Hello everyone. Love the forum. I've been "mini curious" for a while, so I bought a super nice '07 with 90k miles. The owner said he was driving when it lost power, he limped it home(not sure if it was actually "limp" mode, and it wouldn't restart.

He said the compression test was not good. I bought it and did about 3 days worth of research and bought all the tools I need(so far).

i did not try to start it. I wanted to check the timing.

today:

1)intake cam #4 main cap was not fully seated. There was daylight between that cap. Lots of loose bolts. Retightened. Will torque later.

3)middle valve cover bolt was snapped off. (Indication that someone has been in here)

4) checked timing with Amazon cam timing tool. Flywheel pinned, cam numbers facing up and locked down...checked good. 27mm tensioner bolt wasn't that tight. Tightened slightly, and it tightened up the chain. Timing good.

5) propped open the throttle valve, did a compression test with two different kits. Cranked for 10 seconds. One being a $100 Napa kit I bought yesterday.
Readings 0,15,45,70lbs respectively.

6)added lots of oil to cylinder to remove doubt of oil getting to rings. Absolutely no change to compression readings.

7) not a leak down, but added air to each cylinder at tdc on compression stroke. All intake valves leaking...bad. shut off air supply and it drops quick! 20lbs to 100lbs input, same result.

8) removed intake and exhaust manifolds. Redid compression test, pretty much the same. Little variance. Added air to each cylinder once again while turning engine slowly. All intake valves leak all the time, throughout the rotation.(all intake springs go up and down. Exhaust valves do not leak at all.

On compression stroke, tdc, and intake off, I visibly saw the air coming out of the intake ports and gurgling around the valve seats(due to oil there)

now, this can't happen at once if the timing is good? There must be a different failure causing the previous owner to lose total power. Leaking intake valves don't happen overnight. Oil looks good, water looks good.

can I get a sanity check? Plan on pulling the head and reconditioning it.

I have a foxwell scanner on the way(can't check codes yet)

pull the head, right?

 

Sounds to me like the PO blew it, took it apart and decided not to fix it, put it back together so all the parts are there, and sold it.

If you're committed to fixing it, go ahead and pull the head. If you're in doubt, find a borescope and check piston tops for valve contact damage. If timing gets way off, these are "interference" engines --- piston / valve contact is possible. Maybe you'll get lucky and find only a bad head gasket. Best of luck ---

 

Thank you so much for reading AND the reply, old brokenwind. I am committed. I feel like I needed to write that out for my peace of mind. Slept on it and just can't come to grips with leaking intake valves leading to no compression, and catastrophic failure.

Just now, I reinserted the flywheel pin. The interwebs said it goes in halfway and I found that I hit the raised recess on the flywheel yesterday that locks it in the cw position. Today, I layed eyes on the actual hole with a mirror and flashlight, and the oin goes in further. Guess what?

Intake cam was 180° out! Put cam tool on and loosened cam sprocket to get everything in time. Tightened back up and ran a compression test.

Numbers are:175,160,240,185
160 turned into 265 when I added oil. So although these numbers on a cold, oil filled engine can't be trusted, they indicate healthy pistons.

Added air and intake valves so leak. Must have kissed the pistons ever so slightly.

I can live with this info. Now I can replace and relap valves, and timing chain.

Thank you guys for the invaluable info on this site.

 

Here's a couple pics you might find interesting ---

'07 MCS flywheel showing locking pin hole. Other similar holes are probably for balancing.


Dinged piston from really bent valves. Note it's a 9.0:1 CR and has a recessed top. All four looked like this.


Here's the same piston with the dings ground out. Lost some symmetry and all were re-balanced, but performance is still pretty good.

 

Interesting. Thank you for those pics. It appears as though the intakes did not hit the pistons...somehow.

The exhaust valves open wide. And the intakes open only a tad as pictured when turning the cams with a wrench. The other intake valve on each cylinder opens even less! ALL intake cam lobes mic out roughly the same...1.632".

I notice that there is a separate actuator that turns the cam lift further? I have a Bentley manual on order and on its way.

 

Have you checked the illustrated parts list --- https://www.realoem.com/bmw/enUS/select --- to see if all the valve lifters and rockers are correct and in the right place? You'll need the last seven characters of your VIN to access the correct part lists.

