1997 S600 Front main seal replacement
This write up describes front main seal replacement on a 1997 S600 sedan. I have no experience with other model years. Things may be different on your car. This is not necessarily a difficult job, but it is a little technically involved and a lot time consuming, especially if you’re like me and you’ve never done it before. The job is made much easier with the right tools and a lift. I have a low-rise lift in my garage, and it got a work-out during this repair as there are a couple of things to do from underneath. DO NOT WORK UNDER YOUR CAR WITHOUT PROPER SUPPORT. BARE MINIMUM, USE SUITABLY RATED JACK STANDS OR RAMPS.
Special tools for the job that you may not have in your tool box:
Mercedes tool #602 589 00 40 00: This is a tool that holds the ring gear to keep the engine from turning while you loosen and tighten the bolt holding the crankshaft pulley to the crankshaft. My dealership quoted me $334 for it. Don’t even think about buying it. You can get away without it.
Mercedes tool #119 589 01 14 00: This is the seal insertion tool. My dealership quoted me $140. I did not buy it opting instead for the shade tree mechanic’s method of tapping the seal in with various tools. I describe my method below.
27mm 3/4in drive deep well socket (1 1/16in is the same size)
3/4in drive breaker bar (with a pipe cheater)
3/4in drive torque wrench . You need 300 ft-lbs (400 NM). This is a big wrench.
1. Remove the fan shroud and fan. Follow Pete’s directions here: http://www.v12uberalles.com/fan_clutch.htm. Because I was also planning to do a coolant flush, I gave myself more room by draining the radiator and removing it. The extra room is not necessary if you’ve got the MB tool for main seal insertion. I didn’t want to buy it. I used a rubber mallet and hammer to insert the seal so I pretty much needed the extra clearance that removing the radiator provided in order to work the mallet and hammer. It’s easy to remove the radiator once you have the fan shroud and fan out. Drain the radiator by opening the stopcock on the lower left of the radiator. Disconnect the transmission cooler lines on the right side of the radiator. These are the hard-line banjo fittings. Place a drain pan underneath and unbolt them. About 100 mL of transmission fluid will spill out and make a mess. I don’t see that this can be avoided, but it is a good idea to remember to replace the lost fluid when the job is done. Disconnect all coolant hoses, remove two nuts and bolts that hold the radiator to the AC condenser, and simply lift the radiator out of the car I plugged all openings in the radiator to prevent dust and dirt from entering.
2. Remove the belt and clean the engine. Take a picture or draw one of the proper belt path. Slacken the tensioner with a 15 mm wrench on the bolt in the middle of the pulley, and remove the belt. The pics below are before and after cleaning pics. I used Gunk Engine Brite. It had been leaking slowly for a while, but the Gunk worked wonders. I was impressed. I’ve also removed the tensioner pulley (one bolt in the center of it) and power steering/hydraulic suspension pump pulley (3 bolts in the face of it) as noted in the pic. This gives more room and a better view of the crankshaft pulley.
3. Rotate the engine to top-dead-center (or close to it). To do this, put a 27 mm socket on the crankshaft pulley and rotate the engine clockwise when you’re facing the engine from the front until you see the 0T mark on the crankshaft pulley. Line this mark up with the point cast into the engine block as shown in the pic (or just get it close). Actually, this could be TDC or 180 degrees past TDC, but it’s not important for this job. The reason for doing this is to ensure that the Woodruff key that links the crankshaft pulley to the crankshaft is on top of the crankshaft. Otherwise, the key may fall off the crankshaft and inside the engine into the oil pan. See below for pics of the key. If the key falls into the oil pan, you have no choice but to remove the oil pan to retrieve it. When I removed my pulley, I found the Woodruff key was stuck to the crankshaft. I couldn’t remove it with mild pressure from a right angle pick, so I just left it in place and figured I had nothing to worry about losing it. WARNING: Do not rotate the engine counterclockwise. Always turn in the normal running direction of the engine.
4. Prevent the engine from turning counterclockwise while you loosen the crankshaft pulley bolt. The factory tool mentioned above prevents the ring gear from turning. We’ll do the same thing much more cheaply using a Mercedes mechanic‘s trick taught to me by my father-in-law. He owned a MB repair shop for a while in the past. First, remove the ring gear access hole cover on the transmission shown in the pic. Wedge something in between the ring gear and the transmission housing so that the ring gear won’t turn counterclockwise (as you’re looking at the engine from the front of the car). I used a 3in long piece of 1/2in square solid steel bar. See pic for how the bar is put in place. NOTE IN THIS PIC THAT THE BAR IS PLACED TO PREVENT THE RING GEAR FROM TURNING CLOCKWISE. FOR THIS STEP, THE BAR SHOULD BE ON THE OTHER SIDE OF THE RING GEAR.
5. Remove the crankshaft pulley bolt. This is where you need a big wrench. The factory torque spec on the crankshaft pulley bolt is 300 ft-lbs. Hopefully, the steel bar placed to stop the ring gear holds. When the bolt is out, keep the four washers on the bolt as they are. They are concave and should stay in that orientation with the concave side facing the engine. The bolt should be a little damp with oil. It is oiled when it is installed because of the high torque it receives. When I was replacing the pulley and torquing down the pulley bolt to 300 ft-lbs, the bar didn’t hold the ring gear as placed in the above pic. It got gouged by the ring gear teeth and slipped out. I had to resort to a long bar inserted through the torque converter bolt access hole and through the ring gear. In this position, it catches a spoke of the ring gear and stops it from turning. This is clear in the pics below in the steps on reinstalling the pulley.
