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Compression Dilemma On Built 25 Neo

smithers

By smithers,
in Engines & Forced Induction

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smithers Enthusiast

smithers

Posted
Posted

hi guys a few months ago i started seeing moisture vapour coming from the rocker cover breathers. The hoses go to a catch can, i put one into an open plastic bottle to keep an eye on it. I thought it may be a leaking headgasket as there were lots of tiny bubble in the radiator. I put in some seal up and that seemed to fix the problem.

Now it has come back again and i noticed the car isnt as responsive now but still idles fine and goes good on boost. There is only the moisture coming from the breathers not oil. I dont think its blowby and the plastic bottle a breather hose goes into only gets a slight amount of a sort of watery oil film on the inside, no great amount.

Anyway i did a compression test yesterday and here are the results.

180 psi in cyl1

180 psi cyl2

180 psi cyl3

180 psi cyl4

130 psi cyl5

155 psi cyl6

Doesnt use oil, maybe half a litre between 5000km changes.

Engine is fully built with cp pistons, eagle rods, cometic headgasket, arp headstuds. What are your guys thoughts? Should i change the headgasket or does it sound like something worse?

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The Mafia Grand Master

The Mafia

Posted
Posted

Do a leak down test.

Also, put a little oil down cylinder after you test it and test it again. If te compression doesn't come up after the oil, then it's not the rings, but a head gasket.

Sounds like a was gasket if there is water amongst the problem.

smithers Enthusiast

smithers

Posted
  • Author
Posted

Tis is the first comp test. I put a cap of oil in and the results only came up around 5 psi on the low cylinders. Run on full synthetic motul oil. The only issues are as stated in first post.

The plugs were dry when i took them out to do the comp test.

Room42 Proficient

Room42

Posted
Posted

I thought it may be a leaking headgasket as there were lots of tiny bubble in the radiator. I put in some seal up and that seemed to fix the problem.

Now it has come back again

Classic head gasket symptoms. You can get your radiator "bubbles" analyzed for about $25 to see if its leaking exhaust gas into it. Then you know for sure.

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