Engine is out of the car, so I can't do a standard compression test on it using the starter. I did do a leakdown test on the engine though.

 

The results, with 70 psi:

1: 68psi, hissing from valve cover breather

2: 64psi, hissing from exhaust valves

3: 63psi, hissing from exhaust and VCB

4: 60psi, hissing from exhaust and VCB

 

I had suspicion of a blown HG, which is why I pulled the engine and dropped in my EJ20G block. However, after I did this, I discovered a hole in my radiator, and the misfire issues continued(indicating something other than a mechanical issue).

 

So what does the leakdown test tell you about this engine? What else should I do at this point with it?

if you want a diagnosis you may want to start with what the engine was doing and symptoms previously, the leak down tests probably aren't a good place to start.

 

compression tests and leak down tests are generally pointless on DOHC EJ25's...all EJ25's for that matter. they *do not* show headgasket issues. almost all failed EJ25 headgaskets even pass both of those tests - they just don't fail that way. if you flog it, beat it, overheat to oblivion and such eventually those tests will show something. but for original headgaskets and normal conditions those tests are pointless.

 

your results are probably from just carbon build up hanging the valves open a bit. i've disassembled a bunch of heads where that's common. just did one last week. the valves are just hanging open a little bit due to carbon build up. no big deal, a leak down test is nice in some situations but is nothing like the high RPM dynamic situation in an engine where minor losses don't mean anything over those kinds of durations.

 

if the engine was overheating - then you probably had headgasket issues. EJ25 DOHC headgasket issues are easily diagnosed, they're so easy that i've never had to really do any tests at all. car overheats completely randomly. radiator or coolant losses will be completely predictable overheats - EJ25 DOHC headgaskets are not predictable at all. bubbles in overflow tank indicate exhaust gases getting pushed into coolant passages. and when running hot - if you turn the car heater on it'll blow hot for a minute and then cool down to ambient temps even when the car is running hot. all of this is DOHC specific, the SOHC have different symptoms and failure modes...though are just as easy to diagnose....

Edited October 15, 201213 yr by grossgary