles came out but nothing big. I parked it on my steep as driveway and had the wife run it at 3k rpm for a good 2mins nothing changed the temp at all, will see what happens tomorrow. I did make a video ill upload here soon of what it does

 

[SupraMario]

Well that didn't help at all...fuck me. It almost hit the red driving today, I think the tstat is stuck closed...

 

[SupraMario]

Well, tore off the water neck today to make sure it wasn't clogged. Also replaced the t-stat...putting on the water neck again I pinched the O ring on the water bypass line...now I gotta order them...FUUUUUUUUUU

At least I got new tires for the BMW, and getting it ready to be my DD, just need to burp the system and it's good to go.

 

[Canuckrz]

Don't forget to put that little bypass valve towards the top, and cut the little nib thing off of it as well. Was there any evidence of damage to the T-stat?

 

[SupraMario]

Don't forget to put that little bypass valve towards the top, and cut the little nib thing off of it as well. Was there any evidence of damage to the T-stat?

Nib thing? The top hole is at the top, made sure of that. As for damage, the gasket around it was basically stuck to the ring, the tstat seemed harder than normal to push in, but it could just be my imagination. Didn't have time to check to see if it opened. I just hope this is the fix as when I burped it water was moving around so, I don't think its the waterpump, and it doesn't get hot when just sitting and idleing, even for long periods of time so its not the clutch fan. If its not the tstat...im out of ideas and the last thing would be radiator...

 

[Canuckrz]

The tiny metal check valve in that top hole, basically just a tiny peice of metal with either end crimped.

Some people call it the jiggle valve, helps with getting the air out of the system with it removed.