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How much damage have I done?


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calgaryborn
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May 11, 2007, 6:59 PM

Post #1 of 21 (2465 views)
How much damage have I done? Sign In

I have a 96 Chev pickup 4X4 with a 5.7 L Vortec in it. The intake manifold gasket failed so I pulled it off and replaced the gasket. When I started it back up it was making a really loud knocking sound. I have asked around a little and the general concensus is that I must have dropped something down the intake. Could I pull the intake off again and fish it out or am I faced with pulling the heads now? How much potential damage have I done when I started it up? Also I replaced with a Felpro gasket set but was wondering it this is the best option for the intake manifold as this is apparently an ongoing problem with the first generation Vortec. Any help appreciated. Thanks.


Tom Greenleaf
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May 12, 2007, 5:52 AM

Post #2 of 21 (2459 views)
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I have the same engine in a 1997 and intake manifold gasket did leak coolant and was replaced under warranty which bothered me as I wanted to do it myself but they did a very nice careful job. Felpro is a favorite gasket maker of mine.

The noise probably is something dropped or lost into the head. That is NOT good news. Don't run engine anymore till you find this. If that happened it could be game over for the engine -- arggh!! You may have to pull the head off and with any luck if this is something dropped in there I hope it's caught up at the valve and not playing ping pong in a cylinder. It can kill the engine. Get it out and cross your fingers that it didn't,

T



calgaryborn
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May 12, 2007, 5:57 AM

Post #3 of 21 (2458 views)
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Thanks. I'll tear it down again and see what I can find.


Tom Greenleaf
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May 12, 2007, 7:01 AM

Post #4 of 21 (2457 views)
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This type of thing has happened four times in my experience. Once a carpenter friend and customer used a nail to hold a choke open to start his engine that needed a choke pull off and a fair size nail went down thru carb and made it to the cylinder - I was shocked that it could make it that far but did. He had a neat tool to light and see around corners and we looked in the spark plug hole and saw the damage. Nail was gone but there was total cylinder wall damage, piston damage valve damage and the car was such a piece of junk in general that ended that car.

Another while working on an Olds 307 with my brother who is impatient for details did an intake gasket job for a water leak and when all done a washer was missing ???? Before start up we did an intense search for this as I was keeping everything organized and he wasn't so we just wrote it off as lost on the floor and started the engine (don't do that with a known missing part) and all was fine. Upon revving up the engine you could hear something move, rattle away for a second then stop. Dang washer made it to cylinder and out and spent the next 100K stuck at the converter. That's total luck that it didn't hurt anything and if I had done that job alone would have torn it back down before start up but there was a lot of reason to think it didn't get into the engine and we gambled and it was there. Watch out when working with another as you forget who has done and accounted for what.

Another time with another mechanic we had replaced pistons, rings and bearings and had the engine running fine and I was cleaning up the work area and found a wrist pin retaining clip. Two of us looked at each other and said some bad words and went all they way back and sure enough that was it and saved an engine. Scary stuff and these minor mistakes can make a total disaster.

I hope this is some other noise for you with this one but you were at a spot where something could happen. Hit back with your findings and hope it's good news,

T



calgaryborn
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May 12, 2007, 11:07 AM

Post #5 of 21 (2455 views)
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When I put it together I used a Felpro 'Problem Solver' gasket set. Is it possible to reuse the intake gaskets or should I just buy another set?


Tom Greenleaf
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May 12, 2007, 7:13 PM

Post #6 of 21 (2450 views)
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I have to say it's best to go new again but use your judgement,

T



calgaryborn
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May 21, 2007, 6:38 PM

Post #7 of 21 (2437 views)
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Well had to go away for a few days but finally got back and took off the heads. Tried to take only one off but go figure I picked the wrong one. I found a screw on top of the number 5 piston. Looks like it put some dents on the top of the piston but didn't pierce through the piston. Do I have to do anything with the dents on the piston or will it be alright? Does't look to be any valve damage either. Is there anything that I should know as far as setting the rocker arms on a Vortec? I haven't done it before but the book says to tighten down on the rocker arm nut while spinning the pushrod. When you feel pressure on the pushrod then go another 3/4 of a turn and your all done. Is it really that simple? All help appreciated. Thanks.


Tom Greenleaf
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May 21, 2007, 7:10 PM

Post #8 of 21 (2436 views)
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Arggh! Your call on the piston. Of course a new one would be best. Look for damage to the cylinder wall and close look at the valves.

