#4 filled with oil...
 

So, I recently got my car tuned maxing out my wastegate actuator at 10psi. Drove it for two days and bam starts missing, oil in number four cylinder...I'm not exactly sure where its coming from as of now, but I guess lets talk rebuild.

Cometic Headgasket
ARP Head studs
Possibly supertech valve guides, valves, springs, head porting, 5 angle job?

Any other suggestions?

Where are the new piston rings that you need?

Well, I just put new bearings and rings in the bottom end two months ago...for that matter, I just had the head rebuilt two months ago. Do you think I need to overhaul the whole engine again?

Do you have a better idea where the oil came from?

Well it could be guides or head gasket. I haven't taken it apart yet so I don't know for sure. I will take a closer look at it and come back with more info.

You are seeing this "oil" with the plug out correct? Are you sure its oil? Antifreeze and fuel could "wet" the piston as well. A leakdown sounds in order. The miss if say a plug or wire etc, could leave unburnt fuel on the piston. Just wonder if you have cause and effect in the right order.

One of my friends has my compression tester, I will be needing that. I guess I need to go hunt it down. I'm pretty sure it was oil, yes plug out. I can always check again.

Check to see if you can find where it is coming from before you rebuild it but if you do have to rebuild it I would put piston rings in it for sure.

Compression test in this case = fail. Get a leakdown test.

if the top of the plug had oil on it, its the valve cover gasket.

Yes, well the valve cover gasket seems to be fine, with very minimal leaking if any at all. I did a compression test on the motor and got 150 across the board, and #4 was dry as were the rest this time. I did a little checking and there is a slight oil film in the intake but no pooling of oil. The car seems to be running fine now with no misfiring issues. The oil level was slightly above the full mark so I drained a tiny bit out just to make myself feel better about hitting the line. The oil also felt right and was still mostly clear as it was changed 250 miles ago. I took it for a drive and there is no smoking and it seems to be driving good on 12psi. I guess we just wait and see.

I was just going to say this.


A compression tester will not do anything helpful at this point. If you can, find someone with a leak down kit. Do that, if they come back at a decent %, then I would just forget about it and just drive your car. IIRC, you shouldn't really want any more than %5-%10 leakdown. Obviously less is better.

If you have %10 leak down for example in all 4 cyls and #4 is the same as the rest, then just leave the motor and drive the car. If you get say... #1 %4, #2 %5, #3 %5, #4 %20, then something is bunk with the 4th chamber. If that's the case, then pull the head to check the valve seating and change valve seals.

Did you hone the motor when you put the rings in it a few months ago? Let's see some datalogs with a wideband trace as well.