SFDon has been talking me off the ledge on a few engine issues I am working on (thank you Don), one of which is my low idle chain noise. A few years ago I replaced my original tensioner rail with a new Febi one and that's when the noise began (goes away above 1000 rpm). Now that I have my car up on blocks for the 5 speed I am also doing the front engine cover work again. Don has said in the past that the new rails don't fit the piston well and I am documenting this to show that it may also not have enough travel to keep the chain taught. He kindly offered to alter one for me but upon removing the current one and comparing it to my original one (thankfully I kept it, for once my packratting paid off), there is a huge difference in fit and quality.
I can see evidence of the Febi tang hitting the cover wall, there is not enough clearance so the tensioner piston bottoms out the tang and causes noise. Now I know why, the original has between 7.25 and 8.5mm more width at the critical area nearest the wall. Therefore preventing chain slap etc. The original rail is also longer, better made, and has a different curvature. I am putting the original back in and trashing the Febi.
Comparing the dimensions and clearances:
Original on the right, Febi on the left, The original is heavier and solid, the Febi is light and flimsy:
Height difference - original on left:
Clearance difference - wider is original, picture the cover wall coming up in between the arch of the tang:
Hopefully this will show you what you will be up against if you have to replace this part, I think the Febi came from BMW but am not positive, if anyone has bought one of these from BMW please post a pic for comparison.
Bottom line, if you get the Febi or MTC version of this part, be prepared to grind out/bend the tang to increase clearance and alter it to fit the piston (this may weaken it however), even then it may not be enough. A few extra millimeters makes a big difference when tensioning chains and preventing slap/noise.
I just ordered one from BMW just to see what shows up. If it is the crappy version it's being returned.
I can see evidence of the Febi tang hitting the cover wall, there is not enough clearance so the tensioner piston bottoms out the tang and causes noise. Now I know why, the original has between 7.25 and 8.5mm more width at the critical area nearest the wall. Therefore preventing chain slap etc. The original rail is also longer, better made, and has a different curvature. I am putting the original back in and trashing the Febi.
Comparing the dimensions and clearances:
Original on the right, Febi on the left, The original is heavier and solid, the Febi is light and flimsy:
Height difference - original on left:
Clearance difference - wider is original, picture the cover wall coming up in between the arch of the tang:
Hopefully this will show you what you will be up against if you have to replace this part, I think the Febi came from BMW but am not positive, if anyone has bought one of these from BMW please post a pic for comparison.
Bottom line, if you get the Febi or MTC version of this part, be prepared to grind out/bend the tang to increase clearance and alter it to fit the piston (this may weaken it however), even then it may not be enough. A few extra millimeters makes a big difference when tensioning chains and preventing slap/noise.
I just ordered one from BMW just to see what shows up. If it is the crappy version it's being returned.
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