Well I wanted to check my plugs today on my 1.5 month old MCS since my car has been feeling sluggish. First thing I noticed when pulling off plug wire #2 was this completely dented down tube:



Once I pulled the plug, it was completely doused in oil and metal bits. After closer examination, it looks like the bits are from the spark plug threads on the head . I'm guessing they fell into cyl and scored the walls, causing oil blowby, which is why the plug was completely covered.



I'm at a loss as to what to do. This is a HUGE problem and I think my best course of action is to get an extended warranty to fix it (considering it most likely needs a new motor!).

I am extremely furious that I didn't check this when I bought the car.

The only people who have worked on the car are Mini and the previous owners extremely reputable shop (from the service records available). I don't understand how the downtube could have been butchered up so much.

 

I'm just guessing...but maybe the plug got blown out, and a helicoil was inserted.....any picture of the plug/threads? Usually lots of grease is used when cutting the helicoil to try to get the bits of metal to stick...so they don't fall into the motor.
I would clean it up...button it up, and have a compression test done...unless you can find a driveabilty issue...the extented warrenty is not likely going to cover something that is not YET a problem.
Sorry to see you found this problem, but it might not be a major...post a picture of the plugs and metal bits....it will help us guess a bit what might have happened?
PS...be sure to torqe the new plugs very carefuly...not just because they tend to loosen on a Mini, but because you MAY have a heli-coil, or partialy stripped head/spark plug hole.

 

From the looks of the picture, I can visibly see missing threads and it doesn't look like a helicoil is in place. The oil was 100% motor oil, not a thick grease. It was pooling off the plug pretty much.

The threads on the plug were perfect.

Here's some clearer pics:




and the bits:






What I also found strange is all the other pisons had carbon buildup covering them, but this one has a smooth metal ring around the top that you can see in the pictures.

 

Pics of the spark plug...both the one from the suspect cylindar, and the good ones will be of help, since the condition+colour will help identify if there is a compression issue...which could be you issues when it comes to performance.
It looks like it might be time to do a heli-coil...in the very near future.

 

Is there a seal around the top of those downtubes that stop oil in the head from seeping into the tubes?

I'm thinking that could be the cause of oil, since the tube is dented and not completely circular, allowing seepage. The tip of the plug was dry, but the threads and body had oil on them. The threads are definitely toast on the head, but I feel fairy confident in doing a helicoil. Is there any writeup that you know of on helicoiling with the cyl head still attached?

My camera died while I was trying to take pictures of the plugs, but the plugs looked pretty much identical, minus a little soot removed on the suspect plug from cleaning with brakes parts cleaner.

Also, how are those downtubes removed since I will probably need to replace it.

 

We'll I went to helicoil it today and SURPRISE! It's been previously helicoiled... I just didn't realize this until I finished tapping, pushing the previous helicoil into the cylinder! ... I guess it's time for a Big-Sert. I'm hoping the M18 bore size will allow me to pull the helicoil out from the cylinder with a magnetic wand. If this fails, I guess its time to pull the head

 

We feel your pain. Good luck.

Rich

PS-You should also find someone with a scope to be sure all the parts are out. Bits of helicoil in the valve seats won't do much for compression.

 

To get the Helicoil out you will need to invent a stainless magnet to retrieve it. If it is a Timesert or one of the Sav a Thread solid insert types you could use a magnet.To be safe you should pull the head and repair it off the car.It may take some welding/machine work to repair the seating area for the plug as it looks to be quite uneven and probably won't seal.It would eventually burn away and you'd be in the same prediciment.To even use the 18mm tools I think the plug tube will need to be removed.I'll bet that is why it is so buggered in the first place.You might also consider a good used head for a replacement if welding etc. is needed.

 

It's a Save a Thread insert stuck in there. I have a magnetic wand so I should be able to pull it out once the hole is big enough.

As for the plug tube, that was the first thing I removed. It was bent and not sealing at the top, so I pulled that sucker out with some vice grips. I have a new one on order (along with a seal and a VC gasket)



I don't think the sealing will be a problem, as the Time-Sert cuts a new seat into the head. According to the website, the Big-Sert is just a hair (.01") under the outside diameter of the Helicoil. That in addition to the new seat being cut leads me to believe I should have no issues with sealing. It's hard to tell from the pictures, but the seat is actually ok minus the top couple threads which will get shaved out anyways.

I'll keep you all posted.

 

Good to see you are handy with this kinda stuff!!
Before you spend too much $$, remember used heads can be had for $500 or bucks...and the gasket is pretty cheap...so pulling the head to either just clean out the cylindar of debris is an option...or even a head swap..sounds like you could do it diy from your background...
Either way...good luck...I'm sure we will keep reading to see how it turns out...heck similar things have happend before...but most folks stop posting...so it is great to see continued posts. It will certainly help future posters!!

 

We'll the downtube and gaskets came out to $40 shipped and the Big-Sert plus inserts came to $180. It's worth a shot trying it this way first IMO. Chances are if I pulled the head, I would inspect the SC and find out it needs to be rebuilt . I'm keeping that out of sight, out of mind right now .

