Hi -

I have a skipped timing chain and would like some advice about whether I have timing chain cover damage and should take the cover off.

I have a 2004 Cooper S that has had a sticky timing chain tensioner plunger. I have been meaning to replace it but hadn't done it yet, because usually it pops out when I start driving the car.

It seems things got worse and it didn't pop out when I last drove the car - I had it at fairly high RPM when the check engine light started flashing and the car went into limp mode (wouldn't let me go faster than about 35mph). I could drive the car normally again after turning it off and back on again, but I had about 25% less power and it felt like the engine was fighting itself.

So after reading the OBD codes and thinking about it, I concluded that the chain must have skipped a tooth or two.
I took the valve cover off and set the engine as close as I could to top dead center, and found the camshaft sprocket was off by about 45 degrees! (Looks like the camshaft was retarded by this amount. No valve train damage though - the car was still drivable until I parked it and took it apart.)

I tried realigning everything, but when I manually turned the sprocket with a wrench, it slipped teeth again on the crank sprocket. I have done this before and it never skipped a tooth before. This has me worried that the lip on the oil pump/timing chain cover, that is supposed to prevent this, might be damaged.

I can't see well enough into the timing chain cavity to tell whether the lip is damaged or not, but the chain and both sprockets look ok, although there was a bit of metal shavings stuck to the magnet on the cam position sensor, which I would expect due to the chain slop and skipping.

Has anyone seen or experienced this before? Should I remove the timing chain cover? What steps involved to do this? Do I need to remove the bumper/crash tubes?

Thanks for any help,

 

You should dig in and check or replace anything that needs replacing. It sounds like you milked the cheap fix as far as you can. There are steps in the bentley manual.

I think you take off the harmonic balancer, so the tutorial on that will help. My manual is at the garage. You can line everything up, get that tensioner, check the guides, replace the balancer. There is plenty to do on an 04 in that area.

https://www.northamericanmotoring.co...oem-tools.html

 

Thanks, I thought so. I have already replaced my pulley with an ATI pulley. Hopefully I can find the various parts to make a pulley remover tool again.

Has anyone ever pulled the timing chain cover? Any suggestions or tips of what not to do? I just had the car in pieces last week for LSD install (awesome on the track!) and not looking forward to taking it all apart again.

 

I took the front timing chain cover off and found this damage. Looks like I'll need to remove the oil pan to clean up the mess.

When the camshaft sprocket is set to the correct removal position, what position should the crankshaft be at? I have the crank pulley removed. I can see two arrows but I don't know which way they should be lined up.

I know that when the cam pulley is correctly lined up, all of the pistons should be in a row at the same heights....

 

I took off the timing chain cover and found some damage to the chain guide at the bottom of the oil pump cover. The part came off as a single piece. No big deal, $37 at Pelicanparts.com

However, I also found a bunch of black plastic bits in the oil sump, even though I see no damage to either of the timing chain guides. Does anyone know if there is any other part of the engine that would produce this kind of 'shrapnel'? Other than the piece that broke off the oil pump cover, I can't see any damage at all, even using a mirror to look inside the crankcase.

I am suspecting that this might be leftover from a previous incident before I bought the car??

 

There are two guides, one for each side, not much else.

http://www.realoem.com/bmw/showparts...95&hg=11&fg=25

 

Thought so... both guides are in good shape. Now I am wondering what other skeletons this engine has in its closet. The car had a clean Carfax report, but then again, none of the crazy stuff I have done to the car is ever going to show up in a Carfax report...

 

I got a new oil pump cover and put the car back together. It starts and idles fine but the oil light is on. I took off the oil filter and it is dry. The filter is not in backwards and the spring inside the housing is intact.

Does the oil pump need to be primed or is there any special precaution during reassemble that I missed? Everything went back together without any problems, I did not put the oil pump gears in backwards... just this oil light problem.

 

Did you crank it over a few times with coil unplugged first? Pack the oil pump with petroleum jelly?

Jeremy

 

I didn't have the coil disconnected but it took about 5 seconds of cranking before starting (because it took a while for the fuel rail to fill up with fuel). I squirted a bunch (not a lot) of assembly lube in there, but it rattled quite a bit for around 10 seconds. I turned it off and back on again and it sounded fine. It sounds totally normal now and the timing chain tensioner is pushed back out to its extended position, but the oil light is still on and the oil filter is basically dry.

I'm going to check the filter housing again to make sure there is nothing wrong there.

Will the oil pressure light go out if I crank it with the coil unplugged?

 

If I were you I'd go to a parts store pick up a tee and mount a mechanical oil pressure gauge at sender to see what kind of oil pressure you can build while cranking with coil unplugged. I'm not sure if dummie light would go out without engine running.

Jeremy

 

Ok, simple and stupid mistake. I discovered that the oil pressure regulator spring is not included as part of the oil pump cover. I wasn't getting any oil pressure because it was just dumping all the oil right back into the crankcase. It should work fine when I transfer this part from the old oil pump cover to the new cover. :-)

 

Ouch. that is learning the hard way. Sounds like one of my projects.

 

I got the part installed and the car is working fine now. No harm done, just a couple hours of time...