I have a 1991 420 SEL with 196K. I bought it one year ago. I have all of the service records and the local shop that i go to is very well respected and treat me very well. Anyways the records show that at 158k the valve job was done with the chain and chain guides the cost was $2100.00. Lately I've noticed that there is a bit of a rattle at start up if it sits for 8 or more hours. The shop said that it could be the tensioner. Can I just replace the tensioner without having to take off the valve cover and secure the chain? I could have them do it but they want about $225.00 to change out the tensioner or $500.00 to do a new chain and rails. Since it has been less than 40k since the last chain it doesnt make much sense. I have searched as much as I can but all the topics include changing the rail at the same time. It looks as if its two bolts to take the tensioner off ,and of course two to go back on. Is it really that simple?? Sorry its so long.

Thanks for all of the help given on this forum,
Tyler

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1979 300SD 255,000 miles (sold)
1989 Jeep Cherokee (wifes)
1991 420SEL 196,000 Miles.