84 "Washing Machine"

[sidepipe]

Well, I got the 84 out from its winter sleep. She started after about 15 seconds of cranking. Watching the oil pressure, which was at 40lbs when it fired, the engine ran smoothly and quietly. Oil pressure up to 62. It idled like this for about 2 minutes (approx 800 rpm), when this high mettalic rapping noise started.It sounds like sheet metal hitting something rotating. It follows the rpm. No water in the oil, oil pressure steady at 62 at 750-800 rpm. I tried listening to various areas of the engine with a screwdriver to my ear, but couldn't locate it. I took off the belt, still the same noise. I removed the valve covers and checked for collapsed lifters. Nothing.. I pulled plug wires, one at a time, to take the load of of the wrist pins and rods, but the sound remained unchanged. I'm going to pull the oil pan and see if anything is hitting a crank throw, altough I wouldn't know what could let loose in the pan. Could something be hitting the ring gear? It's the 4+3. Sorry for the long post, but I know there are alot of sharp people out there with more experince than I have. Man, Do I need help!!
:confused Thanks in advance...Frank

 

[sidepipe]

84 Washing Machine

Anybody???:confused Even a Silly Wild A** Guess at this point would be welcomed:L It may be a rod bearing, but never having heard a bad one before I'm just not sure. Can you tell a bad rod bearing by feeling play in the rod on it's journal, or do I have to take the caps off all of them? I said in my previous post that it sounded like "sheet metal" hitting the crank. Maybe that's what a bad rod bearing sounds like. Anybody had a rod bearing go and what did it sound like to you? :cry Thanks, Frank

 

[Ken]

... this high mettalic rapping noise started.It sounds like sheet metal hitting something rotating.

I need a little more information than what you provided. I've got several things in mind, but don't want to start down the wrong path.

 

[sidepipe]

Thanks for response Ken. I know this is tough trying to diagnose a "sound" on the forum. Other than the info in my previous posts, the Vette sat for 5 months with the battery disconnected and had not been started in all that time. I'm thinking that maybe that was my mistake. Do you think not running it for 5 months let the oil drain off the bearings enough so that on start-up one of them got hot enough to spin after approx. 2 mins. of running? There was no water in the oil and the level was full. Both throttle bodies were spraying as they should. I pulled all the plugs out, disconnected the wires to the throttle bodies, and just cranked it over without hearing the knock. I figured I didn't hear it because the engine was spinning fast enough with just the starter. I haven't gotten the pan off yet, starter still has to come out. I don't think I left anything out...Thanks, Frank

 

[Ken]

Do you think not running it for 5 months let the oil drain off the bearings enough so that on start-up one of them got hot enough to spin after approx. 2 mins. of running?

It's not likely to cause you any problems; although it isn't any good for the engine to be started without full oil pressure (that's the idea behind pre-oilers), it should not cause immediate and severe damage such as spinning a bearing.

Sixty-two pounds of oil pressure does seem a little on the high side; is this when the oil is still cold? Does the pressure drop to around forty pounds or so when it warms up? That would be in the normal range unless you changed to a different (higher pressure) oil pump.

One suggestion is that it could be the catalytic converters ('84s had pre-cats, right?) breaking up. When mine went bad, they rattled like crazy and the car ran fine. But when they got quiet, the car wouldn't get out of its own way. When they got quiet they were actually plugging off the passages and the engine couldn't exhale. As I said though, when they (the pre-cats) rattled, they sounded to me like a connecting rod gone south.

Another thought is that there is a tin heat shield or two under and around the engine/exhaust assemblies; have you checked all of those suspects?

Manual transmission or automatic? Checked for anything making contact with the flywheel?

If I think of anything else...

_ken

 

[oldace84]

This is a very tough question.....to tough for me to answer as I'm not there to hear the sound.....I would not have left my 84' sitting that long without restating it a couple of times a month....
Your best option before tearing into the engine, is to seek out a good, and I did say good, mechanic.
Sorry I could not add more...
tony

 

[offshore]

check the flywheel & listen to the trans.too.

 

[vette-dude]

I wonder if this might be a throw out bearing? Does the sound get quieter when you engage clutch? Just a SA thought. Another might be the baffles in the muffler. Sometimes when they sit they rust and you start it up and the internal welds come loose. another SA thought.

Randy

 

[Eagle85C4]

My Blazer just went through the same thing...it turned out to be a bolt from the flexplate to the torgue converter came loose and was tapping the bellhousing.

Get underneath and remove the inspection plate and check for loose bolts between the flywheel and the pressure plate...

 

[Vettelt193]

I have even had a sound like that with a bad belt tensioner... is it possible to localize the sound front/rear left/right? you make it sound like it is coming from the middle of the engine, but could it be coming from the rear (tranny) area, or front belt area?

Narrowing the location even somewhat will help in trouble-shooting the problem.

Thanks, and good luck!

 

[vigman]

The 84 had no pre cats

But I was thinking the same thing Ken..

BTW running 20/50 casterol I have 62 psi oil pressure on a cold start up.. then it settles down to 40 ish...

My 84 rattle was the down pipe going to the cat for Oxygen injection.

Get the car up in the air.. and let it idle...


Vig~

 

[sidepipe]

Thanks for all the suggestions I never let the engine run long enough to let the oil warm up, so the 62 lbs of pressure was with cold oil. I ruled out the belt idler by removing the belt for a short time, noise still remained. The loose bolt in the flywheel is interesting..although I'm going to have to wait 'till the weekend to pull the clutch cover. The weather here turned cold with snow again and the Vette's in an unheated garage bay. I WILL find the problem and be happy to let everyone know what it was Thanks to All...Frank

 

[sidepipe]

Got It Fixed!

Well, the knocking was a dry pushrod for the exhaust on cylinder 1. I put on an old valve cover with the top center removed, it holds the oil in but you can get at the rockers. Oil came out of all the pushrods to the rockers, except # 1 exhaust. I pulled the pushrod and it had a piece of , what looked like varnish or carbon, blocking the oil passage. I replaced the pushrod ( I had a spare) and she's running great! Thanks to all who responded to this problem. Save the Wave!!