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Old 02-23-2003, 05:49 PM
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After several months of working on my "winter project" I find that it is pretty much completed but winter is still in full swing.

When I last posted to this thread I was still trying to sort out the problems in the valve train of the M116 in my 1982 380SL. As it turns out the terrible hammering noise was being generated by a couple of collapsed ball studs. Added to that the chain was stretched 8-10 degrees and the left cam sproket was dangerously loose on the cam. The car had been converted to a dual row chain about 80,000 miles ago. I had the engine out of the car, on a stand and proceeded with a major freshening up.

As I had stated the previous owner had taken the car to a shop where a certified mechanic worked at eliminating the noise. He did not detect the collapsed ball studs. He also left the compensating washer off when installing the camshaft sprocket. The only thing that was preventing the sprocket from spinning freely on the camshaft was the woodruff key. I was lucky it held as the rehab would have been much more involved and expensive if the interference had come into play.

I decided to replace all of the ball studs. With 133K on the clock and two ball studs collapsed additional failures seemed a distinct possibility.

I replaced the valve stem seals- no big deal really since the engine was on a stand and access was simplified.

Seemed like a good time to replace the injector holders, rings and seals as well.

While replacing the timing chain, tensioner, rail and guides I came across the compensating washer the mechanic had left off- it was jammed in behind the chain guide on that side. It seemed to me that using a slide hammer was a better idea for removing the pins holding the guides since there was plenty of room with the engine out. I was wrong- it was actually easier to use a bolt with the appropriate sized socket and washer set up as described several places in the archives.

To relieve my mind of the possibility that there might be some rod noise I pulled the oil pan and checked the rod bearing clearance. All were between .0015 and.002" (checked with PlastiGage). Amazing that at 133K they showed no wear.

I replaced the rear main seal.

A special thanks to Chuck Taylor for answering a lot of questions that came up during this project. He was especially helpful in understanding the process of checking and adjusting the valve lash. I was skeptical at first when he explained the process and the need to allow the ball stud, rocker arm and thrust washer assembly to "sit awhile" before using the gauge to check the clearance- but of course he was right as was evidenced by doing it. Of the 16 thrust washers in place 14 needed to be changed to get the correct specs. 13 needed to be stepped up one size and 1 jumped two sizes.

I installed new oiler kits and cam cover gaskets.

Before installing the engine and transmission I replaced the motor mounts. I also replaced the front and rear seals on the transmission. I made a tool to remove the special fastner that held the rear flange in place on the transmission.

I replaced the heater hoses as well as all the other cooling system hoses and drive belts on the car.

The engine and transmission had been removed seperately from the car. I decided to install them as a unit. While this was easier in some ways it was a trade off. I only had an 8 foot ceiling in my work area. Since the combined components had to be installed at about a 45 degree angle I was not able to put the car on jackstands and lift the engine/transmission high enough to install. Leaving the car on the floor meant I had very little room to get to the motor and transmission mounts. It worked out.

I had kept very detailed notes and took pictures that I hoped would make the install/start up go much easier. I'm sure it did. After completing the procedure in reverse I threw the battery in the car to give it a quick crank only to hear the fuelpump run. That pointed to the starter solenoid wire not being attached as well as a gas line that had not been tightened. I attached the wire, tightened the fuel line and disconnected the fuelpump. This time I cranked the engine over and before long was rewarded with 3 bars of oil pressure registering on the gauge. Over a period of about a half hour I repeated this process four or five times. I was getting a good flow of oil over the cam lobe visible through the oil filler cap.

I reconnected the fuelpump and set up two C02 extinguishers for easy access if they should be needed. My son was assigned firefighting duty. I cranked the engine over and it immediately fired up and then died. The second crank was a little longer but it caught and after 10 or 15 seconds of rough running smoothed out and idled fine. After about another 15 seconds of smooth idle I pressed the accelerator some and raised the RPM's slightly only to hear a muffled "pop" which caused my son to peer under the car from his assigned position. His shout caused me to turn it off and when I looked under the car two or three quarts of ATF had been deposited on the shop floor. Seems I had neglected to tighten one of the cooling lines on the transmission. After adding more ATF (and cleaning up the mess) I started it again and all was fine.

I have yet to get the car out for a run. The weather has been terrible and my long driveway is currently a mixture of ice and mud. I havn't set the timing other than the static timing when replacing the distributor. I am amazed at how quiet the engine is when running. The loudest thing under the hood is the fuel injection component that "buzzes" (frequency valve??). Inside the car the fuelpump can be heard but the engine sounds are hard to distinguish. I had toyed with the idea of not changing the thrust washers and leaving the valve lash where it was. After hearing (or in this case- not hearing) the engine with the correct lash setting that would have been a mistake.

Thanks to those who have read and responded to my posts concerning this project. It is not over but at least now I can begin to enjoy the car (assuming winter ends as it has always done in the past).

Attached Thumbnails
M116 Valve train- source of engine noise??-m116.jpg  
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