97 temp sensor in a 89 'manche

[Oizarod115]

quick question, any help is... well, helpful. lol.

background info:

1989 4.0liter MJ 4x4 BA10

head and block replaced with 97 head and block, all renix systems, just 97 block and head. closed coolant system

 

the question:

97s heat sens. was in the thermostat housing, 89 was at the back of the block, my heat sensor is in the thermostat housing, and is a 97 unit. would this cause my temp to read high? like 240-250 high? cause if not... I'm burnin up my baby here.

 

(tried putting a meat thermo in the coolant bottle and running it that read like 190-210 but i wastold that won't give accurate readings)

[Cabz]

on the 97 that sensor is also for the ECM to read engine temp , so chances are it is very inacurate .

 

Take the old temp sending unit that was in the old head and get a brass adaptor that will let it screw into the Tstat houseing ( 1/8th fine ID threads / to 3/8 th's or 1/2 OD in the plumbing section of hardware stores)

and then extend the ole wiring to it.

.

[512tr]

The early HO's have two water-temp sensors, one for the water-temp gauge and one for the PCM.

 

Here is my 94 mod.

 

[Eagle]

Between 1990 and 1991, Chrysler changed the temp sensor. They did two things: First, they reversed the polarity, and second they changed the ohm range.

 

At this point I don't recall which was which, but let's assume the Renix (which includes your '89) has a range of 0 thru 88 ohms. 0 ohms is "cold" and 88 ohms is "hot." The range for the 91+ was 5 thru 105 ohms, but it went in reverse, so 5 ohms is "hot" and 105 ohms is "cold."

 

I don't think they reversed the polarity again when they went to OBD-II, so your '97 sensor is reading backwards for your electrical system. You need to find the correct sensor for your year.