I've had my engine knocking for a while now at low rpms. Never at high rpms. I've been doing some reading in other forums and have found possible causes. Egr, carbon buildup, bad bearing, etc.
It's a 2.5L SOHC I believe. It's annoying to me and probably the neighbors as well since I leave early in the morning and need to start the truck up before. Any ideas for a low rpm knocking?
My dad blocked the EGR valve off for years. It's still is blocked with aluminum foil.

 

EGR prevents pre-ignition pinging/knocking, just FYI

To see if its a bad bearing or pre-ignition pinging/knocking run some high octane fuel, 91 or 93, in the tank
Bearing knock at low RPMs can be an oil pressure issue, but damage done
If knock is less when oil/engine is cold and only gets more noticeable after warm up then it is most likely a bearing noise

As engine RPMs go up so does oil pressure which can quiet a bearing knock, but it will get worse

 

Will do. Last summer I found out I was leaking oil. It had gotten to the point that there wasn't nearly any oil left in the motor at all. The idiot before who had this ranger decided to DIY the valve cover gasket and instead of replacing the gasket, used a create your own gasket kit. So I replaced it along with the PCV valve. Anyway, it has more oil in it right between the min and max line on the dip stick. The knocking is less since then but still very annoying.

I'll run 91 in it next week and see what it does. Thanks RonD.

 

Ran some 91 through the system and the knocking noise is quiter for sure, however is still continuous at low rpms. New info, it doesn't start knocking until a few seconds after startup and rpm drop after cold start. The O'REILLY'S guy said it might be oil pump but oil pressure is good and so is the sensor. Is there anything else it could be?

 

If its lifter knock then oil pressure could be the cause at lower RPM, but this noise is much different than pinging/knocking from pre-ignition

There is no "real" oil pressure gauge on a Ranger after 1988, its just an on/off switch on the engine that activates the gauge in the dash
The switch on the engine is OPEN(no oil pressure on gauge) under 5psi, then CLOSED(gauge goes up) with pressure of 6psi or more needle only changes position based on electrical voltage at the cluster, i.e. alternator's voltage output can go up with RPMs so mimics oil pressure going up, but its not really, lol

In a 1989 and up Ranger you need to hook up an oil pressure gauge to the engine to test actual oil pressure

 

Alright. Will do. Is there a way to attach a video here? Just seeing if you would listen to it.

 

Just Google: What Lifter Tap Sounds Like

Watch the video
Now oil pressure can quiet down lifter taps at higher RPMs because the lifters internal spring has broken, so when oil pressure gets high enough it quiets down because hydraulic pressure keeps it tight against valve train parts

Pinging/knocking sounds like a diesel engine normally does, has the rattling sound, and usually only occurs in gasoline engines when accelerating, when engine is under a higher load

 

If the video I watched is correct, it is lifter taps. And maybe I do have good oil pressure if it gets quieter as rpms increase. I don't hear it as much at 1500 rpms, but at 1000rpms it's loud.

 

What weight oil do you run?
10W30 is common

And how may miles on the engine?

Good news is that all the lifters and rockers are under the valve cover on a 2.5l SOHC, so easy to deal with

 

Yep, running 10W30 from O'Reilly's. It's got 151k miles on it. According to my dad this has been going on for years though.

 

Thicker oil probably won't help, but 10w40 at next oil change won't hurt either, in case it is a lower oil pressure at idle issue

There are additives that do work to quiet the noise, but don't fix the the reason for the noise
They coat the metal which reduces the noise, and reduces wear a bit
Marvel Mystery oil
Lucas HD oil treatment
Liquid Moly Hydraulic lifter additive

Look at reviews

Servicing the valve train down the road is the only real solution, but its not really hurting anything now, just an annoying noise
2.9l V6 did this after a 50k miles or so, but ran fine past 300k miles

 

Sorry for the late reply. Been very busy last few days. I have added the Lucas HD oil treatment but it doesn't seem to be doing anything. I will probably have to take the valve cover off again and replace the lifters and/or rocker arms. Yeah it is just annoying noise, but neighbors are even more annoying when they are annoyed.