Chasing Idle/Temp issue after many parts replacements '93 4.0 ohv

[Eddo Rogue]

Looking better indeed! Yes, it is during defrost selection... I've always preferred the heat coming out of the defrost vents, keeps me and the windshield warm, instead of cooking my face and feet. Thanks RonD, I feel better now lol

Things seem to be looking better

When Defrost OR AC is selected the AC is on, thats about the only connection that should effect idle RPMs

So if Defrost is selected then "heater" on/off would effect idle RPMs

I think the blower motor(fan) is always on unless you turn it off, blower is an electrical load and if motor is drawing more amps than it should it could cause higher load on alternator which might effect RPMs

Also that got me thinking, will this affect burping the cooling system? I've been bleeding it w/ the heater on defrost, should I do it on panel/flr setting instead?

 

[RonD]

Doesn't matter, you can't turn off the heater core flow on these, there is no valve on the heater hoses, that was added in 1995, but only by-passed heater core flow in MAX AC setting

Best way to clear air from cooling system is:
Cold engine
Remove both heater hoses at the firewall, refill radiator until coolant starts to come out the heater hoses
Put heater hoses back on, air is OUT of the engine

The thermostat prevents air from coming out of engine when refilling, the heater hoses are on the engine side of thermostat so let the air out

Some thermostats will have a "jiggle valve", its a hole in the thermostat plate with a metal pin that "jiggles" to keep that hole open
Its there to let any air out when refilling or if there is a leak in the system and air gets in
You can just drill a hole in the thermostat plate that does the same thing
The Jiggle Valve or hole would be put at 12:00 position when installing a new thermostat, the high point where any air would collect

Remember to reverse heater hoses at the firewall every year or so to keep heater core cleaner, it back flushes it while driving

 

[Eddo Rogue]

Doesn't matter, you can't turn off the heater core flow on these, there is no valve on the heater hoses, that was added in 1995, but only by-passed heater core flow in MAX AC setting

Best way to clear air from cooling system is:
Cold engine
Remove both heater hoses at the firewall, refill radiator until coolant starts to come out the heater hoses
Put heater hoses back on, air is OUT of the engine

The thermostat prevents air from coming out of engine when refilling, the heater hoses are on the engine side of thermostat so let the air out

Remember to reverse heater hoses at the firewall every year or so to keep heater core cleaner, it back flushes it while driving

Do you mean with the engine running, or off? I ask because I tried this with engine running and it just pissed coolant everywhere...it was warm though....

Core is new, but I plan to switch hoses next coolant flush.

 

[RonD]

Cold engine, engine OFF

Air flows to highest point on its own, there is no where that air can be trapped in the system with heater hoses off

Any remaining air would find its way to top of radiator after warm up, thermostat opened, and it would be purged via overflow system and replaced by coolant at cool down
The system is self purging of air
Assuming no leaks in the cooling system

 

[Eddo Rogue]

Cold engine, engine OFF

Air flows to highest point on its own, there is no where that air can be trapped in the system with heater hoses off

Any remaining air would find its way to top of radiator after warm up, thermostat opened, and it would be purged via overflow system and replaced by coolant at cool down
The system is self purging of air
Assuming no leaks in the cooling system

Copy that. and yes my thermostat has a jiggle valve, which is at 12 o'clock. I made sure of this chasing my temp fluct problem....Also I'm assuming top off the heater core before reconnecting hoses? Good info, thanks again!

I will do this after swapping radiators soon as my new one arrives...Im currently running an Explorer unit that is 2 1/4" inches thick, and ordered a ranger automatic w/ ac unit that is a slightly thinner (but still thicker than stock)1 3/4" inches thick to swap in. This is because at the moment my new Efan is just shy of clearing the fan clutch threads on the waterpump pulley. Im hoping the 1/2" extra clearance will do the trick.

 

[Eddo Rogue]

Figured I should update this post, as a conclusion for those w/ the same problem.

I still dont know what got my temp gauge to finally settle, but it was either the thorough fill/bleed job, or new heater core I swapped in. Probably both. After a nice long drive was when it settled, so simply running it may have also helped.

The idle issue again Im not sure, but think it was a bad IAC (swapping in a motorcraft unit helped), and the throttle body (my cleaning job fubar'd it). Again driving it also helped settle things.

that is all..... thank you, come again.

 

[RonD]

Good stuff

Thank for the update, I am sure it will help some one down the road

 

[Eddo Rogue]

Good stuff

Thank for the update, I am sure it will help some one down the road

Thank you RonD for your replies, and everyone else too! I forgot to mention all the replies and suggestions were also a great help chasing this down. And probably kept me from going nuts during the hunt. Thanks guys!