Hi,
2008 Mini Cooper S 86000 miles.
Went to accelerate up a slight incline and got a misfire and the engine light started flashing. Car continued to misfire. Fortunately I was close to home, and got the car into the garage.Engine light on permanently.
I have a Scangauge so was able to get the codes. I have P0300 (misfire multiple cylinders) P0301 (misfire cylinder 1) and P0301 (misfire cylinder 2). I purchased the car with 67000 miles on it a couple of years ago, so am not sure what service has been done. I have done the obvious stuff, air filter, oil,etc but not the spark plugs.
I have put in new spark plugs on all 4 cylinders, same codes. I switched coils 1 & 2 with 3 & 4, same codes.
Could this be the intakes needing walnut blast/cleaning?.
I mainly use the car to commute to work, approx 24 miles each way, mainly highway, so it gets a good run up to temperature.
Comments appreciated.

 

Ya, probably intake valves are carbon coated. If it's never been cleaned, probably past due. Pull off the intake and take a good look. Know problem on '07-'11 n14 engines..

 

Tried to run once engine cold.Still have misfire, engine light on. Will take a look at the inlet valves for carbon build up.

 

before I start taking parts off.....a compression test may be a good idea. I will see if I can get a tester.

 

I just had these codes on my 2008 Mini Cooper Base R56. I changed all the plugs and changed out the fuel injectors by vod. It was cylinder 1 and 2 and the codes were gone. P.S. check your vacuum pump also. My was leaking oil there. My Mini has 84232 miles on it.

 

pardon the ignorance VOD? Vacuum Oxygen Decarbonization?

 

My mistake, it is the make of the fuel injector. Mini Fuel Injector (Copper) - VDO 13537528176. I think your fuel injectors are clogged and needs to be replace. I bought these at FCP Euro. I hope this helps.

 

Ok here are the cold numbers....#1 cylinder 5 psi #2 130psi #3 155psi #4 150 psi. Here we go!

 

Now a leak down test can help pinpoint the source of the low compression.

With #1 cylinder pressurized leaking air noise from the intake is a bad intake valve, from the exhaust a bad exhaust valve. From the #2 cylinder spark plug hole a bad head gasket. From the oil fill opening in the valve cover bad rings/piston.

'course, almost certainly the head's going to have to come off or maybe even the engine needs to come out and be disassembled. At 86K miles you might want to address some other things at the same time you are addresseing the low compression issue.

 

Feel free to give us a call with any questions on the job; we've got everything you should need to get the car back into running order in stock!

Oddly enough the last few heads we've sent to the machine shop for a dead cylinder it was carbon buildup on the exhaust valves, but we still see our fair share of burnt exhaust valves on these cars as well with the occasional car that jumped time and bent all the exhaust valves.

 

Shop has done a leak down test. Exhaust valves on #1 leaking. Suspect burnt. Strip down of head next $$$
Not sure why this has happened on a car with 80,000 miles.
Is this a common problem...I know about the cam chain/tensioner fiasco.

 

So what are we looking at here parts wise to get up and running
Cylinder head gasket kit and head gasket
Torque bolts for head.
1 or 2 exhaust valves...not sure yet.
Not considering replacing cam tensioning system, vacuum pumps......yet
Special tools?

 

Feel free to give us a call and we can get you a detailed estimate together.

I would recommend all 8 exhaust valves, I'm not a fan of replacing just one or two, especially if you had burnt valves.

You may or may not need to replace the whole timing cassette, but you're going to have most of it taken apart anyway so why not just take care of it now vs 6 months down the road?

I wouldn't jump right to replacing the vacuum pump, you can take it apart and clean it up, and reseal it within an hour. Unless it's making noise I wouldn't spend the money on one.

Give us a call, we'd be glad to help you out!

 

A burnt valve is pretty rare. Co-worker had one in his Subaru's engine.

One possible explanation could be a tiny inclusion in the valve head metal that causes an area of the valve head to run hotter and over time this takes its toll.

