Hi guys, I just bought a very original 81K mile '84 Fiero for not a lot of cash. I really wanted one of these back in the early 90's when I first saw one on a trip to the USA (I lived in UK at the time). This one popped up on Craigslist with engine trouble and I like a challenge, so I bought it. It needs a fair amount of TLC to make it nice and it does have a problem that I haven't come across before...

The rocker on Cyl 1 intake is too loose - it won't stay in place. Cyl 2 intake is a bit loose too, but the rocker stays on the pushrod. I haven't measured cam lift, but there is some, maybe a normal amount when you consider the huge gap it has to take up before opening the valve.

The story on this car is that it overheated because the belt broke, then the head was decked and new followers installed. The guy picked it up and it rattled pretty badly so he only made it 150 miles before parking it. He has had a couple of mechanics tell him that the camshaft is worn, but before I go to the trouble of pulling it out, I wanted to see what the experts think.

The pushrod on the worst valve is the same length as a good one, the rocker looks good, no excessive wear in the cups, the pivot isn't worn. I tried a rocker assembly from another valve and got the same huge gap. Could it be a collapsed lifter? I think I know what to do next - check the cam lift and compared with 'good' valve, then pull lifters to see if there is a problem with them. If lifters are OK, pull the cam.

If the camshaft wears easily on these engines, I'll just dive in and do that instead - what do you think?

Your on the right track. I would check lift as well as the valve stem for abnormal wear.
I believe the 84 2.5 have solid roller lifters in them so a collapsed lifter is low on my list. (but not out of the picture)
How many miles are showing on the OD? Any way to do a compression check at this time on it?
That would be a tell all to me.
Is the lift on 3 & 4 better?

This is a little rare and im not sure if the 2.5 heads are the same as the old gm v8s but check the height of your rocker studs in rare instances i have seen them pulled out of the head as the old setups where just pressed in from the factory.

quote Originally posted by MaverickFiero84: This is a little rare and im not sure if the 2.5 heads are the same as the old gm v8s but check the height of your rocker studs in rare instances i have seen them pulled out of the head as the old setups where just pressed in from the factory.

These fit all the way down and are non-adjustable. Bolted, no studs.
Nice thought though.

I could see how a wiped cam lobe could cause the lifter to drop lower in the valley along with the pushrod, thus causing the loose rocker arm. I say change the cam and lifters.

Sounds like bad cam Lobes to me. A 1984 does NOT have roller Lifters, that did not happen 'till mid 1985. the Lifters Can be removed by taking off the "Side Cover". It COULD be collapsed lifters, but I thought you said the cam Followers (lifters) were replaced. If you end up changing the block for any reason, replace it with 1985-86 so you get the benefits of the Roller cam.

quote Originally posted by Lou6t4gto: A 1984 does NOT have roller Lifters, that did not happen 'till mid 1985. .

Many 84s had the later roller lifter engines swapped into them by GM during one of the recalls.

Thanks for the replies. I will pull the lifters and see what's going on. I find it hard to believe that the cam lobe base circle would be worn so much, because it doesn't have the force of the valve spring acting on it, just the hydraulic pressure and a small spring. From my understanding of lifters, the hydraulic pressure is not that high - it just fills the gap and a check valve prevents it from squirting back out. Looks like I'm in for a treat with the cam replacement - where do I go to get the timing gear pressed off and on? Do you guys recommend the fiber or aluminum gears?

quote Originally posted by loach1: Thanks for the replies. I will pull the lifters and see what's going on. I find it hard to believe that the cam lobe base circle would be worn so much, because it doesn't have the force of the valve spring acting on it, just the hydraulic pressure and a small spring. From my understanding of lifters, the hydraulic pressure is not that high - it just fills the gap and a check valve prevents it from squirting back out. Looks like I'm in for a treat with the cam replacement - where do I go to get the timing gear pressed off and on? Do you guys recommend the fiber or aluminum gears?

quote Originally posted by Lou6t4gto: Sounds like bad cam Lobes to me. A 1984 does NOT have roller Lifters, that did not happen 'till mid 1985. the Lifters Can be removed by taking off the "Side Cover". It COULD be collapsed lifters, but I thought you said the cam Followers (lifters) were replaced. If you end up changing the block for any reason, replace it with 1985-86 so you get the benefits of the Roller cam.

