Metro - carbon on the piston head?

[an0nymous]

So finally got the head on 1.0l 3 cylinder metro mostly off and I was surprised at the amount of the carbon sitting on the head of the #1 piston. Is there some official way to clean this off? I guess I'm worried about breaking it loose and having it slip down between the cylinder and piston wall and jacking up the piston rings. I appreciate your patience and support.

Think I'm going to go ahead and order a xfi cam while I'm at this. Might as well. I'll probably just disassemble and clean the lifters though.

[Daox]

Would you mind posting some pictures of the piston and combustion chamber along with intake and exhaust ports? I'm interested as to what could be done with some head work.

[Johnny Mullet]

Mine had a lot of carbon on one cylinder and it happened to be the one with the burnt exhaust valve. I cleaned the top of the pistons with a roloc disc and use compressed air to blow out any debris. Usually, the clogged EGR port causes this buildup.

I use Seafoam once a month to keep the carbon from building up. If you need any help with the rebuild, please ask us first! Make sure the new head gasket is cut properly for the drainback hole.

[an0nymous]

Wow. Quick responses.
Okay, I can get some pictures up tomorrow. I'm not usually home during the daylight hours but will be tomorrow afternoon. Most of my wrenching has been in the pre-dawn and post 10pm range lit by lantern so good pictures will have to wait a day.
Johnny, I am pretty much following your rebuild thread, but have decided to go ahead and order the xfi cam from delta in addition. Will I need to replace any bearing surfaces or should they be left as is?
I've seen the drainback hole thread and think I get the notion. I bought my gaskets from ebay for the cheapest price possible (cue groan from readership) so I am sure they will need a trim. Got the diagonal cutters ready. I also saw the little brass (?) check valve thing for the first time this morning and well. I'll try to retrieve it for safe keeping tonight.

[Johnny Mullet]

You should not have to replace bearing surfaces unless there is obvious damage. The XFi camshaft is a "Drop-in" mod, but I suggest checking and resetting the timing after the swap.

[metroschultz]

definitely reset your timing!
We originally set my timing at 8* but I have since had to cut it back to the spec of 5* (pinging don'tcha know)
I love the Xfi cam in my Geo.
It runs like a whole different car.
Schultz

[metromizer]

Originally Posted by metroschultz

definitely reset your timing!
We originally set my timing at 8* but I have since had to cut it back to the spec of 5* (pinging don'tcha know)
I love the Xfi cam in my Geo.
It runs like a whole different car.
Schultz

Johnny, Shultz, do you guys think the need to trim-back back the ignition timing a little (after a Xfi cam instal, to keep it from pinging) is the result of a higher dynamic compression ratio after the cam swap?

[99metro]

I used gasket remover for all 3 pistons. I had the engine disassembled when I did that though. I still have my "economy cam" from 3tech and haven't installed it yet. Maybe the next time I have to replace the timing belt, I'll get her in there...

[an0nymous]

Hey fellows, sorry to drop out for a bit, but rain and domestic junk held me up. Currently the story is this: the head is entirely disconnected except for two pieces. One very stubborn hose and some kind of sensor? (maybe o2?) I plan to remove these tonight. Any thoughts on removing the sensor? a 17mm crescent wrench wasn't quite big enough. I forgot to lift the head up and get pictures of the carbon but I will tomorrow morning. Stupid hose is glued in place. I am about ready to cut and replace it. Once I get the sensor thing off i'll pull the head off the engine and that will allow me to more directly yank on the hose.
The camshaft hadn't showed up.. I hope it does today. I will be able to work on this thing this weekend... provided I can get the *&^&* hose and sensor off.
You might notice the distributor is still in place.. I was just going to leave it on the head until I can get it onto a workbench.

[metroschultz]

The hose isn't really glued on.
They get very difficult to remove after thousands of heating and cooling cycles.
You can use a razor knife to cut a slit lengthwise from the end where the clamp was and peel it off the nipple, or you can cut it through just beyond the nipple. Either way you are going to need a new hose.
If you are very careful, you can take a small screwdriver and work it between the hose and nipple and move the screwdriver from side to side until you break the seal then remove the hose. This method will save the hose, but requires a lot of patience. I prefer to replace hoses whenever possible. They are subject to ozone decay and if it is that difficult to remove it probably has little, if any, life left.
As for the sensor, you should be able to find a connector to separate. The sensor in your picture that was left connected is the ECT (engine coolant temperature) There is a small catch on the black plastic connector that must be released (by pushing, usually with another small screwdriver) to remove the wiring from the sensor. If the problem sensor really is th O2 then you have to follow the wire to the top and pull its connector apart. The O2 has a small round connector (if yours is older than 1996) and pulls straight apart. You might have to use a little persuasion.
Have Fun,
Schultz