gearwhine
NAXJA Forum User
- Location
- Denver, CO
I'll try to be as complete as possible. I feel it's all required to provide some input
I bought a 1996 Jeep Cherokee I-6 AW4 NP231 with ~135,000 a few months back.
Starting off....everything runs great, no stuttering, no rumbling, no shifting issues. It's all tight and doesn't feel under-powered. No OBDII codes are present.
I changed the oil to NAPA Synthetic 10w-30 with a NAPA/Wix Platinum Filter. I changed the air filter with it.
A week or two later, I noticed a slight rattling sound. I'm not necessarily saying it started at that point...I'm just saying I noticed it. It happens under extremely light load and up when moving or not moving. I can re-created it with my e-brake on and a press on the accelerator. It's pretty much unrecognizable at idle. It does become prevalent (to me) when I lightly place my foot on the accelerator....so light that the RPMs don't even go up. I feel that detail might be important...maybe?
I first checked all the basics...fluid levels etc. Recognized I forgot to connect my air intake back in the throttle body, so I essentially ran ~200 miles bypassing the air filter. Whoops...likely a non-issue from my diagnosing at this point.
I then looked at the shop information from the previous owner, and it was always maintained with 5w-30 Amsoil synthetic for the 5 years of back data I received.
I have now driven it around 5-600 miles since that time. The sound has not appeared to get worse. It's hard to hear if I have HVAC on medium to high....but my ears are tuned so perfectly to hear the rattling now.
My current diagnosing-
I have gotten nearly everywhere with a stethoscope (stethoscope diagnosing is new to me, so I don't know what sounds are normal). It does sound like the bottom end has a more metallic sound at idle. Not ticking, not thumping...just sounds like the crank bearings are dry or something similar. I take it that's a normal sound...but throwing that out there. I'm likely going to change back to 5w-30 this weekend to see if that sound changes.
Valve cover sounds great even when applying gas with my hand at the throttle body lever. Head sounds smooth.
I have have tried 85, 87, and 91 octane fuels...no change....so very likely not pinging.
I am not seeing any issues with exhaust....but that doesn't mean it's not a leak or a metal contact I'm missing.
I have placed the transmission into neutral with no accelerator during cruise speed. The rattle is still there, but it's not as loud.
I have used sound deadening tape at many interior plastic contact points...my interior is pretty damn noiseless.
Any other thoughts on potential causes? I'm beginning to think it's a non-issue.
Thanks!
-Nick
I bought a 1996 Jeep Cherokee I-6 AW4 NP231 with ~135,000 a few months back.
Starting off....everything runs great, no stuttering, no rumbling, no shifting issues. It's all tight and doesn't feel under-powered. No OBDII codes are present.
I changed the oil to NAPA Synthetic 10w-30 with a NAPA/Wix Platinum Filter. I changed the air filter with it.
A week or two later, I noticed a slight rattling sound. I'm not necessarily saying it started at that point...I'm just saying I noticed it. It happens under extremely light load and up when moving or not moving. I can re-created it with my e-brake on and a press on the accelerator. It's pretty much unrecognizable at idle. It does become prevalent (to me) when I lightly place my foot on the accelerator....so light that the RPMs don't even go up. I feel that detail might be important...maybe?
I first checked all the basics...fluid levels etc. Recognized I forgot to connect my air intake back in the throttle body, so I essentially ran ~200 miles bypassing the air filter. Whoops...likely a non-issue from my diagnosing at this point.
I then looked at the shop information from the previous owner, and it was always maintained with 5w-30 Amsoil synthetic for the 5 years of back data I received.
I have now driven it around 5-600 miles since that time. The sound has not appeared to get worse. It's hard to hear if I have HVAC on medium to high....but my ears are tuned so perfectly to hear the rattling now.
My current diagnosing-
I have gotten nearly everywhere with a stethoscope (stethoscope diagnosing is new to me, so I don't know what sounds are normal). It does sound like the bottom end has a more metallic sound at idle. Not ticking, not thumping...just sounds like the crank bearings are dry or something similar. I take it that's a normal sound...but throwing that out there. I'm likely going to change back to 5w-30 this weekend to see if that sound changes.
Valve cover sounds great even when applying gas with my hand at the throttle body lever. Head sounds smooth.
I have have tried 85, 87, and 91 octane fuels...no change....so very likely not pinging.
I am not seeing any issues with exhaust....but that doesn't mean it's not a leak or a metal contact I'm missing.
I have placed the transmission into neutral with no accelerator during cruise speed. The rattle is still there, but it's not as loud.
I have used sound deadening tape at many interior plastic contact points...my interior is pretty damn noiseless.
Any other thoughts on potential causes? I'm beginning to think it's a non-issue.
Thanks!
-Nick