Evaluating 305E engine noise
 

I'll try posting a Google Drive link to a short video I made of my '63 Suburban 305E and its noisy running; just received it this week. Seller said it ran weakly; shipper said it had almost no power. Seller replaced many parts, rebuilt carb, new plugs and wires and fuel pump. Plugs look to be correct and not fouled, firing order seems correct.

https://drive.google.com/file/d/1YhC...ew?usp=sharing

Brad

Re: Evaluating 305E engine noise
 

It's hard to tell really, but after all the simple stuff (Plugs, Points, Timing, etc), I believe I would be checking on the Valve Adjustment. These engines have Solid Lifters and need to be set with a Feeler Gauge.

Re: Evaluating 305E engine noise
 

Greetings!

I agree with Bill. It is most likely valve train noise. I heard nothing to suggest that there is anything wrong with the lower end of the engine. The engine itself appears to be idling roughly, and I would definitely check valve adjustment, and timing among other things, including the idle speed mixture adjustment. When I owned my truck, I had my 305 idling so smooth that you could place an orange juice glass half full of water on top of the air cleaner, and barely see a ripple in the water. Yours should be idling just as smoothly. The engine appears to be extremely clean, suggesting that the previous owner may have replaced the valve cover gaskets, and may have made an attempt at adjusting the valves. The lack of power that you describe can come from valve adjustments being too tight, thereby holding valves, especially the exhaust valves, partially open when they should not be, which could very well contribute to loss of power, and to the rough idling of the engine that I observed in your video. Hope this helps, and good luck! Sometimes it takes a little time to chase down those mechanical Gremlins, especially when you don't know what the mechanical aptitude of the previous owner(s) was!

Re: Evaluating 305E engine noise
 

Also, a compression test will tell you where the problem is. Cylinders should be fairly equal in compression. If they are, then you have other problems. At least you will be narrowing it down. Remember to use compressed air to blow out the dirt around plugs before loosening them and after just loosening them to prevent it getting into cylinders. Critical! Also a timing check will tell you if possibly the timing chain has worn so much it has skipped a tooth. Bill T and George have excellent advice also.

Re: Evaluating 305E engine noise
 

You may find bent push rods also. What bothers me is tight valves, tight enough to cause a miss, do not make noise. No lash, no noise! You may have both tight and loose. I really hope it is something like this to make repair easy for you.

Re: Evaluating 305E engine noise
 

Off topic, but George, I sure would like to see you doing a writeup on how to tune one of these engines like that. :thumbsup:
:hijacked:

Re: Evaluating 305E engine noise
 

This is what the President of the "United V6's of America" advises. https://www.youtube.com/watch?v=dyoTQ0xaLBo
We all need to save this link for our children and their children.

I don't know what noise you are referring to in your video. First thing is to get a stethoscope and listen to every inch of the motor, pumps, exhaust and hear all the different noises. You may have some normal noises and some not normal. They may be melding together. It does not matter what the seller or the shipper said. What matters is how it's running for you. Noises and how it runs may be unconnected. Report an actual issue and we can help. The motor does not sound abnormal after you view the video I linked.
If it has lack of power, there is a list of checks and causes we can go over after you describe in detail what you experience. In other words, what is the question? What is the problem?

Re: Evaluating 305E engine noise
 

I like this - the "Zen of V6 Maintenance"! I am eager to dig into this; I haven't attempted an old school tune up for 30 years! Back in the saddle again). My FIL is my Obi Wan Kenobi; he passed away 25 years ago, but was a maintenance maniac with his 1962 GMC Custom Suburban (which I drove afterwords for several years). That V6 reached nearly 500k miles w/o a rebuild. "Feel the Force!

Brad

Re: Evaluating 305E engine noise
 

We should just transcribe it and add it to our libraries here, bein honest. At least that way we always have it even if YT deletes his stuff. Never know what'll set people off anymore.

Re: Evaluating 305E engine noise
 

So I made some progress today; confirmed spark to all six cylinders, then pulled the valve covers. lo and behold, cylinders #1, #3 and #6 all had bent intake valve pushrods! The seller said the vehicle had sat for years, and I presume this is the result of stuck lifters? I turned the engine by hand and could see all three push rods move up and down; am I correct this means the lifters are unstuck now? Plan is to replace with a new set of push rods, then do a valve adjustment. Feels nice to move forward!

Brad

Re: Evaluating 305E engine noise
 

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!!

Re: Evaluating 305E engine noise
 

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.

Re: Evaluating 305E engine noise
 

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

Re: Evaluating 305E engine noise
 

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.

Re: Evaluating 305E engine noise
 

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?

Re: Evaluating 305E engine noise
 

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.

Re: Evaluating 305E engine noise
 

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.

Re: Evaluating 305E engine noise
 

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. :ok:

Re: Evaluating 305E engine noise
 

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.

Re: Evaluating 305E engine noise
 

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

Re: Evaluating 305E engine noise
 

Excellent! Glad things worked out well for you without too much trouble! Enjoy your truck! I miss mine, and wish to God that I had kept it!