302 sat unstarted for a year. Has about 250 miles on it. Ran it the other day for an hour just sitting in the driveway with no problems. (Put mystery oil in each cylinder through the spark plug hole before cranking. Cranked with the spark plug wires disconnected first to prime the oil pump) Today I was about to take it for a test drive and noticed greyish white smoke coming from both sides of the rear of the engine. Quite a bit of it. From what I can see with flashlights and mirrors and such, it looks like it's coming out of a hole in the rear of the head... does this make sense? Didn't know those holes went anywhere. (91 mustang heads - or so I was told) Gonna be searching the forum about this, but figured I'd post in case someone was like "oh - that's easy!" Thanks guys! -Phil
Valve seals? ATF overfilled and getting into a vacuum line? Clogged oil ports? Needs to have the snot run out of it for a few miles? High RPM Jazz.. Those are the options I've come across so far as possibilities. Thoughts? Tips?
it would start with the smoke almost immediately. Was smoking out of the tailpipes pretty bad too. Only ran it for the one hour the other day at idle. Then I filled the transmission and turned it off. Unhooked the C4 vacuum line at the carb and I'm letting it run hoping maybe it's just sucking trans fluid in. You got a theory?
That was the ticket! I guess I must've overfilled the trans some Should I do anything about it, or just drive and let it suck it through til it burns off?
The only way it can be sucking fluid through the modulator is if it's diaphragm is ruptured... The holes in the rear of 5.0 heads are for the air pump connections so will cause a serious exhaust leak if left open... I assume you must not have mufflers installed??? If you did it would surely be obvious there was a exhaust leak at the back of the engine...
Consensus seems to be replace the modulator. Drivable until this is done or will I break something? So should I plug the holes for the air pump connections with something? Maybe a squirrel, bolt, or small rock... I currently have flextubing running from headers (medium or long tube) to two cheapo mufflers in the back. Exhaust shop is gonna be getting a visit soon... Thanks for the help guys!
While it would certainly lead to a nice clean combustion chamber(old mechanics trick to clean carbon off).. I would never recommend driving a vehicle around for very long while it was sucking trans fluid through the intake tract. And as Krazy Comet mentions above.. you'll need the thermactor hole plugs to seal those heads up.
Picking up a green stripe vacuum modulator at 3pm today. Advanced auto didn't have it listed in their computer but came up with the O'reily part number on the forum threads. Not a pioneer brand, but guessing it's the same. Thermactor plugs are not to be found locally, but I'll probably use bolts until I can order some. For ppl's future info.. Mustang heads all seem to use 5/8x11 threads about 1" long from what I've been reading. Thanks guys! I'll just go for my alignment on thursday instead. Forgot how fun the Mav was to drive!!
if its was transmission fluid from the modulator you would have a super thick fog that lasts a long time. its definitely the thermactor holes where the smoke is coming from. chances are the mystery oil may have gotten them and is what is creating the visible smoke. you can get oil drain plugs in that size thread that will screw in and seal the holes. they are much easier to put in than the factory plugs when in the car.
Thanks! The drain plug idea is probably gonna save me alot of headache Smoke was definitely coming from those holes, but it was also coming out of the tailpipe like a beast. Went away when I unhooked the vacuum line.. I don't put it past my ride to have both things wrong. The modulator is pretty cheap, so I'll just change that while I'm at it to be on the safe side. Thanks for all the help guys
if it went away with the modulator unplugged then you are right and need to replace it. its most likely got a small leak that will get big fast.
When I pulled the modulator and pumped it by hand, I could hear the diaphram was shot. Unfortunately I got a green stripe one and it didn't have threads so I couldn't use it, but I'm picking up a white stripe one today.
