dsmyth

I just removed my timing chain cover to replace the gasket and noticed considerable play in the chain on the left bank lower level. The first picture shows the right bank with chain under tension by the ramps. Top and bottom.The second picture shows considerable play in the chain with my finger easily lifting it at the bottom. The lower ramp seems close to the casing.The top is under tension. Is this normal? I have not noticed any chain noise.Thanks in advance for any input.

Mike J

Second picture??

The tensioners are spring loaded and should keep some tension ; the oil pressure does two things - it adds to the pressure a bit, and provides a damping function.

Normally, the chains are reasonably tight, and should not be loose, so it sounds like a collapsed tensioner.

Cheers,

Mike

dsmyth

Thanks Mike. In picture #2 I can see the tensioner above doing its job holding the top chain tight but what is supposed to be holding up the bottom ramp? If one tensioner works both why would the top be tight?
I could find only one reference to replacing the tensioner and it sounded like an easy task. The vehicle has 70k on it. Is it as easy as it looks? thanks Doug

Mike J

In picture #2, the bottom ramp is fixed. The top ramp pivots on one end (the end in the case) and the other end is supported via the tensioner.

The tensioner is basically bolt in/out, with a gasket. You can remove it pretty easy and see if its binding and not pushing the tensioner up.

Take a look at my site, and check this out to see a home made tensioner:

http://www.pcarworkshop.com/index.ph...308_-_0022.JPG

This would test if the ramps can be moved (not binding), and if the tensioner is truely no pushing.

Is there much slop in the chain? It should not have much at that mileage.

Interesting that the position of the ramp looks to be about the same on my picture and yours.....that is a bit weird. I think you need to play with hit a bit. You can take the ramp out as well, look on my engine rebuilding pictures, you can see it there.

Cheers,

Mike

dsmyth

If there is more pressure on the top rail from the tensioner will that tighten the lower chain? I ask that because it appears that in the first phote it seems that there is more of the tensioner rail pushing on the chain, hence more pressure?

Mike J

The idea of the tensioner is put put pressure on a ramp in order to keep the chain relatively tight. If the chain gets slack, it can cause the timing to change on the camshafts, and in the extreme case the chain can skip on the sprockets - and that can cause bent valves, etc.

In the second picture, the top rail should be pressing down on the chain, taking all the slack off the chain. If it does that in your picture, the camshaft will move relative to the crankshaft by a few degrees - thus changing the timing.

is the chain slack, or you have to actively pull it up to get that slack? And how about the other side, is it the same?

dsmyth

Thanks again Mike. In the first picture the top and bottom are tight. In the second the top is tight where the tensiner is . That tensioner seems like its working properly. Its only the bottom that is loose. You can almost put your finger under it.
If that chain is stretched the top tensioner will take the slack out of the top but leave the bottom loose. Would that be a possible diagnosis? If thats correct do you have to take everything apart to replace a chain? Doug

dsmyth

Mike that movement in the second picture is with no effort. If it was like that in the first picture the chain would be hanging down on its own. Someone on the 964 board suggested it was normal without the engine runnung. Just don't want to risk it.