A rattle with a twist....

[moriver]

Hello all I wanted to ask about a rattle I have in my 4.0 The rattle only makes noise when heated up to temp between 2 and 3K and of corse changes with the engine RPM. I pulled the drive belt off hoping but nope...noise still active. Now some background. The truck is a 05 Explorer with 157K and just last year had chains, guides and tensioners. I had a set of lifters so I pulled the covers and did the lifters I figured what the heck. While there I checked the chains and guides. Front was good and tight. The rear chain had some slack in it. I turned the engine over and the adjuster promptly tightened up the chain and the slack was gone. I used my scope and looked over the rear guides and found no cracks. So other than any normal wisdom I was wondereing if someone could tell me

1-Should that rear adjuster be totaly colapsed like that until the engine is started?

2-Knowing the engine only makes noise when warmed up whats that telling me and what does a failed tensioner cause??

Much thanks, you all helped me out last year with my chain job and I am thankfull for whatever help you can give.

Scott

 

[Flash]

When the engine warms up the oil loses some viscosity meaning it's too old and needs changing or was too thin to begin with.
Lack of oil pressure means the timing chain tensioners aren't working properly.

If you change the oil and maybe use a thicker viscosity and the problem goes away I'd say that means that the tensioners and or chains and guides are right at the end of their useful life.

If after an oil change you still have the problem than that means that the tensioners and or chains and guides are at the end of their useful life.

Or it's something else.

 

[2000StreetRod]

compressed valve springs

. . . The rear chain had some slack in it. I turned the engine over and the adjuster promptly tightened up the chain and the slack was gone. I used my scope and looked over the rear guides and found no cracks. . . Scott

There are certains positions of the right camshaft when stationary where two valve springs are compressed enough to push the cam lobes enough to create slack in the chain on the traction side (the side that does not have the spring/hydraulic tensioner). That is one reason not to rotate the crankshaft counter-clockwise. It is normal and no reason to worry.

Your symptoms sound more like a failed primary (crankshaft to jackshaft) chain tensioner or a failed balance shaft chain tensioner if you have one. It also could be your exhaust system mounts or your flexplate or torque converter. You might try listening thru a length of flexible hose with the other end near the items. Please do not crawl under the vehicle when the engine is running. If you lay down, stay outside of the tire tracks.