Hi guys. I have a 95 z34 and the engine is ideling extremely high (4000 rpm)! Also there is white smoke when it starts. The car did need a radiator when i bought it do you think that i have a blown head gasket or could the white smoke be from all the fuel that the car is dumping into the engine? The oil looks and feels good but i could swear that i could smell just a hint of gas on the dip stick although 2 of my friends said it smelled fine. Im baffeled!!

 

Donnie:
Heres a cpl tests to perform to check out your issue...

I would first do a leak down test on your cooling system..
Did you bleed all the air out of the system when you replaced the radiator?

I would also recommend removing the plugs to see what they look like..
another tell tale sign of a possible blown head and or leaking UIM and LIM gaskets..
Have you been losing Anti Freeze?
a bad head gasket/head or uim lim gaskets could explain the white smoke.
Does the exhaust have a "sweet" smell to it? It could be using/burning coolant.

The high idle could be a vacuum leak...
spray WD40 around all vacuum lines and if the motor raises idle and or starts to stahl out ..that area would be the Vacuum leak is.

I'm sure others will chime in with more suggestions/Ideas.
Keep us posted on the fix and let us know..Maybe your experience will also help others.

 

Those 91-96 DOHC z34 engines are notorious for the upper intake leak. ESP as the weather turns cold. Start em up and idle high as hell. Once engine warms most the time they would seal off as everything expanded and the idle calms down.
Spray some brake clean or carb/ intake cleaner around the intake when it idles like that and listen for the idle to change.
Bet back in the day I'd change intake gaskets on those z34s at least 3 times a week.
Even though it's usually the upper plenum gaskets that cause that leak, I'd suggest to change the lower intake gaskets while already got it half way apart. If that is the problem as I suspect.
I've also owned 4 of the lumina z34s and 95&96 monte z34, had to change gaskets on all but 2 of the luminas lol.

 

Would that upper intake gasket being bad cause white smoke and or a slight smell of gas in my oil?

 

Also i havnt had a chance to test any theores yet because ive got to put the radiator back into it. Thae radiator was bad when i got it and ive been so tied up with work anc the holidays before that but i plan on doing it this weekend. Thanks guys.