Leak Down Test results mechanics please help

[watchdog153]

My car has been using a quart of oil every 250 miles since i bought it.... i still cant figure out why.

I changed the headgasket after my car blew a water hose and overheated. When i put it back together i used arp headstuds and a metal gasket with copper spray. I also installed a brand new turbo at that time from force performance. bla bla this is a long story...

As of right now after all the work ive done to this car it still uses a quart of oil every 250-300 miles

I did a compression test after the headgasket change. I got 190-195 compression on all cylinders. That was a a couple months back.

I just did a leakdown test today. It showed only 5% leakage on all cylinders, but im not sure if i did the test right...

I bought my leakdown tester from Harbor Frieght. The second gauge that shows percentage lost only works at 15psi !!! Also it seemed like it was sticking. When i tested using that gauge set at zero i showed between 40 to 50 percent loss on all cylinders.

I wasnt satisfied with that much loss so I did a test at 100 psi. When i plugged into the cylinder the pressure dropped to 95 psi. Thats only a 5% loss!!

I did the same test now at 50 psi and still only dropped 5% on the main psi gauge ( between 47-48psi)

SO HERE IS MY QUESTION FINALLY... If my compression and leak down are in good (great) shape then how could i be using so much oil??? I put in a quart a week, and its not leaking on the ground.

My pcv valve is brand new from mitsu and doesnt leak. I have a wideband installed and the car Idles/ Cruses at 14.7 and pegs rich at WOT, just like it should with the factory ecu still installed

No dark smoke comes from the tailpipe anymore since i put on the new turbo, but it does have light smoke when you gas it hard (running rich?)

PLEASE ANY MECHANIC TYPE WHO KNOWS THIS CAR GIVE ME A CLUE WHY I WOULD STILL LOSE A QUART OF OIL PER 250 MILES

Thanks for any replies

 

[viperlp01]

When does it smoke. First start up, when it is warm, when you boost, when you let off the gas while the car is in gear giving a high vacuum state in the engine, or you don't even notice the smoke? IF you don't notice it is leaking from some where else.

 

[turbo24]

ok most likely i would assume that your losing the oil due to your rings im assuming there are alot of miles on the block if it is the rings ive had good results with removing the plugs and filling the cylinders with marver mystery oil to free up the oil rings on the bottom of the pistions its worth a shot just make sure u change the oil shortly after oh and let the stuff stay in the engine overnight

 

[watchdog153]

Theres light colored smoke when you give it alot of gas when its just siting in neutral.

I havent noticed any smoke at statup

I think i might retry the leakdown test at 15 psi (the motor was cold when i did it the first time) But i warmed it up to normal operating temperature before i did the test at 100psi and 50psi

 

[3kgt2nv]

do the leakdown test with 100 psi any drop you get at 15 psi isnt going to be noticeable.

And I would think if the gauge is hanging up its not working properly. You should get about a 10 percent drop at 100 psi so it should settle around 90 psi.

 

[watchdog153]

I re-tried testing at 15psi. Honestly i think the Harbor Freight gauge is garbage. The regulator too. Its just way to inconsistent. When you disconnect the gauge from the cylinder i would think the gauge should go back to the reading that you first set it at? This one doesnt even come close. Plus you have to turn the regulator like three turns or more to get the needle to adjust at all. I dont trust this leak down tester

Having said that, the gauge did seem more consistent at 100psi. I think it took a fairly accurate reading with that high of pressure. At 100psi I saw only a 5% drop in psi when i hooked up to the cylinder.

I was just reading on some forum that the 100psi test is only good to search where the flow leaks out, but its too much pressure to test the rings?? Something about the pressure being so high that it pushes the rings against the cylinder wall causing them to seal. They were saying that the 15psi test is a natural operating state for the rings... sounds like BS to me i hope thats not true

 

[3kgt2nv]

the point of a leak down test is to see where you are loosing pressure. if your loosing it past the rings you will hear air movement thru your oil cap or dip stick. if you hear air in your exhaust the valves are not sealing. If you get bubbles in your coolant you hg is leaking.

I was just reading on some forum that the 100psi test is only good to search where the flow leaks out, but its too much pressure to test the rings?? Something about the pressure being so high that it pushes the rings against the cylinder wall causing them to seal. They were saying that the 15psi test is a natural operating state for the rings... sounds like BS to me i hope thats not true

your cylinder compression of 190-195 is the rings sealing. 100psi is fine for sealing rings to test them.

after you set the cyl to tdc of the compression stroke you lock the crank in place with a breaker bar and pressurize the cyl to 100 psi in about 5-10 mins it should only settle to like 95 or 90 psi

 

[blue75blazer]

I have bought a lot of mitsu's with oil usage problems or smoking and fixed with a simple set of valve stem seals. You can replace them without removing the head if you get the right tools.

 

[watchdog153]

Again i dont notice any dark smoke coming out of the tailpipe, ever. Oil burns dark right? So if its not burning it and its not leaking on the ground where else would it go??

Lately ive been thinking maybe the crankcase ventilation system is the culprit. But i dont know im not a pro mechanic. I fixed my own headgasket so i can work on cars but i have alot to learn

My head was just rebuilt by a good shop.

At 100psi I didnt hear evidence of any valve leaks. I did however hear bubbling in my radiator cap and air coming from my dipstick tube on all four cylinders. Also when i tested cylinder 4 i heard air coming from the top of cylinder 3... Even so the test was started at 100psi and only dropped to 95psi, so i shouldnt be worried right?

So back to my original question. If my ring compression is good and my valves are sealing how else could i lose so much oil?

Thanks for the quick replies and for taking an interest. I would really love to fix this shit

 

[cbr600teardrop]

have you changed vavle stem seals?