ok if the tranny thud wasnt enough fun to try to figure out.... the ranger has now developed a perfectly timed knock, but only at idle. and also on the bad side is its on the bottom end of the engine. it still performs perfect other then the irritating knock. it started up after i did the oil and hasnt stopped since. no CEL and oil pressure is good. only other strange thing that has happened lately is after running the a/c there is a strange droning hum that comes from the air intake. i pulled off the intake hose and it was real loud just past the throttle body. never a dull moment with a ranger. any help is appreciated.

p.s. if its the rod bearing im gonna shoot it!

 

Ouh... Are you sure knock is somewhere inside engine? What oil pressure reads at idle speed and at 1200 RPM? Low oil pressure may cause not only bad rod bearing knock but valve lifters and cam knock too.

I use medical stetoscope to locate these bad sounds....

Well, bad valve lifter can not cause something very bad inside engine, but rod bearing.... it is not too difficult to drop oil pan and inspect rod bearings. If you change rod bearings too frequantly you orobably have to resurface krankshaft.

 

On the whoo sound, maybe pull & clean the IAC valve with a MAF spray cleaner.

On the engine knock, if it sounds like "marble noise" clatter. If it came about maybe 30 seconds after starting the engine, after the oil & filter change, I'd guess maybe you didn't fill the oil filter completely before installing & it has an air bubble in the system.

If so, in my expierence it'll likely work its way out in 3-10 days.

You may be able to prevent or greatly reduce it by completely filling your 4.0L's oil filter before installing it next time. Also do the oil filter cange first, then drain the pan.

Disable the fuel pump, crank the engine to build oil prssure & burp the system, before running the engine after your next oil & filter change & see if it helps.

Thats what I've had to do to eliminate my marbling after an oil change.

Just a bunch of thoughts for consideration.

 

oil pressure reads good on the dash. i will try troubleshooting with another oil change this weekend. i ran a quart of atf in this last one to try to clean stuff up a little. i used to put deisel motor oil in my old 3.0 so get rid of all the chatter. but that was in the valves, this sound is coming from the bottom end near the sump, by where the motor and tranny housing meet up. thanks.

 

Well good grief lets see, are you saying you mixed in a qt of tranny fluid on this last oil change?????

Are you using 5W-30 motor oil before you mixed in the tranny fluid????

The oil pumps flow volume rate on our pushrod 4.0L isn't rated to pump lube thinner than 30wt, so by thinning the oil out with tranny fluid, it's flow volume at hot idle is going to be decreased.

Also the oils synergy has been upset with the addition of the tranny fluid, so you really don't know what the heck is going on in there chemically!!!!

Our OEM oil pressure gauge doesn't register true oil pressure. It's been modified by Ford to read mid scale at anything above about 7psi, so it ammounts to a 7 psi on/off switch/idiot gauge, not much better than a danged idiot light imo & sure doesn't reflect flow volume at hot idle!!!!

Tranny fluid is for trannies, not for engines, so I'd get that concoction out of there pronto!!!!

If you think your engine is dirty inside (& it probably isn't, if you've been using a good quality oil & filter, that says it meets or exceeds Fords specs & you've been changing it to Fords specified OCI for your type of driving).

But if your still bound & determined to give it an enema, maybe try cleaning out the innards of your engine with something slower & safer, like AutoRx, which is a ester based lube, that is a heck of a lot safer than tranny fluid in the crankcase imo.

Just some more thoughts for pondering.

 

Like pawpaw mentioned, you could be hearing the infamous "marbling" sound of the Ford '98+ 4.0L OHV engines.

See: Ford Truck Enthusiasts Forums - View Single Post - 4.0L V6 engine noise

The marbling sound is most pronounced at idle and low rpms, and usually loudest right after an oil change.

 

oh i have been told by ford mechanics that tranny fluid has alot of detergents in it and is ok to run with the oil for a short time. i did use a castrol 5w 30. and i also dont know exactly how dirty the engine is, being i just got it. the oil was clean when i got it and it wasnt making the knocking noise. but like i said i will pull whats in it out tomorow and give it a shot again and hope for the best. thanks!

 

Well oil has a lot of detergents in it, so if you change it regularly, you should rarely need to add extra detergents to the oil. And when you do, there a products meant specifically for that, namely AutoRX. If you run synthetic oils, you never need to add oil cleaners, since esters are excellent detergents.

 

And its harmless. Mine has done it for all of its 150K miles...Almost sounds like a diesel at times.

 

well thats what kinda sucks about buying private party is that i dont know how the truck was taken care of. if it looks clean when i inspect it then thats all i can go off of especially with all the DIYers out there...not even i keep all my maintenece paperwork. but it seems to most likely be the marble knock and i will just have to get used to it. and i just pick up some MAF and air intake cleaners to spray those down and try to get rid of that droning hum. thanks guys!