TunerMaxima3000

iTrader: (4)

As some of you know, I recently picked up another 5th gen. 5.5 to be exact.
The car ran like crap, to keep things short, so I started investgating farther today. I know the front bank spark plugs are bad, today I found the rear to be not too bad, but I'll be replcng all 6 of course.

Down to the main issue, Compression.

FYI, FSM reads the following:
Standard Compression = 185 PSI
Minimum Compresion = 142 PSI
Maximum Difference between cylinders = 14 PSI

EDIT: I just thought of this, but by the time I got everything apart, I had to run out and get a replacement compression tester, so the bloody engine was probably cool by the time I got the test done. I'll be reassembling and posting results again.

My test results (PSI) :

Cyl #2 >>> DRY test (base) = 150 >>>>> Wet = 210***
Cyl #4 >>> DRY test (base) = 165 >>>>> Wet = 235***
Cyl #6 >>> DRY test (base) = 195 >>>>> Wet = 245
Cyl #1 >>> DRY test (base) = 200 >>>>> Wet = 230
Cyl #3 >>> DRY test (base) = 200 >>>>> Wet = 245
Cyl #5 >>> >>>>>>>>>> Wet = 235

Cylinder#5 has oil in the spark plug hole, so I was unable to get a baseline for that cylinder.

Obviously, it seems cylinder #2 and #4 have bad rings, I thought this was strange though, does anyone else feel that way? I find it hard to believe that just 2 cylinders would wear the rings out and the rest are perfectly fine. Especially 2 cylinders that are right next to each other.

When I did the dry tests I assumed I had a bad headgasket, (hoped it was a headgasket anyhow) but the wet tests don't really lie, so I guess I'm asking if you guys think there could be anything else that is wrong, or am I into doing piston rings on #2 and # 4?
I should mention, the spark plugs on #2 and #4 were carboned up BAD, which re-enforces bad rings IMO.

Also, I am assuming that the oil in my # 6 spark plug hole is just from a bad seal on the valve cover? Can these be replaced without replacing the whole cover?

Thanks for any help here boys, I'd love to get this car up to snuff so I can decide what to do with it.

Oh, here's a couple pics of the process, just cause we all like pics so much







Ready for bed:

Xpcgamer

iTrader: (5)

I think a leak down test may be benefical. You need to find out if the valves are sealing correctly before you start thinking about rings. Turn car over and listen for leaking valves on the compression stroke.

TunerMaxima3000

iTrader: (4)

I'm not disputing that a leak down test may be a good idea, but I have a spike of 70 PSI on one cylinder when I add a touch of oil to the hole. How could that indicate valves as a potential issue?

Xpcgamer

iTrader: (5)

Ahh...Good point. Try the cheap "hearing" test of air leaking pass the valves. I think your rings might be toast.

Stason

Woot I have the same amount of oil in the same cylinder! HIGH FIVE!

spock

iTrader: (5)

Unfortunately, you have to replace the valve cover-no seperate seals available. Fortunately, 6th gen valve covers are far less expensive and are said to be of better quality.
I'd order one from the U.S. Nissanparts.cc for example. They only charge $20 for shipping.

TunerMaxima3000

iTrader: (4)

Thanks kindly.





So, has anyone tried to do 2 pistons worth of rings only? And NOT pull the engine?

If possible, I'd like o keep the head on too, but I doubt that's possible on the maxima.

Thoughts? Don't we have any engine guys inhere wtf?

knight_yyz

iTrader: (40)

getting the heads off in the engine bay isn't impossible, but it is pretty freakin hard to take the timing cover off. How do you get at the pistons without pulling the heads?

I think most of the engine guru's hang out in the all motor section.

bamboomerang

iTrader: (14)

The pistons can only come out from the top. New rings without a light hone probably aren't going to seat any better than whats in there now.

Those readings aren't that bad...i'd do the plugs/valve cover/check the cats and some other maintenance and see if it corrects anything. Hopefully you don't need a new TB after sticking your fingers in there.

TunerMaxima3000

iTrader: (4)

I've pulled pistons from the bottom on diesels, it's tough but can be done, I have never worked on a car engine so I have no idea. I know you're SUPPOSED to have the head off. Oh and I tried the All motor forum no replies over there.

Thanks buddy I should have thought to PM you.

Its funny you say that, I was doing some reading of guys with much, much worse numbers that have run the cars for a substantial amount of time with minimal performance loss, just e-test issues.
This car flew through it's etest just a month ago.
I'm going to clean every sensor, and every part removed, replace the rear cover with a 6th gen one (on the way), new plugs, and we'll see how it goes. If it jumps back to life as I suspect it will, I'll make the final decision whether to keep it or sell. I'm currently leaning toward selling.

And what do you mean about the TB? Not sure what you're implying.

I also didn't get the car up 100% to operating temp, by the time I got the gaskets and pulled the IM the car was probably cool, didn't think of that until just now. I bet those numbers won't be too bad at all once it's warm. The difference between cylinders will still be large though.

bamboomerang

iTrader: (14)

haha trust me, there is absolutely no way you can drop down pistons on a VQ- it's one of the better design features on these blocks. The E-gas/fly-by-wire TB's are finicky about being touched, people say you can manually move the plate when the sensor is plugged in and the accessory is on - dunno, but I have personally fubared a TB by opening it to clean it - hopefully yours pans out.

Ya make sure the cam/crank sensors/coils/MAF/plugs/injectors/fuel pump are good, that you have the proper oil filter on there and it'll probably run like a champ. Were you pulling any misfire codes or any codes at all?

Rochester

iTrader: (3)

That's another 5.5 gen thing you haven't run across yet, Tuner. The TB valve is wicked sensitive. I'm on my second TB, the first was whacked by the dealership after running a BG Products cleaning service. (They replaced it on their dime.) Sometimes after being compromised, there no way to get a relearn to take hold.

TunerMaxima3000

iTrader: (4)

Well gosh-darnit. This is my first Fly by wire, I had no idea, just kind of went off what I read online saying to open it up with a screwdriver when doing compression tests, so I didnt' think anything of it.

Well, grab yourselves some opcorn: I'm getting the rear VC from Nissan tomorrow hopefully, and in the next couple days I'll be cleaning and reassembling everything, then we'll fire it up and see what happens.

Boomerang:
No misfire codes, though I'm horribly surprised, considering that 1-3 of the cylinders probably weren't firing given the condition of the plugs. Who knows, I'l find out soon enough.

For now need to check out the IACV on the 2001.