Let the games begin! Thanks in advance for everyone's help. My car is a 1995 355 GTS with about 15,800 miles and Tubi. Rattle 1: cold start rattle coming from engine compartment. Pretty loud and noticeable for about two minutes with small bits of white smoke when revving. After about 5 mins of driving, no rattle, no smoke, engine runs very smooth and pulls hard after warmed up. No check engine or other warning lights at any time. I'm thinking maybe an issue with the cats? For now I can live with it but I'd still want it addressed sooner than later. Rattle 2: low speed rattle that disappears at higher speeds. I only notice it when driving through the neighborhood. Does not rattle during idle. Comes on with light or trailing throttle. Doesn't necessarily sound engine related, maybe another loose heat shield? My car has never thrown any warning lights, consistently runs in the 180 to 210 range and feels strong. It does need a major soon. Thanks everyone!
White smoke is a sign of burning coolant. Does the smoke have a sweet smell to it? The most common rattle are heat shielding and the bypass valve.
It looks like smoke to me. It is a very small amount. The smoke and the rattle disappear around the same time, so I'm pretty sure they're related somehow. Doesn't seem to be a major issue but it definitely was not there until recently. Nothing seems to be leaking, at least not that I can see from underneath.
The only extra noise that is supposed to be there at startup is the Secondary Air Injection systems air pump. It is noticable above the exhaust. It goes off after several minutes. The air pump is sending fresh air into the exhaust system to help with emissions/cat heat up at cold start.
The air pump you mention works perfectly and does shut down after a few minutes like clock work. The rattle I'm hearing is definitely not supposed to be there. Would it be related to the cats? I have heard rattling cats before in my SLK 320 and this rattle sounds similar.
(1) Are you in a cold climate? What is the ambient temperature when you see this smoke? (2) Bypass valve rattle is my guess.
Car is located in Florida with temps in the 70s and 80s right now. Although it has fluctuated, last week the temps were more in the 50s.
