Random Blue Smoke after freeway drive

[SolidSnake84]

Hey guys - I have a new to me 1983 F150 - that was a friend's grandpa's - who had to sell it because he had a stroke and couldn't drive anymore.

Motor is a 302 - around 78,000 miles. Runs / idles great - lots of power and good acceleration. The ONLY issue i've noticed with this engine is after a freeway drive, i notice that the tailpipe is puffing a little blue smoke after coming off the ramp.

When you then accelerate - that baby becomes a mosquito fogger that will completely block out everything you can see behind you. It will blow a solid plume of smoke for about 1/4-1/2 a mile and then clean out. The truck runs fine the whole time. It may not do it again when you are out, or, it will do intermittant plumes of smoke.

The weird thing is - Engine doesn't seem to be "losing" oil on the dipstick. The antifreeze also looks good and green, tested well, and doesn't seem to be losing any levels. My dad and I did a compression check - around 160-170 lbs on all cylinders. Dad thinks valve seals could be bad - what are some of the opinions of you guys? Just want to know what i might be up against...

 

[martin]

It might be oil getting sucked in through the pcv. you don't need a lot of oil to make a lot of smoke.

 

[SolidSnake84]

I wanted to update everyone - it ended up being the transmission vacuum modulator. The diaphragm must have had a small hole in it or something because it was sucking up ATF into the intake, and then being burned off.

Weird thing is it didn't shift weird. I ended up testing it by pulling the hose off the back of the modulator - the hose was full of ATF. Popped in a new one and now we're good to go. I've driven it all week and it hasn't made one puff....