My 2008 350z base almost has 50k on her. I noticed a vibration sound and while searching for that I noticed a sweet smell coming from the engine bay. Everything about the car is normal besides that vibration ( sounds like that is middle or back of car). Smell gets stonger when I get close to the coolant reservoir. Coolant level is normal and engine oil looks good. What should I be looking for?

 

Masphx, the ethylene glycol used in most all antifreeze mixtures has a characteristic sweet smell/taste, look for a leak.

You also mentioned a “vibration sound” do you mean a sound that has the tone and frequency of a vibration or is the engine/car vibrating?

 

That would be a tone and ferequency type of vibration. Will check for leaks tomorrow.

 

J2's right about that. Follow all your coolant lines looking for green/white residue. And below them.

If that fails, drive till normal temp, leave it running and look for evidence of overflow or steam. Radiator and cap, reservoir, upper and lower hoses, upper and lower heater hoses.

It might be something simple, but be careful and do not work on hot pipes.
GL.

 

Ok, so the area that the upper coolant hose goes to... is thst the water pump? I felt around with my hand (as I cant get a good look of the area) and felt some wetness. No drips or anything. Just a wet feeling with a bunch of black dirt attached to it. Sorry but on my tablet or would post a pic of the area im talking about.

 

Here is a picture with and arrow pointing to the area. Coolant reservoir is blocking the view but it right where the upper coolant hose goes to the engine.

 

Either if you cannot find anything else or as an easy thing to take care of while you keep investigating, go buy a new radiator cap. I noticed a sweet smell from my car as I walked around the front of it in the garage after getting home from work. It turned out that I was in a state of neglect at the time and forgot all about a good working cap as part of coolant maintenance. Mine was allowing some coolant to escape and by the time I noticed it the overflow was empty and was down about 2 oz in the neck by the cap. Caught it just in time even though I had changed the coolant in the car a couple of times already.
Even if your fluids are up to level you may be catching this much sooner than I did. At least put it on the list of things to do/check.
Make sure you clean the area you found real good and look for residue to come back. keep a good eye on fluid levels until you find the problem. They can change pretty quick depending on where it is escaping.
If all else fails look into if the coolant is a fluid you can add dye to and check with a light. I thought you could do that for oil, A/C, and coolant.