How did those leakdown tests turn out James? haha guess i wish i woulda hung out longer last night!
-DD [/b]
remember the disapearing blue smoke last night after the redneck tuneup?
yeah well the engine has rusty bores... i did the leakdown tests last night with each at TDC comp and got 6%with 10% max on 3 (the worst) at almost 160* engine temp, the real story was this morning after soaking in marvel mystery oil last night and getting spun over to coat the bores (i got new wires to correct the lightning storm when i got the spark plug antifouler that i modified to work with our heads deep threads and the testers short reach threads, works great i might add lol)
this morning after the oil had a chance to work in i cranked it over a few times with the plugs out, threw em in with the new plug wires and ran it up to 160* with a couple redneck tunes pulled the plugs and retested the front bank, 4% with 6% on 3
when i was testing 3 last i decided to back the piston down from TDC compression to the begining of the compression stroke what i just found out leads me to suspect rusted/pitted bores
i wish i had done this last night but i was tired...anyway just past TDC i would move the crank/rod down the rings would unseat i'd get 2-30% leakdown and it would take ~3-4seconds before the airpressure forced the ring back to it's seated position
(let me clarify for those wondering, on the compression stroke our rings are seated at the bottom of the ring groove, this lets the high cylinder pressure get behind the ring and apply more pressure to the ringseal between the ring/wall/piston ring groove, when the ring is unseated (aka piston moving downward) the ring unseats and now can leak combustion gasses into the engine crankcase from the combustion chamber (i wont even get into ring flutter and how much power it can cost you). on the power storke the massive cylinder pressures help keep the compression ring (top) seated against the bottom of it's groove as the piston moves down...unless there is rust/pitting on the bores that creates friction that unloads that top ring
this tendance would be very noticable at low engine speeds where pistons speeds are fairly low)
/\ that is about as laymans as i can get i think lol
anyways no big deal ~3-4 seconds before the ring would seat, the next time i moved it, same amount of time for the ring to reseat and leakage to drop to 6 same thing for the next bump to the ratchet on the crank (~5* each i'd say) then it got wierd...
the next bump (4th) took ~ 8-10seconds to seal up and did so till i got to ~90* BTC then bam it went back to the normal 3-4 seconds before the ring would seal up all the way to bdc...
so then after i hit BDC i removed the leakdown tester and squrted another shot of oil in there, not much probably 1/4-1/2 teaspoon, and brought it back up to TDC compresion, hitched the leakdown gauges back up and redid the test...well it started out at less than 1% leakdown...but as the oil was forced past the rings by the air pressure it went up to 4% and pretty much stayed there for a minute so i started to back it down from TDC doing the same as before well it improved to say the least (oil does that) with about 1-2 seconds for the first bumps but as i hit the tight spot it started with 8 seconds!, the next bump and susequent bumps were at ~4-6 seconds till i hit ~90* after TDC where it went to ~2seconds.
the best i can guess is maybe at the begining of the rust patch the ring kinda hung up a little longer because the rust may be concentrated on the bottom of the bore where dew/condensate would settle and just needed to overcome the oil/rust
i am pretty sure there is rust and/or pitting in the bores, i have seen this before on stored engines...and with the rust in the IS3 intake ports i wouldnt doubt that condensation got in there...thats the only way i can account for the 8 second spike on the second test of cyl 3...
i probably should have pulled the IS3 heads off when i got the car as soon as i noticed the condensate rust in the intake ports....
all i can hope for is that it is just a light surface rust that will wear away...but if it's pitted it and the other 3 like it are gonna have more blowby...
keep yer fingers crossed folks...please
