PeachParts Mercedes-Benz Forum - View Single Post

t walgamuth · #5 02-02-2008, 10:41 PM

So Early Friday morning we got about 7 or 8" of heavy snow. It was interesting, to walk in it felt a lot like walking in dry sand. I got up and took my scout out to plow my parking lot. As I was heading back to my house to do my driveway as I took off suddenly I had a dead miss on one cylinder. I assumed that I had fouled a plug and went on home on three cylinders.

When I got home I called my indie and asked if I could bring it out. I have a 123 in my garage and my 123 autocrosser parked outside on its slicks so I was pretty sure I didn't want to go to the trouble to move them so I could get the scout in and work on it myself.....and the snow was still coming down pretty thickly. They said to come out after lunch. I went to the former NAPA store and bought oil change stuff, oil flush, a set of spark plugs and some Rislone to add to the oil.

I had noticed on the last snow that it was ticking and pulled the valve cover to discover a sticking hydraulic lifter. So I figured the fouled plug was on the cylinder with the sticky lifter.

When I got there my indie first ran a compression test. #1 had no compression. He pulled the valve cover and found the reason.....the exhaust pushrod (maybe it was the intake) was missing and the lifter as well. You could look in and see the cam lobe turning. We pondered the fact that it had enough oil pressure to supply the bearings without the lifter in there.

He fished out the pushrod and then the lifter and found the pushrod, which has a cup on top and is bullet shaped on the bottom had the side of the top cup blown out. Apparently the lifter collapsed completely and allowed the lifter to slip low enough to have the edge of the cup come up under the lifter and break itself ( I wonder if the valve hit the piston at this time?)....I hope not.

So we ordered a pushrod and lifter. Lifter was about $5 and pushrod was like $7. They can both be installed without pulling the head. I am still in shock at the cheapness of these antique parts. Benz shock I suppose.

So the parts will be in probably monday or tuesday.

Moral of the story....if your four cylinder scout has a collapsed lifter....don't let it go.

BTW, I found the four cylinder is rated at about 98 hp and about 175 torque, out of 196 CI. The v8 is twice the displacement and only about 1.5 times the power.....and the power is developed at about 500 higher rpm, with the same compression ratio. I am thinking it has a more aggressive cam than the v8.....possibly contributing to having enough lift for the pushrod to get caught on the edge of the pushrod cup.

By Monday I think the snow will be melted off my driveway.

Tom W