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  #1  
Old 09-21-2009, 08:10 PM
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Question How does the 617.95x chain tensioner work? (and R&R)

Folks,

I have been chasing a noise from which I have gotten indications from a couple sources that it might be the timing chain slapping, and that I need to check my chain tensioner.

The thread about the noise chase is here: (tapping/slapping/knocking when cold, from front right of engine bay)

here:Strange random noise puzzle from engine, only when 'cold'...

Question #1: How does the tensioner work exactly? I know what it looks like from the FSM. How does the oil pressure and spring interact? How would the oil cooler thermostat opening up affect the tensioner operation?

Question #2: How can I inspect it by taking the valve cover off? What can I look for? Can I take the spring out easily?

Im trying to deduce if the noise I am hearing when the engine is cold could definitely be (or not be) the tensioner before swapping it out.

Thank you,
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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  #2  
Old 09-21-2009, 08:44 PM
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The spring keeps it tensioned with the engine off....oil pressure pushes on the pin when its running. Oil cooler opening should have 0 effect on the tensioner.

You can see the end of the pin pushing against the stub on the back of the chain slide rail with the valve cover off. Make sure they are both lined up and not crooked or worn. One one of our SD's the rail is cocked and the tensioner pin and rear pin of the slide rail are worn/damaged. We are replacing them soon due to this issue.
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  #3  
Old 09-21-2009, 08:56 PM
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There is also a circular wire clip around the Chain Tensioner Piston. The clip fits into grooves in the Chain Tensioner Housing. People refer to it as being a "Ratchete".

The prupose is to help retain the Chain Tensioner Piston in place when you first start the Engine and the Oil pressure is low.
The older non-turboed models do not have the Ratchete feature.

If you look in the FSM you will see the Clip and the Grooves.
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Old 09-22-2009, 12:15 AM
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thanks fellas. So it doesn't make sense for the tensioner to make noise just until the engine oil gets up to temp.

So can I just remove just the tensioner spring, inspect it (i have another one for comparison) , and it put it right back in?

It seems from the FSM I can do this (woodruff key article, 05-215) , but I wanted to check here before disturbing it.
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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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  #5  
Old 09-22-2009, 12:46 AM
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Quote:
Originally Posted by dieseldan44 View Post
thanks fellas. So it doesn't make sense for the tensioner to make noise just until the engine oil gets up to temp.

So can I just remove just the tensioner spring, inspect it (i have another one for comparison) , and it put it right back in?

It seems from the FSM I can do this (woodruff key article, 05-215) , but I wanted to check here before disturbing it.
If it is working correctly???
And, assuming good Oil pressure which is normally higher at idle speed when you first get the Engine going and lower ounce the Engine gets hot at idle speed; you would think you would have the problem with a hot Enigne if Oil pressure was the problem.


I would get a Mechanics Stethoscope or put something against the Chain Tensioner Housing and listen to see where the sound is comming from.

Perhaps there is an issue with the Chain Rail the Tensioner pushes on.

At any rate it should be safe to pull the Chain Tensioner Spring out.

Just for some more information; before you pull the Chain Tensioner Spring out have you tried lining up on the compression stroke the Camshaft Gear to Camshaft Bearing Housing timing marks and looking down at the Crankshaft Damper degrees to see what it is.
When the Engine was new it should have lined up on 0 degrees (Top Dead Center) when the Camshaft Gear and Camshaft Bearing Housing timing marks are lined up.
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Old 09-22-2009, 09:39 AM
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Quote:
Originally Posted by Diesel911 View Post

I would get a Mechanics Stethoscope or put something against the Chain Tensioner Housing and listen to see where the sound is comming from.

Perhaps there is an issue with the Chain Rail the Tensioner pushes on.

At any rate it should be safe to pull the Chain Tensioner Spring out.

Just for some more information; before you pull the Chain Tensioner Spring out have you tried lining up on the compression stroke the Camshaft Gear to Camshaft Bearing Housing timing marks and looking down at the Crankshaft Damper degrees to see what it is.
When the Engine was new it should have lined up on 0 degrees (Top Dead Center) when the Camshaft Gear and Camshaft Bearing Housing timing marks are lined up.
1.)RE: listening. I did some stethoscope work on it yesterday. I put the scope on the chain tensioner bolt / housing but didnt hear anything remarkable. I also could not rev the engine while doing this and make the sound appear, so this was at best inconclusive. Ill try again with a helper today. I think I may have them drive the car forward while I stand on the bumper and listen to engine sounds.

2.)RE: cam mark line up

Ill do this today. Last time (2k ago), it was 4 degrees with the 2mm valve lift method, verified by the timing marks.

thanks diesel911 -
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 09-22-2009, 08:25 PM
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Arrow Videos

In an effort to document what I am seeing / hearing and help you guys help me, I took a series of videos. the detailed description of each is on the you tube 'info'.

Each video is about 90 seconds. If you only want to watch one, watch #3.

Video #1: Driving, you can hear the noise I am talking about.
http://www.youtube.com/watch?v=IizCazECkhc

Video #2: Rev'ing at idle in the arage
http://www.youtube.com/watch?v=pu7LKjVNJUQ

Video #3: Timing chain is loose?? Inspection under the valve cover.
http://www.youtube.com/watch?v=QhxIm4zfNZU

Chain stretch is still at about 4 degrees. Same as it was before.

