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  #1  
Old 12-07-2013, 10:35 PM
Ben Froelich's Avatar
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OM617 Valve Adjustment Changes as Valve Rotates

Hello Everyone! Thank you all for the great info and help on this site!

I readjusted the valves on my 617 today. I noticed that when the adjusting nuts are jammed and the adjustment is set, if I twist the whole valve assembly (using the adjusting nuts) the adjustment changes slightly. I.e. as I rotate the valve with a feeler gauge inserted, sometimes it is loose, sometimes tight on the feeler gauge. Could this be due to the valve height changing as it rotates on the seat? Is it something to worry about? Also I can hear a squeaking/grinding sound as I rotate the valves on a few cylinders, probably from the valve or spring rotating on the seat or head respectively.

Background on the car:
130k miles
Recent Work:
New injectors, pump timing set, new fuel and air filters, cleaned fuel tank
Symptoms:
White smoke at startup, some smoke under heavy accel. (not sure what color). Cylinder three is knocking, low on power (hoping it's not low comp.)

Thanks!
Ben

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Old 12-07-2013, 11:47 PM
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Valve and seat are worn oval. I've heard of in situ valve grinds, but I think it's usually done w/ the head off.
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Old 12-08-2013, 01:15 AM
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One of our Member said that depending on the position of the Valve Rotators the Valve Clearence can be different.

I forget the other detailse He mentioned and I did not save his Thread to My notes.

I suppose it is also possible some Valve Rotators are damaged but I have not read any symptoms on that.

White smoke is either Coolant or unburned atomized Fuel. You can tell by the smell or if you have evidence of a Head Gasket Leak.

Was there any change to the good after the Injectors, Valve adjustment and IP Timing? Or is it the same?

You could line up the Camshaft Timing Mark on the back of the Camshaft Gear with the one on the Camshaft Bearing Tower and take a look at the degree marks on the Crankshaft Damper. Alothoug at 130k miles you would not expect that to be off very much.
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Old 12-08-2013, 01:30 AM
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Quote:
Originally Posted by Diesel911 View Post
One of our Member said that depending on the position of the Valve Rotators the Valve Clearence can be different.

I forget the other detailse He mentioned and I did not save his Thread to My notes.

I suppose it is also possible some Valve Rotators are damaged but I have not read any symptoms on that.

White smoke is either Coolant or unburned atomized Fuel. You can tell by the smell or if you have evidence of a Head Gasket Leak.

Was there any change to the good after the Injectors, Valve adjustment and IP Timing? Or is it the same?

You could line up the Camshaft Timing Mark on the back of the Camshaft Gear with the one on the Camshaft Bearing Tower and take a look at the degree marks on the Crankshaft Damper. Alothoug at 130k miles you would not expect that to be off very much.
Thanks for the responses. Forgot to mention that the smoke is raw fuel. After doing all the work, a knock that was present at highway speeds under a specific load went away. Not much of a difference otherwise. Also checked timing chain, its where it should be. Will look up the rotators thing.

moon161- does this happen often? Should I do a leak-down test first?

Thanks!
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Old 12-08-2013, 02:03 AM
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If you take off the head you'll probably find that the valve guides are worn and that amount of wiggle is allowing the valve to float about its seat.
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Old 12-08-2013, 03:07 AM
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Originally Posted by Stretch View Post
If you take off the head you'll probably find that the valve guides are worn and that amount of wiggle is allowing the valve to float about its seat.

DITTO!

this is what leads to uneven wear of the valve seats and the valves.

As you turn the valve, the thick spots on the valve meet with the high spots on the valve seat due to uneven wear.

Adjust the valves at the tightest setting you can find.
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Old 12-08-2013, 03:54 AM
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If all was normal the clearance wouldn't change. I believe these have some sort of device that rotates the valves as the move doesn't it? To promote even wear?
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Old 12-08-2013, 04:33 AM
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Originally Posted by dude99 View Post
If all was normal the clearance wouldn't change. I believe these have some sort of device that rotates the valves as the move doesn't it? To promote even wear?

In a perfect world, they should prevent uneven wear. But nothing will stop the wear on the valves and seats which leads to the tighter clearances.

The valve rotators (rotocaps) at the bottom of the spring align the spring forces to parallel with the valve stem and are designed to spin so the wear is even.

Valve guides wear regardless of this.

Over time, it seems that particles settle in the recess where the rotator rests and prevent the balls from rolling freely. Once the valve guides are worn, the rotocaps are less effective.
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Old 12-08-2013, 03:59 PM
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Quote:
Originally Posted by Diesel911 View Post
White smoke is either Coolant or unburned atomized Fuel. You can tell by the smell or if you have evidence of a Head Gasket Leak.
Coolant smells sweetish, fuel smells nasty, is that correct? I have what seems like one cylinder missing a little after a cold start, problem goes away as son as the car warms up. Glow plugs recently done, not losing coolant or anything. Wondering if it is time for new injectors
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Old 12-08-2013, 04:33 PM
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Quote:
Originally Posted by jt20 View Post
DITTO!

this is what leads to uneven wear of the valve seats and the valves.

As you turn the valve, the thick spots on the valve meet with the high spots on the valve seat due to uneven wear.

Adjust the valves at the tightest setting you can find.
Thanks, folks!

Got done adjusting them as you recommended. I also recorded how much the valve height changed as I rotated it:


The only valve that was way out of spec was the intake on cylinder 1. Cannot tell a major difference in performance. Cylinder three still knocks. Talked to a Benz mechanic friend who suggested Redline and driving at 70MPH for a while. He said there might be carbon in the cylinders or algae buildup in the IP (the car was sitting for a while). Possibly the valve before the injection line is sticking.
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Old 12-08-2013, 08:16 PM
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Originally Posted by aieeegrunt View Post
Coolant smells sweetish, fuel smells nasty, is that correct? I have what seems like one cylinder missing a little after a cold start, problem goes away as son as the car warms up. Glow plugs recently done, not losing coolant or anything. Wondering if it is time for new injectors
I had removed the Fuel Injection Pump on My Volvo Diesel to change the Seal on it. When I re-installed it I had huge billows of white smoke coming out out the Tail Pipe (and this is with rebuilt Injectors).
It turned out I timed the Fuel Injection Pump extremely late/retarded.

You might try scribing a line arcossed the front Fuel Injection Pump flange and the Engine Block where the Fuel Injection Pump mounts into the Block. That allows you to return the Fuel Injection Pump to where it was origionally.
Loosen 3 Nuts on the Front Fuel Injection Pump Flange and the one that is on the rear bottom of the Fuel Injection Pump and rotate the top of the Fuel Injection Pump towards the Block just a bit (and tighten the Flange Nuts); start the Engine and see if that improves your white smoke issue.

If it improves the smoke issue then rotate it untill the White Smoke is gone and tighten all the Nuts and see if it drives well like that.

If the above does not help rotate the Fuel Injection Pump back and line up your scribed marks to return it to where you started.

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