power loss/ smoking

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1990 300zx N/A manual

I bought a second Z32 so that I could learn about cars. The one I bought did not run when I got it, but after a little research, I was able to figure out that it just needed a new starter along with new injectors and and Coil Packs/connectors. After I installed those the car ran fine for a while. Now the problem is once the car has been driven for about 10 minutes, it starts to loss power and starts to smoke. I have talked to some people and they give me mixed answers. Some say it's an engine problem and some say it's a transmission problem. I have been checking the oil level daily and it has not changed. The engine does not seem to be overheating either. The smoke looks like it is coming from the back of the engine bay, but in my opinion it looks like the smoke is starting from somewhere lower than the engine and raising up through the engine bay. I will get some pictures in the near future to help aid my description.

I will keep updating with more information. Could I get any ideas as to what I should check next to get these problems solved? Don't hesitate to ask for more information.

Also, I don't know if this information is necessary but the transmission makes a hissing sound when the clutch is disengaged.
One last thing, where is the transmission fluid dipstick located(if there is one)? I'm still learning lol. All help is greatly appreciated.

[t.mcginley.jr]

Could be smoking from the exhaust manifolds/pipes? Possibly bad exhaust gaskets? Or oil leaks higher up dripping onto the exhaust causing smoke? Pictures would be great, or a youtube video clip. Not sure if exhaust leaks would cause that noticeable loss of power though. Since it starts only after 10 minutes of running it must be related to the engine getting warm/hot. Pop the radiator cap and see if the fluid bubbles at all when the engine is running (after its warm).

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Alright, I popped the radiator cap and let it run for a bit. The fluid is bubbling some, not quite overflowing though.

[mrmoose]

There is no fluid dipstick for a 5 speed car..... the fluid will bubble up and over flow out idf the cap is off, what you are looking for is an oily film or lots of bubbles coming up. not a few, a lot of constant bubbles. from what you posted id say a bad t/o bearing from the hissing sound, maybe egr, still got the egr? more info please! vacc leak is verrrry possible...

[t.mcginley.jr]

The more I think about it the more I think it's the EGR valve... a vacuum leak would cause problems all the time not just when its been running for 10+ minutes.

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Ok, the fluid is bubbling a lot with the cap off. It is not quite overflowing, but it is close. The bubbles do look a little oily. EGR valve is a new term to me, so I will research it and let you know what I find.

As for more info about the transmission, There is a small grind sometimes going into 4th, but once in forth, there is no hiss. I don't really know what else to tell you at the moment, but if there is anything specific you want to know, tell me and I will find out for you.

EDIT: Smells like it is running a little rich after being driven. When I let the car idle nothing seems to be wrong. It idled for an hour with no problems. Drove it for about 5-10 minutes and the problems started again.

[t.mcginley.jr]

a consistent stream of bubbles + oily film coming out of the radiator neck while idling = head gasket leak(s)

the EGR valve basically recirculates exhaust gas into the intake manifold to be burned again, which reduces combustion temps while cruising at a steady speed. It's located dead center on the back of the engine. If it leaks or the diaphragm is shot, it will cause idle/driving problems and loss of power. It's a b**** and a half to remove with the engine in the car. One of the previous owners could have already removed it (aka EGR delete).