hi, Im pretty new to this site, and wanted to know if anyone could help me with my engine problem. i have a 78 bronco with a 400. last time i started it i notice smoke was coming out of the oil gauge and oil cap in the valve cover. i know basic stuff on engines, and wanted to know if anyone knows what is causing this. It runs fine and idles right and no smoke from the exhaust.

 

So it smokes from the cap area when the cap is on? Or...when you take the cap off?

And coming from the oil gauge inside the cab?

 

both on and off and where the oil gauge goes in the motor

 

Just to clarify, are we talking about the valve cover on the right or left of the truck?

Also, do you have trouble maintaining the oil level; i.e. does it burn oil?

Any oil leaking from those areas? Smoke from the exhaust?

Also, have you noticed any oil in the radiator or water in the oil?

 

its not leaking, its sweat from all that horsepower!!!

but seriously i would definately pull the dipstick and check for whitish foam at the top of the oil level, (assuming you have oil on the dipstick) which means water in the oil, pull the radiator cap and look for oil pooling on top of your water level. what you describe could be many things, from sludge, blown head gasket to a spun main bearing. no measurable water loss means no blown head gasket, and a functioning oil pressure gauge usually means no spun bearing and then you have sludge. the way you describe the oil sending line may point to a bearing issue, and while the engine will run and idle fine there may and may not be a rattle in the top end since the oil routing is what it is in these models. hth

 

oil level is fine and no smoke in the echaust, no water in the oil and no oil in the radiator. how can i get a good check on the oil pressure and if it is low what does it mean.

 

I've always ran a mechanical gauge from behind the intake and through the firewall. you can usually pick up a new one for 25 bucks and install it, if you're not familiar with the plumbing on this you should be able to look up that info somewhere perhaps check the details with the new gauge. As for what the pressure should be, the usual school of thought is 10psi per 1000 RPM, and around 20-30 for warm and idling. I'm still concerned as to what you were describing as smoke form your OP gauge, and as to exactly where the smoke was coming from? Is it from the line or the gauge its self? could you describe what kind of line is running on your gauge cause plastic will sometimes split if it's older line. had a plastic line split on me while i was out of town once and dumped 3 quarts b4 i got it off the road.

 

I think what you are seeing is blow-by. this is where combustion gases that sneak past the piston rings and make it to the crankcase.
THese are usally sucked up by the PCV valve andsent to the intake manifold.
Your valve may (probibly is) plugged up.

 

yeah I have seen something similar when the pcv valve is disabled or not functioning on a motor

 

is it bad for it to smoke where the pcv goes when off

 

pcv(pressure crankcase ventilation) valve is cheap and very easy to change, buy a new one and see. Just a normal maintenance. my 02.