Hello everyone,

We are the second owners of this '04 Mini Cooper S JCW package. I've noticed lately that the car is missing boost. It used to boost to ~10psi nearly instantly, which I understand is normal for this car. Lately it only boosts to 5psi until the RPM gets very high, then the boost jumps up. I've read on this site that a worn/bad bypass valve can cause this. I replaced the bypass valve with a new one from the dealer. Didn't seem to make a difference. I've also read that a separated crank pulley / harmonic balancer can also cause issues with boost. As far as I can tell, the crank pulley is in one piece. I don't understand what actually goes bad here and what the symptoms are of a bad crank pulley.

I have 3 videos that I recorded. First is from a stop to WOT. Second is ~60mph downshift to 4th and WOT. Third is HWY Speeds, 6th gear WOT and then down to 5th WOT.

Any help would be awesome! I'd really like to get this fixed because it really kills a good deal of the fun that this car is to drive.

Thanks in advance !


1st Video
https://youtu.be/7NvQc98YsCU

2nd Video
https://youtu.be/kpZYhYX2Vfo

3rd Video
https://youtu.be/FpyB64S0eV0

 

When my crank pulley went on the track car it was the opposite, it would make boost up till about 3500 rpm then it would drop off a cliff and throw codes, fall on it's face yada yada that's when the destroyed pulley guts could no longer hold and it would free spin

the pulley was still in tact and looked fine from the outside but it the inside rubber was destroyed

I limped to within my AAA towing range with a track trailer behind it lol

 

Oh man.... Did you put a stock crank pulley on, or get one of these performance ones?

so does that mean my car isn't doing the "bad pulley thing" ??

 

I put an ATI damper on, I would not rule out a bad damper, see if it's dusting metal shavings, if they slip they do that they also make some noise.

even on the lift mine looked good, felt good, I tapped it with a crow bar and it knocked it loose and then I could move it freely with my hand.

 

So here is a video that I just made of me using a pry bar on the crank pulley. It appears that the rubber isolator is intact and separated anywhere. The outer pulley ring obviously flexes on the rubber isolator, which I think should be normal. The rubber moves and flexes with it without any noticable separation unless I'm looking at this incorrectly.
I already threw a hundred dollar bypass valve at it and I don't want to throw a pulley at it by guessing it's the problem.

What actually happens? Does the outer ring walk on the isolator? I put a couple of paint marks on the metal and rubber to see if anything moves or shifts.

 

It looks like its starting to separate at the 6 to 9 o'clock position. I too have an ATI damper in the car. Interested in your findings and I now need one of those boost gauges for our 03' JCW looks like it works well.

 

lotta separation showing, but it does not look like it's bad

 

I have no direct experience with failed crank pulley. However I will give my 2 pence. If you still have the stock pulley and high mileage, the rubber on pulley can be rotted on the back side, and you cannot see it unless you remove it. That can cause the pulley to bounce around. The belt tensioner cannot keep up with this bouncing around and leads to belt slip when the belt is called upon to do the heavy lifting. Belt slip and boost drop. It takes immense static friction to keep the belt on the tiny SC pulley.

If the crank pulley is not the cause, the next suspect is belt tensioner. The last suspect is belt.

 

Just going to chime in here, helpful info being presented but throwing in some of my own.

OP did not mention experiencing "fluctuating boost" as one would expect from failing crank pulley separating, grabbing and separating again. And absent any other engine running issues / codes I would rule against crank pulley.

However, looking at that video of the damper, your belt above right to damper, it seems to have chunks missing from the ribs ?

Check the hydraulic belt tensioner, the center metal strip through the spring have a series of holes in it. There should be at least one hole showing out through the top. If not, the belt may the issue. Special tool is needed to replace the belt to retract the belt tensioner. Should be some threads on that here. While there, inspect the hydraulic tensioner as well to be sure that is functioning putting pressure on the belt.

