Mercedes Benz 560 SL / SEL / SEC Timing Chain Replacement

[SELLC]

I am making this thread for people that may consider trying to replace their timing chain guides by themselves. I must give fair warning to people that are not mechanics that this job is by no means a DIY (Do it yourself) kind of job unless you have a solid background in automotive repairs. While it's not impossible to do, there are some procedures that could end up costing the inexperienced a lot of money.

Here is what a fractured guide will look like on the left passenger inboard side. Keep in mind this guide is not supposed to move. This guide was factured in the center. Keep reading for more details.

[video=http://www.youtube.com/watch?v=dyrA3ys1vms]



Above is a thumbnail photo of what happens soon after the guide fractures. In the video we are showing a fractured guide that has not yet fallen into the path of the timing chain and sprockets. 90% of the time when the top portion of the guide falls into the chain path it will create an interference situation that bends the valves.

In addition to the 3 cylinder head guides and the tensioner guide there are also two more nylon guides down low behind the timing cover in addition to another tensioner guide that runs on a separate chain drive for the oil pump. Given their location and the extreme amount of labor involved in getting at them, often times these lower guides are left until such time as the engine is overhauled. Luckily these other two lower guides are not known to be as problematic as the upper guides and the tensioner guide. That's not to say they shouldn't be replaced, just that often times the cost and amount of time to do so usually merit pulling the engine and going thru the engine. At the very least pulling the cylinder heads will make for a cleaner re-install of the timing cover should you elect to replace the lower block mounted guides.

So often times many will just replace the 3 upper cylinder head guides, the tensioner guide, the tensioner itself plus the chain. I highly recommend using ONLY OE Mercedes-Benz parts for this job or parts approved by Peach/Pelican parts. But everyone knows what SELLC would say.

These repairs shown are of a 1989 Mercedes Benz 560 SL and are about the same for all 560's except for little differences with regards to the engine attachments. While this procedure is shown with the intake manifold removed, removal of the intake is not necessary and is removed on this vehicle to address other seal related maintenance not related to timing chain guides.

The photos pick up assuming you have already removed the valve covers, power steering pump + bracket, Alternator + Bracket. The power steering pump and alternator can often times be set off to the side.



In this photo above we are getting the timing marks in line and marking the position on the left drivers side. In this photo you can see the small marks in the center of the cam shaft are aligned.



In this photo we are showing the timing marks on the right passengers side.



In this photo we are showing the engine set to TDC. Sometimes when I am doing the job by myself I use tie-wraps to keep the chain and sprocket together when the time comes to pull them. It also helps when you use an impact to loosen the center cam bolt. Be careful when removing them so they do not fall in the engine.



This photo shows the left drivers side cam marked and secured prior to cam sprocket bolt being removed.



This photo above shows the crankshaft timing marks. Notice it's pointing to the Zero position. You will also want to ensure the ignition distributor rotor is pointing to the #1 position. If the crank reads zero and and the distributor rotor is pointing to #1 plus your cam marks are lined up your ready to start.



Using an impact wrench put a quick zap on the bolt just to break it loose. It would be a very good idea to secure the camshaft with a pair of channel locks. There are nubs in the center of the cam you can use to secure the cam but you must mind the camshaft oiling tube, it has plastic clips that can break very easy. Once the bolt is broken free it should thread out by hand. Set the bolt to the side and then run a wire from the hood down to the cam sprocket. Leave enough slack that you can use the wire to suspend the timing chain. Use the wooden end of a hammer to tap on the back side of the sprocket. Mind the timing chain, try to center just below it. Remember you are doing the tapping with the wood end of the hammer. Never use the steel portion of the hammer. A rubber mallet may work but small bits often fall off and I don't care for them in this situation. A good couple taps and you should see it moving. Wiggle it and pull towards you near the end. Mind the chain!



When the cam sprocket comes off you want to hold the chain up and work the gear out. DO NOT LET THE CHAIN FALL IN THE ENGINE! IT MUST REMAIN TAUGHT. Use the wire to keep it up while you begin to replace the guides.



You want to mind this washer. It could fall in the engine. Re-Install your bolt now to ensure it does not fall.



Here the bolt is screwed in hand tight to retain the sprocket to cam washer/timing mark.



Pulling the guides is somewhat easy once you have done a lot of them. There is a nice little tool out there to pull them but as of yet I have been using extra valve cover bolts with a socket and washers to fashion my own pin puller. If you cant get your mind around the concept just buy a puller. When pulling the pins without a puller tool you have to be VERY careful not to jam the pin into the tool while its pulling. Some areas have un-even surfaces and you will have to fill the gaps to get them to pull out. It is possible to strip and bend these pins. What I mean by stripping them is you can literally pull the threads out of the pin if the pin lacks the clearance to pull out without hitting on the socket. This can happen even with the tool if you are not careful but the tool greatly increases your chances of success. In the event you pull the threads out of one I have found that a high quality big steal screw and a pry bar will work them out, but then you will need a new pin.



Here you can see the pin has been pulled. From here you should be able to pull the pin out by hand.



The pin shown in this photo is the last one that holds the guide. Be sure to be holding the guide so it does not fall into the engine once this pin is removed.



Here is a side by side of the old guide with the brand new Mercedes-Benz guide. You can feel how brittle these parts get with age when they are side by side.



Slide your new guide in and push the pins thru. Be sure to line up the holes on the guide to the holes in the head. You may have to lightly tap them in order to get past the resistance of the plastic but I mean lightly tap! Remember you have to be sure they are slightly in their bores once you clear the guide before driving them the rest of the way in. You will also have to apply some sealant to the end to prevent oil seapage. This is shown in the next photo.