w126 after timing chain replacement.....engine is SHAKING!!!! Please HELP!!

Hello everyone!
i have a 1985 500SEL with 204,000mi. al lot has been done to it because i love this car and want to keep it for a while. my last job
was to replace the timing chain with new guides and and to do a valve job. i have a professional mechanic who only works with mercedes to hepl me and he does.
after replacing the the timing chain, when we started the car, it was shaking soooo bad. when we looked at the econo guage, it is obvious that it is a vacuum leakit was arounf 3/4 away from its normal position while idling. could not figure out the problem. this car has all new vacuum lines with switches.
with this in mind, we also did a valvejob (sent it to a machine shop) hoping everything is done properly. after replacing new gudes, seals, rocker arms, headgaskets, intake was sent out to clean, new intake gaskets, intake plenum gaskets, used air meter, new fuel distributer o ring, all new air hoses and fuel injector seals and holders, new throttle body switch.....WHEN THE CAR STARTED, SHE IS EVEN WORSE. CANT UNDERSTAND WHY. ECONO GUAGE IS NOW AT 1/2 POINT WHEN ENGINE IS IDLING.
please help. what are we missing here? has anyone else had the same problem? could this be due to bad fuel pressure regulators? my mechanic said he has to plug it in to a scope to further understand the problem.
thank you in advance Lushan
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Are you sure the valve timing is correct?
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Kenneth,
timing is positioned to Top Dead Center 0|0 mark on the harmonic balancer. The left and right cam timing marks aligned perfectly. i had separated the airmeter to clean (rubber air guide) and inspect for any cracks or leaks. when i re-assembled, i did not use any sealer. would that be an issue? thank you Kenneth!
Lushan
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You can find vacuum or air leak by spraying carburator cleaner at suspected joints.
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Suggest you check the valve timing. A cam could be "off" by one tooth on its sprocket - more than that and your shiny new valves might start hitting the pistons!
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Or he may have the correct valve timing but he skipped a tooth or more on the injection pump timing sprocket. He won't damage a valve but the car won't run.
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Oh, I didn't know that 5.0L gas engines used a chain driven injection pump. Learn something new every day.
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A few thoughts: 1. Check compression. 2. Check Ignition timing. This engine is timed by the dist and could get off when doing the chain. 3. Did you run the engine long enough for the "hydrolic lifters" to adjust? This could take some time. (several min) 4. Check for vacumn leaks with carb cleaner. Also the carb cleaner can tell you if the engine is lean or rich. When sprayed in the intake, if it speeds up, it is lean. If it slows down, it is rich. Spray just a short shot, it doesn't take much.
Keep us informed.
Paul McKechnie 84 500SEL

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Paul, thank you soo much since the new chain, i remember my mechanic taking off the plug wires. just put it in without checking the firing order. could that be an issue? could it cause the econogugae to show at 1/2 point?
thanks Lushan

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Yes it can be an issue and cause the guage to read at the 1/2 point. On the 85 and older, the timing is handeled by the dist and it must be adjusted correctly. On the 86 and later cars the timing is handeled by the Ignition control moduel. Just use a standard timing light and set the timing to 0 deg . Later you can advance the timing a little for better performance and mileage.I run my 84 500SEL at 10 deg BTDC. Also make sure the ign wires are installed correctly. I don't remember the firing order right off but I'm sure some else knows off the top of their head.
Good Luck Paul McKechnie 84 500SEL

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On 2004-09-28 12:29:24 -0700, snipped-for-privacy@yahoo.com (Lushan) said:

Um, Yeah
If the wires are not on the right order that is your problem for sure...
Marty
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YES!!!!!
it worked! it was the wires. i got the proper firing order right off the valve cover. i cant remember the order but on the distributer, 2 wires were in the wrong position.....im soooo happy. thanks again for all of your advice and help. we live to learn.
Lushan
(Lushan) said:

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