spearman

Hey guys, my roommate owns a 1996 F-150 4x4 with the 5.8l V8 and approximately 160,000 miles. Lately his oil temperature gauge has been leaping from mid range, where it usually sits, to well past cold, then back to midrange(although never higher than where the temp actually should be). At about the same time the gauge issue started the truck randomly started making a pretty loud tapping noise that corresponds with engine revs, faster revs, louder tapping. It seems to be coming from the area of the engine block, maybe below it. The noise would best be simulated by taking a flat head screwdriver at hitting the top of the block with it. It's very clear and distinct, metallic in nature. Ive got working experience with engines, It's not a bent fan blade, it isn't a belt bearing or anything like that, and its definitely not an exhaust leak. The noise itself doesn't change besides in how fast it repeats itself, no matter how high you rev the engine. It also isn't consistent. Some drives it won't happen at all, other times it starts as soon as the truck is turned on. Any ideas? I read on some forum or the other that these engines could "blow" a spark plug... like out of the valve cover I guess, anyone have a guess as to what is going on?

Just call me Sean

iTrader: (1)

This year doesn't have the spark plug problem. You say oil temperature gauge, did he add one because that isn't a factory gauge. Or do you mean water temperature or oil pressure?

spearman

I guess its the oil pressure gauge then, although it doesn't look like any pressure gauge ive ever seen, it has a blue low and a red high and doesnt feather up and down with rpms like they usually do. It has the little oil lamp picture beneath it. I suppose its possible they added it although the display is definitely old... All the pressure gauges I have seen have numerical markings, this looks just like the coolant gauge next to it, but with a picture for oil... Although that is less worrying than that tapping noise

spearman

scratch that, had another look, it must be a pressure gauge. the faded white with the green backlight made the top end seem blue. sorry, well the pressure gauge is freaking out(he also told me it was a temp so i kinda took his word)

Just call me Sean

iTrader: (1)

Well mine doesn't move with engine RPM's, it just hangs in the same place. It has the low and high marks with NORMAL in between. Mine hangs near the N. First make sure you have oil in it, although I'm guessing you already did that. Then you need to determine what the oil pressure actually is. The factory gauge isn't all that accurate, it just gives an estimate. A mechanical oil pressure gauge will do the trick, and if you don't want it permanent you can hook it up temporary.

spearman

Yeah this one hangs, I used to drive a gmc 7500 and when I had a load there was a definite amount of movement. The oil was a little low, so I changed it out and did the perfect measurement, it seems to have stopped the gauge problem, but it still ticks.

aliens8mycow

That ticking noise may be a valve/lifter issue, and it may not. I thought that I had a lifter problem on my truck, but recently had the valve covers off and checked tolerances, torque, etc. Everything was right on. Everything is moving, not worn, you name it.

So... I'm in the same boat - got a tick, and can't find it. Could it possibly be the bearing in the idler pulley? I think for some reason that mine is coming from up front, and that's about the only thing that I've kept coming back to.

mitchalvin

For the most part these have moving idiot light in them for gauges. If you watch the oil pressure jumps to the normal reading as soon as it starts and does not move from this position due to engine rpms as normal.