chasrahm

Driving the 97 1500 5.7ltr on the highway a couple weeks ago, I let off the throttle from about 65mph and the throttle stuck open. A quick blip of the throttle and it let go. It happened again about 15 minutes later and on another day.
I have lubricated the pivot hinge point under the carpet area.
I wanted to lubricate the cable in its jacket, but can't figure out how to disconnect the cable from the bell crank on the throttle butterfly? Help?

Or is it better practice to just replace the cable assembly?

Thanks! Charles in Dallas, TX

Gumby22

It’s more likely that the throttle plate is what’s sticking.

To remove the cable from the TB, remove the air cleaner intake boot and release the cable from the support bracket.

Manually Rotate the throttle plate lever (bell crank), then release the cable from the lever by lining up the cable with the notch in the lever and pull the cable stud sideways.

Once released, pull on the end of the cable and release - it should retract and you should be able to hear the gas pedal “thud.” If this doesn’t happen the cable should be replaced.

chasrahm

Part of my recent tune up on this 194k mile truck was to clean the air flow sensor and the throttle butterfly. I did notice the front of the butterfly, the underside, has a surface pointing down perpendicular to the butterfly on the front under side. It was slightly deformed as if someone else had a pry tool on it for some reason. I tried to get it back to an arc shape matching the curve of the butterfly edge. Wonder if it is slightly proud hanging on throat of the throttle?

I did spray the butterfly and area down with carb cleaner, there was a light coating of black grunge.

Gumby22

Could be - the only way to know for sure is to remove the cables and rotate it by hand to feel for sticking/binding.

If you’re comfortable doing so, the throttle body can be disassembled for cleaning and inspection. Just make sure the throttle plate is installed in its original orientation and note the position/number of turns for the springs.

The black grunge is normal as long as it’s a light/thin coat. Heavy accumulation is indicative of other problems.

chasrahm

Thanks gumby22! Soon i hope to change the thermostat. I think it is either stuck partially open or is a 165 in there. My fully warm running temp is about 160. Factory should be 195. Why someone changed to a lower if they did is rather silly to me. Engines need to be hotter for more efficient fuel burning.

Regarding the butterfly assembly, I'll examine the movement closer and slowly to see if some kind of interference causing butterfly to hang open.

Gumby22

Usually the reason most people switch to a lower temp thermostat is because the engine starts running hot and they’re hoping to avoid causing damage instead of resolving the cause of the higher temps.

If it turns out to be a lower temp thermostat, check for a restricted radiator - not just sludge accumulation inside it, but also for excessive accumulation between the front of the radiator and condenser.

chasrahm

Yes, lower stat reason is a probable. This was my dad's truck from new and I don't recall him telling me he was having overheat issues. I will be interested to see what temp stat is in there now.
I'm also the guy with the very recent post about mice in the engine compartment. One of the things I did looking for the nest was to remove the top of the radiator shroud so I could get to between the condenser and the radiator. I was surprised how little debris was between the two and disappointed no mouse nest (never did find, and have had any recent mouse activity of finding chewed acorns). But I did clean out the leaves between the two devices and tried with compressed air to clean the fins. Lots of very find dust blew into the air so I'm glad I was wearing a dust mask.

edit added:
Just got a call from my dad and I asked if he had trouble in the past with overheating and his reply was, "Absolutely not. If a lower possible thermostat was installed it was the product of some mechanic somewhere in the past who probably just put in what he already had." (Dad has lived in the hills of Arkansas, and a few small towns since)

Thanks again for your help Gumby22!

chasrahm

Thermostat isn’t the problem. Installed the new one, after testing it in a pan of heating water, and the old one, and they both fully opened around 200.
I’ll get a new coolant temperature sending unit for the gauge. Again, the gauge is showing about 165-170F.

chasrahm

Installed the new engine water temperature sensor for the gauge and it now indicates a warmer engine as it should.