Temp sensor broke...

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Bextreme04

Full Access Member
Joined
May 13, 2019
Posts
4,191
Reaction score
5,091
Location
Oregon
First Name
Eric
Truck Year
1980
Truck Model
K25
Engine Size
350-4bbl
Exactly. With the sender in the pressure port, your basically reading the temp of the case. The temp is probably slow to rise, and just as slow to cool down.

I just realized I screwed that up. I meant to say the fluid IS NOT circulating at that point, which is why it is a terrible place for a temp sensor. You obviously got what I meant though, so at least there's that.
 

Matt69olds

Full Access Member
Joined
Jan 8, 2018
Posts
2,351
Reaction score
3,597
Location
Central Indiana
First Name
Matt
Truck Year
81
Truck Model
GMC 1/2 ton
Engine Size
455 Olds
You must be registered for see images attach
You must be registered for see images attach
I just realized I screwed that up. I meant to say the fluid IS NOT circulating at that point, which is why it is a terrible place for a temp sensor. You obviously got what I meant though, so at least there's that.


No problem. I have been guilty of thinking faster than I can type many times. My wife and kids never miss an opportunity to correct my grammar, spelling or punctuation.
You must be registered for see images attach


To which I usually reply with one of these smart ass comments.
 

Dutch Rutter

Full Access Member
Joined
Aug 13, 2013
Posts
1,074
Reaction score
1,197
Location
Independence, Or
First Name
Joshua
Truck Year
1984
Truck Model
K20
Engine Size
5.7
That makes sense. And exactly what you guys said, the gauge took a while (20min) of highway driving to raise up to a 1/4 of the gauge. In heavier traffic it would rise pretty quickly from that to 1/2 to just under 3/4 (top being 250, and the gauge is quite accurate) and wouldnt really fall until shutdown. All of this got me thinking that I needed a different location for the sender. Plus a bigger external cooler. Currently I'm running this thing with an electric fan.
https://www.summitracing.com/parts/hda-699
It does ok. Unless im going through low speed, stop and go traffic, hills, offroad etc.

I will be switching to this one. With an electric fan and I'm prepared to put a second one and fan if need be.
https://www.amazon.com/Tru-Cool-H7B-ENGINE-OIL-COOLER/dp/B003TQ3BG2

With buying a house closer to town. Trans temp management has been on my mind alot. Plus I want to actually tow with the truck and not have to worry about the temps as much as I have to now.

Btw: I'm also running one of these pans, so I'm going to be throwing as much cooling at this thing as I can fit. And as much as I can think of for now.

https://www.summitracing.com/parts/...02IFwms3bHkqKyfu_8iIJ9qr1eusTXy8aAjOIEALw_wcB
 

Bextreme04

Full Access Member
Joined
May 13, 2019
Posts
4,191
Reaction score
5,091
Location
Oregon
First Name
Eric
Truck Year
1980
Truck Model
K25
Engine Size
350-4bbl
That makes sense. And exactly what you guys said, the gauge took a while (20min) of highway driving to raise up to a 1/4 of the gauge. In heavier traffic it would rise pretty quickly from that to 1/2 to just under 3/4 (top being 250, and the gauge is quite accurate) and wouldnt really fall until shutdown. All of this got me thinking that I needed a different location for the sender. Plus a bigger external cooler. Currently I'm running this thing with an electric fan.
https://www.summitracing.com/parts/hda-699
It does ok. Unless im going through low speed, stop and go traffic, hills, offroad etc.

I will be switching to this one. With an electric fan and I'm prepared to put a second one and fan if need be.
https://www.amazon.com/Tru-Cool-H7B-ENGINE-OIL-COOLER/dp/B003TQ3BG2

With buying a house closer to town. Trans temp management has been on my mind alot. Plus I want to actually tow with the truck and not have to worry about the temps as much as I have to now.

Btw: I'm also running one of these pans, so I'm going to be throwing as much cooling at this thing as I can fit. And as much as I can think of for now.

https://www.summitracing.com/parts/...02IFwms3bHkqKyfu_8iIJ9qr1eusTXy8aAjOIEALw_wcB

That's a lot of cooling... are you also running in-radiator coolers? What are you planning on towing?
 

Dutch Rutter

Full Access Member
Joined
Aug 13, 2013
Posts
1,074
Reaction score
1,197
Location
Independence, Or
First Name
Joshua
Truck Year
1984
Truck Model
K20
Engine Size
5.7
That's a lot of cooling... are you also running in-radiator coolers? What are you planning on towing?

Currently, I do have the in radiator cooler hooked up. I was running without it and just to the Hayden 699 with the Derale pan. And with the sender in the test port (could have been the main problem) it was reading as described above. Which I felt was on the warm side of things being unloaded. Really I'm not looking to pull alot. I have a small flat bed trailer maybe 12" L x 8" W that I use to pull a dirt bike, and a quad with a second quad in the bed. Plus riding gear and other stuff. Sometimes up hills at highway-ish speeds. Sometimes gravel roads up hills. And so forth. Not pulling a big 5th wheel or anything along those lines.

The trans itself had a main pump fail and was "rebuilt and upgraded" by a local shop maybe a year or year and a half ago. Shop is now out of business, and I had a pretty tough time dealing with them. So I would not be suprised if they cut corners on it.

I'm really hoping to see better temps once I get that new sending unit and install it in the pan. But if not I'll try and throw all of this at it in hopes of prolonging its life. With a last resort of ordering a rebuilt/upgraded 700r4. Or biting the $3400 (trans and swap parts) bullet and swap an nv4500 in it.
 

Dutch Rutter

Full Access Member
Joined
Aug 13, 2013
Posts
1,074
Reaction score
1,197
Location
Independence, Or
First Name
Joshua
Truck Year
1984
Truck Model
K20
Engine Size
5.7
The plot thickens.. got home from work only able to use D because the trans would not shift to anything else. I figured it was the linkage, pulled the bar off tried shifting it with the fork on the trans itself and low and behold, nothing..

Drained, took the pan off i was able to bounce it into 3rd, 2nd, and 1st but now it will not go back into D or above. Nothing looks out of place to me. I was able to roll the truck as if it were in neutral but the internal linkage should have been in gear. Any ideas?

Here is the new thread on this new issue. :emotions122:

https://www.gmsquarebody.com/threads/700r4-locked-up-in-gear.30670/

You must be registered for see images attach
 
Last edited:

Dutch Rutter

Full Access Member
Joined
Aug 13, 2013
Posts
1,074
Reaction score
1,197
Location
Independence, Or
First Name
Joshua
Truck Year
1984
Truck Model
K20
Engine Size
5.7
With this new trans the testing of the temp sensor location might be skewed, but from what I've seen so far, the pan is by far the best place for a temp reading. I am getting better readings and like what was said above, the temp reading does seem to fall faster when using the electric fan that is in front of the trans cooler. Where as when the sensor was in the test port I was able to watch the temp rise but it was VERY slow to fall (basically reading the temp of the actual trans case).

I am really hoping this new trans gives me several years of reliable service. I have not yet added the new larger aux cooler but I do have it and all of the needed fittings just in case it gets too hot next summer. I also feel as though the Derale cooling Pan, and the Hayden 699 after the factory cooler should be more then adequate to keep this thing's temps in check.
 

Forum statistics

Threads
42,124
Posts
909,601
Members
33,616
Latest member
pete08
Top