1965 289 oil cap ID

SurfnSnow · 4 Weeks Ago

hi all
I've got a 1965 mustang with a 289 and I need some more information on a part. sorry for what might be a newb question but this is the first mustang (60's era) car I've ever owned.
First, is the item circled in the picture an oil cap? It is the push on kind but I wanted to make sure before I perhaps buy a new one.
Second, when the car is running, there are some fumes that come out of that part. Not a lot but enough to make me smell like exhaust fumes after taking the car out for a drive. Is this normal or should I buy a new one?

Dave · 4 Weeks Ago

Fiil cap/vent, usually has a wire mesh inside that gets clogged up. Your's look new. How fresh is the motor? '66' Mustangs from CA had a tube from the fill cap going up to the bottom of the air cleaner to prevent fumes from getting out into the air and were fed back into the motor. Real quick info.
Dave

SurfnSnow · 4 Weeks Ago

thanks for the reply Dave. The motor was rebuilt roughly 5 yrs ago. I see a replacement fill/cap with the tube extension online, would that be a better way to go?

Ivy66GT · 4 Weeks Ago

Yes, that is an oil fill/breather cap. Those look like '67 style valve covers for which that cap twists into place but possibly not. A real 65/66 oil cap would have been a push in but that one may not be. Turn it and/or pull it to see how its connected. Whoever re-did your engine wasn't much for originality so hard telling what you may find.

There should be a PCV connection on the opposite end of the OTHER valve cover that goes to the base of the carb. Air should go INTO the cap you circled, pass through the engine and draw any fumes into the intake via the PCV on the opposite side. If there is no PCV then that likely explains why fumes are coming out of where they shouldn't. If you do have a PCV hookup then it may be plugged or your engine has such excessive blowby that the PCV can't handle it all. All engines make fumes like that so you have to do something with them. The more worn the engine the more fumes produced.

I doubt that air cleaner has any provision for a hose from the oil cap so such a cap wouldn't do you any good.

SurfnSnow · 4 Weeks Ago

thanks Ivy. the cap is a push in kind. I checked the other cover and couldn't find a connection that goes to the carb. Should I get the oil cap with the valves and connect them to the carb, and if so, where on the carb? here's a couple more photos to show what I'm working on

Ivy66GT · 4 Weeks Ago

Even the twist on valve covers could usually have an adapter to use the push in caps.

If there is nothing on the other valve cover then there might be a road draft tube on the back of the intake manifold which dumps the fumes down on the transmission. Ford would have had one or the other. If you have neither then the only place for the fumes to get out is through the cap you circled which was meant to be where air went IN. If that is the case, then you have to decide what you want to do. Maybe you just want to wipe fume glop off the valve cover regularly.

The PCV connection is into the back side of a spacer under the carb. It looks like the spacer is there but it may or may not have a connection on it for a hose.