Engine Temp pegs, then drops

With your overheating problem I would get a can of radiator clean and follow the directions on the can. Then reverse flush the radiator and refill with new coolant.
If that does not solve the problem you will be in the market for a new radiator. The diesel knock that you got was preignition caused by the excess heat of the motor.
The ABS light being on is most likely from a wheel sensor damaged or not placed correctly after the front end repairs that were done.
Your heater fan and power windows will most likely be a bad (loose)connector in the electrical wiring. Any time you see a connector plug just give it a good wriggle and push it making sure it has a tight fit.
I would reset the computer to get rid of all your old engine codes and that check engine light. Remove the negative battery terminal and stand on the brake pedal a number of times then reconnect.
You will also loose your preset radio stations when you do this. Now if the check engine light comes back on get someone with a OBD2 scan tool to see which engine codes are set.

It could be the thermostat but you need to check the fluid level and for any leaks (these could even be pin hole) first. If you have one of those infra-red temperature gauges you can check the temperature of the cooling system in the engine bay to double check. Generally the engine temperature should not go much about 90 deg C - this is when the electric cooling fans kick in - are these turning on?

you need to replace thermostat and radiator cap.look under hood around engine compartment.look for a radiator cap near radiator,add 50/50 antifreeze and water to coolant system to bring up boiling point.pure water will cause engine run hotter because water evaporate away,remove radiator pour coolant in the radiator until coolant stop dropping in the radiator now some vechicle pour coolant in the coolant overflow jug,pour coolant until coolant level stop dropping and the coolant level stay at cold full mark.start engie let idle few minutes, watch coolant level in radiator if coolant start dropping add more coolant, when coolant level stop dropping put radiator cap back on let engine idle until both top radaitor hose and bottom coolant hose get warm turn off engine wait until it get cool then take a large rag slightly open radiator just a litle at a time to keep from getting scaled.once radiator remove add more coolant if low,put radiator cap back on start the engine let it idle watch the temp gauge if temperature gauge going hot zone stop engine wait until cool then add more coolant,keep doing this until engine stop overheating going into hot zone and coolant level stop dropping,make the coolant overflow jug coolant level stay at full cold mark, dont let jug run empty if so air will get in the coolant system causing engine to overheat.

If the temp is high at freeway speeds then the thermostat would be suspect. If the temp is high in slow traffic then suspect the cooling fans or its controls

Hello jcs... Usually the water pump squeals loudly and there is water on the ground under the car. For the definitive test, get the car up to operating temperature, run the A/C. Once the temp is about 80-85 deg. Park it and let it sit idling with the A/C on for about 5 minutes, then turn the car off. Let the car sit for about 5 minutes with the engine off. Then turn the ignition so that the temp gauge registers. You will probably see it spike to over 100 because the car has been sitting with a hot engine and no coolant flowing through to take away the heat. Note the temp, then start the engine. If the temp doesn't come down to normal within about a minute, then you probably have a bad pump. When functioning properly, as soon as the car is cranked the pump will move enough coolant through the head to drop the temp very quickly.

Joe

Hi,

The overheating and lack of cabin heat both point to a failed engine thermostat which would be stuck closed. At the warm up stage, the coolant stays in the engine block to bring the engine to efficient operating temperature, then it opens and circulates the coolant through the radiator and heat core. If the thermostat is stuck closed, the engine will overheat, and coolant will never reach the heater core, and you will not get cabin heat.

Blinking oil light at idle which goes away during driving could be a low oil level, but may also be a drop in oil pressue. You could have a clogged oil fliter (at best) pickup tube, or a failing oil pump.

You are describing a slow coolant leak and the resultant no heat and blockoverheating symptoms. The no heat is because there is insufficient coolant to cycle through the heater core, and the chuggin you describe is the engine indicating serious overheating.
With engine cold, you must add water--not anti-freeze--to the radiator itself, until it reaches the top of the radiator, then start the engine. If you do not have a radiator cap in addition to the overflow bottle (some vehicles don't), you must still add water to the radiator, even if you have to bypass the overflow bottle hose to do it. Add water until no more will go into the radiator. Start engine, let idle until operating temperature is reached. Thermostat should open and a good bit of the water will "sink" into the depth of the radiator. If you have no radiator cap, observe the temperature guage. When it reaches normal operating temp, when the thermostat opens, the temp will drop briefly at first, and you will notice warm air from the heater/defroster.
Once engine is warm and known to be full of water, seal radiator cap and/or system, and let idle for 30 minutes. Use this time to locate the "mystery leak." They can be very hard to find, and some won't leak until after the engine is turned off. During this idle period, observe the vehicle exhaust from the tailpipe as well as looking for actual water leaks: sometimes a bad head gasket can be diagnosed this way; if the exhaust is white and thick like steam, and smells like anit-freeze, you have a more serious problem. It is possible that after the repeated overheating cycles you have endured you may now have both a "mystery leak" and a blown head gasket.
Once leak is located, your next step is to let engine cool completely, drain the water, fix the leak, and then and only then add new antifreeze of the proper rating and ratio recommended by Chevy for your vehicle.
Anytime you drain a cooling system and refill it, it is necessary to check the overflow bottle at least 3 times in the first week after repair to ensure that you have the proper coolant level, and have not either missed another leak or not correctly repaired one. You MUST check it before you drive the vehicle the second time after the first repair attempt because it is normal to need to add more coolant than you added initially after the repair because of air trapped in the cooling system that will only be expelled after the first start/stop heating cycle. If after 1 week of daily normal driving you have only added a little more coolant once, and there are no more problems, you can be very comfortable that you have fixed your car.

Here's the way I usually approach problems such as this. First I'll hook up a scan tool that allows me to see the actual engine coolant temperature is [not just what the gauge says] as the vehicle is being driven down the road at highway speeds. The coolant should be near the 192 - 200 degree range to get the best heat out of the heater. If the coolant temp is below that level then the amount of heat you'll get will drop according. IF the coolant is reaching full temp but the air coming from the heater isn't very warm then you could have a restricted heater core or a temp control door in the ductwork that isn't working properly and is allowing cold air to sneak past the heater core. Usually if you have a water pump impeller problem you'll also have an overheating problem as the pump often isn't able to move enough water through the radiator to keep the engine cool. Hope this gives you a starting point and good luck!

Sounds like the sending unit is bad, can't exactly tell you where its located, don't have my manual at the moment.

check your t stat