I stand corrected on the lifter issue I didn't check my parts book, but doubt still remains due to recalls.
About the cam gear, I wouldn't worry about getting the old one pressed off, just buy a new retainer to install on the new one.
If you don't mind a little bit of extra noise go with the metal gear, any machine shop should be able to do the procedure for you.
I would still do a compression check to see if the engine is even worth saving. Just make sure the valves work at least a little while doing it.

Another thing to check -- see if the pushrods are bent, especially on the loose ones.

The pushrods are straight, well the worst one is straight anyway.

I'm clinging to the hope that the cam is OK. My reasoning is that to have as much clearance as I have on base circle, the base circle would have to be incredibly worn. I just can't see the small spring inside the lifter making that kind of wear happen. A worn lobe peak I can understand - the valve springs are pretty stout.

Another optimistic thought is that this was repaired by a mechanic in a shop, and I am sure they know how to install rocker assemblies and would notice if there was a clearance large enough to just swing the rocker off the pushrod. No self-respecting mechanic is going to notice a gap like that and ignore it.

.180, with the 1.5 rocker arms, thats only .270 Valve Lift ! should be something like .398 . sounds like worn lobes. Check the Lift on the "'known good ones".

quote Originally posted by Lou6t4gto: .180, with the 1.5 rocker arms, thats only .270 Valve Lift ! should be something like .398 . sounds like worn lobes. Check the Lift on the "'known good ones".

The rocker arms are in the neighborhood of 1.7

even at 1.7, that still only about.300 , almost .100 Short of that it should be.

Thanks for clarifying rocker ratios and valve lift.

I'm a metric guy really, so I am thinking to myself that the 1.3mm difference between what I measured (4.6) and the designed lobe lift (5.9), is a lot and is important, BUT... my measuring technique could easily have overshot the peak of the lobe. If I had removed the plugs and was turning slowly by hand I would be very worried, but bumping the car forward while in gear with all plugs in makes for some pretty big rotations each time I bump it. The clearance I have between the rocker and pushrod is way more than 1.3mm (more like 3mm), so I think I have a collapsed lifter (yeah, I'm still in denial!). It just doesn't make sense to me that the base circle could have worn out causing this amount of clearance. Can anyone argue with that?

Is there a way to gently persuade a lifter to unstick by tapping the end of the pushrod with a rubber mallet? I have considered running the engine with ATF and holding the rocker in place by hand so it stays on the rod, but prefer not to touch moving parts on a running engine! Perhaps a squirt down the pushrod hole of some penetrating oil?

I happy that it was a bad lifter after all!
Was the spring broken inside the cup bore?
Did it have roller lifters or what?
About the metal found, bearings comes to my mind.

The spring was fine on the one I took apart. It now works like new (I will replace it though!). They were flat, not rollers, but they don't look new at all - I think someone got short-changed on the repair job. Seems the mechanic kept a few nuts and bolts for his private collection too....

I hope it's not bearing material, but I can't think of anything else it could be. Once I get it running I'll know more about the general health of the engine. I'm not planning on spending much on this engine so if it has problems, it becomes a 3.8 project instead.

It's running, nice and smooth and quiet. It has a couple of issues though - low compression and smoke. One cylinder has only 80psi, the others are around 120. The smoke is the kind that is typical of valve stem seals - idle for a while then hit the gas and poof! loads of smoke. Driving along there is no smoke to speak of. The head has been worked on very recently, but judging by the rest of the engine work I wonder if he used new seals when rebuilding it?? I have a nifty keeper remover that you whack with a mallet that I might try...

seals won't fix 80 psi compression.

quote Originally posted by Lou6t4gto: seals won't fix 80 psi compression.

No they won't, but now I have no smoke and before I put in new seals I double checked compression with a warm engine - now I have 120~150 across the board. I think she's basically sound now, got as much get up and go as I'd expect from the old 4 banger.

I've never done valve stem seals with the head on before, but it went quite smoothly. I used the magnetic keeper remover tool from Lisle to remove the keepers, then used the screw down spring compressor on loan from Autozone. Getting the new seals seated in their grooves is a bit tricky, especially if the rope (yes I used the rope trick) lets the valve drop a tad.