Evaluating 305E engine noise

[George Bongert]

Hello again!

Your lifters were never stuck. Your intake valves on the cylinders you referred to are more than likely stuck, and that is why you have bent push rods. Trust me on this. I've seen valves so securely stuck that they required removal of the cylinder head and the valve springs from the offending valves, and then the valves had to be driven out of the head with a hammer and a punch!!

[massey478]

I would say it is more the result of stuck valves, that is usually the cause I see. I cannot remember if these engines are interference motors; that is, if the pistons can hit the valves if they are stuck open. I think they can, just cannot remember. Yes, if the piston can hit the valves, then if a lifter was stuck in the up position or a valve in the open position because it stuck in the guide, the piston would force the valve back toward closed, and if stuck lifter or valve guide resistance is enough it could bend a push rod. My experiences tend to make me doubt the stuck lifter though but Murphy is an expert at making unexpected things happen! Your lifters are not stuck as you describe so they are not the problem if they ever were. Now, if the pistons hit the valves, a valve head could be bent. Take a hammer and tap squarely on the valve tips hard enough to move them and see if the ones in question snap open and shut with the hammer blows as they should. If they do not do this then they are sticking in the guides. If repeated hammer blows do not loosen them then also try to get some aid like Liquid Wrench applied through the spring at the top of the guide then continue hammer blows until loose. After all is well replace the rocker train, set lash, and then is is best to run a compression test to see if a bent valve is dropping compression in those cylinders. We get a good idea of even compression across all cylinders quickly by just grounding the coil wire and cranking the motor with spark plugs in and the throttle wide open. If you hear a speed-up of the starter motor on certain cylinders as it cranks then suspect low compression in them and go ahead with an actual compression test.
Actually an engine that has had recent repair work done to it like new valve guides, new pistons and rings and such is worse off in long storage if it has little time on it because clearances are still tight and a coating of oil residue has not yet built up to protect parts. When we get a motor we take the valve covers off and check it. When we see the old greasy coating from oils on the parts we know we are probably OK it has been preserved. If it is very clean, then careful checking is needed to be sure it has not had rust form somewhere like the valve guides, cylinder walls, etc. We have found that motors that have had synthetic oil run in them do not survive as well in long storage. Synthetics do not build up the protective coatings mineral oils do.

[62Burb]

Thanks for the helpful replies; i am beginning to get a better idea of how this should work. here are pix of the bent rods. i found an archived post with the NAPA numbers; (215-4052); is it advisable to replace the whole set/ Are they made in Chromoly?

The valve covers came off like they had been on their a long time; does the appearance suggest traditional oil use?

Brad

[massey478]

Top of heads looks normal. I would replace all of the push rods. Definitely do the hammer check of valve movement. On valves with no bent push rods try it, not hitting them like you were driving a nail but hard enough to make the valve 'pop'. Do not hit the keeper edge, just squarely on top of the valve. If it is stuck it either will not go down and pop back up with the same force it took to do it on a good one or will go down a bit and not return as it should. With rocker arms off look for any valves that are sitting at a lower height than others. If they are stuck bad enough, in the open position their height from the top of the spring to the head will be shorter than others.

[62Burb]

Originally Posted by massey478

Top of heads looks normal. I would replace all of the push rods. Definitely do the hammer check of valve movement. On valves with no bent push rods try it, not hitting them like you were driving a nail but hard enough to make the valve 'pop'. Do not hit the keeper edge, just squarely on top of the valve. If it is stuck it either will not go down and pop back up with the same force it took to do it on a good one or will go down a bit and not return as it should. With rocker arms off look for any valves that are sitting at a lower height than others. If they are stuck bad enough, in the open position their height from the top of the spring to the head will be shorter than others.

So far so good with the valves; one was definitely still stuck but yielded to the hammer. They all appear at same height. i should have had the pushrods by now but the Amazon shipper screwed up and sent me "2" instead of " 2 sets of 6' so i went with Rock Auto and will have them Monday.

I pulled all the pushrods out to make sure only the 3 I knew about were bent. When I went to slip them back in place (awaiting replacement) one of the #5 pushrods hung up, and will not fully insert. Not wanting to do any damage, I'm wondering how best to deal with this when the new rods go in?

[massey478]

You did not say how far it missed go0ing down, hopefully it was not too much, so here is my best answer for now. With the push rod out, look down into the head to see if anything has fallen into the lifter push rod socket. Also if the lifter has been pulled up higher in its bore and is just sticking there. If it appears to be just sticking high, put the old push rod back in and tap on it lightly with a hammer to see if the lifter will go back down.

[62Burb]

What happened is that when i pulled out several pushrods to make sure no additional ones were bent, oil suction (I guess?) caused a couple of the lifters to pop out of the block. The pushrod hole in the head is just large enough to let the lifter tip out of alignment with the lifter hole in the block. I found I could just reach the top of the lifter with my finger and wiggle it around until it felt centered, and then tap it into place. The last one required more effort; I think because it was compressing air inside the block, with a piston-like effect, however small. I'm hoping that solves the problem; thanks for the counsel! Before the week is out I hope to fire it up.

[TJ's GMC]

Bent push rods means possible stuck valves at some point. I'd put some sea foam spray on the valve stems as it's a little acidic and a lubricant. It'll help break down any gunk build up and lubricate as well. Should be back in business soon man.

.012 intake and .018 exhaust adjustment at 160 degree operating temp if you need.

[62Burb]

Project update - new pushrods installed and adjusted; BEYOND a night and day difference. Purrs like a kitten! The tune-up will continue later this week; the open road is calling! Thanks to all for the priceless advice.

[massey478]

Good work Brad! Happy you have had a successful outcome to your hard work. Enjoy!