Pre set on older chev 350s was something like bottom out the 9/16 nut and back off six turns back when. Not sure what's up with that one but might be the same or what you mentioned. Better a little lash than too tight which can burn the valve right out pretty fast,

T



calgaryborn
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May 26, 2007, 10:26 AM

Post #9 of 21 (2426 views)
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Well I got it all back together and it runs good but has a knocking sound coming from around the #3 or #5 exhaust valves. Likely be the #5 exhaust valve as that is the piston that had the screw in it. Would the knocking sound be a stuck or collapsed lifter. If so can you tell if a lifter is damaged or collapsed when you pull it out. I have never done it before. What else could be causing the knocking sound? When I found the screw on the piston head the threaded part was there but the screw head was gone. I did find a couple of metal chunks on top of the piston and of course removed those but could a piece of the head be on top of the exhaust valve? If the lifter is stuck or collapsed would the rocker arm still move? Also would you do any damage by driving the vehicle while it makes the knocking sound? Need help. Thanks.


calgaryborn
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May 26, 2007, 10:28 AM

Post #10 of 21 (2425 views)
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Also forgot to mention that I ran the engine with the valve cover off and tried tightening and loosening the rocker arm to see if it was a out of adjustment valve.


Tom Greenleaf
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May 26, 2007, 11:46 AM

Post #11 of 21 (2423 views)
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If the head of that screw is still hanging in above a valve it will wreck the valve. If it's part caught up in the valve you couldn't get an accurate valve adjustment. I would think it would backfire or run on just the uninvolved cylinders if a valve can't do its thing.

A valve out of adjustment because of any reason should be a single tick if too much lash/freeplay. Double clicks and knocks are either a wrist pin, rod bearing. Again - the lifter would make a tick. Knocks are more trouble.

This isn't a good scene here. When you had the head off the valves should have been removed for that cylinder if there was a chance of a piece still being there. If it made it thru intake a piece would probably make it thru exhaust and then you can forget that.

You are still listening to a tick. Just valve adjustment off wouldn't be harmful unless too tight and that would burn the valve but would probably be quiet about it

What did the cylinder wall look like when you were there? That matters a lot!

T



calgaryborn
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May 26, 2007, 3:07 PM

Post #12 of 21 (2422 views)
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The cylinder wall looked great. Couldn't feel any gouges or scrapes. The noise is more like a metallic tick that tones down alot once the engine warms up and the oil gets up top. Would the rocker arms still all move if a lifter was collapsed? Is there a way to tell for sure as to which cylinder is the problem?


Tom Greenleaf
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May 26, 2007, 3:52 PM

Post #13 of 21 (2420 views)
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Just a collapsed lifter would cause a problem with that valve. If it leaked out all it's pressure at the lifter it probably would reduce available oil pressure to the others and then they wouldn't behave. The oil that gets up to the valve cover is metered waste from the lifter when it's happy and then lubes the rocker arm with just a drip down type of lubrication. Some engines really spray oil around in there and you can't run those with valve cover off without rain gear on!

T



calgaryborn
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May 26, 2007, 5:02 PM

Post #14 of 21 (2418 views)
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There was one rocker arm that wasn't getting nearly the amount of oil circulation that the others were. Would this indicate which lifter in the potential culprit? It was still getting a little but maybe 1/4 of the oil of the others. Could it just be a stuck lifter or is it likely failed. Would there be damage to that head as a result?


Tom Greenleaf
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May 26, 2007, 9:37 PM

Post #15 of 21 (2417 views)
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If it got any it's probably fine. Take a note of that though and watch that one for a problem more than others,

T



calgaryborn
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May 28, 2007, 3:19 PM

Post #16 of 21 (2410 views)
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Started the truck today to get a better listen to the mysterious sound. Could barely hear anything now except for the occational rattle/tick under the valve cover but quite a bit quieter than before. Since the timing is controlled by the PCM and the only adjustment from the distributor is for the cam retard offset, but requires a scanner. Is it possible that this could solve the problem or am I dreaming? If it is the problem wouldn't the noise occur on all cylinders? I revved the engine up and while before there was a louder tick that increased with engine RPM is made virutally little difference now. I'm baffled. Help me please!!


Tom Greenleaf
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May 28, 2007, 6:40 PM

Post #17 of 21 (2409 views)
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This is like some kind of remote surgery! Just re read the thread to come up with some ideas.

