Check your basics. Make sure the radiator is full of clean coolant. Make sure your belts are properly adjusted. Check the fan clutch. Look through the radiator core using a light on the backside and see if the fins are restricted with bugs, birds or debris (one of the most common and overlooked issues). Check your ignition timing. Check EGR operation. Try filling at a different station. Then drive it until the Check Engine light comes back on and retrieve the code before disconnecting the battery.
to add to what bd said the overheating and knock are related. as for what causes it coolant problems or spark problems. since bd covered the coolant ill cover the spark. if you have problems when your running the truck harder than normal it could be spark and a colder plug might be your fix. when your checking things out remove a plug and post the numbers on it. you could step the up the octane on the fuel also to see if that helps. some low quality and/or low octane fuels can burn hotter than the higher ones. also timing be too advanced and/or a lean running tune will cause this problem
Overheating while driving or idling?
i had a problem with overheating i found out that my hose had a whole in it not a big one but big enough for a leak and the core may be a problem
...Fan clutch feels good when I spin it with engine off....
...Fins on radiator are severely smashed in....
...The truck runs "really good", I mean it really sounds smooth and like new when you start it and drive down the road. The pinging started at least a month after I bought the truck and until last week I was running RaceTrac "Regular".
...I check the radiator level every day or every other day and it's losing fluid. I've seen leaking somewhere around the radiator, not sure where....
...The check engine light also comes on sometimes....
Does the fan clutch allow more than ~3/16" play at the fan blade tip if you wiggle the blade fore-and-aft?
Estimate the percentage of radiator surface that's blocked to airflow due to mashed fins, etc. If you have access to the front of the radiator, do you feel any 'cold spots' as you move your hand back-and-forth across the core with the engine running at normal temperature? Is the fan shroud intact?
Id say
Run the engine to operating temperature and verify the ignition timing with a light after bypassing EST by unplugging the single tan/black in-line Weatherpack connector located near the driver side bulkhead plug at the firewall.
Diagnose that "fluid leak." Does the 'leak' appear to account for the amount of coolant you have to keep adding to the radiator? Is there "white smoke" issuing from the exhaust pipe?
...The check engine light also comes on sometimes....
Retrieve and post the diagnostic code(s) the next time the SES light comes on with the engine running.
In the meantime, since the engine was previously removed or rebuilt in-frame, verify the grounds.
- There should be an ECM ground wire plus a braided ground strap from the firewall bolted to the back of the right cylinder head,
an ECM ground wire should connect to the right front of the intake manifold,
the battery ground cable should fasten to the air pump bracket at the right front of the engine
and a jumper should connect between the right frame rail and battery negative terminal.
In addition, you can check for exhaust restrictions by measuring the exhaust backpressure. It shouldn't be greater than ~1.5 PSI at 3,000 RPM. Also, verify the EGR valve is working.
Thus far, our strategy has been painfully broad, because we're fishing for something tangible that may benefit you. The trouble code(s) could prove key to a solution.
Does it have the O2 sensor?
Quote from: bdRetrieve and post the diagnostic code(s) the next time the SES light comes on with the engine running.
The above is new to me. A mechanic buddy of mine, ASE certified, Level ? GM Mechanic, has subscription to some kind of GM software and online access to GM service info. (Works at American Yachts right now but pulled all this stuff up on his computer to show me).
He showed me to take a u-shaped paper clip, stick it into "B" and "A" terminals, to the key to ignition on and then showed me how the computer will talk to me with a series of flashing lights. Told me to write down the numbers and then I can use these to get the error codes.
But he showed me how to do it with the engine off, key on. You're telling me to do this with the engine running? You probably mean if I had the actual tool that you plug in to check codes, I just have the paper clip. :)
Does it have the O2 sensor?
I know O2 sensors are the norm for most cars but I don't know where to look?
There's a wire going to a fitting on the exhaust header, driver's side, I don't remember looking to see if there's one on the passenger side? I can go look.
Would this be the O2 sensor?...