Replaced chain tensioner yesterday - dirty oil in the "well"

[7502]

My engine has started to occasionally exhibit random clattering noise when cold, not valve noise as best I can determine, so I decided to open 'er up and replace the chain tensioner and spring. I found the oil in the "well" was surprisingly thick, dirty and black. As far as I can tell the oil in the "well" must be supplied from the top of the cylinder head and then run down the forward most drain path, eventually filling the little reservoir that feeds the tensioner/spring assembly. Do I have that correct and is this oil typically filthy, or should it cycle sufficiently to remain as clean as the overall engine oil.  And yes I do religiously change my oil and filter.

 

One more thing that's always puzzled me. What's up with the single-row chain on my engine? Why would somebody go to the trouble of replacing the duplex chain with a single chain?  PO mentioned the engine was some kind of factory replacement engine made in 1980 but I'm not sure. Maybe the single chain is just a newer evolution?

 

 

[AustrianVespaGuy]

Not sure about the oil, how've I can confirm that the single row timing chain is both newer (factory design on e21s I believe) and a common 'upgrade' on 2002s. I went to a single row when rebuilding my engine, mostly because the chain and single row sprockets are cheaper than the double row versions. Other minor benefits from less mass,  less fiction, etc. I'm sure the double row still lasts 'longer,' but my feeling is that's a 1,000,000 vs. 500,000 mile order of magnitude type deal, and I'm fine with that compromise. 

[jimk]

The oil pocked for the tensioner never gets "flushed" with any new oil from an oil change.  It's like a low spot in a gutter, fresh water may flow past it but dirt lays in the bottom of the low spot.  No worry, this design runs with muck in the pocket.  Good oil (not just fresh oil) = less muck

Also the spring doesn't have much to do with holding tension on the shoe.  There is a small steel ball in the end of the tensioner follower that the spring pushes against.  The oil in the tension can't get out because of the ball and the tensioner holds the shoe by hydraulic lock. Spring just keeps the slop out of things until the hydraulics take over.

[PaulTWinterton]

My engine clatter came from my oil pump chain.  While you are in there it may be a good time to change it as well.  They sell a version with a removable link so you can install it without removing the oil pump sprocket.

[7502]

Thanks guys, I learn something new from each little job. 

 

1 hour ago, PaulTWinterton said:

My engine clatter came from my oil pump chain.  While you are in there it may be a good time to change it as well.  They sell a version with a removable link so you can install it without removing the oil pump sprocket.

 

I'll monitor for the clatter going forward, didn't notice the noise much at all since replacing the tensioner but it's probably too early to tell.  The sound generally seems to be coming from the very front of the engine. I picked up an el-cheapo mechanics stethoscope from Harbor Freight the other day, if the sound comes back I'll be sure to listen into the oil pump chain locale. 

['76mintgrün'02]

Mine has clattered a little at idle for as long as I have owned it (6 years).

It is somewhat intermittent.

I have decided I don't mind it.

I do appreciate learning from your attempt to fix yours.

Thanks for sharing.  Nice photo too.

[Henning]

No duplex - no M10.

 

hen

 

[TobyB]

Quote

 the single chain is just a newer evolution

 

That's it right there.  Coincided with the destroking to 1.8l in 1980.

 

Jim called the tensioner- you can always drain it when you change the oil,

if it bothers you, but generally they're pretty close to foolproof until the whole

chain system wears too far for the tensioner to take up slack...

 

t

 

[jgerock]

8 hours ago, TobyB said:

 

That's it right there.  Coincided with the destroking to 1.8l in 1980.

 

Jim called the tensioner- you can always drain it when you change the oil,

if it bothers you, but generally they're pretty close to foolproof until the whole

chain system wears too far for the tensioner to take up slack...

 

t

 

...and then the chain starts hitting the cover.