Hey fellas, I'm no stranger to turning wrenches, but my wife's '92 F-150 is really throwing me for a loop. I has 90,000 miles, a 5.0 and an E4OD, 2wd. It runs just fine, but makes a hell of a "knocking" noise under acceleration, it sounds like a damn diesel, and at idle there is a slight "knocking" from the bellhousing area. Also, the breather at the airbox pukes out water and oil at a fairly good rate(i rerouted the PCV hose to the center of the vacuum tree and replaced the valve with no change), and the coolant looks like mud. Now, I know what you're thinkin', that motor is F-ed! Well, on the surface that's what it looks like to me to, I just can't find a smoking gun to tell me FOR SURE before I plunk down some cash on fixing it.

Under the truck, the noise is by far loudest in the bell-housing. At first I thought something was rattling around in the converter, but I swapped it with the old stock one from my Lightning, and no change. I had an assistant pull off one spark plug wire at a time while running, and no change in the noise (was thinking rod knock), I did a compression test, and even though it has a lot of blow-by, average was 150psi warm on the cylinders. The plugs all looked way lean, so I did some more investigation and found a bad 02 sensor, and a bad ECT sensor. Gas mileage is way up now, but still the knock is there. It also uses a little coolant, pressure test and it holds fine for 30 minutes, did a combustion gas test (for a blown head gasket), and no CO2 was detected. I'm pretty sure they are leaking some, but not enough to show up on the test.

Also, the motor rattles for about 5 seconds when it's started the first time of the day (it has a good motorcraft filter) and occasionally one of the lifters will tap for about 5 minutes after start-up and then just stop.

When going up even a slight incline, and the converter locks up, it bogs really bad, doesn't cut out or miss, but it's like it doesn't have enough power to move the truck with the converter locked. It has 18" of vacuum at idle, after a quick WOT in neutral, it bounces back up to 24-25". Fuel pressure is good.

I'm at the point where, I don't know what else to do, but hook a mechanical oil pressure gauge up and see what oil pressure is, or figure out some way to scoot the tranny back far enough to start the motor without turning the torque converter. Unless one of yous guys has a better idea? Or maybe put some 15w-40 in it and see if it quiets down? - as a test, not as a fix.

 

Also, I did an oil change on the truck, there were no shavings, the oil was black as **** though, didn't look like it'd been changed for years, and also cut open the oil filter and there was nothing in it but oil! Good thing I only paid $1200 bucks for this sucker!

 

bUmp.........................

 

Check the trans fluid and see what color it is. The trans cooler is inside your radiator unless it has an external cooler which a lot of those still run through the stock cooler in the radiator. When you did the converter swap did you take a good look at the flexplate/flywheel? If it is cracked it will make a hell of a noise and under throttle it may flex enough to be hitting something. I put some lucas in my engine and it stopped the bearing rattle in my bottom end.

 

The trans fluid looks great! I did look at the flexplate really good when the trans was out, and it's fine. I think I'm going to try the 15w-40 tonight and see what happens.....

In the meantime I'm looking for a motor, is there a thread anywhere breaking down the differences between the 5.0 truck motors per year? From what I've read, my '92 motor has a flat tappet cam, I would prefer the later F4TE roller cam. Did the trucks switch to roller-ready blocks the same time as the mustangs?