Another possible explanation is valve or combustion chamber deposits came loose and a piece got caught in the exhaust valve. It doesn't take too many combustion/exhaust cycles to result in an overheated exhaust valve.

If two exhaust valves are bad... Could be a marginal batch of exhaust valves. You might want to consider replacing all exhaust valves when you have the head apart. Be sure to give all the valves a good examination. Check the contact the head and valve seats have. You want to see full contact being made. It is by being in contact with the valve seat that an exhaust valve gives up its heat.

It could be a "valve job" is needed, that is the valve seats machined (ground) to bring them back into spec. (And valve guide/stem wear/play is checked, maybe new valve stems seals are fitted, and so on.)

Regarding machining valve seats: One has to be careful. The less metal removed from a valve seat the better. Too much metal thins the seat and it can run hotter. It also can "sink" the valve and affect flow through the valve, though an exhaust valve is less sensitive to this. The saying is God fills the engine's cylinder man empties it and this refers to the fact the engine has an exhaust stroke that forces exhaust gas out the cylinder.

A reputable Mini head rebuilding shop though should know all of the above and tons tons more.

Another possible contributor to early exhaust valve demise is runing the wrong octane of gasoline. If the too low an octane of gasoline is used the engine controller retards ignition. While this works to keep the pressure in the chamber lower and avoid detonation it works to raise exhaust gas temperature and this over time can take its toll. Exhaust valves work at a near dull red heat and anything that raises their temperature shortens their life.

 

Don't have the specifics for Mini head reconditioning but generally the process involves making sure the head is throughly cleaned. If cast iron magnafluxed to check for cracks. Aluminum heads I think get some kind of dye test. (It has been decades since I worked on engines and I am forgetting some things.)

Then the head is checked for straightness.

Valve stems/guides are checked for excessive wear. Valve seats are checked to make sure for instance the valve and seat are making good contact. As I touched upon in another reponse it is being in contact with the valve seat the exhaust (and the intake valve too) gives up its heat. So good valve head to valve seat contact is paramount.

If two exhaust valves are shot it might be worth the expense to replace all exhaust valves. The last thing you want is to replace just a couple of obviously bad exhaust valves, put the head back in service, then have to pull it again after just a while to fix one or more other exhaust valves.

Other hardware is checked for signs of wear or problems. Before you remove the head/cam maybe you want to check for excessive camshaft chain/sprocket wear.

It might be a good idea to while you are there replace any camchain tensioners.

It is important that valve geometry be checked to ensure all is well in this regard. I'm not sure what geometry there is with Mini head. With some heads valve stem height is critical. (With a Datsun head I had to check lobe to rocker arm pad contact to make sure the lobe was contacting the pad in its center.)

Maybe new head bolts are used. The threaded holes all the bolts screw into should be checked to make sure the bolts thread in deep enough to hold the head down without risk of bottoming in the hole.

Be sure to use a proper assembly lube to protect the cam lobe/lifter interfaces upon initial engine start and shortly thereafter until the engine oil is circulating.

'course, you have fresh engine oil in the engine too.

New head gasket, other gaskets, seals, etc. get used and the head bolted/torqued down according to the factory repair specifications.

The above is not a complete coverage to be sure.

 

Rock C
Always ran max octane 93? fuel while in my ownership. The shop where the car is currently located did a leak down and found the exhaust valve(s) is where the leak is. I am not sure if valve is burnt or is it carbon under valve as I do not know if PO ever had inlet cleaned, although the car was running fine for me. I will see if the shop may be able to get an inspection probe device in to see if anything obvious can be seen.
I may end up pulling the head myself.
Ref special tools...I see mini supplied or aftermarket are available....recommendations? I would use mini head gasket/valves, but again I see mini or aftermarket head gasket set. There is quite a difference in cost ref mini/aftermarket.

 

We have the cam tools for rent and purchase on our website, as most people only need the tools once I would recommend renting them.

We have both options of MINI OE or OE aftermarket for all required parts to tackle the job.

All in stock, ready to ship!