stick lifter or bad bearing???

[Txmusclecar]

We have a 1968 Vette with a 427 tri-power. The car has been sitting for at least 8 months without being started. Restoration work was basically on the A/C system, electrical & vacuum systems. Previous owner had restored the engine and it was running just fine 8 months ago.
Jeff started the engine with a combo of gas & a small amount of race fuel (car always ran a little rough due to lack of octane).
There is a knocking sound and we can't tell if it is a sticky lifter or a bad bearing. When the car first starts up it is a very faint ticking sound, but then quickly becomes a loud knocking. We haven't let the engine run longer than 2 minutes because I am worried that we may cause permanent damage to a very valuable engine.

Can anyone tell me how to tell the difference between a sticky lifter and a bad bearing?

Any suggestions would be greatly appreciated.

 

[matchframe]

Welcome to CAC

What a gorgeous Vette you have!

A sticky lifter will have more of a "clicking" sound to it. A bad bearing will have a "scraping" sound to it. A rod knock will have a "banging" sound to it. A rod knock is usually the result of bearing getting real thin, possibly due to lack of oil pressure.

What you described sounds like there is something not getting good oil pressure, if it increases as the engine runs.

Does the noise sound like it is deep in the engine, or more at the top?

It is hard to diagnose without actually hearing it.

Bill

 

[Txmusclecar]

Thanks for the quick reply.

It is definately a knocking sound and it seems to be coming from the lower part of the engine.

Any ideas as to what could cause this problem to appear after 8 months of sitting?

I dread the thought of messing with the engine because the engine compartment is detailed to perfection finally. The original owner was a fine mechanic (maybe?), but he lacked the patience for the details that truly restore a car. I am going to be irritated if he just slapped this engine together without replacing worn parts. Oh well, what can you do.

 

[cruzer99]

Use a stethoscope or a long screw driver with the handle in your ear and the other end against different parts, (top and bottom), of the engine and see where the sound is coming from.
Did you change the oil before starting it for the first time?
If you have concerns, drop the pan and check the rods. It sounds like a bad rod bearing.
It's like matchframe said, a rod will sound like someone knocking on a door and a deeper thud will be a main bearing. Good luck.

 

[woobie1966]

some thing else you may want to look at is the rocker arms, i put roller rockers on my bb and about a month later i started hearing a ticking sound. turned out to be one of the rocker nuts had come loose and would not stay tight. replacing the errant nut fixed the problem
mike

 

[Txmusclecar]

I hate to admit it, but no we didn't change the oil before starting the car. Oh well, pain teaches dummies and I feel that this one is really going to hurt.

We tried the stethoscope/screwdriver and still couldn't pinpoint where the knocking was coming from. We both tried it and came up with different areas. Jeff will pull the oil pan tomorrow and see if he can't figure this out. I'll let you know what we find.

I wish it could just be a rocker arm, but I have to admit that the noise is too loud and it seems to be lower. This is why I orginally thought it might be a sticky lifter, but it isn't the correct sound.


Thanks for the advice.

 

[bradfordsvettes]

how new is the engine . some times when an older engine sits cabon will break off the valves or top of the piston and make a horrendous knocking noise sounding like a rod knock. got fooled by this myself many years ago and have seen it many other times very scarey sound , may have to be brave and run it for a while if there is a problem the damage is most likely done . you would have to run it to diagnose it any way or bite the bullit and tear it apart and find nothing only my 2 cents steve :cry

 

[Rowdy1]

Beauty!

Nice looking ride. As was said before, without hearing it, it's very hard to say what it is but from what you're saying, it does sound like a bearing knock. Could be a rod or a main. What kind of oil pressure are you showing when you first start it up? From what you said in your original post, starts as a ticking and gets louder as it runs would be due to the oil thinning out as it heats up. To be perfectly sure, drop the pan and start pulling bearing caps. Inspect all of them, even if the first one you pull looks like the bad one. If that's the case, make sure you do the whole thing, mic the crank, if you don't have the knowledge, ask for help from someone that does or if you end up going to a rebuild shop, CHECK THEM OUT!!! Don't trust anything to chance on a rare beauty like that. Good luck and let us know what you find.

 

[cntrhub]

Do something easy first before dropping the oil pan. Remove the oil filter. Take a pair of metal cutting shears, open the filter and pull the pleets apart. There you should find the mystery noise. Hopefully you found nothing but oil, and very minor debris.
If you see a lot of metallic filings, oh boy, you got a bad crank bearing. There is your noise! Now you can pull the pan down. You can quickly see which crank rod is bad by moving each rod back and forth until one has a slight movement to it.

 

[Txmusclecar]

Jeff was ready to put the car up on the lift when I read the suggestion about the carbon build up coming loose and causing a knock. This engine was completely rebuilt by the previous owner and looks very clean, but we are only going on this guy's word that it was completely rebuilt.

This prompted us to take the oil filler cap off of the valve cover and feel (with a very clean finger) the condition of the rocker arm as far as build up. Believe it or not the first rocker arm I touch is sooo loose that even if this isn't the cause of the knock it must be corrected.

The first thing that we are going to do is to take off the valve covers & check the rocker arms. The oil will get changed before we start the engine again. I'll check the old oil filter for any debris. If this doesn't correct the situation then the rod bearings are the possible culprit.

The oil pressure seems to be fine, but we may temporarily hook-up an aftermarket gauge to be sure.

I'll let you know what we find out. Thanks for all the great tips.

 

[woobie1966]

if it does turn out to be a rocker arm problem, maybe you could use this to your advantage.... install roller rockers?
just a thought from the " while your at it" mind set
mike

 

[Txmusclecar]

What roller rockers would everyone suggest? I am sure that this would be at least $300 to upgrade so I want what is considered best by the people who drive corvettes, not the guy at the parts store.

