Smoke/Fumes from Engine Compartment

[DrewA]

I've noticed that for the past couple of months that when I turn the car off some light smoke/vapors will come from the engine compartment deck lid. I can look down from the engine compartment and see it coming from underneath the bottom rear of the engine, under the exhaust cam but above the catalytic converter. Maybe from the cluch/transmission pack; its very had to see and pinpoint.

If I just let the car idle for say 20 minutes no smoke/vapor is observed.

Normally I would suspect the clutch is slipping but I have no symptons of clutch slip from driving the car. Car is a 91 manual with 55,000mi. Clutch replaced in 1997 at 26,000 mi.

Anybody got a thought?

 

[MiamieNeSeX]

might have a fluid leak, check the oil, or radiator

------------------
White 1992

 

[DrewA]

Definately not coolant. Haven't lost any and doesn't smell like it. Could be very slow oil leak but does not happen if I just let the car sit and idle.

Any other suggestions?

 

[MiamieNeSeX]

Once you drive the car the oil pressure is greater, therfore if it is a small leak it might only leak under the higher pressure

 

[Soichiro]

You may need new cam plug gaskets. Are there any small leaks visible on the floor? If not, get under the car and check for oil residue on the engine - this is what happened on my 91.

 

[BadCarma]

Originally posted by Soichiro:
You may need new cam plug gaskets. Are there any small leaks visible on the floor? If not, get under the car and check for oil residue on the engine - this is what happened on my 91.

thats where I would focus first also.had it happen on mine.check it out,my NSX mechanic fixed it for free while doing other work.Mike Percy saves the day again

David

 

[docjohn]

did it happen after spirited driving? the only time I had light smoke from the engine was at the track and it was crank case venting issues.

 

[Option2]

I agree with the other guys. When I had my '91 my cam seals were bad and experienced the same symptoms.

 

[DrewA]

It happens after whenever I stop the car after about 15 to 20 minutes of driving. There is light smoke coming from the vents behind the glass engine compartment cover. Very hard to see exactly where it is coming from. I do have some oil resudue behind the rear cylinder cam bank. I have also noticed some very small drops of a tar like substance on the garge floor under the car. The spots are just below the rear of the engine and middle towards the passenger side of the car.

Where are the cam plugs located? I gather from the search I did that the cams/valve train has to be removed to replace them. Is that correct? But could not find the location of the plugs.

Thanks.

Drew

 

[ScienceofSpeed]

Sounds like your front cylinder bank cam sensor casing may be melting if the tar is a hard substance when cooled.

The slight vapors trails that many are referring to sounds like normal heat dissipation from the engine.

Cheers,
-- Chris

Originally posted by DrewA:
It happens after whenever I stop the car after about 15 to 20 minutes of driving. There is light smoke coming from the vents behind the glass engine compartment cover. Very hard to see exactly where it is coming from. I do have some oil resudue behind the rear cylinder cam bank. I have also noticed some very small drops of a tar like substance on the garge floor under the car. The spots are just below the rear of the engine and middle towards the passenger side of the car.

Where are the cam plugs located? I gather from the search I did that the cams/valve train has to be removed to replace them. Is that correct? But could not find the location of the plugs.

Thanks.

Drew

------------------
Revolutionize your NSX with ScienceofSpeed
www.ScienceofSpeed.com | [email protected] | 877-863-4520

 

[Larry Bastanza]

Drew,

The cam plugs are located at the end of the cams on the drivers side, that is the opposite side from the cam gears. An oil leak would typically show up about mid-drivetrain where the engine and trans meet.

If you look from the driver's side, just past the throttle body on the heads, you will see the spool valves, then the black plastic flat plugs.

If your leak is coming from what appears to be closer to the passenger side, I suggest you let the car cool down and run your finger along the exhaust side of the valve covers to see if they are weeping.

If in fact it is the cam plugs, you will have to remove the valve train (at least the cams) so you may end up actually doing your timing belt, but I have heard this can be donw without removing the timing belt if you have a very seasoned/skilled NSX tech. I do not beleive this procedure is "by the book"!!

HTH,
LarryB

 

[DrewA]

Thanks to everyone who responded.

I got under the car last night and had a real good look. One of the cam plugs on the rear exhaust side was slightly oily/greasy; just bearly though. Also, the seal on the rear cam exhaust side was slightly oily. I have a feeling there is a very very small leak/weep here somewhere.

I'm going to let it alone and just monitor it to make sure it doesn't get any worse. I just can't see spending a couple of thousand of dollars for something this small. However, the next time the car needs service I'll have them take a look at it.

Again, thanks for everyone who responded.

Drew