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

__________________
______________________________

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

anyone??

__________________
______________________________

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

One of the members, thomaspin, I think, wrote a brilliant task description on servicing the tensioner and rails which should be applicable to your engine. I'm sure you will find it with an archive search, but PM me if you can't locate it.

I'm going to try this job myself in a short while once I've fixed the bollixed cooling system on the SL, about which I have been complaining in other posts. I'll follow up with notes of my own to match the original.

s/b

I appreciate you responding. I have read all of the posts on changing out the rails with the tensioner, but I just want to change the tensioner only. I want to know if i can just unbolt it and bolt on a new one without worrying about having the chain slip or something like that. I'm hoping that i dont have to take the valve cover off and hold the chain while i change the tensioner.

__________________
______________________________

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

any other help would be appreciated......

__________________
______________________________

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

I don't know about your specific engine but on my 450 slc the tensioner just bolts to the side of the block and can be replaced w/o going into the engine. I would assume that the tensioner was renewed with the chain. Certainly at $2,100 it should have been. Replacing the unit is not very involved on the 450slc since everything is external. Ask the dealer why they are using crap parts that only last 40k miles.