Ok here it goes... Just bought a on my 84 SE 2.5L Fiero with 74K. It had been in a barn for many years (3-8 years?) and I was told it wasn't running due to non functioning fuel pump. I replaced the fuel pump and the engine started...it had a high idle @ 3,000+rpms and I then noticed that the exhaust manifold was cracked... grrr! So, I replaced that and the o2 sensor. Still high idle, So I looked for a vacuum leak and then moved to clean and reset the IAC valve. Ok, the idle went back to normal, but then blue smoke!!...?? yikes.

So, I did a compression test.

#1 145psi
#2 less than 30psi (so here's the prob grrr)
#3 145psi
#4 145psi

Next, I pulled the valve cover and wow, a pushrod was sitting off the rocker arm on the #2 intake valve. I took a look at the push rod and it was slightly bent. everything else looked A-ok (valve springs ect...) grrr... So then I thought I should pull the head to see if the valve is bent or the head was cracked...

Pulled the head and the valves on #2 look good and seated nicely...no visible cracks on the head. The # 2 piston had a faint mark on it from the intake valve apparently hitting it a little, but no damage or cracks or dents, just a small mark.

So why the low compression? The pistons walls look nice and smooth and I cranked the engine some and it looked good to me. the rings should be ok as the other pistons were great... Visually they looked nice and tight.

Moving forward, I checked the lifters... I pulled the lifters on # 2 a and they looked nice and shinny, I looked and felt the lobes on the cam and they were smooth and clean. ...Although, I have no idea if the lifters are good or not? The only thing I noticed was when I pushed with my finger on the top of the lifter, while still in the engine, it was a bit weak and compressed easily. While the other lifters I couldn't really push the top down with my finger...

I am assuming the lifters are more than likely bad so I will replace them. Might as well...I'm going to replace the pushrods and refurbish the heads, valves, ect...

All and all what I think happened was.. the lifter went bad and became weak, causing the pushrod to become loose and it probably became misaligned somehow, then causing the intake valve to over extend itself and tap the piston...then it finally just fell off the rocker arm...

Any thoughts on this craziness?? Thanks in advance!

I came to the same conclusion while I was reading your post.

ok cool. Thanks, Hmmm but why the low compression?

The burning oil? I think, if the intake was basically not opening, would the vacuum created by the piston, suck in oil from every where, then burn it off creating the blue smoke?

You could try checking the strength of the valve springs on that cylinder. If the intake valve spring failed then the valve may not have closed completely, allowing the piston to contact it, as well as allowing the pushrod to become unseated from the rocker since there would no longer be any tension holding the pushrod into the rocker. That could also explain the loss of compression if the valve jarred partly open... the blue smoke is anyone's guess but it could be unburnt fuel getting through the loose valve. All speculation though.

quote Originally posted by jasonn674: ok cool. Thanks, Hmmm but why the low compression? The burning oil? I think, if the intake was basically not opening, would the vacuum created by the piston, suck in oil from every where, then burn it off creating the blue smoke?

Yes, and it would also account for the fact that it can't fill the cylinder with air completely. Not as much air to compress, hence low compression. Get it hooked back up and it may still be OK if everything else looks good.

Collapsed lifter allowed the rod to come off. That valve is either in the openor shut position I would guess partiall open allowing the unburnt fuel into the chamber. You can try and pull the intake and attempt new lifters just hope it didn't damage a lobe on the cam.

quote Originally posted by kikinz24: That valve is either in the openor shut position I would guess partiall open allowing the unburnt fuel into the chamber.

The valve spring would have snapped it shut as soon as the rod fell off the rocker unless the spring is broken or the valve stem is bent preventing it from sliding up the guide.

quote Originally posted by kikinz24: Collapsed lifter allowed the rod to come off. That valve is either in the openor shut position I would guess partiall open allowing the unburnt fuel into the chamber. You can try and pull the intake and attempt new lifters just hope it didn't damage a lobe on the cam.

My $$ is on the lifter too... temporarily jammed the rod into the open position until the valve kissed the piston, bending the rod and preventing the valve from opening from then on- and causing the low compression. you're sucking in oil due to the vaccum it creates with every stroke of the rod, thus l would use this car for parts: buy one without any driver-side damage and put the good interior from this car into that one...lol

The valve hit the piston and made a hole in it.

nitroMusky: buy one without any driver-side damage and put the good interior from this car into that one...lol

hahaha! I never mentioned my car had any driver-side damage... Perky! lol

quote Originally posted by jasonn674: Pulled the head and the valves on #2 look good and seated nicely...no visible cracks on the head. The # 2 piston had a faint mark on it from the intake valve apparently hits in advance!

doesn't sound like a hole in the piston to me