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-   -   9 degrees of chain stretch (http://www.peachparts.com/shopforum/diesel-discussion/305365-9-degrees-chain-stretch.html)

cell 09-18-2011 03:16 PM

9 degrees of chain stretch
 
3 Attachment(s)
ouch.

http://imgur.com/Txfj1.jpg

http://imgur.com/edh2H.jpg

http://imgur.com/eTrMF.jpg

looks like 20.5 on the indicator, which for a '78 617.950 means 9 degrees of stretch. man, I should have checked this sooner.

this is on the engine which I pulled from a '78 300SD to put in my '67 chevy pickup. the odometer had stopped working on the 300SD at 278k miles, and I've been driving it for about 2 years now, so I'm guessing its over 300k by now.

charmalu 09-18-2011 09:06 PM

I remember that thread, I was following along and really liked your fabricating skills on that project.

Several weeks back I thinking about your swap and what happened to you. so It`s been running pretty good for you??

Yeah its about time for a chain replacement, you don`t want to break one.

Reminds me, I need to check the 240, sooooon.

Charlie

gatorblue92 09-18-2011 10:00 PM

That is on my list this coming winter for the 300D... the odo reads 345K and I have no idea if the chain has ever been changed :eek:

cell 09-19-2011 02:38 AM

this forum is such a gold mine. you guys rock!

I've done a lot of reading and I'll try to summarize it here for future chain replacers (and to improve google's pagerank score for the sources by linking to them).

first, check your chain stretch (actually, "wear-induced elongation") [1]

next, decide to either use an offset woodruff key, or replace the chain. your call. chain stretch past 6 degrees can cause smoke, idle misses, loss of performance, etc. [2]

replacing your chain? you'll likely want to replace more than just that. the safest thing to do is replace everything in this diagram [3], but that decision will likely be made based on your budget:

http://i.imgur.com/ZDfn8.jpg

parts:

the chain:

http://img.eautopartscatalog.com/liv...1608200IWI.JPG

don't buy the WIPPERMAN chain [4]. the IWIS chain is higher quality [5][6]. order here: [7].

you'll also need a link. order here: [8]

you'll need a tool to crimp/rivet the link into the new chain. either rent one of the nice tools from a board member [12], or try the harbor freight tool [13][14].

make sure you get the chain crimping right. don't let this happen to you [23].

chain tensioner ("a" in the diagram):

http://img.eautopartscatalog.com/liv...1614990FEB.JPG

I'm unsure if I need to replace the entire tensioner [9], or just its spring [10]. either way, you'll also need a gasket [11].

infrequent oil changes can possibly clog the tensioner's oil gallery with sludge. no oil pressure in the tensioner = no chain tension = broken guides [25].

my understanding is that's all you can do without removing the timing cover from the front of the engine (still searching for a write-up about that, I'll add a link when I find it).

if you are willing to remove the timing cover, you should replace all of the guides. if you don't and they fail, they can get eaten by the chain, which can cause it to jump a tooth, which is catastrophic [24].

tensioning rail ("85" in the diagram):

http://img.wpac.com/live/thumb/W01331628793SWA.JPG

sounds like the best one is made by SWAG [15]. order here: [16].

I'm unsure if I should replace its pivot pin. the link in the parts catalog seems to be broken [17].

slide rail ("89" in the diagram):

http://img.wpac.com/live/thumb/W01331640524SWA.JPG

order here: [18]. again, not sure if its necessary to replace its pin. its link in the catalog appears to be broken as well (part 186 052 14 74).

130mm and 120mm guide rails ("93" and "93a" in the diagram):

http://img.eautopartscatalog.com/liv...1641635SWA.JPG

http://img.eautopartscatalog.com/liv...1641639SWA.JPG

I'm unsure which is which, but if you're replacing both, its irrelevant. order here [19] and here [20].

again, I'm unsure about the pins for these, and couldn't find the pins in the catalog.

replacement procedure / advice / notes:

dieselgiant.com has a writeup [21]. from this and another forum post [28], I had the idea that you might use (a lot of) zip ties if you don't have the proper vice grips on hand.

remove the rail tensioner before rolling in the new chain [29]. you may also need a thermostat housing gasket?

you may have to remove the cam sprocket and the vacuum pump to replace all of the guides/rails [22] (however, that post was about a 240D).

how much would all of this cost if a shop did all of the work? at least $500 for just the chain and tensioner [26], and $900 (or possibly more) for all of the guides as well [27].

Stretch 09-19-2011 03:06 AM

Nice collection of data - well done.

Really nice conversion - great thread (the one in the sig).

cell 09-19-2011 11:05 AM

So it looks like the pins are a special-order item.

I'm interested in opinions -- is it typical to replace the pins along with the guides? Or are the pins typically durable enough to go beyond 300k miles?

Thanks for the kind words about the conversion, guys :)

jeffr0000 09-19-2011 12:44 PM

Should one expect to pull the motor to do all this?

Stretch 09-19-2011 01:45 PM

Quote:

Originally Posted by jeffr0000 (Post 2793679)
Should one expect to pull the motor to do all this?

Nope - not necessary but you'll probably have to remove the cooling fan shroud and possibly radiator to get enough working space.

Stretch 09-19-2011 01:46 PM

Quote:

Originally Posted by cell (Post 2793630)
So it looks like the pins are a special-order item.

I'm interested in opinions -- is it typical to replace the pins along with the guides? Or are the pins typically durable enough to go beyond 300k miles?

Thanks for the kind words about the conversion, guys :)

I would guess not. However when they are out is the best time to replace the pins with knackered threads - if you are unsure do a trial fit out of the car and see what you think.

tankowner 09-19-2011 01:52 PM

This is great, thank you. I will be measuring the chain stretch on my 240 soon. She coughs a little at start up and puffs a little white smoke. All the plugs are new, the fuel is fresh, compression is fair across the board and the fuel system appears to be secure. This leads me to think the chain is probably stretched out. As far as I know it is original, so I will probably replace along with some of the other hardware. This will be helpful.

cell 09-19-2011 02:19 PM

Quote:

Originally Posted by jeffr0000 (Post 2793679)
Should one expect to pull the motor to do all this?


For me it's easier to just remove the front bodywork.

http://67-72chevytrucks.com/vboard/showpost.php?p=4156276&postcount=3

Marvelicious 09-19-2011 02:25 PM

So are all these links going to be updated automatically for the new board address or are we on our own?

charmalu 09-19-2011 02:38 PM

Fastlane is going to dropped as far as to what I read in Pellican parts thread above. so they should be to keep from having dead links.

as it is, some things are not available on FL for some reason.

Cell really knows how to organize his projects and lay out things in an organized manner, there should be no fears.



Charlie

cell 09-19-2011 03:01 PM

Ah, bummer if we get links with the pelican switchover. I'll try to keep the links updated.

I also was just reminded by another thread that the oil pump also has a chain...

charmalu 09-19-2011 05:18 PM

The oil pump chain also has it`s own chain rail it rides on.

we had the lower pan off one time to check out some things, and noticed there was a crack on both sides where it fits onto the shaft. cracked the full length except for about 1/8 inch, and the opposite side cracked the same. wouldn`t have taken much more time for it to break off.

http://img.eautopartscatalog.com/liv...1638970OES.JPG

Charlie


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