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rcf925

Timing Chain Tensioner ?

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Would a sticky chain tensioner ( Sticking and not pushing on guide) cause a knocking sound from upper timing chain cover area. This started yesterday so shut it off, I noticed when I put motor together I had to push tensioner over with some force to fit in slot of piston. I can't think of anything else that would cause a knock in that area, I've heard rods knock and this ain't that

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You should be able to see where the tensioner is by just taking the valve cover off.  I would suspect a valve adjuster has backed off over a tensioner failure. 

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Something I've noticed for a while now is the generic tensioner rails have been installing with the top tipping in too much towards the block/head, and the the tab isn't lining up with the piston. The problem is mostly that the holes where the pivot shaft goes through aren't exactly straight. Now, I mock up the rail on the block, dry install the front cover with the piston and verify that it detents. If it's off, I pull it off and put the tab in a vise and twist the rail a little, just enough that the tab slips in the piston channel without argument. Genuine BMW rails don't seem to have this problem though.

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Definitely check to see if that tab is still intact though, very possible you have a broken rail and it's slapping around between the chain and front cover.

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(edited)

It's not good news, I've checked tensioner, Polished piston, Made sure it's working freely and bled according to service manual, It's working correctly. Checked whole valve train and rocker clearances. Checked compression again, 150lbs on all 4 cylinders, My oil pressure is normal, If I spin motor over and don't start I don't hear a thing, As soon as I fire it up it's knocking and I think I have come to the realization it might be a rod. Today I'll drain oil and split open filter, I have about 50 miles on car, Been tuning and just normal driving. This is a complete motor rebuild with all quality components, I'll talk to my engine builder today, But I'm really not looking forward to tearing whole thing apart again

Edited by rcf925

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I got a weird knocking sound at low RPM's and discovered the pushrod for the fuel pump was sticking and was knocking against the cam.  Sounded a lot like a rod knock, was extremely relieved when I discovered I didn't need to tear the engine apart.

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28 minutes ago, FunkyLaneO said:

I got a weird knocking sound at low RPM's and discovered the pushrod for the fuel pump was sticking and was knocking against the cam.  Sounded a lot like a rod knock, was extremely relieved when I discovered I didn't need to tear the engine apart.

 

I have electric fuel pump, I wish it was that

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Well , I drained oil, put it through a filter, It's clean enough to drink, No glitter, No chunks, No nothing, Same with filter so now I'm not so sure whats going on, More investigating I guess

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4 hours ago, saaron said:

This Wikipedia post has a pic of a cut-away M10.  Maybe having a beer and gazing at the cutaway can help you figure it out.  

 

https://en.wikipedia.org/wiki/BMW_M10

 

Scott

 

Good Idea, I'm sure I'll figure it out sooner or later, Just frustrating, Cars been sitting 20 years and I just want to drive it

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Post a video or sound clip.  There are some very good ears on this forum.

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Do the basic 'unhook one plug wire at a time' check to see if it tracks a cylinder 

before you dive in.

 

t

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(edited)
3 hours ago, TobyB said:

Do the basic 'unhook one plug wire at a time' check to see if it tracks a cylinder 

before you dive in.

 

t

 

Just pulled valve cover again and from a visual standpoint everything looks normal, I may have to run and pull plugs one at a time. When I checked compression no plugs in it spins over quiet no knock until you fire it

Edited by rcf925

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