[SpartanPete]

Hello all, sorry if this has been covered before but I searched to no avail. I am trying to remove the chain-driven timing device on my om617 turbo to see what's causing a racket and the FSM calls for removing the upper pin on the lower chain guide so you can insert the chain holding tool. Is it truly necessary to remove this pin? If so, can someone help me locate it? I have a feeling it's near the a/c compressor but I can't find it even after trying to clean that area of the block

 

[SpartanPete]

Ok, so I managed to remove the timing device and the associated parts but I didn't find what I was expecting. The engine has been making a noise from the vacuum pump area and when I removed the pump there is play in the shaft. I removed the timing device expecting the bushing to be worn but it doesn't show much wear. With everything removed I can move the shaft back and forth quite a bit. Is there a lot of play because of all the parts in front have been removed or should there be little to no play into the injection pump?

 

[SpartanPete]

I have another question concerning the chain tensioner. Should the circle spring clip be able to move back and forth on the groove in the tensioner pin? This play causes the tensioner pin to move about 1/8-1/4 of an inch back and forth in its housing. I know the tensioner also gets hydraulic assistance with the engine running but it seem to me like play in the ratcheting mechanism like I'm seeing would cause the chain to bounce back and forth on the rail.

 

[jrogosich]

I was in the same situation years ago with my 617.912 car. It turns out not many people know much about the injection timer, because there is not much to it. 2 springs, 2 weights that advance pump timing as RPMs increase. Inside the springs there are 2 stops that serve to effectively limit the degree of advance to a fixed amount. When paying close attention, rotating the engine by hand, it is just possible to hear them slide up and down.

Do not worry about axial play in the timing device, the injection pump and timing chain tension keep it in its place while the engine runs.

The clip on the timing chain tightener is supposed to be sort of loose. The running engine oil pressure should keep the chain very tight while the engine is running. The play felt in the pin without oil pressure is negligible. Oil pressure keeps the chain very tight and automatically compensates for wear. If the chain was in fact rattling loose, there would likely be significant collateral engine damage. Check to see if it the chain is excessively stretched or the tension is losing pressure. Remove the valve cover shortly after the engine is run. The chain should appear to be very tight on both sides. Any slack should receive prompt attention.