oil fowled spark plugs on new rebuild

[Anonymous]

hi all,

i have about 500 miles on a rebuild of my 200, and am continuing to troubleshoot a rough idle. pulled the spark plugs on it yesterday morning and discovered that plugs 1 and 3 appear a combination of oil fowled and carbon deposited. sticky black residue all the way up to the threading on one of them. all other plugs look fine. replaced all plugs, leaned out the fuel-air mixture a tad, and it runs much much smoother.

does this mean that i have a problem with my rebuild? wrong rings or incorrect machining? i'm running Rotella 10W-30 in it. i'm worried i'll have to tear the thing down again. one possibility that comes up about every 5th or 6th website on spark plug diagnostics is that oil fowling like this can come from a plugged pcv valve. a friend helping me to work out some bugs on the car plugged the pcv valve a couple of weeks ago, and I drove it maybe a week before replacing the old faulty pcv valve...i'm hoping that this is all it is, and that the plug replacement is all that it needs. thoughts? suggestions?

 

[pedal2themetal45]

When you pluged up the PCV did you have it vented some way ?? Might have just builted up to much prusher while you drove it with out the pcv.. and pushed oil up in the cylender... You might be ok now that the Pcv is working...
tim

 

[BUZZ]

With only 500 miles on it I wouldn't worry to much yet. Some new motors burn a little oil until the rings seat or as you already said it could be the pcv,or just to much oil in the cyl's from piston installation.
Just becareful not to run it to lean, as your motor breaks in its likely to start running a little leaner on its own due to cyl and ring wear in.
On a differant note you have changed your oil since it's first start up right?If not I'd go ahead and change your oil and filter now.

 

[james singleton]

Ranchero63', I also have a fairly new rebuilt 200cid engine installed last year. I am still in the restoration mode on my vehicle, so I probably have less than a couple of hundred miles of actual driving conditions. I do start the engine up once a week or so, and it has had quite a bit of stationary running (in the driveway). I pulled the plugs a couple of weeks ago and all my plugs had a slightly black-sooted carbon appearance to them. No "oily" look to them however! I tweaked my carb a little, leaned it just a little. It seems to run a little bit better as a result; especially when I step on the gas a bit; but like they say, don't lean it out too much (overheating). My manual says the following concerning "OIL DEPOSITS" on plugs: A plugged PCV valve, or a ruptured fuel pump diaphragm. Also of interest:"OIL FOULED PLUGS SUCH AS THESE ARE OFTEN FOUND IN NEW OR RECENTLY OVERHAULED ENGINES, BEFORE NORMAL OIL CONTROL IS ACHIEVED, AND CAN BE CLEANED AND REINSTALLED"! Also the heat range of the plug can make a difference. Good Luck! Jim

 

[Anonymous]

wow, all of these posts are very re-assuring. i'll keep an eye on how lean the fuel-air mixture is, and will give the engine/oil a little more time to equilibrate. i'm not too worried about the leanness of the carb because i just fixed a vacuum leak in the vacuum advance line that probably had my carb running lean (and dialed rich to compensate).

thanks!

nate

 

[Anonymous]

When you pluged up the PCV did you have it vented some way ?? Might have just builted up to much prusher while you drove it with out the pcv.. and pushed oil up in the cylender... You might be ok now that the Pcv is working...
tim

wouldn't the breather on my valve cover work to vent any pressure?

 

[BUZZ]

It should, the pcv's main purpose is to put a positive vacuum on the crankcase which helps with oil control but mainly to cycle vapors back through the engine where they are burned.It regulates the amount of ventilating air and blow by to the intake and prevents a backfire from entering the crankcase.