 

-=gRaY rAvEn=- ,

Wow... I went back and watched that again. I don't know how I missed that. I will go back and look at the rest of the belt. I didn't look at that tensioner in a lot of detail. I know there is bright metal strip sticking out of the top, but I will look at that a little closer in the light today. Thanks for pointing that out.

 

^^ Nice catch, GR knows his R53's

 

So two things. I looked at that belt a little closer. It seems to be in fine condition. Its been replaced. It's a Contitech, and I can't find any other signs of chunks missing or anything. I also took a picture of the tensioner. I don't know if this is correct. There doesn't seem to be any slop or flop in the belt anywhere while running.

 

Looking at your pic I too think there is a chunk out of the belt on the idler but can't say for 100%, but if it is I would replace.

Also seeing how much that crank pulley moves I would for sure go ahead and replace it, even if it isn't the problem it's going to be.
And since you have a JCW you can go with our 2% larger to get a little more boost out of it
https://www.waymotorworks.com/super-...ulley-r53.html

And a new belt
https://www.waymotorworks.com/jcw-su...rger-belt.html

 

It would be too easy if you can see slop or flop in the belt while running. Why? Because with the engine and SC not under heavy load, everything will look kosher. You cannot see when the crank damper/pulley, the belt, the belt tensioner, and the SC pulley working really hard that is when the problem can be observed. This can only be done on a dyno, or you rig a camera up to record it while driving.

 

I need to put it on the hoist so I can actually see things. As far as the pulley goes, I want to figure out what is actually going on with the car first. I don't want to simply throw a bunch of parts at it. I want to know what the issue is first and address it, then I'll replace parts that are going to go bad.

Thanks.

 

I figured as much. Unless something is really bad, it would be hard to notice issues under load. I'm just looking at it like this. Tensioner $100. Belt $20. Crank pulley $75 - $400 depending on which way you go. I don't want to spend hundreds of dollars guessing only to find out that something else is the problem. I could spend $500 just to find out that the SC is bad or something like that. I'm somewhat stuck at the moment. Do I throw a tensioner and belt on it? Do I trust the tensioner and throw a pulley at it? I'm just rolling the dice with money. I don't know what is next. I was hoping that this would be either a common issue which 99% of the time is replace X. Or at a minimum, something being obviously visually wrong. It seems as if this particular issue is not a normal problem.

Is it possible that I'm leaking boost somewhere? I'm just not familiar with these cars. I've tried to read up on everything I can find, and I'm just not getting a whole lot of help.

 

I would put a belt on unless you have within the last 20k miles you need one anyway. Watch out a lot of web vendors have the wrong part numbers for the pulley sizes

personally I would not touch the tensioner unless the shock is unable to dampen at all, ie dry. Mine all leak right away but they still dampen a little bit

 

Have you done a pressure test? After my mod tune had to do a bunch of debugging to figure out an issue. When I did a pressure test I found allot of leakage around the by-pass valve. I ended up removing the euro clamps and putting on some good old american worm drive clamps.

 

By chance you are not using a foam type cover on the air filter are you?

 

And last, that pulley has seen much better days.

 

To drive home my point about very likely your crank damper is rotten in the back side, here is one video.

I differ from above commenter that you should replace the belt if over 20k. If you don't track your car the belt will last very long, and the belt is very easy to inspect. The tensioner is a bit more difficult because of the damper on it.


When I first saw your video with the pry bar, I wanted to comment that the movement is excessive. However I had no way of telling how stout a bar you use, and how hard you pry on it. Way have done trillions of this dampers and his opinion I will trust.

 

Hindsight is 20/20. I know you are gunshy to buy a bunch of parts after misdiagnosed the BPV. BPV has been the most common misdiagnosed part. It has little to fail for a thing with a spring and a butterfly valve, and yet people tend to replace it on first sign of trouble.

 

that's a facelift pulley, the eaerly mini pulley the rubber is visible on the front so when they fail you can see it from the front

 

I am pretty sure new or old style dampers both have massive amount of rubber on the inside/backside, and fail in near identical fashion. Do a google image search.

 

the new style has a metal front so you cant see the rubber at all