Hot Hot Hot

[K-S]

No i'm not referring to nudes.

My exhaust manifold (in the engine) goes very hot when I turn the car on and let it run for a few minutes and when cold and cold only the exhaust produces some white smoke (not a lot tho) but I hear that is common when cold? I don't know if I'm being paranoid or what? My temp gauge needle has snapped off which is just fantastic so to those that were going to ask what it reads, I don't know.

Excuse my stupidity I'm new

[Steve220]

All very normal. Exhaust gas temperatures are extremely hot and can heat a manifold up within seconds of an engine running. White smoke is an indication of water vapour burning off, which in an exhaust is common due to the condensation forming on the inside over night.

[Light Sabre]

Exhausts are designed and do get hot. I have been to many engine developers and seen engines on test beds where the exhausts are glowing red hot. I did have some video somewhere of a visit to Janspeed where they were developing the exhaust for the ZR and also producing the club cup engines and the exhaust and manifolds were glowing almost white hot, so I would not worry about it too much. It is why there is a heat shield around it (or should be) to protect the alternator and the radiator from radiated heat from the manifold.

Regarding the white smoke when cold it is perfectly normal. Petrol (well most fuels) are hydrocarbons and when combined with oxygen in the right ratio and a source of ignition added, they will burn. This change of state results in various by-products including carbon dioxide (CO2), carbon monoxide (CO) and water (H2O). Due to the temperature of the exhaust gases is well above 100 degrees centigrade, the water will be a gas but as the exhaust gases begin to cool as they pass through a cold exhaust system so the water gas begins to change to water vapour (steam) and eventually condense into water which can very often be seen dripping from an exhaust tip.

As the exhaust gets hotter in use so the water gas stays as a gas for longer as it does not cool so readily so as the exhaust heats up so the amount of vapour seen becomes less. If the car is only ever used for short journeys then the water does not get a chance to evaporate and can and does accumulate in the exhaust, normally in the silencers. This then combines with the other chemicals in the gas producing hydrochloric acid which tends to rot the exhaust from the inside out. It will also result in increased vapour as it combines with the vapour already in the exhaust gasses.

People tend to assume that when they see water coming out of the exhaust that it is head gasket failure, generally that is not the case especially if your coolant level hardly changes.