Hi, everyone! My dad bought me a 2008 Mini Cooper S as a graduation gift. Everything ran fine at first, but recently I noticed a strange noise when starting the vehicle. It sounded like a bucket of bolts on a cold start. Initally, I just assumed that the noise was from the engine needing to warm up or from the new serpentine belt we replaced having oil on it or something. However, the startup noise got progressively worse, and I also noticed that the RPMs were all over the place when idle (the last time I cranked it they dropped so low the engine nearly cut off). After some googling, I found out that R56 has a tensioner issue and that's likely the source of the issue. Sure enough, I pulled out the tensioner and it came out in pieces.

How does this even happen?

I got lucky removing it as the head came out with the spring and I didn't have to go fishing for it, but what would cause the tensioner to come apart like this? Am I looking at serious possible engine damage? For more information, I have already installed a new tensioner; however, it is the old revision (78mm) which only made the noise worse as now not only does it make the bucket of bolts noise, but also you can hear the chain rattling - almost like a diesel engine (Previously, I never actually heard the chain rattling about). I stopped running the car immediately when I heard the chain slapping around, so hopefully no additional damage was caused. Any help/advice is appreciated.

EDIT: I've already purchased the new OEM 82mm tensioner PN: 11-31-7-607-551. Also, I understand that I probably should install a new timing chain kit, but due to the fact that I would need my dad's help and he lives out of state and money issued right now, I can't do the whole kit just yet and am hoping the new tensioner will be a bandaid for about a month until I can replace the whole thing.

 

I took a timelapse of me removing the old tensioner and installing the new one. It gave me some nice pictures to describe the problem, so I'm glad I ended up deciding to record it.

Pulling the old tensioner out of it's little hidey hole.

The spring just relaxing in place

Thankfully it and the head came out together

 

From your description, you have the dreaded "death rattle" --- stretched timing chain. If this is the problem, driving it will soon cause chain breakage and then valve-to-piston contact resulting in bent valves. Sometimes fixed with the latest tensioner but usually not. Unfortunately, to measure the stretch, you need a special tool that's part of the timing chain replacement tool kit. Then to replace the chain, it's best to find someone with experience to walk you thru the process. Youtube has videos showing it done, but there's lots of them and most are not complete or hard to understand. Bentley manual has a good illustrated procedure.

Often, when the chain makes noise, it's because the top chain guide is broken. This can be easily checked by removing the valve cover and looking at the guide. Compare it to the pic in RealOEM or other threads in NAM. If it's broken, do NOT start the engine again until a kit has been installed AND broken pieces removed from the oil pump screen and pan. If not broken, I still wouldn't put it back together unless there was plenty of tensioner engagement.

If you're gonna own a gen 2 mini, plan on lotsa DIY repairs. First buy should be a Bentley manual, great car descriptions and repair procedures for everything except engine block internals. Then budget for all the metric tools, including a full set of male and female torx wrenches, and good torque wrenches. Then bookmark the website links for RealOEM --- https://www.realoem.com/bmw/enUS/select an illustrated parts list for the entire car, and a BMW Repair Guide --- https://www.bmwrepairguide.com/category/mini-r56/ another set of repair procedures written mostly for the N12 (no turbo) but mostly applicable to N14 too. Any time you order parts from a non-dealer, be sure to order by part number from the applicable RealOEM chart.

Here's a pic showing how to use the special tool for chain measurement. Maybe you can find someone that will loan you theirs until you find the $$$ to start the process --- a local Mini club or a friendly Mini repair tech. Welcome to our world and hang on tight ---




Ignore the tensioner BMW part number. This is an old document and the part number has probably been replaced with a later one. I've seen at least three different versions described in various threads.

 

Thank you so much! So if my chain is the correct length (unlikely, but if) and assuming only the top guide is broken, would it be possible to replace just the top guide rail without needing a whole new kit and without performing the full disassembly required to install a new kit? Also, do you have any idea what would cause my tensioner to break like that? Thanks again!

 

Real OEM shows a separate PN for the top guide, so it should be available separately, just not recommended, by anybody. However, there will still be all the pieces floating around the oil pan and in the oil pump screen, blocking flow. That will need to be cleaned out. Original OEM tensioner was a bad design and was replaced by new versions at least twice, so cause of failure, IMHO, is design failure. If you decide to inspect the top guide, take a close look at the other two guides (at least the part you can see) and compare to the various pics available. Chances are they're also shot. Also pay close attention to the top guide torque specs. People have been known to over-torque the two bolts due to confusing diagrams.

 

You're a godsend! I went ahead and ordered the kit that has the tool to measure the chain and I'm planning on removing the valve cover later today. Also just for clarification (I'm not sure if it was in the post), the tensioner I removed was the updated part and there wasn't any actual chain rattle besides about the first two seconds after cranking until I replaced it with the older model tensioner. I didn't run the engine anymore than 10 seconds - that's being generous - as I shut it off the second I heard the chain rattling so I have my figures crossed that the guides aren't damaged and that a new tensioner (the new revision) will fix it. I'm taking your advice to heart and not cranking it until I check for damage and measure the chain length though. Also I read that BMW updated their service manual and state that the chain can be 72mm in length before being replaced. If my chain is 72mm or under and there's no perceivable damage to the guide rails, do you believe that I can hold off on installing a new kit for just a little while? (≈1000 miles). I apologize for asking so many questions, sir, and thank you again for everything!

 

I wasn't able to verify the spec change from 68mm to 72mm. If you trust your source then go for it. As long as there's no obvious "death rattle", 1000 more miles shouldn't be a problem, but you should check the 72mm measurement often. A broken chain or mis-timed engine causes catastrophic engine damage. Spend your spare time during this 1000 mile run reading some of the chain replacement procedures I sent, you'll appreciate the familiarity when you get started with the actual work. And to be safe, use the longest tensioner available to you.

 

I pulled the valve cover off and there are indeed broken parts on the bottom and top guide rails. Sadly, it's gonna be out of commission for a while. Thank you for everything, and to anyone who's worried about this, it only takes about 10 minutes, an 8mm and a 10mm socket, a flat head (optional but extremely helpful), a ratchet (obviously), and love and care to take the valve cover off. I highly recommend it, youll be better off in the long run. Also make sure when you buy the tensioner you get the 82mm variant. It's more expensive than the 78mm but lasts longer. Sure it costs more money but it won't have to be replaced as often. Hopefully this thread will be of help as I didn't find anything close enough to my scenario and had to piece together information which ended up being correct.

 

Now that you know the guides are shot, you can spend time doing the disassembly and identifying all the tools needed. Just be sure to not manually rotate the engine without the chain being fully engaged and never rotate it CCW (as viewed from the chain end). Follow the cam positioning directions BEFORE starting teardown. This will eliminate valve / piston contact when installing locking tools. Again, familiarize yourself with the procedures, and you'll be OK.

Best of luck ---