Engine Noise Knocking - need help diagnosing - Valves??

[tmsnyder]

Rick called it!

Ok, Your buddy needs a little education on how engines work, oil pressure drops at idle and goes up with RPM. Sitting makes no difference. I have run engines that have sat for 50 years with not a problem. In your case you have a problem but I am not sure it is all that serious yet. You need to take the passenger side valve cover off. It sounds like you have bent or broken a push rod or rocker arm. The chirping sound is a little disconcerting but you have oil pressure, ( I could not really see it but will take your word for it). You do have a miss on the right side and if it lost a rocker arm it could be pulling oil past a worn valve seal into a dead cylinder hence the smoke. You do have an exhaust leak also, sounds like more than one. The loud knocking sound may have been the push rod hitting the valve cover, you may even have dents in the cover over the one that went. But pull that passenger cover and lets see what you have. Look at it this way, if the engine has to come out this stuff all has to be done anyway. If you have the relay mounted over and behind the alternator be sure to disconnect the batteries before starting this job. A stray wrench hitting a terminal will make things real exiting.

[tmsnyder]

Just one rocker arm was loose right?

Yep, bent push rod, found the lifter floating around in there, and the the rocker arms were loose.

[legomybago]

Ok, So you found exactly what I thought you would find, The lifter does not look bad from that picture. What does the base of the lifter look like? Is it dished or worn through? Rocker arm broken? If lifter is good and rocker arm is good buy one pushrod for a few bucks and put it back together and start it up. Put the box end of a big wrench over the rocker arm and see if the valve will operate, if it goes a bit and stops make sure the piston is down on that cylinder. As long as that valve goes down alright then I say put a pushrod in it and fire it up. The smoke should go away as it burns the oil out of the cylinder.


The lifter floating around is not good since you would have taken a BIG hit on the oil pressure but try it and see what you have. A LOT cheaper than a crate engine.

X2....Make sure that lifter still pumps up. Inspect the rest of your pushrods for correct length, put it back together and adjust/torque the rocker arms correctly. You may be lucky on this fix i??

[Rickf1985]

They will be the correct length as long as they are not bent and you can see if they are bent just by reaching in and turning them, no need to remove every one.

[solracem]

Just one rocker arm was loose right?

The one that is obviously loose was one but, a few others on the same side were also loose, however, they didn't spin like this one.

[Rickf1985]

When it is not running there will always be some loose and the fact that the lifter popped out you had no oil pressure on that side and little to the other. I am hoping it held enough flow on the bearings so they survived. They should have since the flow goes through the mains and then to the cam and lifter journals. So bearings should all be good. Now as far as why it bent the pushrod since you have not asked and I am sure you want to know, It could have been a lot of things from a defective pushrod to over revving to a backfire at the wrong time to sucking that mouse into the intake and through the valve. a solid will not compress, well, at least after all the ..................eh...um you get the gruesome picture. Don't laugh, I have seen it happen on old vehicles that have been sitting in fields where someone just throws gas and a battery in and cranks it up. Did not check to see that the mice were living in the air cleaner.

It all depends on how much you trust the engine at this point. I would put it back together and start it and see how it sounds. If it sounds good with no rod or main knocks then personally I would pull the heads and have a valve job done, put a timing chain set on it and button it up. This can all be done in the vehicle, is a tenth of the price of a big block crate engine and will last you longer than you will own the vehicle.

If it sounds real good you could just button it up and go and probably not have any problems for many miles to come. These engines are very robust and tend to be quite dependable. I have NO idea what the history is on this thing so I am just throwing out a couple of ideas.

[tmsnyder]

Have you done this kind of work on a chevy engine before?  I'm just wondering b/c the rockers shouldn't be loose, you might be able to wiggle them a bit but if you grab the rod there shouldn't be any up/down play in them by finger tip force at least.  Do you know how to set the rocker lash?

[Rickf1985]

Yes, I have built over a hundred big blocks.

[solracem]

I have not built an engine before. I'm relying heavily on a couple of mechanic buddies for their advice on what to do and where to take it if needed.

[cncsparky]

Did you get a picture of the bottom side of the lifter like Rick asked earlier?

The adjusting nut for the rocker arm looks about the same position as the others.  Something caused some slack.  Either the PR got bent allowing the lifter to come out, or a severely worn lifter/cam lobe created some clearance and the PR was bent as a result.

Maybe the rocker arm is worn?

[solracem]

Here is the pic

[solracem]

The rod broke - here is a better pic

[Rickf1985]

That head is far to dry, the four rockers in in the center have not had oil in a long time. The head surface under the last two is even dry. I question if this engine has any oil pressure. See if you can maneuver that lifter back into the hole with a magnet, I am assuming it came out through the distributor hole? Either get a pushrod or not but start the engine up and let it idle, the lifter will stay in the hole. You should have oil coming out of the rockers within 30 seconds. If that top end has been dry as long as it looks then you need to start pulling the rockers off and checking the sliding surfaces for galling. This may have been the cause of the broken push rod. Pull off that one and check it.

[legomybago]

Yes Rick....I was going to mention the "dry" looking head also. All the pictures look like that head hasn't seen oil in a long time..... Some of the rocker arms look "baked".....

[Surfinhurf]

Buy an old set of valve covers, cut the top out, and mount them after you get it back together.  This way you can watch the valve train and not leak oil all over your engine/manifolds.

New set $29.99
http://www.ebay.com/itm/1965-1995-BBC-Orange-396-427-454-Short-2-5-8-Steel-Valve-Cover-Chevy-Big-Block-/390766005257?hash=item5afb780c09:g:b80AAOxyRhBS9RlZ&vxp=mtr

HURF

[Rickf1985]

Or get these.
https://www.summitracing.com/parts/mrg-1015/overview/

[BrianB]

If it were me, I would take both heads off and have valve job done and new seals. Buy full set of pushrods and top end gaskets.

If I remember correctly, you are planning Alaska next summer.

Also have water pump replaced and alternator bearings replaced.

[Rickf1985]

It all comes down to do you want to just get it running or do you really want to put a new motor in it and are just looking for an good excuse to do it? 
A crate mill is going to cost you roughly 5 grand for a NEW motor. If you want to go with rebuilt then you can go cheaper. I have my own ideas on rebuilds since I have had to change many engines for people, twice, three times. If you want to go the rebuilt route then rebuild it yourself and you KNOW it is done right. Are you aware of what you have to do to change the motor in that rig?

[fasteddie313]

Rick is a freaken boss, good call man..

Going through this thread I was thinking that squeak was coming from the valve train..

What I would do if I was you is just reassemble it with a new pushrod-lifter-rocker from the junkyard for basically $0$ and see what it does.. Rotate your engine to get that cam lobe down before you put it together..

If you felt froggy..
You could get a borescope and check out the cam lobes own there to make sure that is good..
You can get really cool 7mm HD borescpoes for your android or iphone for like $20 these days!!

You could also do a leakdown test on that cylinder to diagnose a bent valve..

Or you could just slap it together and see if it works.. If it's fubar then its already fubar IMO..

If it misses on that cyl try a new spark plug.

If the smoke doesn't go away about before it comes up to operating temp then its prolly fubar..

if it keeps making noise, again prolly fubar..

[kenwautoone]

You still have not diagnosed the problem,just the end result.please listen to what Rick is telling you..
Ken