Just started tearing down the engine on my 89 420 sel with 210k miles. Plan to rebuild the top down to the heads and to remove the front cover as well. Have found a great deal of info so far on the site but have a few questions:

I have the water pump ready to remove but I cannot remove the bottom bolt. The book says to line up the balancer so that the slot is in line with the bolt head to allow it to come out but I still can't get it out. Only about half the bolt head is in the slot. Any tricks?

Many of the wiring harnesses and wires in general have cracked or damaged rubber - the wires seem fine but the protective coverings are getting old.

Should I plan to replace these altogether or just attempt to repair the covers? I don't want to have to replace them later after everything is put back together. If you do suggest replacing them, are most these dealer items?

Looking ahead to fuel and break lines: steel, stainless,etc.? Anyone replaced these this rolled material and if so how hard was it to bend into the right position? I'm assuming the parts from the dealer are pre-bent to fit but will also cost a fortune... Any thoughts would be appreciated.

Thanks in advance

There should be a good sized relief in the balancer to get at that bolt, well good enough to get a 3/8" drive socket extension thru it so don't know why you're having trouble there. The plastic gets cooked on these cars and I don't think you ned to replace them, just get some shrink wrap or split loom and patch them up, as long as the conductors are still intact. All the steel lines should be fine unless they are kinked or rusted just leave them and reuse.

You can and should replace all the plenum donuts, plastic injector holders, rubber lines that go to them and possibly the lower CIS plenum.

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Chas

Had a 380SL, 450SL, 380SEL, 420SEL, 500SEL

Got a Euro 500SEC right now.

the distributor and the harmonic balancer need to come off before you can get to that bolt on the water pump. its a major pita. On the harmonic balance there are little bolts in there that need to be lined up and you can get them misaligned. It has to be done by feel unless you want to tear off the radiator and aux fan and ac condenser. I believe the indentation on the harmonic balancer was there on the older engines (pre 1986) but when I did the water pump on my old 420sel it was not there. It was a 1986.

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1984 300SD Orient Red/ Palomino
1989 560SEC
2016 Mazda 6 6 speed manual
1995 Ford F-150 reg cab 4.9 5speed manual

How about some pictures?

I recently replaced the water pump on a 1986 420SEL and the notch in the harmonic balancer was clearly designed for another purpose. I had to take the balancer off to complete the job. Took the distributor out too - not as bad as it sounds. The radiator stayed in; replaced every belt while I had everything apart. Have you done this project yet?

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Simon Shearer

1986 420SEL

2000 Porsche 911 Millenium Edition Carrera 4
2010 Lexus RX 350
2002 Kia Rio
2002 Hyundai Accent

I think that this notch actually DID work on iron M117's. From firsthand experience, I can say that removal on an M116(380, and a 420 is a bored 380) or aluminum M117(560) is essentially impossible without removal of the balancer.

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86 560SL
With homebrew first gear start!
85 380SL
Daily Driver Project

http://juliepalooza.8m.com/sl/mercedes.htm

I did replace the pump years ago and don't remember having to remove the balancer but I remember what a pita it was getting it out though. I'll pull the balancer and it should be fine from there - thanks.

My second question is related to the cylinder heads. I have the shop manual and was planning on removing the camshafts but have found what I think is a broken or partially broken lower guide. I was able to turn the engine to TDC (only had to move it an 1/8 of a turn but am afraid to move it anymore. With that said, how easy is it to remove the heads with the cams in place? Is it possible to remove the cams (specifically the lifters) without turning over the engine?

thanks

Turn the bolt out until it almost touches the balancer. Use a hacksaw or sawsall on the bolt as close to the pump as you can. That will give you room to slide the pump off the bolt.

When I did this on my 380 I notched the bottom of the new pump and used a shorter bolt. Someone here had a better solution and used an all thread with a nut which I believe to be best for reassembly.

If you are changing the front chain guides won't you have to remove the crank balancer anyway?

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84 300SD
85 380SE
83 528e
95 318ic

Yes I will have to remove the balancer to take the front cover off. I am waiting for the locking tool to arrive and have been trying to get the engine stripped down as much as possible in the meantime.

Your suggestion about the stud into the block and a nut holding the h2o pump on is a good one - thanks.

My second question is related to the cylinder heads. I have the shop manual and was planning on removing the camshafts but have found what I think is a broken or partially broken lower guide. I was able to turn the engine to TDC (only had to move it an 1/8 of a turn but am afraid to move it anymore. With that said, how easy is it to remove the heads with the cams in place? Is it possible to remove the cams (specifically the lifters) without turning over the engine?

If that is possible, is there a bolt near the fire wall in each cam tower also holding the head in place? I'm looking at the manual and I can identify all the bolts needed to remove the heads except one near the fire wall on each head - can't see anything else but a cam tower bolt in that location.

Yes that last bolt for cam toqwer also holds head down, same bolt you lossen but cant remove untill head is removed, the bolt is too long to completely remove , i put a rubber hose on bolt head to raise it when removing head so the bolt wont snag the block or headgasket

Finally got some time. Heads are off and the harmonic balancer is off. Couple of questions:

1. How do you remove the TDC sensor under the distributor? I removed the nut but can't tell how it comes out - it's still pretty solid.

2. One of the cylinder walls is scratched. The piston is 1-1/2" down right now and the scratches go down at least that far. Any thoughts about what to do with it? There are several pistons that are up all the way. Is there a way to check those cylinder walls?

3. Several rocker arms are worn. I've read that you should replace all of them if you replace some - is that correct? In addition, do I need to replace the cam shafts too - the lobes don't appear to have any wear?

thanks for any input

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Anyone have any thoughts on this?