Ok here's the story of my problem, I hope someone can help me out , I purchased my 300zx :zlove: about 4 months ago from a dealer, since purchase It has been running quite hot, around 3 1/4 the way up the heat gauge about 3-5 mins after start up, regardless of whether its just driving or stationary idling, I have recently done a complete plenum pull, coolant hose bypass, coil pack, injector and a few other plug rewires, along with every single under hood hose, so I can eliminate them from the picture now, so after I finished the plenum pull its still running very warm, and it seems to be dropping its coolant level straight away, after a few minute drive, I keep topping it up and checking it a few hours later and sure enough gone, no visable coolant, I have no reason to believe its a head gasket as its not pushing coolant backup into the overflow, and when i changed my oil it didn't seem to have traces of coolant? but Im no expert, the exhaust is blowin out a a fair bit of white smoke, but it smells more like oil so I think its the turbo seals.., sorry for the huge article, but I didn't want to miss anything out :
Check you passenger side foot well carpet?? Is it damp?? The Z heater core up behind the dash on the passenger side is prone to leaking! & is often the reason for losing coolant!
Its defiantly not damp around the floor, I often have a passenger and I they would probably notice if it was wet i suppose, ill keep an eye on that either way, but I am thinking it has to be something to do with the head or radiator it self, cheers
A couple of things to start with... first, don't trust the temp guage, they are terribly innacurate. second, are you sure you have bled the air out of the cooling system when you refilled it. It is best to have the front of the car raised a little while you do this and to return and check it over a few days... it can take a few goes to get it completely full again As for the smoky exhaust, it's possible that your turbo seals are on their way out, but I have found that mine will do the same if I let it idle for more than a couple of minutes ( and mine have been overhauled).. . It could just be that they leak a little bit of oil past the seals while they're cold. Have a look again once the car has warmed up. If you dont go through much oil on the dipstick stop worrying. Lastly don't take any chances and go get the cooling system pressure tested. It will be the best money you have spent given that you've been working on the car recently. Hope this helps. Andy.
There is really only 3 positions on the temp gauge. At the bottom - < 50 degrees Somewhere between cold and hot - running temp Off the scale - overheated The exact position for running temp varies. However the needle does not move with smaller temp changes. Same position for 60 degrees as for 95 White smoke = water Blue smoke = oil Get a gas analysis of the coolant too when you get it pressure tested At least your thermostat must be working if it comes up to working temp quickly (as opposed to mine)
A head gasket can go in a few ways. It can break between oil and coolant galleries, and it can break between coolant and combustion chamber, or coolant and outside. Oil and coolant mixing is a symptom of the first case. High coolant temps and magically dissapearing coolant is a symptom of the later. Your white smoke...is it constant? or just on startup and idle. Shine a torch through it, if there is a blue tinge it's oil. I personally can't tell visibly easily between oil and coolant smoke without light shining though it. If it's white with the torch then it's water/coolant. Also, chock up the front of the car so it's higher and the radiator is the highest place on the system. Start the car with the radiator cap off and let it idle up to temp, have water handy and keep topping up the radiator as you need to so you can see whats going on. You may have a really temperamental air pocket in the block. Shut the car off once you get it to temperature and stick your nose in the radiator...if you smell exhaust, your gaskets gone.
Thank you guys, you've been very informative, I will bleed the system tonight and see if that will keep the levels up, as for the smoking problem, it seems to be very intermittent, it will smoke just after its warmed up, then stop, and then will start smoking again after I let it idle after a hard drive, it will not however smoke under throttle
Yes, well smoke symptoms sound like turbo exhaust seal or stem seals. Recommend a stop off at a radiator joint so they can test for hydro-carbons in the coolant. It's a quick test, only about $50 or so.
