I''ve just completed having the head rebuilt on our 2008 R56 N12 Cooper (128,000 km). I did the dismantling and reassembly and had a local engine shop replace the valve stem oil seals (the suspected problem) and the valve lifters (the actual problem).

The engine had no compression on cylinder 4 - all four valve lifters for that cylinder had collapsed. We checked the piston rings on #4 but they were fine.

After almost two months of work and waiting for various parts to arrive at different times, today was the day.

I started the engine for the first time this morning (yay!) but rather than seeing blue smoke from excess oil coming out the tail pipe is came up through the engine bay. It's pouring out the join between the manifold/cat pipe and the mid pipe.


Leaking exhaust clamp

The clamp is new and is this one from @ECS Tuning https://www.ecstuning.com/b-genuine-...p/18302756351/

Any suggestions? It's done up pretty tight, but I could turn the bolt a bit more - was worried about deforming the band? Or is it more likely that the pipe joins aren't seated correctly? I've not use a V clamp before.

With the exhaust leak I didn't have time to use my diagnostics app to see if the engine was happy. But at least it didn't turn into a bucket of bolts.

I also installed a new timing chain and guides, water pump, water pipe, alternator belt, exhaust manifold and PCV pipe (the original snapped when I was doing up the last nut on the intake manifold about 3 weeks ago - thanks @ECS Tuning for your help on locating a part number for the pipe for Australian cars. It just arrived from Latvia!).

 

When you're installing the exhaust headers, did you completely install the header flange bolts first then go on to install this V-clamp to join up with the exhaust? I suspect you may want to loosen up the header flange bolts and the V-clamp a little bit. Then tighten the V-clamp first, and lastly tighten up the header flange bolts. There could be an angular in-precision created when you tighten up the headers first. I could be wrong, only did service on two N12 coopers so far, most of my experience has been with N14's. And down pipe can be a lot different than headers of the N12 to work with.

 

I did the clamp first... my wife held the weight of the header downpipe while I did the clamp.

Which bolts on the exhaust to loosen? I’m not sure what you mean by the exhaust flange. I don’t want to loosen the top of the manifold with a new crush gasket just installed They aren’t easy to reach with the car all back together!

Am tempted to use some exhaust paste...

 

With a v-band clamp, you want to make sure they are well lined up before tightening the clamp. If there is any misalignment, the clamp will not pull it together, and you will get a leak.

 

+1 make sure that the two pipes are aligned and the flange is straight with mating on that bevel.

 

All buttoned up and exhaust no longer leaking.



No error codes from short bit of idling (a bit of smoke from oil cooking off though).



Just waiting for a pressure bleeder to arrive so I can blend the air out of the clutch slave cylinder and go for a test drive. Feeling pleased but will only believe it’s really ok after a 50 km drive...

 

 

Thats great!

 

is there a gasket on the muffler to cat. pipe. mine is leaking have a new clamp...still leaks...or could the muffler be clogged...116,000 miles

 

Yes the V band clamp : https://www.ecstuning.com/Search/Sit...h/18302756351/