The oil has been drained and it seems very thin to me, but it is very clean.

Jeff & I are having an amicable discussion about the type & weight of oil to put back into the vette. It is a 427, which tends to get very warm and the fact that we are in Texas, which tends to get very hot I would think that a heavier weight would be in order.

What do y'all suggest?

 

[Rowdy1]

Do You Know How?

You are I hope aware that you need to know what style lifters you have, solid or hydraulic and you have to adjust them accordingly. If you don't know, ASK someone as you can do a heck of a lot of damage by doing them wrong.
You'll probably get as many opinions on the oil as there will be people posting, it's just that, an opinion. I like Rotella T 15/40.

 

[iron cross]

I presume it`s a hydraulic cammed engine as GM didn`t like air and solid lifters together. If you found a loose rocker arm, it may be as simple as a broken valve spring. Rocker arms don`t tend to loosen up over the winter or in storage. But some BB chevys are hard on valve springs which is easily repaired. It`s a noise that will not go away by oil pressure as a hydraulic lifter will do. I use 30W racing oil in all my BB chevys. And if a few rocker arms need replacement, do NOT use roller types, factory stock GM`s or aftermarket replacement parts are more than adequate. I really doubt if you have a serious problem or it would have been there when it was parked. My BB`s run from 396`s, 427`s, L88`s and 454 LS7`s in several pieces { Vettes, Camaros, ski, and drag boats} and set for months without starting only to fire up without any problems. I love those high HP BB`s, I put them in everything. Check my photo album under iron cross on this forum and you will see what I mean. Good luck :bar

 

[Txmusclecar]

They are hydraulic lifters. There is too much play in the rocker arms to be adjusted correctly. The previous owner used poly-lock nuts, but one in particular looks like it has backed off of the stud more than the others

Jeff had to run in to town to get a new oil filter. When he gets back we will finish the oil change and bump the engine to the #1 position and start the adjustments. We are just reading a tech. manual when it comes to this kind of thing, so if anyone has any wisdom they would like to share, we would be appreciative.

 

[cntrhub]

You want the NASCAR racing valve adjustment? I call it the EO-IC valve adjustment. Here's how simple it is. Simply look at one cylinder at a time. EO means = Exhaust Open. As soon as you see the exhuast open, STOP! Now you simply adjust the intake valve lash. To adjust the exhaust side, turn the crank until you see the IC = Intake Close. STOP! Now adjust that exhaust valve to specs. Remember, the key is...."As Soon As." So, as soon as you immediately see the valve move either closing or opening, stop!
If you want to look at 16 valves moving all over the place and try to remember where you left off.....go right ahead. It will work the same. But you will be doing yourself a favor if you just keep turning the crank and adjust one bank at a time. Adjust the valves by starting from the front to the back on one side. You'll be turning the crank a lot more, but if you attempt watching the other valves move to their EOIC positions, mark the one's you've already done with say, a magic marker mark on the adjusted valve rocker arm, so you know who's already been adjusted.

 

[matchframe]

That is GREAT news!

Adjusting the lifters is not a real big job considering what it could have been.

The way I have adjusted hydraulic lifters is, first tighten the obviously loose rockers until they are snug. Then, with the engine running, back off on the rocker nut until the rocker starts clicking, then tighten it back down until it stops clicking, then a 1/4 turn more, then move on to the next rocker.

You might look in your manual for the exact proceedure and torque. But it should be simular.

When you do this, you will get oil on the exhaust, and smoke will soon be everywhere. If you can put something to block the oil from getting on the exhaust, there will be less mess to deal with.

Hope this helps!

Bill

 

[iron cross]

Thats exactly what I was sending, we use the proceedure all the time. You can start anywhere and it`s simple. As ex starts to open adj the intake, and as the intake starts to close adj the exh.

You want the NASCAR racing valve adjustment? I call it the EO-IC valve adjustment. Here's how simple it is. Simply look at one cylinder at a time. EO means = Exhaust Open. As soon as you see the exhuast open, STOP! Now you simply adjust the intake valve lash. To adjust the exhaust side, turn the crank until you see the IC = Intake Close. STOP! Now adjust that exhaust valve to specs. Remember, the key is...."As Soon As." So, as soon as you immediately see the valve move either closing or opening, stop!
If you want to look at 16 valves moving all over the place and try to remember where you left off.....go right ahead. It will work the same. But you will be doing yourself a favor if you just keep turning the crank and adjust one bank at a time. Adjust the valves by starting from the front to the back on one side. You'll be turning the crank a lot more, but if you attempt watching the other valves move to their EOIC positions, mark the one's you've already done with say, a magic marker mark on the adjusted valve rocker arm, so you know who's already been adjusted.

 

[matchframe]

You want the NASCAR racing valve adjustment? I call it the EO-IC valve adjustment. Here's how simple it is. Simply look at one cylinder at a time. EO means = Exhaust Open. As soon as you see the exhuast open, STOP! Now you simply adjust the intake valve lash. To adjust the exhaust side, turn the crank until you see the IC = Intake Close. STOP! Now adjust that exhaust valve to specs. Remember, the key is...."As Soon As." So, as soon as you immediately see the valve move either closing or opening, stop!

Isn't this method for a solid lift cam? If not, disregard my previous post!

Bill

 

[woobie1966]

i installed a set of competition cams roller tip rockers on my 454 , they are relatively cheap (about $150) a set, and the roller tip reduces a bit of friction. also, one thing to keep in mind, if you have power brakes, dont go with a full roller rocker, apparently there will be clearance problems with the driver side valve cover ( where it is dimpled to clear the booster)
good luck,
mike