chain tensioner problem?

[Ziggy]

Recently I exchanged my 08 cam for a type 02. After installation, I couldn't get above 15 miles because of a loud rattling sound. It sounded like the timing chain, but before I exchanged the cam, I never had problems with it and it was only about 5 years old.
So I checked all the spots which the cam could hit, but everything was ok.
Took out the (front part of the) chain tensioner and put in one from another engine. After a couple of minutes of driving, the noise faded away. But I can still hear the chain between 20-30 miles and in turns.

Somewhere on this forum I read the new chain tensioner MB sells is of poor quality. So I rather fix an original one.
What could be the problem? I exchanged the spring, ball, piston and a small plastic cup. Could there be a problem with the chain tensioner housing?
How can I check this? The head was milled 2 times so I can't see the stretch on the timing marks. Also isn't the chain tensioner supposed to give pressure immediately, instead of after driving around for a minute?

[mbzse]

quote:Originally posted by Ziggy
.../... How can I check [the chain stretch] this? The head was milled 2 times so I can't see the stretch on the timing marks.

Chain stretch and cam timing in general can only be set using a dial indicator and measuring the valve
held open at specified lift. This lift is a nominal valve play of 0,4mm.
See section 00-9 in the M-B 1968 workshop manual (BBB) for this procedure

quote:Also isn't the chain tensioner supposed to give pressure immediately, instead of after driving around for a minute?

The tension is provided by the internal spring in the tensioner, which extends when the chain shows some slack behind cam sprocket
on our M127, M129 and M130 M-B engines. Then there is a "cushion" of oil inside
the tensioner which ensures it can only be compressed at slow pace.
Note: be sure to bleed the tensioner after installing it.
Most important, in order for it to function well  [:0].
Spend time doing this bleeding procedure! You find it in the BBB.
Ensure the oil pocket in the engine head is well filled during this work.
.
 

[Ziggy]

I see the spring can be ordered seperately. Would it make a difference to replace it with a new one?

[glennard]

Just to reinforce 'mbzse' advice to prime the tensioner with oil.  Make sure the reservoir is full of oil.  Pump the tensioner until it will not move- is full of oil.  Otherwise- bye, bye engine.

[Ziggy]

I put in the original tensioner again, filled the reservoir with oil and pumped.
No problems during warmup, but once the engine was hot I could still hear it rattling (although not very loud) when coasting at around 50km. Couldn't detect the noise at other speeds, not when accelerating fast, only when accelerating slowly at around that speed.

So the initial problem must be that I didn't pump the tensioner the first time.
But how do I test the tensioner now? How many hours is it supposed to stay hard, how many mm may it move when hard?

[glennard]

Ziggy, Once oil is in it, it doesn't move-not 1 mm.  How about the guides?

[Ziggy]

Ok, I checked it with a hot engine and the chain was slack. The tensioner had about 1 or 2 mm play and I could not pump it, the chain remained slack.
When the engine was cold yesterday this was not the case. Since the rattling also is only audible when the engine is hot, the chain tensioner housing must be leaking when the oil gets hotter/thinner. Does this sound right :?:

[glennard]

Stretched chain? Milled head?  Take out a chain link or get a new chain?

[Ziggy]

The head has been milled in the past. I don't think the chain can stretch just in 1 day. The only thing that I changed when this happened was the cam and the bearings.

I put in a complete chain tensioner from a well running spare engine which I put aside couple of years ago. It made no difference  :evil:  once the engine heats up the noise remains. It is almost a chopper like sound, but it is not the fan hitting the shroud.

[Ziggy]

I put in a new ball and cap and with warm engine, the tensioner remains firm.
The sound is fainter, but it is still there.
How much play is allowed in the chain between the right chain guide and the chain with the tensioner firm? It was almost 1 cm, which seems like a lot.
Still, I did not have this problem before I put in the new cam. The new bearings must be slightly lower or something.