OK

I am looking forward to a timing chain job.
Note that I am not "looking forward" with youthful exuberation, but accepting the fact that I will be oiling my hands up really thoroughly in the next 30 days.

Upon removing the valve cover I felt my face tighten into a grin as I could find no evidence of wear on the camshaft.

Upon glancing down the timing chain abyss, things are unsettling.

I do not know whether there would be slack in the chain when the engine is not running, but there is enough slack there now to shove the chain past the timing device it would seem.

The tensioner rail has shed some of it's rubber/themoplastic/rawhide? surface and crumb-ules have escaped into the oil filter and deposited themselves at random in the crankcase.

I am concerned about the tensioner because the top end has worn through the facing and it's chewing into the metal, about 5/8" on the very top end, and nearly through the metal at the end.

I am sure this arrangement is a little "out of spec".

Rumor was that this engine was rebuilt. I am glad I checked.

The tensioner- can this be "rejuvenated" by just replacing the spring, or will I have to replace the entire assembly?

I don't recognize the markings on the timing chain. Maybe some generic, "grocery store" buy.

I promise I will start taking pictures. This looks to be fun. Ahem.


snapped_bolt

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'81 240D For now, a good place to borrow new parts
'80 300TD Probably will be put back into service!
'79 240D BACK IN SERVICE SINCE 09/16; limited use, oil leak. Guide pin r/sealed/replaced. Still a leak. Front crank seal....

If someone who knows it would post a free W123 service manual site you could look up how to check the timing chain stretch and other details. Or you could look in the repair links in this forum.

The timing chain tensioner on your Engine has a Spring that could be replaced with a new one but most of the tension is applied by the Oil pressure working on the Piston that is inside of the timing chain tension. Meaning there is no adjustment.

The larger timing chain tensioner rail could also be worn.

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84 300D, 82 Volvo 244Gl Diesel

It reminds me of a poor front end alignment. There is a lot of wear just on the upper edge.


snapped_bolt

__________________
'81 240D For now, a good place to borrow new parts
'80 300TD Probably will be put back into service!
'79 240D BACK IN SERVICE SINCE 09/16; limited use, oil leak. Guide pin r/sealed/replaced. Still a leak. Front crank seal....

There is a simple crude test for chain stretch. Set the cam sprocket mark by rotating the engine in the operational direction with the crank bolt. The damper mark should line up. If it does not you can calculate the probable chain stretch. By the degrees it is from zero. Probably more than four degrees off means more accurate methods are indicated. Care must be taken to make sure a correctional offset key was not placed in the cam sprocket. Not that common though but possible.

No absolute milage is possible to determine as having excess wear. It depends on quality of the chain and the amount of regular oil changes. The timing chain premature wear is an indicator of those two items. This style of chain does not do all that well in really dirty oil that is well overdue between changes with a higher soot level.

I mentioned replacing the Tensioner Spring but I supposed if the Tensioner Piston or piston bore is worn it would not hold the oil pressure as well as if it was not worn.

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84 300D, 82 Volvo 244Gl Diesel

If that rail is wearing unevenly, it's probably not doing it's job. Out it comes.
I took a couple of pics, but I need to power up a computer that can read the card, I'll see if they are worth posting.
I replaced the valve cover gasket with a Victor Reinz when I put it back together. I bought these about 8 years ago- VICTOR REINZ GERMANY in large print. We'll see if there has been a change in the sealing quality. That 15NM torque comes awfully early on the wrench, it's near barely noticeable. I degreased the sealing area with a rag soaked with electrical parts cleaner.

I wonder why they didn't put a "knife edge" on the valve cover like on a watertight door?

Later

snapped_bolt

__________________
'81 240D For now, a good place to borrow new parts
'80 300TD Probably will be put back into service!
'79 240D BACK IN SERVICE SINCE 09/16; limited use, oil leak. Guide pin r/sealed/replaced. Still a leak. Front crank seal....