1995 351...

When I am cruising and accelerate I get a lot of noise that sounds like rocker chatter. It happens most when in overdrive and going up a hill or accelerating slowly - when the engine bogs down a little bit.

If I remember correctly, this engine has made the noise for some time, but it seems like it has gotten worse in the past few months.

Ive searched a lot and seen different suggestions like worn lifters, loose rocker arms, or poor oil pressure- but I'm not sure if those items cause the noise all the time, or just when the engine bogs down like mine.

The engine has 137k miles on it, 25k since a rebuild.

Thanks.

 

sounds like your hearing predetonation or Pinging. you need to pull codes, double check your timeing which should be at 10* btdc with spout connector removed. what spark plugs are in the motor? what oil/filter are you using?

 

Agreed, sounds like detonation. Pull Codes FIRST! The 5.8 has no knock sensor so spark timing, plug efficacy, and fuel quality are key factors. Remember to warm the engine to operating temperature BEFORE you check spark timing as well.

 

Thanks for the quick responses. I went out and pulled the codes this afternoon:

KOEO:
539 - looks like i had the A/C on...

CM:
327 - DPFE or EVP circuit below minimum voltage of 0.2 volts.
332 - EGR valve opening not detected.

I had previously replaced the sensor on top of the EGR valve, but I have no idea if the valve itself is functioning or if it is getting the vacuum it requires

I am not sure what plugs are currently in the motor. I am using motorcraft oil filter with 10w/30 castrol

 

To check the EGR valve, you can apply vacuum manually and observe the diaphragm through the holes in the side of the lower valve casting. You can also check the resistance changes in the EVP (EGR Valve Position) sensor (on top of the EGR valve) by disconnecting it from the harness and putting a meter across the center and left hand pins of the sensor's connector. Observe the changes to the resistance as you apply/release vacuum. Minimum SIG RTN voltage not being achieved, tends to make me think the sensor may be the culprit OR you have a weak connection at the sensor. Since all sensors are fed VREF (Reference Voltage) of approximately +5VDC, you can test that the sensor is getting this voltage by disconnecting the EVP sensor from the harness and taking a voltage reading between the right-hand terminal in the EVP wiring harness connector and the frame of the truck. IF VREF is at or very near +5VDC with the key on, there is no VREF problem.

Check that the green vacuum line between the EGR valve and the EVR (EGR Vacuum Regulator) solenoid is intact. Make certain the EVR is connected electrically.

 

Thank yall for the help.

After working through some the issues during a couple of evenings, I think the issues are resolved.

This evening I replaced the plugs with new motorcraft units and made sure that the wires weren't crossed. After that I went ahead and tackled the timing, which turned out to be about 8* off. It is now set at 10* and after a quick test run on the highway I could not reproduce the pinging sound. I will drive it this week to see if it is in fact gone for good.

The EGR valve codes... this turned out to be a ridiculously easy fix, and I am mad at myself for not catching this one earlier. There were two vacuum plugs not connected (4 lines). I honestly don't know how I never caught this before, but its fixed now and I am finally free of the check engine light. The vacuum lines were the ones in the green box below.

Thanks again everyone.

 

right on, i like it when the fix comes easy

 

TAB (Thermactor Air By-pass) and TAD (Thermactor Air Diverter) solenoid vacuum connections were the issue then. Glad it was a simple fix.