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Old 04-27-2015, 05:25 AM   #18
rah rah 986
1998 Boxster
 
Join Date: Aug 2012
Location: Lakewood, Ohio
Posts: 110
Thanks for all of the feedback. I am at a bit of a standstill, and not sure what to do next. My goal when pulling the engine was to rule out or fix any conditions that might lead to catastrophic engine failure. My greatest source of concern being the cranking of the engine that sounded as though there was little internal resistance. My first thought was that I had better check the timing before doing anything else. When attempting to remove the cam plugs, I knocked one into the the cavity behind the valve cover. Retrieving the plastic plug seemed near impossible without removing the cover. Being that we were well into winter, I decided this would be a good opportunity to pull the engine; check the timing; hopefully rule out any major internal problem; and then do some more in depth maintainance procedures such as RMS; check IMS; replace clutch; replace cam to cam chain pads; replace other tensioner ramps as possible; and maybe replace the lifters.

As noted earlier, timing is perfect. Leak down...awful. A few posts above suggest the leak down may be inaccurate for a few possible reasons. Jake suggests that sticky lifters can sometimes cause poor results. In order to rule out the lifters, I removed all of the lifters. My assumption is that the valves should all be completely closed. Also, without the lifters in place, I thought the piston being at exact TDC would be less critical in assuring the valves are all closed. (If I am way off in my thinking....just learning). With all of the lifters out, I have retested, and am still getting near total leakage. It is very audible through the exhaust.

The other suggestion above is that the results are skewed because I am either performing the test incorrectly, or that the results are skewed because the engine is cold. I am open to either possibility; because I can't argue with any certainty otherwise. I will say, I can remove the test hose from the spark plug hole, and control the readout on the gauge simply by applying pressure with my thumb to the end of the hose. This would tell me that indeed, the gauge is accurately reading that the cylinders are not holding any pressure.

Can this really be simply because the engine is cold? It would seem that even a cold engine would hold some pressure. it is probably worth repeating that the poor leak down numbers of 90%+ is at almost every cylinder.

I also should comment on what I have seen as I have been involved in the dissassembly of the engine. To my untrained eye, everything looks pristine. Everything under the valve cover is extremely clean. Nothing that I can see with having gone as far ar removing the cams and lifters looks out of order.

Since the high leak down numbers are at every cylinder, I need to ask; based upon what I have reported here, is there any problem that comes to mind that would affect every cylinder in this way?

At this point I don't know what to do next. If the best advise that I get is to ignore the test results, move forward, and reassemble the car; then, that is what I will do. I would be thrilled to find out that I have no significant internal engine problems. I only hope that my problem is as minor as a crankshaft position sensor.

If anyone can tell me with any certainty that these leak down results are insignificant, then I will ignore them. (What is difficult to ignore is that I can hear the leak through the exhaust....the leak is real)

Once again, thank you all for you help so far.
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