560sl water pump replacement now will not start - PeachParts Mercedes-Benz Forum

sarastew · #1 05-31-2015, 10:24 PM

I am a newbie that needs some help. I recently replaced the water pump on my '87 560sl and now cannot get the girl to start. The car ran great before I pulled the pump. Of course my focus has been on ignition timing as I had to remove the distributor to get the water pump off. I should also mention that I replaced spark plugs, spark plug wires, distributor cap and rotor while changing the water pump. I know there are many posts on proper distributor alignment and ignition timing on this forum and others. I have read as many as I could find, but still need help diagnosing my problem.

I have the factory service manual and followed the proper steps (or at least thought i did) for reinstalling the water pump and distributor.

1. Rotated the crank pulley to 0 degrees on the dampener. Looking inside the oil fill cap it appears the cam lobe is in the up position. I think originally I was 180 degrees out but corrected that issue.
2. Aligned the rotor with the mark on the distributor housing and reinstalled the distributor. Pointed to the #1 plug wire.
3. Double checked all plugs, wires, firing order, etc.

I had my wife crank the engine with a plug out and verified spark on the #1 plug. The plug did spark but I do not know what a strong or weak spark looks like (or if it matters). I smelled fuel on the plug so I am pretty sure I am getting fuel.

I should note that the engine does not turn over smoothly when attempting to start. The air intake burps a bit when cranking and the engine hiccups rather than turning over smoothly. The symptoms make me think of timing, but I hate to get fixated on that. Lastly, I should note that I rotated the engine counterclockwise slightly (quarter turn of the crank at most) when pulling the dampener. I have read some scary posts that this could cause the timing chain to jump, but I can't imagine a quarter turn could make this happen.

I am just looking for a fresh perspective on how to diagnose my issue.

meltedpanda · #2 06-01-2015, 10:19 AM

Ok one step at a time
I assume she was running fine before your surgery.

Retrace your steps - for the obvious ( sounds like you did this)
make sure you get number one cylinder to TDC by removing #1 spark plug , insert long dowell turn flywheel untill you get maximum travel, then check distributor rotor to make sure you are pointing at #1 plug wire. One tooth off can make a huge difference

make sure then that you have no ground shorts,I had a no start issue that was from a short between condensor and housing.

I beleive however , your dizzy is off.
Good luck

rowdie · #3 06-01-2015, 12:21 PM

Another way is to remove the right valve cover and check the right cam timing mark when the crank is at TDC. It should be close. Number one lobe positions should look like what has been described as "bunny ears".

After you get the distributor in correctly rotate the crank and bring the cam mark into alignment. Look at the crank timing mark to measure the stretch. If more than 8-10 degrees timing chain service needs to be done.

sarastew · #4 06-04-2015, 08:40 AM

Gents,
Thanks to the advice of both of you I figured this out. You may be surprised at what I found though. I figured I should close the loop with the outcome and findings to help some other poor soul that may run in to the same situation.

As Ron suggested, I used a long dowel in the #1 cylinder to find the top end of the #1 stroke. As Rowdie suggested, I then checked the location of the cam lobes (looking for the bunny ears) and valves when the #1 reached its highest point of travel. Well, this is where I thought I was losing my mind. At the highest point of travel of #1 with the cam lobes in the "bunny ear" position or highest point, the timing marks on the dampener were no where to be found. What I noticed at this position was that the timing pointer was directly on an obscure mark on the crank pulley. The mark reads 18|0. I have attached a picture for reference. I also found another post on this forum where a SL owner kept referring to a 180 degree mark on his dampener and that the engine was running fine.

Coincidentally, this 18|0 mark is on the complete opposite side of the standard 0 TDC timing mark on the dampener. Keep in mind that I never fully removed the crank pulley when changing my water pump. I was able to slide the crank pulley forward far enough to get to the bolt on the under side of the water pump without pulling the pulley all the way off. To be completely honest, I snuck a hack saw in and cut the last bolt off. I found a bolt that was 1-2mm shorter to go back with. From what I read previously, the crank pulley only goes on one way because of a woodruff key. Well, I have discovered that is not exactly true. Apparently the dampener will go on correctly with the standard timing marks on the correct side as well as 180 degrees out from the correct position.

I suppose the previous owner or a hack mechanic installed the dampener 180 off at some point in the car's history. I really did not want to take every thing down and pull the dampener off to rotate it and try it in the correct position since everything was buttoned up, belts on, etc. I pulled and aligned the distributor at this position knowing the #1 cylinder was also at TDC with the valves closed. The car fired right up and runs great. I will put a timing light on it this weekend just to check everything out, but the car is running great.

So in summary an '87 560SL crank pulley can be put on correctly and 180 degrees off even with woodruff keys. Thanks again to Ron and Rowdie for responding to my post and helping me think through this. Perhaps at some point down the road I will pull the crank pulley and rotate to the correct side so the standard timing marks show. I think I will enjoy her for a few weeks before taking that task on.

Stewart

meltedpanda · #5 06-04-2015, 08:38 PM

I love happy endings, good job! For some reason I thought after I wrote my post - "it is possible to be 180 degrees off ..the I thought ..nahh, again great work!
enjoy the ride!

Frank Reiner · #6 06-04-2015, 09:32 PM

It is very interesting that the 180 mark on the dampener was aligned with #1 TDC. The V-belt pulleys and the dampener are held to the crankshaft hub with six bolts, one of which is offset. The pulleys and dampener go on to the hub but one way, and by virtue of the crank to hub key, the whole assembly goes together but one way. So what has happened? I'd venture that the dampener was mis-assembled during manufacture; 180 out from the correct location with reference to the offset bolt hole, or looked at another way, the offset bolt hole is 180 from the correct location with respect to the 0 TDC mark.

Incidentally, the center crank bolt need not be removed; removal of the six bolts that retain the pulleys and dampener clears the area for removal of the water pump.