5.0 making concerning noises

[GT2000]

Had little bit of time to mess with it today, started up and oil pressure gauge went up immediatly when i started it, doubt oil is the problem. I know the oil pressure gauge is just a “dummy” gauge but still. Also another thing, when its sitting there if idle is at 1200 or lower it runs mostly smooth, rev it up any higher and starts shaking BAD and runs awful. Under load at idle smooth, even while making that horrid noise. Also i have a PO300 code now...

 

[CDW6212R]

With the general miss code, you can concentrate on engine ignition and fuel items versus outside things like the EGR pipe. I've had two coils end up being bad for two 98 302's, how sure are you about yours? If you have a spare, swap it around, and note really huge plug gaps can kill a coil fast. So it's not uncommon to find old plugs, and then end up with a bad coil next.

 

[GT2000]

I thought "no way this awful noise would be because of a coil" but i was out checking around, ran it and pulled the wire off the coil and sure enough, it starts arcing all over the place. So i went over to my local mechanic and got one for 20$ he had laying around. Pop it on there and holy crap, the tick faded quickly, and it ran good. ITS A MIRACLE, my motor isn't completely ruined?!!! I started it this morning and it ticked for only about a second and completely went away, so maybe it's gotta reset itself in there from missing so bad? Drove it this morning tho, and heat as sculding hot as normally is, and then temp gauge all of the sudden shot up-and i lost all heat!! Pulled over and shut off immediately, opened the hood, and didn't even seem hot, so i started it up again, and the heat went back to its normal "crazy hot" and temp gauge fell to normal in just a couple seconds, so maybe it needs a thermostat now?? A coil and a thermostat is a drop in the bucket compared to a BAD motor!! Thanks for all the tips guys, but i thought for sure that motor was a goner!!

 

[CDW6212R]

I hope the engine is going to be fine now, at this age it can take some time to catch up with items that have degraded etc.

That heat issue unfortu8nately isn't going to be related to the engine, most likely. The AC/heat unit under the dash has a weak link in the blend door design. In many of these models the blend door will crack/break at the upper pivot point, and if that happens, the heat and AC will be randomly hot or cold, or anything in between. Keep a watch on the temps coming out, for a given temperature setting on the control. If it doesn't match what it should be, the blend door is suspect, but don't immediately jump to "fix" it. The repair is either a long process to change the whole unit(nobody does that), or under the dash unit cut a hole carefully to access the blend door, and replace it, sealing up the cut afterwords.

First be sure it is the bland door, search on here for examples of others, how they checked it out, and repaired if needed. My newest 98 is that way, I keep it on 90 for now to leave it on full heat, and adjust the fan etc, as needed. I'll fix mine in the Spring.

 

[GT2000]

I put a Tstat in er and no more issues with the heater, but coolant temp gauge still seems a bit weird, will shut off for 5 mins and get gas, start back up and temp will be way down in that short time, and then rise in a minute or two, which seems weird, dont think in cooled off in that amount of time. Tstat i pulled out said motorcraft on it, so maybe is original, everything on this poor thing is original. Maybe my coolant temp sensor is on the fritz, the truck does have a long start problem, which i heard can be a symptom of a bad temp sensor.

 

[C420sailor]

Depending on the ambient temp, fluid in a heat exchanger (your radiator) can cool RAPIDLY with the truck off. Depending on where the temp sensor is located and other factors, that can result in an initially low reading that jumps up quickly once the cold coolant mixes with the warm in the rest of the system.

 

[GT2000]

Well I'm reviving my old thread because... this same noise had returned !! I checked the other coil, and sure enough its arching and sparking weird, like the first time. So I thought ok, get a coil, problem solved right. Well, that was a few weeks ago, and several times I started it up and makes the same exact tapping tone that it did when this all first happened- except, it clears up faster and is not quite as loud. Like last time, its only on cold start, but it does not happen every time like it did last time. The first time this happened I replaced the coil with a used MSD coil, so maybe it went bad, but that would be odd that they both fail like that, and the MSD one seemed fine when I pulled each wire off when running.