Hey all, I have a '09 G37X coupe around 100k miles. I noticed a bit of oil on two of my plugs when changing them late last year so I figured it's time to change the valve cover gaskets/spark gaskets, etc. I did a bunch of research and found how to remove the upper intake manifold (after a few tries). I found a few things in removing the manifold I thought interesting.

Firstly, the valves seem remarkably clean for a car with 100k miles. Is this usually the case?

I also found some light carbon deposits/burned oil on the intake journals. Is it worth cleaning? It looks pretty superficial, but I'd be happier know they're nice and shiny. I'll assume this is normal, esp given that I found some oil on the intake manifold gasket.


And lastly, I did notice some gunk and oil floating around inside the manifold. Any recommendations on cleaning? Citrus de-greaser, toothbrush, and a hose?

This is my first time doing this to any car so I'm learning as I go. So far so good. I appreciate anyone's feedback.

 

Answers:
(1) Clean valves are normal for any port injected engine. (which is not true for the direct injection engines)
(2) Some oil in the intake is normal, as it is part of the PCV system. There is no need to clean it and it doesn't reduce power or efficiency.

Props to you for doing your own work!

 

That's pretty much exactly how mine looked at 150k. I just wiped it best i could and put it back together. Cleaning it is probably pointless.

 

All together just shows you that this engine is healthy and there is very light oil contamination from the PCV which is completely normal.
The only benefit cleaning will do is it will show you how long it takes to get dirty if you were to clean it.
Doubt you'll be pulling the manifold after this is done however you a visual check at 5-10k will show you how the engine is doing as far as this goes.

 

Hey guys, thanks for the info. I did end up throwing some citrus degreaser in there (because I'm **** like that) and just washed the gunk out. I affixed all new gaskets, cleaned the throttlebodies, etc. I'm taking a slow and measured approach to this since it's my first time and thank you for your feedback.

 

Hey iCrap, were in MD are you?

 

Hey, I'm in the DMV area

 

Alright guys, I am about 99% finished with his job but I've hit a snag. I've found one connector that doesn't seem to fit anywhere. It's 4 wire, on the driver's side by the rear spark plug position, and doesn't seem to have much slack or anywhere to plug into. Everything else fits in fine and easily. Any ideas?

 

Can you see what colors the wires are?

 

Dark green, light green (or yellow), purple, and orange. Everything else is plugged in (MAF, coil plugs, throttle body, everything behind the upper manifold).

 

No guarantees, but that looks identical to the connector for the A/F (air fuel) ratio sensor... commonly referred to the front or pre-cat O2 sensor.

Edited to add image from FSM:

Closely verify your wire colors, however, if in doubt report back.

The pigtail from the sensor likely dropped down. Just route it back up and you should be good to go if that is the mystery connector.

 

Ok, I'll check that out but my wiring looks a bit different.

 

I'm going to assume that LG = Light Green, V = Violet, W = white, and Y = Yellow

 

That is correct. Just check your AF sensor... If it's connected, then we know that is not it...

 

Yep, you nailed it! The sensor dropped so I had to fish it out while scraping my knuckles. All plugged back in now!