 

If you are very careful, and you need a SC, you can find good coated (extra 5 hp) SC on e-bay for about the cost of a rebuild...$600. I got a 7000 miles one for a spare, and I know of others that got low milage, usually dealer takeoffs(when folks got JCW kits) for sililar $$, so don't stress too much...they are outthere much cheaper than the dealer....there are a fewmonster threads out there on the subject....some of the cheap rebuilds/eBay rebuilders are iffy....but deals are around...the guy I got my SC from was parting out a 7000 miles 2005 s, and the SC was beautifl...if you need the head...maybe he still has it avalable....

 

I've done a helicoil before on one of the rocker studs in a small block Chevy head. I was told by several mechanic friends that a helicoil for a spark plug in an aluminum head just does not work. The fact it is working in a MINI head tells me there is some luck to it.

 

Looking at your photo with the tube out of the way and cleaned up it looks like the sealing area will work just fine. Take extreme care to get the hole square to the seat area because the size of the bit in the Time Sert kit will make it very,very difficult to get a smooth cut. If it is off a little the plug gasket will make up for it but much over a couple degrees it will leak.

When Honda was calling the Isuzu Rodeo their own they had a problem with the spark plug tubes leaking and filling the holes with oil. The solution for that was Honda Bond 4 which was made by Three Bond and is a non hardening rubbery sealer that works really well.I think Yamaha dealers sell it too under Yamabond 4. A smear on the end going into the head should prevent any leakage into the hole.
Have fun and good luck!

 

wdietz186, good tip on the bond sealer. Will remember that should I ever have tube leakage.

 

I was planning on using some high temp rtv or low hold loctite to seal up the tube.

 

Matt suggested that when/if you get around to cutting threads, to stuff some nylon panty hose in the cylinder to catch any shavings that may fall inside.

 

Well I wasn't able to pull the helicoil out through the newly tapped hole so I've begun tearing down the engine. I have to say the Bentley manual has been a godsend. Makes the process so easy. Pretty much all that is left to get the head off the car is removing the cam sprocket and undoing the head bolts. I'm pulling the SC as well which is only a few more bolts. Here is how she sits right now:



I ran into a brick wall though, and was wondering if someone could give me insight on how to remove the two plugs to access the chain tensioner. I used the appropriate sized allen socket, but it still stripped the hole out.




Also, what's the deal with reusing head bolts? Is it like most where they can be reused once before they're stretched too much?

I plan on just picking up a headgasket and using copper spray on all the other metal gaskets (intake mani, etc).

 

You can try to tap in the next size up allen head if you have one available. Use a hammer and hit it only as much as needed to get it to bite.

As for head bolts... the rule of thumb I go with for domestic engines is three uses. That's what I was taught, but I never looked into a book for a reference. When you retorque them, do them in three stages and make sure to follow the explained bold pattern (usually starts with the inner-most bolts and works outward). Reference your Bentley manual (if you have one).

An example: Small-block chevrolet heads call for 65 ft. lbs. of torque for the bolts. I divided the torque specs into three stages: 30 ft. lbs., 50 ft. lbs, and 65 ft. lbs, following the pattern for all 17 bolts (yes, 17 bolts, and it's a workout, too). Remember, only click the torque wrench once. An extra torque click means you just added a couple of extra ft. lbs.

 

Well I cleaned up my block surface the best I could. Theres slight pitting around the water passages but everything around the cylinders and oil passages looks like it should seal. Warpage aside, does this look adequate for sealing the MLS? The little bits of black don't seem to come off with a razor blade or Scotchbrite pad (don't worry, I plugged the cylinders and oil passages with towels and grease so no particles got into the oil).





Also, would it be a bad idea to put a thin bead of RTV on the timing cover gasket and reuse it? My local dealer is still kind of far and they don't take orders over the phone (they don't stock the gasket).

 

Finally got her back together. No leaks, nothing burning, no codes. Also hooked up my oil pressure gauge during the process to make sure the engine is nice and primed before start up. Once warm, I get about 23psi idle, 60psi at 3k rpm. I just bought a compression tester and will be checking that tomorrow afternoon.

I used blue rtv on the timing cover and the thermostat and neither one has leaked a drop. I'm surprised this whole process was relatively easy.

Thanks to everyone that helped! I'm sure I will need more in the future!

 

WOW....those pistons are squeaky clean!! I'm surprised they don't have a bit of carbon on them!! Was that your handy work? I bet it was not THAT clean when you opened her up!! If it was WOW!! Especially on an 02!!
Congrats on getting it all back together!! You are sure one handy person!

 

That's how it was when I cracked her open!



JK


I did wipe them down with some brake cleaner and paper towels. It didn't take much effort at all clean them up.

This project has definitely given me some hands on experience. I was a bit nervous thinking the hg wouldn't seal due to a botched 7M-GTE mls headgasket job on my old car, but everything worked out.

 

That is still pretty good....heck....I've seen some pistons that have some much crap on them, they look like my BBQ at the end of summer!!
I think it is a good sign that it was well cared for (good fuel, and it seems to run pretty clean anyway) before you got it, even though you had to do some work on her!!

 

If the manual says to replace them, it's a good bet that they are torqued to yield. If that is the case, they definitely need to be replaced. Chevy has been doing this in recent years on the LSx series engines. The head bolts are a one time use.