Ok, so I guess this thing is the R56 version of H1N1 ... Literally a few days after reading a post on the "cold start rattle" I went out to start Ollie, who had been sitting for 3 days, and there was a distinct rattle coming from the passenger side of the engine compartment. It wasn't nearly as bad as the videos I've seen posted on the matter ... more of a "something's loose in the engine compartment and is vibrating" noise. I backed out of the garage and popped the bonnet, but by the time I got out and walked around to open it, the sound was gone. Because the sound went away after a few seconds, I really didn't think much of it. However, b/c of the post I read , I did wonder if it might be a problem. Specifically, there's an article from motoring file that stated: "Usually this rattle occurs during the first start of the day when the engine itself is “cold” and oil has drained into the sump. Appearing to originate along the left side of the head near the cam chain, the rattle is out of synch with the normal cadence of the engine and has a metal on metal tapping quality to it. It seems to decrease with higher RPMs and as the engine warms up to operating temperatures. For most the noise starts off as an infrequent occurrence and only a minor annoyance and many don’t feel the need to bring it to their dealer’s attention." So, fast forward our local club's DIY day on Saturday. I mentioned this problem to one of the MINI techs, and he suggested that I go talk to my SA, to see if one of the techs could "officially" check it out. As it was explained to me by the SA and Tech (someone feel free to jump in here if I'm wrong), the cam tensioner is hydraulic, and by leaving the car for extended periods, the tension that the chain puts on the tensioner slowly pushes the fluid out of the tensioner. Then, when you go to start the car (i.e - "cold start") there's no fluid in the tensioner and no tension on the cam chain. Thet's where the rattle comes from. Once the pressure builds up and the tensioner has fluid in it again, it puts tension back on the chain and the sound goes away ... as what happened in my case. The problem is, when this happens, the chain actually get stretched out a bit. Once this happens a few times, then the change is too stretched out to work properly, or fails altogether, which is when you get the horrible sounds that you hear in some of the videos. Well, Gabe the tech was great. He, along with some other techs, managed to find that the tensioner was bad and that my cam chain was out of spec. So .. I got a nice little Clubbie to use for the weekend, and, hopefully, Ollie's surgery will turn out well. So, if your car has a few squeaks and rattles (and remember, this engine by nature has a bit of a "tappity-tappity-tappity" sound due to the DI) please dont' freak out and flood your dealer with inquiries. However, if you start your car and hear something that you KNOW isn't copacetic, make sure to get it checked out early.
At some point the factory incorporated the fix in production. Does anyone know when this took place as to vin number or date?
Unfortunately there are many reports in other online forums of further occurrences and recurrences of the death rattle, both in MINIs that have had the latest iteration of the tensioner fix and in new '09s that rolled off the assembly line well after the date when the latest cam chain tensioner parts were integrated (sometime in March or April of '09). It is fairly clear that BMW-MINI has not yet nailed down the root cause of the problem and this third iteration of the cam chain tensioner fix is just a band-aid applied to one of the symptoms of the problem. The focus among independent experts in valve train engineering is on the design of the HLAs and the possibility that they don't remain fully fluid filled under certain ECU shut-down conditions along with the driveshaft coming to rest in a particular position. I don't claim to be an expert...just a voracious consumer of credible information on this topic.
There is an engineer on Metroplex Minis who has done the best root cause analysis I've read to date. It's not the tensioner that's the problem, he claims its the hydrolic lash adjusters. (anyway, this allows for impulse shock to propogate down the timing chain and that causes or contributes to the stretching of the chain.) All the BMW fixes to date don't address this issue, so I'm skeptical that any cure will really deal with it. To date, it seems that at best they've found a bunch of related issues and are fixing them one at a time. At worst they've been doing a bunch of band-aids on symptoms. Time will tell.... It's good that you got some help at the dealer. Lots who've experienced the problem just get the brush-off. Matt
From personal experience I'm not sure you'd ever actually hear bad lash adjusters on the MINI engine since them failing sounds a lot like the tapping sound from the DI system itself. This would make me think the rattle is still the chain, just the damage has already been done. Did the engineer say exactly what the problem was with the lash adjusters? I know older Mitsubishis the orifice was too small and they would clog, not allowing them to fully fill with oil and take up the excess lash. Or is the orifice too large and allowing too much oil to drain out, then not getting sufficient pressure with the MINIs smart oil pump system to refill them quickly enough? If this engineer's correct a revised lash adjuster and/or reprogramming to have the electric oil pump generate more pressure on cold starts would be pretty easy fixes for MINI to institute.
Too much range of motion so that when they aren't pressurized, the lever looses contact with the cam, and then when the lobe hits the lever you get a shock impulse throughout the valve train. This is what causes the damage. Go over to Metroplex and do some searching. I'm sure it's probably one of the longest threads over there! Matt
Actually, a guy on MM.org linked to an article from MotoringFile, which linked to the original valve-lash post, which was on the Michigan MINI site... COLD START NOISE
Thanks for finding the source.. it was one of those sites I don't frequent very much. But the info in it is good, that's for sure... Still, I wonder what's going to be next seeing as some of the cars with the "wunderfix" are having recurrence. Matt
I don't think I have experienced this yet..... But I think my car always sounds like a little diesel :lol:
If the guy at MM.org is having a problem with a cold start noise, it's not something his MINI dealer can help him with :ihih:
Sorry ... us members of Metroplex MINI sometimes shorten it to MM.org when we're talking about the site on the site... Anyway, I have Ollie back now. He's got a new timing chain and tensioner along with all of the associated goodies. He seems to be running fine and no worse for the wear ... so far.
So apparently MINI checks the chain to determine if the length is in specification when you have the dreaded "cold start noise". Assuming the chain is stretched beyond specification, you get the "full treatment" (if you are still under warranty, that is). From what I have read about this, a stretched chain can be the cause of the noise of the rocker arms slamming down on the cam lobes. Then once the chain tensioner fills up with oil, the slack is removed, and the noise subsides. One can only hope they are looking for any possible damage to the camshaft lobes, etc. Of course, this damage might not show up until later.
See what they are suggesting as a solution over in the UK! Timing Chain Tensioner (May 2009 on) - R56 at minigenuineparts.co.uk Mini Genuine Parts Mini Servicing Parts & Spares, BM11.31.7.597.895, This is the latest replacement timing chain tensioner fitted from May 2009 to get rid of the timing
If only there was something like this for the R56: For those who don't know, this is a setup that replaces the timing chain on a small-block Chevy with a pair of gears.
The first time my 07s had the rattle was 6/30/10 with 49,000 miles. The dealer replaced the timing chain tensioner and the noise went away. In the past month the noise had started to return with 63K. Took the car into the dealer and complained of a diesel noise on startup. Dealer said oil in car was slightly low and topped off the oil. The noise was still present. Dealer found noise was caused by the timing chain tensioner running low on oil. Dealer stated they updated the hydraulic tensioner since it was replaced the first time and replaced it free with no argument. I'm skeptical about this as the same replacement part number was listed as the first time. 11-31-7-597-895
I guess this is the closest we will get to that timing gear set......:confused5: [ame=http://www.youtube.com/watch?v=8LqTjIhf2rM]Mini Cooper Clock - YouTube[/ame]