Oh noes! Thin film of oil on plugs.
#1
Oh noes! Thin film of oil on plugs.
I pulled my MP62 off to permanently sell it this winter. Having prepped everything for higher boost, save the engine, intuition tells me that taking a step back to naturally aspirated on this engine is the correct decision.
While swapping the spark plugs back to OE, I found every plug had a thin film of oil around the threads and washers. So, I did a compression test and compared numbers to last year.
May 2011
Dry Wet
166 185
168 180
152 175
150 175
Nov 2012
Dry Wet
160 169
151 151
149 160
143 159
I've attached a few pictures of the cylinders after the wet comp test. They sure look like something crispy, no? How quickly do I need to start researching parts for an engine build thread?
While swapping the spark plugs back to OE, I found every plug had a thin film of oil around the threads and washers. So, I did a compression test and compared numbers to last year.
May 2011
Dry Wet
166 185
168 180
152 175
150 175
Nov 2012
Dry Wet
160 169
151 151
149 160
143 159
I've attached a few pictures of the cylinders after the wet comp test. They sure look like something crispy, no? How quickly do I need to start researching parts for an engine build thread?
#4
No performance issues that I can quantify. I've run the compression numbers a few times over the past few years, using the same gauge, and they have been consistent enough to show show wear and tear. The MP62 ran almost identical numbers as advertised when it was dynoed last year.
The last two sets of plugs read perfect in terms of color.
Looking back at my records, it looks like I may have changed the CAS o-ring immediately after getting the car in 2009. I do not have any record or remembrance of changing the valve cover gasket.
Your responses put me a little more at ease.
The last two sets of plugs read perfect in terms of color.
Looking back at my records, it looks like I may have changed the CAS o-ring immediately after getting the car in 2009. I do not have any record or remembrance of changing the valve cover gasket.
Your responses put me a little more at ease.
#5
Boost Pope
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I see no problems here.
As others have said, that oil leakage is pretty typical for the Miata. And the carbon buildup on the pistons is pretty normal for any car this age.
I wouldn't fret the compression numbers, either. Hell, they're better than the engine in my '90, and I have absolutely no plans to replace it any time soon.
As others have said, that oil leakage is pretty typical for the Miata. And the carbon buildup on the pistons is pretty normal for any car this age.
I wouldn't fret the compression numbers, either. Hell, they're better than the engine in my '90, and I have absolutely no plans to replace it any time soon.
#10
Boost Pope
iTrader: (8)
Join Date: Sep 2005
Location: Chicago. (The less-murder part.)
Posts: 33,022
Total Cats: 6,589
You know, I remember trying the "Seaform Trick" several years ago on my '92, just before I installed the turbo on it. Aside from putting out a cloud of smoke that enveloped the entire neighborhood (fortunately, I did this in an empty office park on a weekend), it didn't seem to actually accomplish much. I had the head off about a year later to replace the gasket, and the piston tops looked ever bit as foul as the ones in the picture above. So I scrubbed 'em for a while with a toothbrush and brake cleaner. That did the trick.
#12
Water injection won't remove the stuff that is already caked on there. A wire wheel will. Or a chisel, etc. I ran WI for quite a while and when I tore down the old motor it looked just as nasty as yours. I am also unconvinced of SeaFoam's effectiveness, other than killing any insects and small children near the car when you run it through.
#13
I've been a supporter of Seafoam. It's effectiveness is limited, though. I've used it on past cars where I let it sit overnight after choking the engine off with it, and the engine idled notably better after blowing everything out the next morning.
When I ran it on this car, I only ran it while idling. It cleared a thin path from the vacuum port to the cylinders, but that was about it.
When I ran it on this car, I only ran it while idling. It cleared a thin path from the vacuum port to the cylinders, but that was about it.
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