617G

iTrader: (6)

I had infiniti do a compression and leakdown test of my engine and the compression came out as 180 for 3 cylinders and 185 for the other three. The bad news is that my leak down is 20%, according to their tech, who passed the info on to the service manager. Each cylinder is at 20%. Infiniti claims that 20% is within spec. Does anyone have any thoughts on this? From what I've been reading, 20% seems REALLY bad on a stock motor, and I'm about to go F/I? Do I need to rebuild before I go f/i? Is it remotely possible to have infiniti do anything under warranty? The service manager said he called their tech line and they said 20% is good....am I being lied to, or do they not know any better?? Should I get a second opinion? Could the Z tube and popcharger be the cause of this if the air is leaking through the intake maniford?

Also, if my compression is at 180-185, why is my leakdown so high? I only have a 5 psi difference between cylinders and 185 is pretty damn good, if you ask me. Therefore, I'm not really losing much compression, am I? So, I'm a bit confused...

Thanks guys...i'm in a bind here...

Enron Exec

Compression looks good. The 20% leak down is on the high end of "within spec". When i popped one of my cylinders and ran a compression and leakdown test, the good ones showed 15-19% leakage. It seems our VQ's are built kind of on the loose end maybe? But all in all, your motor is in good health. If you decide to FI it, make sure you find someone to get a great tune. Safe air fuel, conservative timming, and no sporadic torque spikes.

Oh yea, to find out why the leak down is on the high side, you have to trace where the air is coming out of. If alot fo the air is comming out of the intake, exhaust, or PCV, then something is wrong. If its comming out of the radiator.. then your head gasket(s) failed.

Sharif@Forged

iTrader: (92)

Compression can be high, while leakdown can be very very poor. 20% leakdown is pretty bad, in my book, but for an OEM engine, maybe Nissan specs call for 20% or less leakdown. Have them show you the specs in the service manual. if 20% is within spec, than you are out of luck. But I would never FI an engine that leaked down at 20%.

Lastly, I have seen a lot of mechanics mess up leak-down tests. If not done precisely, and with a high quality and accurate gauge system....you can get erratic results.

Does this engine consume any oil or smoke under heavy load?

617G

iTrader: (6)

Almost no oil consumption and no smoke from my tailpipes from what I know. Then again, I'm not really looking at my tailpipes. Supposedly, the leakdown test was performed by their lead tech, because no one else was capable of doing the job. I will almost definitely be getting a second opinion. I think I just got a huge setback in my F/I plans...Unfortunately, they did not tell me where the leak was coming from, the headgasket, exhaust valve, intake valve, etc...so I don't know what the problem is. I guess the good thing is that the numbers are all the same, which actually has me raise an eyebrow. The fact that they're all 20% and the same seems a little sketchy to me. I will get a second opinion and have the shop pinpoint where the leak is coming from. What bothers me the most is that if it's the piston ring and I need new pistons/rods, then I would have purchased a turbo and not an s/c. I guess we'll see how things go.

Enron Exec

Yea, get a second leak down test from another shop. I dont trust Nissan techs. The "lead" nissan tech at my dealership didnt re-installed my coil packs on correctly so i was missfiring back in the days i had an ATI SC. Then at another dealership, their "lead" tech was afraid to change my crank belt because there where so many aftermarket parts in my car. Every time i see a Nissan advertisment on how well trained their techs are... i throw a fit. ;"(

617G

iTrader: (6)

You would think that an Infiniti tech would be more competent...Well, I will try to find a good shop to do a proper leakdown test. If the results come out the same, I will at least have them isolate the problem. I am assuming that if it is one of the valves, it can be fixed. But, if it's the pvc, then I would need to rebuild. I chose s/c for the sole reason of not building, at least not yet. I guess I may have to order those Wiseco pistons, Eagle rods, and ARP studs sooner than I anticipated Is there anything else I should consider if it is in fact my piston ring that is causing the leak? What if the leak is caused by my head gaskets? Can they be easily fixed/replaced or should I just build my bottom end while I'm in there?

Thanks a lot for the help guys.

Enron Exec

If all 6 cylinders leak 20%, it could just be the tool, or the tech that consistently measured the results incorrectly. It cant be one valve because all cylinders are showing a 20% leak. There might be a rare chance the timming was off from the factory, but thats 1 in a million. If you had a bad PCV valve and you drove your car hard, then yea maybe the psiton rings are worn and this might be a good excuse to rebuild the bottom end. Still, 20% isnt that bad. Its just not grade A, and few motors are. The head gaskets should not fail in a near stock VQ unless you have overheating issues.

How much oil is the motor consuming? If you drive the car like you stole it every single day, high oil consumption will be normal. Thats true on just about every car.

Oh yea, in the end all it matters is that your motor made good compression. You dont have anyhting to worry about. Well, not until you install that FI kit. lol

617G

iTrader: (6)

lol...I've been driving pretty hard lately and checking my oil consumption. The stick has been pretty steady...only minimal loss. I have my doubts about the tech as well. Not even a 1% variation has me raising my eyebrows. My vortech installer, Scott at Ballistic, is going to do a compression and leakdown test on one cylinder just to see what it reads. You are right, 20% isn't really all that bad. Scott is going to do a once over of my engine to make sure that it is safe for the vortech. The tuner tuning my vortech also knows his **** very well so everything should be cool knock on wood...lol

Thanks for the input.

Zivman

iTrader: (19)

Other thing to think about is the temp of the engine when the leakdown was done. If the engine is cold, 20% leakdown does not suprise me on an aluminium block. If the engine was hot/warm, 20% is unnacceptable.

I ran a leakdown on my motor prior to my build and I was at 15-17% across the board, and the guy helping me out thought it was fine. This was on a completely cold motor. Now, he did say that on a warm block, these numbers wouldn't be acceptable

617G

iTrader: (6)

I couldn't say if it was warm or hot. The service manager did not give me any details. Either way, I'm going to have my installer check one cylinder at first and see what's going on.