RATTLING ENGINE sound on cold start up acceleration/deceleration..

[abe280SL]

I get a rattling sound from the engine on start up specialy when I accelerate or when I llet go of the accelerator and the engine decelerates. It happens with the transmission engaged or in neutral.  Then after I drive for 5 minutes the sound disappears and only faintly heard occasionaly.  Once the engine is at a certain rpm or freeway speeds no noise.  Again, mostly happens first few minutes from a idle rpm to rev up/down.  I thought it could be the chain tensioner...but they say that rarely fails. If it is the tensioner...why does it do it when cold and the first few minutes and not later on?  If I remove the vaulve covers what should I look for?  I know I could press on the chain sprocket to see if its firm. Should I take the tensioner apart, clean it and put it back together...maybe it has crud iin it?  Finally, how do you "prime" it?
thanks in advance
abe

[MichaelB.]

Sure, could be a tensioner... But sounds like it may be wrist pin wear to me.

[johnd]

Of loose chain due to wear on tach drive discussed several places elsewhere.  I'd sure tear into it sooner rather than later. . .

[ja17]

Hello,
Yes as mentioned if the chain is loose it may take the tensioner a little longer to take up all the slack, especially if the oil is dirty.    Cold oil flows slowly. Yes the tensioners seldom fail but there is a limit to how much chain slack they can take up. Eventually the chain will jump time and/or break if this is the problem. I would look into it.

[abe280SL]

Well, I took the vaulve cover off and when I "pumped" the tensioner it stiffined up pretty good.  Also, spring is intact.  I ordered a new chain and I am going to bet on that as the problem. On April 16th I will take it to my mechanic...the nice thing about it is that he lets me work on my car with guidance...don't mind at all paying him as if he did all the work.  I am very fortunate to have him around and let me do the work while he teaches me.  Time permiting we may do a vaulve adjustment too.
We will see, thanks
abe