Video #4: Chain tensioner inspection.
http://www.youtube.com/watch?v=fy4EV_f7MCM

Between #4 and #5 I removed and replaced the chain tensioner spring. The spring that came out was different than the one that I put in (I ordered a new one off this site). See attached pic.

Video #5: Chain tension is much greater. Is it safe to start?
http://www.youtube.com/watch?v=IB3YeStVSTg

Tomorrow I am going to start it back up and see if anything has changed. After that, I don't know what to do next.

Pic #1: The longer spring is the new, correct one.
Pic #2: Wear on the old spring.
Pic #3: Top of valve cover. does this mean the chain was hitting it? Or is this normal looking top of valve cover-ness?

Thanks,
dd
Attached Thumbnails
How does the 617.95x chain tensioner work?  (and R&R)-spring.jpg   How does the 617.95x chain tensioner work?  (and R&R)-spring-wear.jpg   How does the 617.95x chain tensioner work?  (and R&R)-valve-cover.jpg  
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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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  #8  
Old 09-22-2009, 08:53 PM
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Quote:
Originally Posted by dieseldan44 View Post
1.)RE: listening. I did some stethoscope work on it yesterday. I put the scope on the chain tensioner bolt / housing but didnt hear anything remarkable. I also could not rev the engine while doing this and make the sound appear, so this was at best inconclusive. Ill try again with a helper today. I think I may have them drive the car forward while I stand on the bumper and listen to engine sounds.

2.)RE: cam mark line up

Ill do this today. Last time (2k ago), it was 4 degrees with the 2mm valve lift method, verified by the timing marks.

thanks diesel911 -
dd
The above in blue is what we need the Video on !
If no one gets hurt it could be funny.

Added after reading your last post.

Running it with the new longer correct Chain Tensioner Spring has to be safer than running it with the old worn one.
The condition of the Spring makes me want to take a look at mine. I wish it was easier to get at.
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Last edited by Diesel911; 09-22-2009 at 09:04 PM.
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  #9  
Old 09-22-2009, 08:55 PM
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Quote:
Originally Posted by Diesel911 View Post
This is what we need the Video on !
If no one gets hurt it could be funny.
I did it today. It was helpful, my assistant only went 5mph up a hill. I used the stethoscope listening for sounds while moving...
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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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  #10  
Old 09-22-2009, 10:52 PM
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Quote:
Originally Posted by Diesel911 View Post

The condition of the Spring makes me want to take a look at mine. I wish it was easier to get at.
It's easy to get at if somebody stole the EGR

The bolt is right there once the EGR corrugated tube is removed. You dont need to take the valve cover off. Hardest past is squishing the spring upon reinstall.

19mm 3/8 drive socket +1/2" drive adapter on a 1/2" drive ratchet gets in there perfectly.

Get the spring back in by pushing with the ratchet and advancing it forward a few clocks until the spring catches. Its a two handed technique.

90 nM to tighten it back.

I guess I'll start it up tomorrow and see what happens. My goodness Id jump for joy if that fixes it, but Im not that lucky. Plus, what the heck was the wrong spring doing in there to begin with?!

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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  #11  
Old 09-22-2009, 11:09 PM
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Quote:
Originally Posted by dieseldan44 View Post
I did it today. It was helpful, my assistant only went 5mph up a hill. I used the stethoscope listening for sounds while moving...

Did it sound like the sound was coming from the Timing Chain Tensioner?

In the thumbnail below is a poor pic of one of the Timing chain Guides.
When I first got my Car that Guide was loose and made a rattling and tapping sound. Tightening the Bolt to the left of the Arrow cured the problem.

I cannot believe that no one has had their Valve Cover off and could have pulled on their chain for you. I think for some reason this thread is not attracting attention.
I think I would start another Thread and only post the Video where you pull on the Timing Chain and only one question; if what the see is normal Timing Chain looseness.
Attached Thumbnails
How does the 617.95x chain tensioner work?  (and R&R)-z-guide-b.jpg  
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  #12  
Old 09-22-2009, 11:43 PM
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Quote:
Originally Posted by Diesel911 View Post
Did it sound like the sound was coming from the Timing Chain Tensioner?

In the thumbnail below is a poor pic of one of the Timing chain Guides.
When I first got my Car that Guide was loose and made a rattling and tapping sound. Tightening the Bolt to the left of the Arrow cured the problem.

I cannot believe that no one has had their Valve Cover off and could have pulled on their chain for you. I think for some reason this thread is not attracting attention.
I think I would start another Thread and only post the Video where you pull on the Timing Chain and only one question; if what the see is normal Timing Chain looseness.
911,

the sound was not coming from the tensioner itself as far as I could tell. But, I was thinking, if the tensioner is malfunctioning it could cause sounds elsewhere from the chain hitting, or not mating with a sprocket as nicely etc.

good call on posting a new thread. I'll post a new one...this is sort of thread #3 for this issue. but different stuff keeps coming up.

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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  #13  
Old 09-23-2009, 01:18 PM
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hey diesel911,

Put it back together and ran it today- no change whatsoever in any of the engine noises with the new and correct spring.

I am totally at a loss as to what do next. Run it? Shotgun the chain tensioner?

I may take it to an MBZ shop to help me figure it out.

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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  #14  
Old 09-23-2009, 02:07 PM
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A good shop might be a good idea. Better than risking something bad happening to the motor.
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'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)
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  #15  
Old 09-23-2009, 02:50 PM
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OK, off to the shop it will go. Now to find a shop that has an old salty diesel mechanic.

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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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