Hey guys, I came here looking for some advice on what you think may possibly be wrong with my 2005 G35 Coupe. I have been loking for the past week for answers, but nothing has came up. So to start, I have just recently changed the oil less than 1k miles ago. I have noticed that over the few oil changes I have done since I bought the car my motor has stopped with valve lash and has went from the death sound at 3k to slowly being able to get past 4500 without it. Now it will get to 5500-6500 depending on gear before the motor sounds like it is straining. I have also noticed within the last week it seems like the power delivery is going down. 2nd and 3rd still has pretty good power delivery from 2500-3500, but after that when I shift at 4k/5k it seems like the moter doesn't want to pull like it used to. The loss of power is very noticeable after 1/2 of a tank. When I bought the car it seemed to have alot more take off than now. I am not sure what the problem could be or where to start looking so any ideas would be greatly appreciated.

The history on the car would include a K&N drop in filter, Full synthetic Mobile One 10w-40 with 1qt of Lucas synthetic oil stabilizer, I ran a couple tea spoons of sea foam through the crank case to get rid of some of the gunk, I flushed the oil twice afterward, my coolant fan doesn't work so it relies on the ac fan for cooling in city traffic and the temp has only gotten hot one time, very rarely use ac, clutch slave cylinder seems to be going out from what I found on the forum, ran sea foam through a full tank of gas only twice when a very little amount of water had gotten into my tank, have no actual mods besides drop in K&N, JWT clutch/flywheel setup, akebono 14" bigbrake kit.

 

wow i dont even know where to start.
Cliff notes:
-your car has no power over 3500 RPM
-power loss when you have less that 1/2 tank of gas?
-motor has over heated once

-first fix your fans
-check compression
-check fuel pump
-check injectors
-any check engine lights? pull the codes if there are
-check/change spark plugs

 

I changed my plugs tonight and there was actual oil and not just a little oil saturation on one plug. All of the plugs were burnt, but not black. They were a dark grey. I looked at the pistons from the little hole and they were really dirty. The plug with the oil on it was the first plug right in front of the driver next to the firewall. When I started it the usual turn over and a hickup with a brief OMG ****ing my pants moment and I let go and it slowly started running. It started out at 2k. I got out and it sounded like the valves were knocking, which is a first. I let it idle for a moment until it was starting to show on the temp gauge it was close to warm and I slowly backed out waited for the garage door to close and went on the test ride. It made a small amount of difference, but in all aspects nothing improved enough to say its good. On the test ride it was also alot louder at 4k with the overall exhaust note sounding low as if I had an aftermarket exhaust. To me it almost sounded at if it was flooded or maybe a gasket broke loose. At the end I could hear the PCV pushing alot of air out like it was leaking.

I have not actually overheated the car to the point it was the whole smoking radiator, but it has gotten hot before. I have not seen codes yet and I hope I don't. For future reference how much should the compression read on each cylinder? I am starting to think just from the PCV pushing alot of air out and the motor not having alot of oomf I might need to replace the piston and rings. That would solve my burning oil issue so I didnt have to use thicker oil.

 

wth... o.0 wow ...

what is the full history? this sounds like it was overheated badly, or ran out of oil and starved the top end (which using "restore" and like products can do).

was it this way when bought ? what was the onset trigger for the issues described (which do sound like it is longblock time)...

 

I bought it used and when I bought it the motor felt like it strained past 3k after switching to synthetic and doing some minor maintenance it got better. But I think I fixed it.. All I did was add gas. I guess it doesn't like to run far from full.. Lol this car is just giving me one project after another.

 

As for full history idk.. I have swapped it to synthetic and ran sea foam through the tank and crank vase then flushed the oil twice after running the motor five minutes. Put a cleaner k&n drop in filter in it too. Other than that not really anything big, besides maybe plugs, oil, and adding fluids that were low. Never "overheated" on me, but I did see the temp get kinda hot one day but that was it. Topped off the coolant and never happened again. After I added gas to it it started running fine but that has only lasted a couple days and I am back to half a tank in less that a week..

 

Honestly, this just sounds like you have some effed up shib going on. A lot of these things you're saying you're experiencing are immeasurable. You looked in the spark plug hole and saw black? Wtf? Theres no back light in there. How could you see whats really going on in your piston chamber at that angle anyway? This sounds like your car has been overheated, you have an oil burning and leaking (from the valve covers) problem, and your rings are probably bad. Just junk the car, man. Please don't sell this problem to anyone.

 

Check your oil pressure, what you think is valve noise, may be cam chains without enough tension. Cam chain is tightened by oil pressure, if it's low, it makes noise, lots of it.

In any event, I think you have a big check to write in the future.

 

I agree. I think this car was not taken care of by previous owners and now that I have it the damage might be too far gone in the drive train to revert. The pros of this situation is that it still runs and the rest of the car is good. When I have time I will pull the tank to see if junk is in there, but I'm thinking the car is salvageable with the right price. I don't really want to sell it and cannot sell it til the loan is down enough. This is also my only ride at the moment.

 

How many miles are on it?

 

Roughly 91,xxx. The rings might be at the end of their life. So I'm gonna wait til I have enough for the stroker kit and fix that problem and then go from there.

 

Not a good scenario if you still owe money on it and the engine is toast. A stroker kit may be sweet, but it comes with a large price tag.

 

Right. I was talking to a friend of mine about it and he came up with the idea of buying a crate motor and using that as the DD while I build up the other motor and I could also build up a tranny to match it. I just don't see any use in replacing the pistons and rings with OEM parts when it will be close to the same to replace them with something better. I am guessing it would be a couple k to replace pistons, rings, and hone the cylinders. Is that close?