I foyu are talking about trying to push one down alittle compressing th spring inside it isnt going to ahppen atleast I couldnt on my stockers or my performance comp lifters. If thats how you were talking about testing it then they still could be bad but you wont be able to compress them by just pushing on it.

 

The only way you can truly tell is pull them out. Pushing down on them won't tell you anything - at least not in the way you're describing. Not unless you can see where the rod makes contact and see that they are extremely mushy. But I would think that that should take no effort at all - if they are collapsed. You can push in the plungers on stock or any stock-type lifter, but it is a tough resistance. CompRs are the only ones I know that it's nearly impossible. Even if it is a little spongy, the lifters can drain down some and loose their resistance some. That is why you adjust rocker arms, if you have adjustables, on a warm motor. Because they are pumped up with oil.

 

oh man wish i saw this thread earlyer this same problem happend to my truck no codes or anything turnd out to be a bad MAF assembley replace it and see if that works if not then you just return the new one back

 

A big thanks to everybody for all of your responses to this problem of mine because I am lost as to what it could be and it is starting to **** me off.

 

I have a MAF you could borrow to test if you want. You have to pay shipping both ways though I will need it back as well Sounds to me like a issue with a reading from the MAF or another sensor on your intake. Your pushrods are all straight I assume? (roll them on glass), plugs look good, compression is even so I would rule out a bad cam or lifters. Even if you had a collapsed lifter it would be noisy but no loss in performance. You say you have a sewing machine sound........ Rockers look good? No needle bearings missing? Valve springs look good (so you said)....... Any vacuum leaks? That would give you a good hissing sound..... Have access to acetlyene? Run raw acetelyne around all the vacuum lines and intake to see if the motor reacts to that.... Here's what I think is good and could possibly be bad:

Known good:

1. Valves not bent
2. Springs (so you say)
3. Camshaft not flat
4. Lifters (they could collapse but this still wouldn't lack that much in performance)
5. Pistons/rings are good


Possibly bad:

1. Pushrods bent (roll them on glass)
2. Check needle bearings on rocker fulcrum
3. Check for vacuum leaks with raw torch gas
4. Head gasket maybe? See any tint on the plugs from coolant? Start the truck up in the cold for 10 seconds and shut it off right away and remove plugs, see if you see any coolant on plugs....
5. MAF sensor has some garbage on it (I'll loan you one even if you want)
6. Check brake booster diaphragm (disconnect brake booster main line and plug with a huge bolt)


Are you noticing any irratic idling? Does it hesitate or shake sporadicly at a warm dead idle?

 

HEY!!! We do have plastic intakes!!!! You sprayed and maybe cracked the damn intake manifold!
Seems logical, but your idle should seem a bit rough in my opinion if this is the case.
I think the intake is cracked or you blew a head gasket!

Jim

 

LOOK ON YOUR INSTRUMENT CLUSTER AN SEE IF IT READS "REDUCED ENGINE POWER"

 

Im thinking you floated a valve, how did you check the springs?? how high were you turning the motor, and how high will it rev now? I didnt think you could check valvesprings just by looking at them. Good luck

 

Even if you float your valves, it only means that you reached the limit of the vavle springs rate that they can handle at high RPMs.
It will usually be ok. Possible vavle spring broken, but I don't think it would cause a total loss in power. Possible back-firing with an extremely weakened spring. Do we have a dual valve spring set-up? If so, I doubt both failed. It wouldn't cause a total loss in power if that's the case.
There would have to be several of them damaged to do that.
Guess we will soon find out what the actual problem is when he finds it.
Other than that, we can only shoot out possibilities. Guess we can all agree that we could narrow down to something with the motor.

Jim

 

I would pull the plugs and turn the engine over by hand a few times. Sounds to me like a spun or "walked" main bearing, or partially blocked oil pickup/pump. Metal rubbing past metal is about the only thing that creates a sewing machine sound.

All of the valvetrain ideas go out the window with the sewing machine sound. Bent valves/pushrods, broken rokers, failed springs, failed lifters... all pretty much make a clatter sound, not sewing machine... Sorry to say, I think it's bottom end.