We are fixing up my husbands 350z for my daughter. Its a 2004 base model. We repaired an oil leak, put in a new radiator, new drive belts, transmission fluid flush, and new camshaft sensors as the old ones had oil in them from the leak, we also had the engine compartment deep cleaned to get the residual oil cleaned up. Despite all of this, the engine bay smells very hot after driving, not hard driving, just around town, and the floorboards in the cabin get extremely warm. The engine temp gauge stays right in the middle, so it does not appear to be overheating, per se. Occasionally the cabin will smell like burning oil or even gas vapors, but it is not constant. We had the 110k mile service done and aside from the fixes above everything else checked out. Does anyone have any suggestions of where or what to check next? I just want to ensure the car is safe for our daughter to drive. Thanks.

 

It sounds like a fairly substantial oil leak. If I had to guess, there's probably still some residue burning off which is what you're smelling. I would recommend taking it to a trusted mechanic to give it a full shakedown to make sure it's roadworthy for your daughter. But, you may have already done that.

As to your other question - yes. These engines do run hot. I experience similar heat in the floor when driving. It could be from the hot roads or the engine, or both. The Z is not exactly a luxury comfort vehicle. lol. If the engine temp is fine and the oil pressure/level is still good, it's unlikely that anything is leaking and burning off. I imagine you've likely gotten it up to operating temperature a few times and if there were any bubbles in the cooling system, they would have reared their ugly head by now.

 

You mentioned replacing the radiator, did that job include a replacement thermostat and hoses? Given the age of the vehicle I would recommend tackling these items for peace of mind. I would have recommended upgrading the radiator to a larger aluminum unit because YES, these cars do run hot. Ever since I put the Koyorad in my Z, the temps have been noticeably lower on the gauge. The car still gets up to operating temperature quickly, it's just able to more rapidly react/manage operating temps under harsh driving conditions (WoT or hot weather days).

If the floorboards are getting warm, my 1st thought is, are the exhaust heat shields intact? Is there an aftermarket exhaust system installed?

Other things to check would be...
1) Rear diff bushing replacement. (common failure point)
2) Front Compression rod bushing (inspect and replace if needed, common failure point)
3) Front Lower control arm bushings (inspect and replace if needed, common failure point)
4) Shocks/Struts if they're original (common failure point)
5) Brake fluid flush (if fluid is dark). Also clutch fluid if applicable, but sounds like it's an automatic trans.
6) Brake pads and rotors if worn/grooved.
7) Tires if they're 5+ years old or showing signs of sidewall cracking or dry rot.
8) Rear wheel bearings (inspect and replace if needed, common failure item on Z33s)
9) Rear differential fluid service.
10) Sway bar end links (common failure item, inspect and replace as needed)

Regarding the odors in the cabin, that's a bit unusual. Sure you will get some smells if you had serious oil leaks around the exhaust system, have the A/C set for "outside" air or windows down. There will be a burn-off period after having the engine bay cleaned up. But if the odors persist after a week of driving, further investigation is warranted. If you have a leaking injector or a bad seal on the fuel pump or gas tank, there's a potential fire hazard.

Good Luck!
-Icer