Becoming more noticeable now that the temps have dropped in the morning. Only on cold startup first thing in the morning, I get somewhere around 1-2 minutes of a rattle or clatter from the motor. Once it runs for a couple minutes (idle for a minute then ease out into the street and towards the edge of the development), it quiets down completely and makes no other noise.

I haven't found the source, and obviously my first thoughts go to cam chain tensioner or guides, but it is weird that it completely quiets down like a switch was thrown after a couple minutes.

Vacuum pump running harder the first couple minutes to draw down the holding tank, maybe?

Appreciate any suggestions. 08 MCS 6 speed, 62k miles, all stock OEM hardware.

Thanks, Iz

 

Pretty common problem on the mini unfortunately. On start up while the oil is thick and cold the tensioner isn't very effective. Therefore if the timing chain is worn it will flop about and rattle until such time as the oil warms up and thins and the tensioner starts to do its job. You probably need a new tensioner and maybe a new chain and guides as well. Best to get your chain measured to see how worn it is and go from there.

 

Thanks, just what I was afraid of.

 

[EDIT] Just noticed your is an 08... So this does not apply. But it might help others.


============== RATTLE AT STARTUP
SI M18 01 10 December 2010 Exhaust Systems Technical Service

page1image1592

SUBJECT

N18 – Cold Start Exhaust Rattle Noise

MODEL

R55 Cooper Clubman S, R56/R57 Cooper S and R60 Cooper Countryman S with N18 engine

SITUATION

The customer complains about a rattle noise coming from the exhaust/turbocharger area during a cold start. The noise lasts for approximately 20-30 seconds after the engine starts and is audible outside the vehicle.

INFORMATION

In order to meet stricter (ULEV2) emissions criteria, the N18 engine turbo wastegate activation strategy has been revised in comparison to Cooper S vehicles equipped with the N14 engine.

In higher ambient temperatures (between 64° and 86° F), the turbocharger wastegate stays fully open during a catalyst warm-up. This condition produces a rattle type of “acoustic feedback” and is created by the rotating wastegate valve face. Valve rotation is required for proper valve seating.

This type of rattle noise is considered a normal operation/characteristic of the N18 turbocharger wastegate system.

No diagnostic or repair attempts should be conducted for such a condition.

 

N14 here, I'm guessing more along the timing chain or related.

 

Sounds like the beginning throws of timing cassette replacement.

You could try replacing just the tensioner, but it is a band-aide for a short period, if at all with some.

We have been cryo treating all of our chain kits for over 2 years now and the results are showing positive. We've got multiple cars with over 50k on replacements with no problems.

DT Timing Cassette

 

Weirdest thing. This morning, coldest morning yet (about 29*), and it was quiet as a sewing machine from cold start on -- sat there and idled perfectly quiet as I scraped the frost off the windows.

Is the tensioner just a simple spring-loaded plunger? Could it be, or would it hurt to, remove it, clean it good with something like carb cleaner or parts cleaner bin, oil it, and reinstall?

 

I should send you pics of a head I pulled this weekend, every exhaust valve bent to hell! That will motivate you..

 

It has definitely motivated me; or probably stated more accurately, demotivated me to the Mini altogether. It is a blast to play with, but of all the issues I have dealt with in the 7 months I have owned it, I'm not so sure I even want to hang on to it any longer.

 

do you know if the timing chain was already replaced?

if you can take the valve cover off and take a look at the chain and rails.

the kit cost about a 120 or less for the chain, tensioner, and the three rails. It might be a good idea to replaced it before it is too late.

 

I have no record of the chain being replaced. Picked up the car with 58k on the clock and the previous owner (who passed away, purchased from his widow) had kept pretty good records of the service work. I would bet that it is original.

As much as I love the Mini, this may be the last straw as I am a high-mileage driver and, while I do nearly all of my own repairs, this thing has been a constant source of repairs since joining the family.

 

Lol...welcome to the club...we all pretty much had to go through a major repair. I never thought in a million years that i would buy an engine hoist. But guess what, i got one and the whole nine yards to do am engine rebuilt in a weekend, kinda!

 

Yep, been through trans seals, axle shaft, turbo, a few sensors, cleaning intake valves, and a few other issues in the whopping 4k miles I have driven it. I enjoy doing the work myself, but this has been just a bit over the top.

Helps having a lift in the garage -- couldn't imagine having to do all this stuff on the ground.