1995 s500 timing off? - PeachParts Mercedes-Benz Forum

chiwanga · #1 09-29-2012, 11:36 PM

Working on a 95 s500 that I bought. I have spent several days on this car trying to figure out why it runs so poorly. It is only running on 2 cyl per bank. All the tune up stuff was new when I got the car. I'm getting spark and good fuel pressure. I just pulled the valve covers. The chain looks good and tight, I saw no real evidence of chain slippage, but when I turn the crank to 45 I can allign all the cam holes except for the right exhaust. Why would the timing be off?

engatwork · #2 09-30-2012, 08:21 AM

How many miles are on it?

chiwanga · #3 09-30-2012, 11:11 AM

160k

badgator · #4 09-30-2012, 11:45 AM

Do all spark plugs have a healthy blue spark?

As far as running on 2 cylinders per bank, each distributor fires to 2 cylinders on each bank. The 2 center on one side and 2 outside on the other.

Hopefully your engine wiring harness was already replaced.

One way to check pull coil wire at dist cap, insert spare resistor spark plug (you should be using non-resistor plugs on your car) and ground to engine.

If it won't run when one side is pulled, that is the good side, the other side has a problem.

This engine can run fairly well when only one side is working correctly.

Test by switching parts from one side to the other:

dust shield under rotor
coil
coil wires
possibly EZL / ignition module
could still be dist cap / rotor

When the other plugs fail to fire you found your problem!

And of course check fuse(s) on the OVP relay

chiwanga · #5 09-30-2012, 12:05 PM

I have checked everything you mensioned. I even had another 119 car in the shop that I was able to exchange parts with for testing purpose. My problem is not in getting spark to the caps. The issue is with timing. Why is the right side exhaust cam out of time? What if I just take out the tensioner and rotate the exhaust can until the alignment marks meet and then tighten the chain?or is this a crazy idea.

engatwork · #6 09-30-2012, 01:44 PM

Quote:

All the tune up stuff was new when I got the car.

What else was done to the car? They typically don't just "jump time" unless there is an issue with the mechanism that keeps everything lined up and tight. What kind of oil change interval has the car received for the 160k miles?

badgator · #7 09-30-2012, 03:07 PM

Quote:

Originally Posted by chiwanga

I have checked everything you mensioned. I even had another 119 car in the shop that I was able to exchange parts with for testing purpose. My problem is not in getting spark to the caps. The issue is with timing. Why is the right side exhaust cam out of time? What if I just take out the tensioner and rotate the exhaust can until the alignment marks meet and then tighten the chain?or is this a crazy idea.

Have your timing chain rail guides been replaced?

When they disintegrate a timing chain jumping is the least of your problems.

If it jumped a tooth or 2 you might be OK to rotate the cam to line up.

There's plenty of how to - write ups w/pix, search here and benzw*rld.*rg,

Here's a couple pix from my 92 500sl 110k mi, taken last week.

Make sure the cam advancers are in the idle position (retarded).

I used valve cover bolts to line up cams, replace copper washers for these bolts when you reinstall.

Checked out at about 42 1/2 - 43 degrees.

I replace the top guides, as the previous owner died and his daughter couldn't find the maintenance records, the look like they were replaced and even a a made in ??? sticker on back of one of the parts.