2003 Ranger Edge knocking noise

I have a 2003 Ranger Edge with a knock. The knock sounds like a small hammer hitting a large piece of metal. The engine has 80,000 miles. The truck runs and starts fine. Good idle. No knocking at idle. The knocking sound starts at about 2,000 rpm and gets louder till 2,500 where the sound volume remains consistent through the rev range.

The knock started about a year and a half ago. I completed an oil and filter change with 5w-20 oil. That is what is recommended. I started the engine, oil pressure came up, let the truck run for a minute and shut it off. The truck sat until the next day when I drove it 5 miles to work. On my way home I was going uphill on the onramp and oil pressure gauge went to zero. I quickly made the turn to a slight downhill to the freeway entrance and the oil pressure came back. I gingerly drove the five miles home. The oil pressure drop occurred again on the exit ramp going uphill and came back after four or five seconds when I stopped. I got off the freeway and went downhill to my home. I opened the hood and checked the oil level. It barely registered on the dipstick. I added a quart and half of oil and checked the level again and registered about half way through the range. I drove it to work the next day to work and noticed the knocking noise. I drive the truck to work and around town. No long highway drives. I just try to keep the revs below 2,500 rpm.

The knocking has not gotten any worse over the last 5,000 miles. To me it sounds like a stuck lifter. It seems to be a quieter when the engine is cold in the morning and starts later around 2,800 rpm. When it is very cold out 20 degrees or less the knock starts later, 3,100 rpm and is quieter. When the engine is warm the knock is more noticeable at constant throttle than acceleration and when you let off the gas going downhill. When it first happened I changed the oil twice in 200 miles. I have changed the oil four times in the last 5,00 miles. The engine does leak a little oil at the rear of the engine and requires a half quart ever two months. I took the truck to the dealership and said the motor needs replacing but were not specific.

Any ideas what is wrong with my little Ranger? I was thinking the oil pump may need replacing or new lifters. I had a rod bearing go in my chevy 350 and that was a tick at all rpms. As I said the truck runs and idles fine.

Welcome to The Ranger Station!


I suggest you invest $8 in a mechanic's stethescope and at the very least figure out which head has the noise (might be able to tell by removing the oil filler cap). Then, decide whether you have the talent/tools to make a repair (replace the head or lifter).

Many independent shops will do a diagnosis for a small fee and most any shop can quote you the flat rate for a specific repair.

These 3.0's are known to suck a valve into the head.
They are also known for the Cam Synchro drive gear stripping, which starves the engine of oil pressure.

The good news is that they are simple, conventional engines and most mechanics are familiar with fixing them.

It doesn't make any sense to me that you changed the oil, and the first time you drove it afterward it "lost" a full quart and 1/2.

Good luck.

The low oil level and the uphill angle caused oil pump pickup in the oil pan to get uncovered, so it lost suction and oil pressure dropped.
You want to avoid that
Oil is for lubrication but also for cooling, so even momentary loss of flow can cause damage pretty fast.

Large difference between "knock" and "tap" sound
Tapping is valve train noise
Knocking is connecting rod or exhaust leak, these sound similar.

I would get a stick, similar to broom handle(only shorter, lol) and use it against metal parts of engine and your ear for a stethoscope, have someone rev the engine until it "knocks" then see if you can pin point it as upper or lower engine noise.
Lower being worse case scenario.

I would switch to 5w30 oil in any case.

5w20 is thinner at engine operating temps, 190-220 degF, than 5w30

As RPMs go up so does oil pressure(your gauge won't show that) so it is a bit odd that "knock" is tide to higher RPM

On that note Pre-igntion, is described as pinging or "knocking" and only occurs at above idle RPMs, and 3.0l engines are prone to pre-ignition.
Although this wouldn't be associated with the oil pressure dropping.
And the pre-igntion would cause a noticeable loss of power when it occurred, which you didn't mention.