Another timing chain question - PeachParts Mercedes-Benz Forum

hudtud · #1 04-15-2009, 09:41 PM

First of all I would like to thank this forum's members for countless hours of enjoyable and mostly very informative reading pleasure. This forum is totally awesome! After studying the timing chain stretch DIY and following a recent thread by RUMMUR I decided to measure mine (chain stretch) using a borrowed dial indicator. I just had the valves adjusted today and asked the mechanic to check the timing chain and mentioned the 2mm drop method- he didn't seem familiar with it, or at least didn't want to do it, but proceeded to tell me he could tell it did need replacing just by wiggling it back and forth on top of the sprocket. And yes it did have a bit of play maybe 1/8 inch sliding side to side on the sprocket, otherwise chain, cam, sprocket teeth were all good looking. I also mentioned the woodruff keys made for offset and he says yeah, I never used them just put in a new chain. This guy has rebuilt many 240's and 300's so I don't want to argue... but I get home and want to check timing chain stretch, so--- By the crude method (aligning marks on cam and sprocket)I check three times at least and get about 3* each time. So I rig up the dial indicator and check 3 more times. Indicator is at a 25*angle or so, but on the valve keeper where it should be and every time I get 17 to 18*. For my engine 617.952 this should ideally be at 11* according to the DIY article. I DID NOT release valve lash, for 2 reasons- no feeler gauges and valves were just adjusted today, and I don't know what releasing valve lash really means- is it increasing the gap or making the small gap disappear? This must make a difference as my results do not jive. BTW, valve adjustment done has made a noticeable difference in ease of starting, as it has been 20k miles since last adjustment about a year ago. Engine shakes bad as ever and i will hopefully remedy that with a solid gold rack damper screw and new motor mount... Thanks for reading!

leathermang · #2 04-15-2009, 09:48 PM

It means taking out ALL the space between the top of the valve and that next part up which I can not remember the name of...
I hate to run into mechanics like that... he will be offended if you tell him the truth from any source... the FSM or US....

dannym · #3 04-16-2009, 08:24 AM

I agree, stay away from mechanics who don't know MB specific's. Anyone can rebuild an engine, or even swap one. That doesn't make them a good MB mechanic.

Removing valve lash makes a big difference. If you really want to know, do it right.
Feeler gauges are cheap.

Danny

Alastair · #4 04-16-2009, 09:58 AM

IF you dont want to upset the adjustments....

Use a feeler-guage blade to remove the 'lash' or clearance....

Use one that gives a very snug/almost tight sliding fit ....

Make sure the dial-guage is perpendicular to the valve being measured. Dont have it at an angle or it will upset the readings....

Diesel911 · #5 04-16-2009, 12:34 PM

If the Dial Indicator is at an angle it will not measure accurately. I think an extension for the indicator that serews into and adds length to the indicator plunger would allow you to mount the indicator higer and with better alinment.

Assuming the 3 degrees you got with the other method is correct (and no prior owner has installed an Offset Key in the past) the strech is nothing to worry about.

hudtud · #6 04-16-2009, 09:45 PM

Thanks for the info, I think I know what to do as far as removing the lash now. I will get the proper tools, really just an extension post to get the dial indicator vertical and a set of feeler gauges to measure lash when setting back to spec. I will also make wrenches to do the valve adjustment myself next time!