I've read quite a bit here about using a dial gauge to check chain stretch on an OM617 engine as per FSM. It all makes perfect sense in writing but I'm having a hell of a time trying to do it. I have the magnetic holder and a couple of good dial gauges, including a Mercedes factory part German one in mm instead of inches.

The problem is that you are supposed to measure valve opening by putting the dial gauge on the top of the valve keeper and turning engine by hand. The cam is in the way of setting the DG on spring. Unless you have a very long probe, (don't know what that's called), it's impossible to set it straight on the spring. I could set it at a pretty extreme angle but that would negate the accuracy of this method.

The only possible way that I came up with was to set the probe on the top of the tappet near the cam and measure the movement of it, hoping that it's 1:1 with valve stem. It seems like it would be because of the adjuster nut right below it that is directly connected to valve stem, but I don't know.

I tried to take some pictures to illustrate the problem and my solution. Anyone have experience with this?

EDIT: Can't get pictures to load, I'll try later.

I had a similar problem with my dial test indicator (DTI) which is a bit on the cheap side of good...

...like you say the probe is too short...

...to make a solution I found a bit of pipe and fitted it to the end of the DTI so it would reach the top of the valve spring. At a push something like a 1/4" socket extension might do - just make sure it is fitted securely so that it doesn't move. Ideally you need to find the stiffest lightest extension that will not damage the gauge.

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Thanks. My DTI came with two different rods that screw on but even the longer one is way too short. If I could have a longer one made with correct threads, that would do it.

You need to get a longer/extension pointer for your Dial Indicator so it can be positioned properly.

__________________
84 300D, 82 Volvo 244Gl Diesel

Does anyone sell such an accessory? What are others using for this?

I never check for stretch per-se, I just verify cam timing and set the IP and use an offset key of necessary.

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

How would you know which offset key to use if you don't have an accurate way to measure the chain stretch/cam timing?

There are a couple of methods I use.

When I was working at the dealership, I had a super-quick method that helped you stay alive working flat rate.

The quick method is accurate if you pay attention, but I have a background as a machinist, so this was easy for me.

I used a machinist's steel rule, set #1 intake to zero and open the valve 2mm and check the marks on the crank. Then it was easy to select a key that would give me what I wanted.

I used a Caterpillar timing adapter to set the pump timing while the enegin is running.

Alternatively, I have a very old Starett dial indicator. I sharpened the male threaded end of a .22 caliber gun cleaning rod so that if just wedges into the end of the stem on the indicator. I cut this to about 1.75" in length. I then drove a steel check ball into the open end of the rod to ride against the valve retainer.

I attach the indicator clamp to the oil tube and take my readings in this way, but the steel rule is faster and just as accurate...Robert

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

So basically just set a small ruler next to the valve spring and measure when it goes down 2mm? Sounds good in theory, as long as you can get right next to it and see well enough.

I'd love to see a picture of your DTI adaptor but I'm sure I can figure out something for mine. Thanks for the reply.

Here ya go...

Note how the 'C' clamp fits the oil spray bar perfectly....

Attached Thumbnails

   

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

Nice idea with the ruler actually - do you rest your chin on a particular place to make sure you are looking the right way each time Dr Bert? I bet you need good eye sight and good light.

As you suggest the measurement is pretty precise for the offset keys that are available. And to add something into the mix I reckon they're a bit off!

OM617 (non turbo) cam profile specs, piston height specs etc

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

Good point....I use a mirror so I can look at it dead-on.

I can usually set the timing with the rule before you can properly set up the dial indicator.

Again, I have done this a lot and got good at it at the dealer, so just take your time and you will be fine...

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

From your last comment I guess you are kind of saying - do it with a ruler and then check your ability with the DTI!

__________________
1992 W201 190E 1.8 171,000 km - Daily driver
1981 W123 300D ~ 100,000 miles / 160,000 km - project car stripped to the bone
1965 Land Rover Series 2a Station Wagon CIS recovery therapy!
1961 Volvo PV544 Bare metal rat rod-ish thing

I'm here to chat about cars and to help others - I'm not here "to always be right" like an internet warrior



Don't leave that there - I'll take it to bits!

That won't hurt, but if you do it with the rule, it will be 100% accurate.

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership

The Gunson #77089 Diesel Adaptor For Timing Lights is a great tool. No more cranking and pumping....Robert

http://www.gunson.co.uk/items/pdf/Products/77089_Instructions.pdf

__________________
Did you just pass my 740 at 200 kmh in a 300SD?????

1978 300SD 'Phil' - 1,315,853 Miles And Counting - 1, 317,885 as of 12/27/2012 - 1,333,000 as of 05/10/2013, 1,337,850 as of July 15, 2013, 1,339,000 as of August 13, 2013



100,000 miles since June 2005 Overhaul - Sold January 25th, 2014 After 1,344,246 Miles & 20 Years of Ownership