llhat

it is already on the site...

the IAC is a stepper motor, so you do have one. the 'steps' move the pintle in and out exposing or closing the idle air bypass. the IAC is in play at idle, adjusting air bypass to control the idle speed. the 2.5 has a electro-mechanical stepper acting on the throttle lever itself.. as it was a 2.5, i did not include.. all i posted was from the 1989 service manual. thanks OHM for posting an image of the tool.. i had never seen one, imagine scarce

some instructions from manual... have NO idea what a stepper motor exerciser is... lot of reading text comanche.pdf p 584 is stepper.pdf

i wanted to do this few years ago during a fuel pump failure and dang near full of gas... tried a piece of fuel hose ?(5/16 ID) and i could not get it down the filler neck... for a 'test' I took a smaller piece of hard nylon tubing that was like 1/4" and it was troublesome getting it down there... maybe doable, but not easy.

dorman also makes a unit, get at you local FLAPS, or even evilbay...

i'd guess the dye is a good process, as 'some' external coolant leaks will disperse and not puddle or accumulate in cavities

IIRC, the pressure bottle on the firewall has connections on the water pump and thermostat housing... I'd expect some type of flow depending on how the connection on the thermostat housing is constructed ( "behind" the thermosat in the block or on the radiator side )... I also need to top my 89 off periodically, but "I" have some certainty that "I" have a weeping heater core, though my floor is dry as a bone.

i believe a jpeg, save to computer and enlarge.. I see OHM has posted a link also thanks.

only issue I have experienced on my 89 4.0 using these harness assemblies is the 'J' hose connecting to the air filter housing. original harness "J" hose had a increase in ID on one side to connect, new dorman are straight internal diameter both sides. I believe I have documented this in past threads.. finally took the suggestion of a poster here to 'press' a section of hard tube from old harness into the nipped existing on the air filter housing. that "j" hose now fits without being overly stretched and ultimately cracking. next 'project' in my instance is to perform the modification of the rear vacuum tube to valve cover... drilling out the plastic connector and using a larger internal diameter vacuum line.... procedure shown on boards here also.. as far as the rest of the vacuum fittings on these dorman units, mine have always appears secure with no need for zip ties or clamps

was the 'height' of the pushrod checked with the new master cylinder and booster? If too short, full travel maybe not there, if too long, not enough stroke...

been running a gutted housing for i can't remember how many years.... no inspection requirements for me either 'now' but during my life with it, would always pass a visual, did not have Gas testing here.

get the service port leaks repaired, "maybe" as simple as new schrader valves. my 89 had r12, local shop found the rubber hose behind battery going to the condenser was leaking... and it was deteriorated internally... could not easily get to the condenser fittings to replace as a unit, but these guys were good.. silver brazed new fittings to existing pipe made a replaceable hose section, we went with 134a and it has been ok ever since... ( knock on wood) somewhere around 7 years now... (guess)

iirc, The CTS coolant Temperature Sensor, is a two wire, down on the side of the block on the driver's side... could be just above the engine mount. there is an active thread with images just below these threads... read to the end. BTW... that posted manual has testing procedures for mostly all of the sensors.....

I replaced this sensor back in Feb 2025 when I had an idle issue. The issue turned out to be very dirty TB and IAC and was completely resolved after cleaning them and putting in a new TB gasket. Of course it could still be contributing, just not because of age. age may not be a factor on the O2 sensor... many reported DOA