6. Remove crankshaft pulley. Be careful not to damage the rubber outer circumference too much. I used a pickle fork and hammer from underneath, alternately driving the fork between the pulley and engine on either side of the shaft until the pulley began to come off. I then worked the pulley off the crankshaft by hand from the top. You may be able to work a crow bar from the bottom, too. Be careful of the Woodruff key as you remove the pulley. Don’t knock the key into the engine. Like I said, my key was stuck to the crankshaft so I didn’t have to worry about it. If your key is loose, carefully remove it.
7. Clean around the main seal, and remove the old seal. Plug the opening with something (I used lint free wipes.), and use a wire brush to clean around the old main seal. You don’t want junk entering the engine. Cover a screwdriver with a towel and pry out the old seal.
8. Inspect crankshaft pulley for wear. There will be a polished ring where the old seal contacted the pulley. This is normal. If there is an obvious groove or other wear marks, that is not good. Take a close look. Normally, the seal is installed flush with the engine (see pics above), but Alldata and the MB W140 CD both say to install the seal 3 mm inboard of flush with the engine if there is wear on the pulley. This puts the contact area of the seal on the crankshaft pulley 3 mm inboard of the old patch. This part of the pulley will be clean and fresh since it has been inside the engine the whole time. The factory seal installation tool is designed to handle either installation by simply using the other side of the tool to insert the seal. I guess you get two chances to use your crankshaft pulley, then you have to buy a new one. My pulley had an odd rough spot, about 1 mm X 2 mm right in the polished contact patch, so I opted to do the recessed “repair� installation.
9. Install new seal. While hunting around the local hardware store, I found some big nylon washers that happened to be exactly 3 mm thick and about the size of the main seal. I bought one and trimmed it down in diameter so it was just smaller than the seal. See pic. This will be the final depth-setting insertion tool.
My father-in-law then gave me a piece of PVC piping that was almost the exact diameter of the seal, too. I used this to start the seal and get it flush with the engine. You just need something cylindrical and sturdy and about the same size as the seal. As the pic shows, put the seal in place by hand, place your “insertion tool� flush with the seal, and use a mallet or hammer to tap the seal into the engine. Work your way around slowly a couple of taps at a time, trying to keep the seal fairly even all the way around. Note: I taped a large piece of cardboard to the AC condenser to protect it. The condenser is exposed when you remove the radiator, and I didn’t want to risk damage to it. Work until the seal is flush with the engine. If you’re doing a normal install, you’re done. If you’re installing the seal 3mm recessed, time to get out your 3mm thick final insertion tool.
I put my nylon washer over the seal and slowly tapped it with a hammer, working around its circumference. Once the seal was recessed partially, I took a short piece of 1/2in square steel bar, placed it across the seal and washer, bridging the seal opening as shown in the pic, and tapped the bar to finish seal installation. Again, I worked the bar slowly around the seal trying to keep it going in straight, tapping twice at each stop. I tapped until the bar contacted the face of the engine all the way around the circumference of the seal. This should ensure a uniform 3mm depth all the way around.
10. Install crankshaft pulley. First, oil the inner lip of the seal. I used a Q-tip dipped in clean motor oil. Install the Woodruff key onto the crankshaft. (Mine never came off, which made life easier). Align the notch in the crankshaft pulley with the Woodruff key, and manually slide the pulley on the crankshaft until it hits the seal. Don’t force it in. You’ll use the pulley bolt to finish sliding the pulley through the seal and onto the crankshaft. Again, do not knock the Woodruff key into the engine!
You should oil the pulley bolt again with a little motor oil. Not a lot, just a little.
Start the bolt by hand until it stops against the pulley. Use your 27mm socket and breaker bar (or large ratchet) and start turning the bolt to push the pulley onto the crankshaft, until the pulley is all the way on. For final torquing, you will again have to block the ring gear in some way. As I said above, the square bar wedged between the ring gear and transmission housing didn’t work this time. The bar kept slipping out. So I found that I could insert a longer bar through the torque converter bolt access hole and all the way through the ring gear as in the pic below. (The Q-tip is there just as a soft wedge to hold the bar in place as I turned the engine from the pulley bolt until the spoke in the ring gear caught on the bar. I didn‘t have a buddy helping out who could hold the bar in place.)
11. Final torquing. This should be done in a couple of stages. Put the big torque wrench on the pulley bolt and torque to 200 ft-lbs. Wait 30 min, and then torque to 300 ft-lbs.
12. That’s it. Reinstall everything as you took it off. I hope you took good notes and pictures to help you get it all back together. If you removed the radiator, don’t forget to replace the lost transmission fluid. You just add it through the dipstick.
I’ll have to wait and see if my first main seal replacement was a success. Hopefully there will be no more leaking from the new seal. If it leaks, I will probably buy a new crankshaft pulley. I didn’t want to do this because it costs either $700 or $900 from the dealership (depending on my VIN). I didn’t go back and give my VIN to get a final price. I will also probably buy the factory seal insertion tool just to make sure the seal gets in place nice and straight. My father-in-law said I didn’t need it, but he’s an experienced mechanic and knows what he’s doing.
Brett
Linear Mode
