I burned a valve on my '02 Cooper S, with 225K miles in Feb of this year. I found a very low miles '06 head, disassembled it, lapped the valves and put everything back together with a new hydraulic chain tensioner. Just a few thousand miles in, the new tensioner stuck, and I got the rattle. I thought it might be jammed from crud from the head work, replaced it and everything was fine.....until now. Just a few more thousand miles, and it sounds like I need another one! Any thoughts on why this might happen? Oil pressure problem (light is out). Bad luck? Debris from the engine work? Poor quality after market part? TIA.

 

Did you replace the guides and chain when you did the head?

 

If you haven't replaced your harmonic balancer or belt tensioner those can also make that rattle sound.

 

I didn't replace the chain guides because they were in mint condition, even with over 200K miles. Since the replacement tensioner fixed it the first time, and it was quiet after the head replacement, I doubt the guides are an issue. I'll go in with my stethoscope and verify it's not the balancer or belt tensioner. Thanks guys.

 

Removed the hydraulic chain tensioner (HCT) and it was stuck in the retracted position. I can't get it to release. I installed a new one that is genuine Mini and all is well. The last two HCTs are by Febi, I believe, so here's to hoping the genuine Mini HCT will last. If this thread goes inactive for a long time, it means the Mini part lasted!

 

Febi huh, I thought they were supposed to be good? I have one ready to install I gather i should return it.

 

After another few thousand miles, the rattle is back. Which probably means the tensioner is stuck yet again. This is driving me crazy. What is going on here?

 

Finally figured this thing out, and I really dodged a bullet. I replaced the hydraulic chain tensioner (HCT) a fourth time (yes, I'm stubborn). The car was quiet for about two days, and then it started rattling. I was late and decided to go ahead with my commute anyway. Mistake. 20 minutes down the road I got off the gas to brake and a heard a chain related "zing", engine quit, SES light on and I parked it. Towed home, suspected cam chain issues and removed valve cover. Chain was there, but loose. Fault codes were misfires and cam position sensor related. Pulled plugs and loosened cam bolts to close all valves. Pressurized cylinders and confirmed no bent valves. Pulled aluminum chain cover and found the cam sprocket had jumped three teeth and the chain cover keeper ridge was broken, like the Mini pictures you'll see when chains jump off sprockets. Very lucky I didn't bend valves. It appears the problem was the high mileage and 16 year old plastic chain rail on the front side of the engine (not the HCT side) had come apart. The two part, hard plastic, rail had lost the piece that the chain slides over. And I mean lost! It had disintegrated into scores of pieces and was all over the sump and in the pickup screen of the oil pump. I believe the loose chain allowed the HCT to over extend and maybe get slammed back causing it to seize in the retracted position. I spent about $1000 getting a new chain cover, chain kit, sprockets, harmonic crank pulley, motor mounts, etc. The chain cover includes the crank driven oil pump and all seals, which is nice. I cleaned and cleaned and blew air through all the oil passages I could. A smooth reassembly and it now purrs like a kitten. Lesson learned was replace those chain rails if you have your valve cover or head off!