I have a 1979 RX-7 that collects oil on the plate under the carb? I've replaced the oil metering pump lines and rubber hoses and clamps securing them to the carb. I've sprayed brake clean thru the nipples on the carb, thinking they were clogged, plugged? Its not just a mist, its maybe 1/32" thick and runs over dropping onto the thermal reactor. causing smoke. This car runs great otherwise, good idle, great start up cold. what should I check next?

 

sure its oil?
maybe its slime like in ghostbusters?
do you have emissions hooked up?
where is it dripping from?

 

This one has me a bit baffled. The only oil source that high up is the mop lines. Are you pre-mixing, perhaps the gas is evaporating and leaving the oil. The other option may be the mop leaking and the fan is throwing oil up, but it should be all over, not sitting on the heat shield part of the phenolic carb spacer.

I have found the rubber elbows on the mop lines can have tiny leaks that are nearly impossible to see, did you replace those along with the plastic lines? Another option may be the mop lines are not fully seated on the barbs on the carb.

 

ill throw this in here
my oil sump gasket was stuffed leaking a quart every 3days some how when driving the oil would pool onto of the engine myth.... no busted

 

is it possible for the pcv system to suck oil out of the engine if it was too full and spit it out around the carb if it wasnt working right?
cuz i know that it can suck it into the intake and cause smoking.

 

This engine has all the emmisions hardware intact. the MOP lines as well as the rubber hoses were replaced. The small clamps are on the hoses. No, I dont pre mix. I believe I also have a pan gasket leaking as well, but I dont think that would account for oil up that high? I replaced the MOP with one from a wrecking yard that showed no evidence of leaking, still doesnt. if I drive for a week in town say up to 40 mph, then very little residue, if I drive 70 75 mph say 30 miles, then I have more residue on the carb plate. If I knew from where it was dripping, I would not have posted looking for assistance. The only source of oil I know of there is the MOP lines, correct? The other leak, which I think is the oil pan gasket runs down the backside of the lower radiator hose, collects on the pan beneath the eng. oil cooler. Engine oil cooler was tested this week under pressure and passed all tests so it was reinstalled. Oh, the MOP lines and hoses were also from the same wrecking yard car, because it was so dry in these areas. Thanks for the quick replies, but I'm still in a quandry. Can the tubes at the carb base be plugged? and the engine survive 3 months of daily use. I did spray brakekleen into these tubes, but saw no evidence thru the air horn that I was doing so?

 

For a test, you could remove the mop, install a block off plate, cap the barbs on the carb and premix. That will tell one way or the other if it is the mop lines. Clean the engine before the test.

 

The oil dribbles in to the carb from the OMP fittings. Most of it makes its way into the engine. Much of it encounters the throttle blades (butterflies). When you close the throttle at high RPM/high flow, the incoming air above the butterflies slams into them. If there is any suspended oil in the mix, it can then condense and make its way outside of the carb following the throttle shafts through capilary action. Likewise for the dribbling oil which adheres to the venturi walls.

The throttle shafts are hardenned steel I think, and the throttle body is cast iron. As they were, they can get sloppy and lead to vacuum leaks in and/or oil leaks out. A dirty old carb can reach a state of equalibrium where the oil deposits block any potential air leaks.

 

thanks Jeff. That makes some sense.