Coolant flow

[yellow85cj]

Anyone have a diagram or know how the coolant flows through the AMC 258 i6 / 4.2l ?

Is the temp sender in the middle of the flow? Or close to the "exit" point before returning to the radiator?

Trying to figure out where to put in a mechanical temp sender for an engine bay temp gauge.

Oil is simple, just add a T on the block where dash sender is.

This is mostly for a first start on a rebuilt AMC 258 i6 / 4.2l . Don't want to rely on dash electric gauges or running my fat butt back and forth to check.

 

[Torxhead]

Mechanical temp gauge is a must for an old CJ, the way I see it. There are a couple of plugs on the left or drivers side of the block, these are probably the best location if you can get the plugs out. There are the two large threaded holes on the intake manifold, one for the manifold heater and the other for the cto valve. These might give you a cooler reading, but doable. I used the manifold heater hole since I am fuel injected. I have heard of guys using a Thermostat housing from a 4.0 that has a threaded hole that would work. That's about all I know of, I forget which way it flows.

 

[yellow85cj]

Found a couple of videos that explain the coolant flow.
Ones a little hokey but informative. Might want to ship the first 4 minutes or so.
Still not quit sure why the sender on the AMC 258 i6 / 4.2l is at the rear instead of the front where the coolant exits.

Gotta love the narrators enthusiasm.

https://www.youtube.com/watch?v=tPVNCfhZwuc

And a more modern one
https://www.youtube.com/watch?v=V7inC4lOpGs

 

[Lumpy Grits]

I put my sender where the CTS goes, and them installed the CTS via a 't' fitting just above the manifold.
Coolant Temperature Switch

LG

 

[yellow85cj]

I have heard of guys using a Thermostat housing from a 4.0 that has a threaded hole that would work. That's about all I know of, I forget which way it flows.

Yep, I am using a 4.0 t-stat housing. Just don't know if that would be a "highest" temp reading, but then I am assuming that the rear head temp sender is a "highest" temp reading. May not be.

Lumpy - thought about the CTS spot - don't need it here as no emissions and CJ has been Nutter'd. Do you think that the location gives you an accurate reading or is it off +/-. Did you ever compare to OEM gauge?

 

[Lumpy Grits]

I still run my OEM gauge and a mechanical.
That CTS is in the return path and I'm happy with the location.
BTW: The main reason I put it there was the fact the probe was fairly long and that location gave me the room needed.
LG