Loud instant 2-3 second rattle around the under

SOURCE: 1986 FORD 300 SIX CYLINDER ENGINE KNOCKS

Hi Bill 609!

Definitely sound like a rod insert to me. With my practiced ear, I cna tell the difference between a main bearing knock (deeper sound, more of a thudding noise), rod bearing knock (not so deep, gets louder as the engine revs, kind of a rat-tat-tat-tapping noise), and a wrist-pin knock (not quite as loud or deep and gets louder with decelerating RPM).

You can tell which cylinder the knock is on by removing the spark wires to each cylinder one at a time while the engine is still cold enough to knock. (Don't get shocked!)... when you hit the right one, the knock will noticeably quieten or possibly quit altogether!

The 300 Six is a tough old motor and I have seen them survive for years with rod knocks... Just allow the engine ample warm-up time before driving, drive on the conservative side, and keep an eye on oil level and pressure.

An oil and filter change to a higher viscosity oil with a can of STP Oil Treatment (Or something similar) is a good band-aid fix for now, I would recommend Castrol GTX 20/50w... in my opinion, Castrol is the best brand out there, I use it religiously - - - I have a customer with a Chevy Suburban who has followed my advice and adhered to good maintenance discipline that has racked up over 300,000 miles on the original small block and no consumption or engine issues, and is still running strong!

Bill, the temporary fix will work for a while, hopefully a long while --- BUT when it reaches the point that the knock doesn't go away, it is time to park it until the real repair can be done --- otherwise you risk throwing a rod and destroying your engine beyond repair!!!

Please don't hesitate to post a comment or ask if you have further questions. I hope this information answers your question and concerns and wish you well with the Ford. *** And remember to rate my assistance... Your rating is my only compensation for helping you in the free blog!!!***

Thanks!
-WildBill

SOURCE: ford focus turbo diesel low oil pressure with no knocks from engine

Possible oil sending unit problem.

SOURCE: Oil Pressure Gauge/Engine rattle 2000 Ford Explorer 4.0 6cyc 4wd

Your Oil Pump is Out and will need to be Replaced. This is not a Job that you would want to attempt on your Own unless you have been a Mechanic. Trust Me. Been an ASE Certified Mechanic for 35 Years.

SOURCE: low oil pressure at idle

how low does the oil pressure drop?? is it below 40?

Harvey N Tawatao

• 3854 Answers
• Posted on May 29, 2009

SOURCE: oil pressure problem

You oil pressure sending unit has gone bad, it's common to go bad and some even leak oil. 
The oil pressure sensor is on the back of the block on the passenger side, you can get to it from the top and not from the bottom. There are (2) switches back there that screw in to the block and you can only see it from the top of the engine. The Oil Pressure Sending Unit is the one wire harness with a green and white strip on it. The other switch has more wires to it. 
When you pick up the new sensor, make sure you get the right one. make sure you get the Oil Pressure Sending Unit which sends variable oil pressure and has only one quick connect for the wire connector. The oil pressure switch is the one that only activates the oil light on older engine. 
Once you get the right part at Auto Zone for around $9.00, disconnect the wire clip with the green with white strip on it. and use a deep spark plug socket with a extension and u joint to get the sensor out. The sensor comes with teflon tape already and no oil should leak out from the block. It as simple as replacing a bolt and reconnecting the wire connector. 
Good luck and hope this helps, take no more then 10 min to do but about 5 hours for the engine to cool off LOL