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  #1  
Old 03-21-2009, 04:02 PM
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W123: How to check woodruff key?

I'm about to adjust the valves on my 1983 300TD. I did a quick check on timing chain stretch, and it seems to indicate 0 degrees. I will redo the test and then do the dial indicator test as well. The car has 245,000 miles and poor upkeep from the recent PO. Do I need to remove the nut on the front of the chain sprocket to see if it has an offset key in it? Any tips?

Thanks,
Rob

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Old 03-21-2009, 04:11 PM
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Rob,

There is an offset key in there - there is a 0 degree key. There no way to check what they key is without pulling the key out, or having a service record. You don't want to do that if things look good.

If the chain measures within acceptable limits using the 2mm valve lift method, and the chain itself, guide rails etc. look healthy, leave it alone. The FSM itself states that the chain stretch can be adjusted until the greatest value woodruff key can no longer be used.

Refer to the FSM for the 2mm valve lift method, or this sites DIY articles. You get a reading of 11-15 degrees of stretch, and there is a conversion which gives you actual stretch. Its not as straightforward as the cam line up method.


dd
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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car
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  #3  
Old 03-22-2009, 08:49 AM
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Big Second to all of Diesel Dan's post.

' Quick' and ' Seems' do not belong in chain elongation test results...
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Old 03-22-2009, 09:53 AM
ForcedInduction
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Use synthetic oil and it will reduce wear on the chain to prolong its life.
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Old 03-22-2009, 10:13 AM
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So I checked the timing chain stretch using the 2mm valve lift method. The reading was 15 degrees. The FSM says that the intake valve opens at 9 degrees after TDC for the new chain on the 917.952 and 11 degrees after 20,000km. This means that the chain has 6 degrees of stretch.

I'll put it on the list for something to consider changing. One thing at a time. I still have not started the car since purchasing it recently. Four bad glow plugs were found. I'll put in new Bosch plugs after I finish adjusting the valves. I'll also consider sythetic, FI. I'll need to read a couple hundred more oil threads first!

I did encounter one problem that I cannot explain and would appreciate comments. I am turning the engine clockwise using the power steering pump pulley. I loosed its bolts and tightened the belt quite a bit. Still, at certain points in the rotation, the engine seems to lock up and I cannot rotate it further. All of the glow plugs are out. If I reverse it an inch or so on the wrench, it sounds like some vapor lock down at the bottom of the timing chain releases and I can continue rotating. The difficulty seems to be near TDC of cylinder 1. Is this normal? I would think it would spin easily without glow plugs. Is there some check valve for the bottom of the crankcase?
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Old 03-22-2009, 11:54 AM
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Rob,

First off, don't turn the engine by the power steering pump. Its a little bit more of a pain at first, but much easier to use the crank bolt underneath the engine. You need a 1/4" ratchet with a deep well 27mm socket. The issues you are having will go away.

You have 6 degrees total stretch. If you have less than 250k on the clock, and the PO didn't do much maintenance, Id bet you have the 0 degree key in there.

Its up to you at that point as to what to do. Per the FSM, you can put a key in there and be just fine. There is a 4 degree key you could put in that would put you right to the worn-in chain spec of 11 degrees. Total cost, $5.

Then of course you could roll in a new chain, but that is expensive, time consuming, and a risky DIY (IMO) if you haven't done it before.

dd
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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car
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  #7  
Old 03-22-2009, 11:57 AM
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Clockwise looking at it from the front ...

1. DO NOT use the power steering pump nut to turn the engine.
lots of posts on that... the FSM says Don't do it... and I have posted the reason and my experience helping TCane fixing one a PO did that to...
2. Do not turn the engine backwards anymore than you absolutely have to... in general the instructions in the FSM are very specific... there is one time I have found a few degrees are ok... but you are running the risk of getting the IP timing off..
3 . Remember that setting the IP timing can be done without affecting the cam timing with the offset key... much easier.. use piston position to set the IP timing...
4. Check to see that your pulley with timing marks on it is in good condition and has not moved on the crank.
5. Check by moving the crank end bolt to see if you still have the increased resistance for turning while the plugs are out...

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