Need help Identifying Engine/Valvetrain Noise

[TIMMAAY]

I need some help in trying to identify the cause of an engine/valvetrain noise. The engine has made the the noise for as long as I have owned it (I have put about ~2,000mi on it) but I think it's getting worse now that I am driving the truck a lot more. It's beginning to irritate me that my valve train is louder than the flowmaster. The truck runs very good otherwise and does not burn any oil!

89 MJ Renix 4.0L 127,000mi close to 1,000 miles on 15w40 Rotella T Wix filter oil change.

Symptoms:

It sounds kind of marble like, definitely not a knock or tick.

Varies directly with engine speed.

Most evident around 1200-1500rpm.

Not as noticeable at idle or above 2000rpm. I am sure it is still there but it's being drowned out by the exhaust.

Does not go away under load.

Sometimes although it hasn't done it for a while, when you start it up first thing in the morning, it'll make a loud chuh chuh chuh sound for a second or two. Related?

Lifter(s)? Not getting oil to a certain part of head? Piston slap?

I can try to take a video of it tomorrow but I don't know how good of audio quality it'll be.

 

[cruiser54]

Piston slap is common in these motors. Have you ever checked the tightness of your flexplate to torque converter bolts if it's an automatic? 20 minute job and I consider it preventative maintenance. Remove each bolt, 15mm wrench or socket, clean the threads, apply Loctite and reinstall. I don't have the torque spec at my fingertips right now but it can be found.

 

[TIMMAAY]

I took the valve cover off and ran the engine for a bit. Everything looked normal, nothing broken bent or loose. The inside of the VC looked brand new! No sludge what so ever. I think the sound may be from a couple lifters but at this point I am just going to ignore it for the time being.

It is auto and I have not checked the flex plate bolts yet. I will do so soon even though I don't think that's the problem.

 

[cruiser54]

I took the valve cover off and ran the engine for a bit. Everything looked normal, nothing broken bent or loose. The inside of the VC looked brand new! No sludge what so ever. I think the sound may be from a couple lifters but at this point I am just going to ignore it for the time being.

It is auto and I have not checked the flex plate bolts yet. I will do so soon even though I don't think that's the problem.

Good idea to check them anyway. Could be your problem now. If not, it won't be your problem in the future.

 

[joe_peters]

Test your knock sensor and make sure it is torqued correctly.

 

[ILLXJ]

I took the valve cover off and ran the engine for a bit. Everything looked normal, nothing broken bent or loose. The inside of the VC looked brand new! No sludge what so ever. I think the sound may be from a couple lifters but at this point I am just going to ignore it for the time being.

It is auto and I have not checked the flex plate bolts yet. I will do so soon even though I don't think that's the problem.

I had the same problem/sounds. Flex plate bolts were tight but the flex plate was cracked. JIM.