Lifter is probably not involved at all as the whole reason you did anything was a typical intake manifold coolant leak - no other problem mentioned.

Part of screw found and removed, the head of that screw remains an unknown and may have passed thru. Any clue how big that screw was?

A slight tick is still heard but not as bad as before. Hmmmm?? Is that the screw head or some damage?? Unknown...........

You have messed with valve adjustment so that could actually be an issue but lets see if we can think of how to prove that or not.

Try a compression test on the known cylinder and compare it to an uninvoled cylinder. Note whether it gives different readings on another try. Note if noise goes away with engine running and plug wire removed.

I really don't like running this engine at all if it has a chance and it may.

Another thing is to release the valves such that they drop down to the piston on TDC on involved cylinder. If something falls down to piston you should be able to fish it out with a magnet thru spark plug hole. Getting those valves back up to lock back in place will be near impossible so that would risk taking the head off again. Heck your getting good at that by now.

Hit back with observations on compression and maybe I'll think of something that doesn't involve taking this whole think apart AGAIN. A bent valve may be the issue and only maybe we can guess at that with a compression check. If something is still there it can still cause total distruction so cross your fingers,

T



calgaryborn
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Jun 8, 2007, 7:19 AM

Post #18 of 21 (2394 views)
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Well I took it all down again. Looking at each thing as I went. I checked the pushrods. Seem straight with maybe a couple thou variance, lifters looked okay, pulled the intake and exhaust valves on the affected cylinder and they seem fine. Valve seats look good. Pulled the piston and couldn't detect any cracks. Looked at the rod bearings and there is some shiny wear marks on them. Could this be the problem? Don't have a lot of experience with this but want to be sure what to replace so it's fixed when I put it all back together. Also how tight should the wrist pin be in the piston. If I twist the piston and connecting rod in opposite directions I can't detect any play but the wrist pin slides easily in the piston from side to side, is this normal? Anybody have any additional things that I could check? All help and advice appreciated.


Tom Greenleaf
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Jun 8, 2007, 8:30 AM

Post #19 of 21 (2393 views)
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You may want a book on exact specs for this engine now that you are there.

I'll just mention what I know as far as it goes. I don't tear down engines this far but have just a couple times.

Push rods should be about perfect. Roll them down glass and any imperfections they get tossesd.

Valves should not be making the noise at the seat. However they should show even wear on the machined surface which used to be valve ground to 45 degrees and seat ground to 44 degrees or vice versa such that when warm they get the best seating.

Takes tools to measure valve guides, tapering of cylinder wall and checking specs on piston and rings.

Bearings use plasti-gauge and you squish this in the bearing to spec and remove and measure how thick the plastic string got for the clearance.

Wrist pin sounds good by your description and I would be concerned at any noted freeplay with those but they should slide in by hand. They may make shims for end play.

Piston rings can be measured with a feeler gauge and they make shim rings for that too or used to. It's silly if they are bad buy new stuff.

Valve springs are measured to be a perfect match with a straigt edge placed on it on known plane and almost no deviation is allowed.

A machine shop may have specs for this engine and will have the tools to measure and correct.

Man -- you must be fit to be tied about now over this and nobody would blame you. This is the time NOT to make any mistakes or any guessing as you surely don't want to be back in there yet again.

Exact specs are imperitive. They could be different by model year or even production date so don't be wrong now. AllData.com does sell comprehensive books on this or ask a machine shop that does engines of course and they might share their data or tell you what they use.

Others at this site who may know more and could be ignoring this thread right now as it's long and a read might know more about this. DanD is active with this work and Steve(with five digits starting with 0) is a Chev expert, and way2old is awesome with a lot of assorted vehicles. There are others too but I know them the best.

Now is the time not to make any more mistakes so seek and find the specs and advice as best you can. I don't have anything for that engine and I own one but never expect to take it apart. Stay with this, I'm watching,

T



calgaryborn
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Jun 23, 2007, 6:15 AM

Post #20 of 21 (2374 views)
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I'm finally back up and running. Got it all torn apart and found that the #5 piston had collapsed causing the wrist pin to bind in the skirt. While I was in there I replaced the rod bearings, new piston, new rings, and also had the head vacuum tested. All is well now. Thanks to Tom for helping me out.


Tom Greenleaf
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Jun 23, 2007, 11:02 AM

Post #21 of 21 (2373 views)
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God bless! You've had a run for the money with that one!! Glad to hear you have it all set now,

T







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