 

Thank you, Sir!. I will check that out! Got my timing chain kit and serpentine belt ordered from ECS, I'll take the head in tomorrow and see what I need to order head gasket, valve guide, and valve wise when the machinist takes a look

 

Pretty quick turn around. Got all of my parts in and the head back from the machine shop. No bent valves, and they surfaced it .010", cleaned and did a valve job. I bolted it on tonight. I am using a stock head gasket. I absolutely REFUSE to believe that .254 mm will affect anything on an n12 with reliefs in the Pistons. The intake slipped 90° and the valves never hit the Pistons.

Unfortunately, the loose intake cam bearings caps I mentioned were loose, completely beat themselves to death, almost closing up the oil passage. Was really hoping to get this thing back together. Need an intake cam and bearing cap/VVT fixtures. The VVT cam sits in the head, so thankfully there is no head damage.

I may have one located locally.

Also made a crude crank tool, lol...

 

Cam caps are a "matched set" with the block, and NOT interchangeable. Their journal location is determined by a line-bore process --- all five caps are bored in one operation and as a result, the caps cannot be switched or turned around. They must be installed by their number and their numbers oriented in the same direction. Having said that, it might be possible to find some replacements and drill out the mounting holes slightly. No way I'd try it on a hi-performance engine, but maybe OK on an N12. Just so you know what you're dealing with, and don't try to just throw another set of caps on it. Also use some plasti-gage to measure the assembled clearances --- top and bottom. That'll give you an idea of where to shim or grind.

After you get it running, consider trading it in for something else, or selling it to someone you don't like.

 

Thank you! I'm thinking that the "matched set" on the n12 comes as an assembly with a matched cap and cam independent of the head journals. The VVT cam is the only cam on that side with ACTUAL bearing cap to head interface and it swivels, doesn't spin. Dang it. Hopefully VVT cam mating surface puts the actual intake cam in the same spot. This is just getting complicated now. Probably shouldn't have bolted the head on yet. I will do some measuring if I can find the parts.

 

Sooooo blessed to have been able to find this set this morning near my house. I won't say what I paid(yikes) but it came off of a 53k mile car and it's a matched set. The only bearings to be concerned about checking are the VVT cam and it doesn't spin so we shall see.

 

My previous post about matched sets might not apply to the N12, only my N14. Try looking in https://www.realoem.com/bmw/enUS/select to see if there's part numbers for the stuff you need to replace. Also the online repair procedures https://www.newtis.info/tisv2/a/en/ might have some info.

 

I really want to thank you for all your help and keeping me in check. I don't do a lot of wrenching, but when I do I really immerse myself in it(6 hours of you tube videos). I rebuilt the tranny and xfer case in my scout. Hadn't done a head gasket since high school.
Everything is prelubed and ready to go.



here is the difference between the stock tensioner and the ECS tuning tensioner. Stiffer as well...


i borrowed this from work. Does metric and torque angles too.



The cam turns soooooo nice now. Everything is so smooth. I realize now how wrecked those loose main caps made everything. I don't know if this thread will help anyone. Hopefully it can.

Got everything back together. Waiting to start it Monday after fluid changes.

 

Well, we're heading into the perfect storm. Started up the car this morning. Started right up! Ran for about a minute and the oil light came on. Shut her down and pulled the valve cover...hard to tell. I prelubed the valve train so well. Pulled the oil filter housing....new filter dry. Pulled the oil pan...pulled the oil pump

Laugh out loud it never stops!!!!! But I'm committed...​​​

 

Bought a used pump and had it installed two hours later. I let the oil pan gasket material setup up overnight. Started her up this morning, good oil flow. Runs perfect, absolutely dead quiet.

I think we're out of the woods...​​​ I'll have to say. I get it now. I absolutely LOVE this car. I took some sharp turns and it was hilariously awesome how it stuck to the road!

I paid $1000 for it and probably invested another $1000

 

WOW! You are truly dedicated and an inspiration. Kudos on keeping that beauty on the road and congrats on a "cheap" Cooper! Enjoy it!

 

Good job....I applaud your perseverance on this......now with that said.....I really wish that all the problems that I had with my car I bought last year was that simple.....

Grab yerself a cup of coffee, or a beer, whatever your pleasure is, and read my thread that I have here in the forum.......granted, it's a Gen 1, but this is what I went through

https://www.northamericanmotoring.co...ni-or-not.html

you will have to start at the beginning of the thread to get the full effect

Bryan

 

Thanks, man! I'll be driving it easy for a while. I don't completely trust the car yet, but I'm optimistic!

 

That's quite the ordeal. I would not have taken on something that in depth. I applaud you! My expertise is in metal work and custom metal repair so I needed a couple week break from that to some wrenching. It was a nice hiatus with a huge payoff. Non turbo but very fun to drive