454 Sticky Throttle is a death trap

[PlatonicSolid]

Pics of Auxiliary Cooling Fan Switch and Water Temp Switch came out too dark, but Schurkey is correct = The Fan Switch is above plug 6 and Water Temp Switch above plug 3. I haven't done a deep dive into the manual to figure out what a coolant temperature switch does vs a coolant temperature sensor.

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So I now own 3 TPS. The original measuring 0.90V, the one that came with the new TBI measuring 0.77V, and the adjustable. Yesterday I put the original back in to boost the idle so the truck doesn't stall. It's not a smooth idle, so this is just a band-aid.

Today I'm replacing the valve cover gaskets. The oil leak above plug 7 is pretty bad. I've only idled the engine for 5 minutes since replacing the plugs and cables and cable 7 already has oil on it.
My prior belief that the left exhaust flange is leaking may be completely wrong. I now think the smoke coming from the flange is actually oil hitting the flange. The smoking penetrating oil sprayed on the flange bolts probably isn't helping this diagnosis either.

 

[PlatonicSolid]

Changed the left valve cover gasket which had nothing wrong with it. I assume oil must be leaking out from the left head gasket near plug 7 - Crap.
Confirmed the left exhaust flange is definitely leaking - Crap II.
Unplugged the coolant temp sensor and truck ran just fine - though at higher idle, so I'll replace that next.
If the temp sensor doesn't solve the problem, the next assumptions: replace distributor or replace fuel pump. Not sure it's worth tackling either of those if the head gasket needs replacing.

 

[PlatonicSolid]

I'm no longer convinced the leak is oil, though it's hard to really tell as I can't see where it's coming from. Maybe it's leaking oil and coolant. All I really know is the coolant level in the radiator has gone down about 2 inches. Oil level is full and no signs of coolant in the oil.

 

[PlatonicSolid]

Installed the new coolant temperature sensor and it made no difference. It was worth a try since it was cheap and easy. If not for my ratcheting box wrench this wouldn't have been that easy.

Next step is to dump the coolant – flush it out – fill with distilled water – add 2 bottles of Steel Seal and see if that can fix the likely blown head gasket. I did order a block tester kit on the same order as the Steel Seal.

I’ve also picked up some J-B Weld Muffler Cement and muffler patch wrap which is how I intend to deal with the leaking manifold to Y pipe flange.

I’m well aware these are some serious jerry rig repairs, but the cost and effort involved with doing this right would only be worth it if I was willing to dive into a full restoration … and I’m not.

If the Steel Seal doesn’t work then the truck is history.

 

[PlatonicSolid]

Steel Seal solved the coolant leak, but not the idle issue.
J-B Weld Muffler Cement solved the leaking manifold flange, but not the idle issue.
Replaced O2 sensor which did not solve the idle issue.
Purchased Maddox Fuel Pressure tester from Harbor Freight, tested fuel pressure and it measures 3lbs with ignition On (engine not running) and 8lbs. with engine running at idle or acceleration. So fuel pump replacement is next.

I expect to see corrosion at the fuel pump connections, so rather than replace just the fuel filter, I see I can buy a whole new 25 Gal. tank with pump and housing for $220 on Amazon Spectra Premium Fuel Tank And Pump Assembly GM23B1FA. RockAuto is cheaper at $207, but +$40 shipping.