Today I came home from work in the 82 trans am and it ran fine to and from work. HOwever when I left my house again it ran fine until A few feet after getting onto the next street..All of the sudden a small knocking sound turned into a progressively louder one with more throttle..i immediately pulled over and put it into park..still the same sound. It seemed like it was coming from the left side of the engine(passenger)..To explain the sound..it sounded like a rocker was hitting the inside of the valve cover...however it didnt have the length of a rocker motion(tick tick) it had the delay as if it was making the noise everytime the a piston on that side would come to TDC..I didnt loose compression and i drove it home( 2 minutes away) and the sound was always the same level and type..it sounded the same just when i turned it off.... I am assuming that I could have droppped a valve.However I took the valve cover off and all of the rockers were generally tight how they should and the pushrods were still in their normal positions.
-I am assuming that if I actually blew my engine such as the connecting rod broke or something major internally...it would sease up instantly or would get really loud and sound like more damage was occuring. However its didnt stall or anything..
Thank you in advance for any responses

 

Sounds like a rod or main bearing went bye bye. Does'nt sound like you had too much run time on it, so pending minimal debris in pan and how tight your budget is, it's not that big a deal to just drop the pan and swap out all the bearings. time consuming simply because limited work area under the car, but a no brainer fix. 1 day and maybe $50 total material bill.

 

oh well that is a little bad..i have to lift the engine a few inches to drop the oil pan..but wouldnt the crank be scored as well? if it is this..if it is really bad then i will just take the engine out and get a 383 kit(worse case scenario)..but i just turned 18..so its gonna b pricey...
well i am just thinking about how much further damage could of occured...but obviously ill drop the pan to inspect

thanks for the reply

 

just out of curiosity what are the chances of it being flexplate, TC related?

doubtfull I guess but just covering my bases.

 

rx7speed. very smart comment..That is what i suspected as well due to the engines bottom end being professionaly rebuilt 1 year ago....also today I checked again and it seemed to by coming from the midway between tranny and engine..also I checked the oil..perfect..no metal...compression was always stable before, while, and after this happened, distributor is tight......spark plugs are all very good and ligth tan..and non are broken off......all rockers, pushrods, valves seem to operate how they should...also I understand what an internal engine failure would sound like..but this sounded VERY external..ALSO my tranny inspection plate is not there,..so it could be coming from there..When the noise happens it occurs every complete crank rotation..and its not jsut a sound..its a very clear jerk of the car every time..like you can feel it rebound when your foot is touching the gas...I was thinking about this and the only thing aside from an engine issue which it seems like it is farther and farther from...is the next best thing connected to the engine..>flexplate>torque converter...It is a non lockup converter..so there could be some type of fluid transfering issue(converter was sent out 1 year ago so fins can be adjusted for 2200 stall..not sure if this would be an important point)

I hope this recent news can further shed light into this trouble shooting..thank you very much for your replys

 

The best thing to do would be to drop the oil pan to inspect (and rule out officially) the bottom end of the engine.

If you have a non-stock cam that's got a high lift, it is possible that you have a (or a couple) pulled out rocker arm stud(s).

The fact that the motor jerks about once every full revolution would lead me to believe a misfire. I would also take all of your push rods out, and roll them on something you KNOW is flat (emphasis on "KNOW" and "flat")


If you have your computer system connected still, and the knock sensor is working correctly, and there is knock present, then it is possible that it is retarding timing when knock is present enough that it wont shut the car down, but enough of a power surge it surges through the throttle linkage too.


No matter what it is, it has to do with the engine not combusting properly to cause it to be felt through to the gas pedal.




When I spun bearings on my camaro, the car would barely idle, the knock sensor wouldnt let me go any higher than about 55mph. Idle was not present. And it made an audible "KNOCK" twice per revolution.

 

I think it is a spun bearing. I suggest an oil pressure test. Nothing worse than pulling the pan in-frame and then having to pull the engine. If there is a problem in the bottom end it will be reflected in the pressure at idle. If there is a problem with a bearing it will flat-spot the crank journal and the engine will have to come out anyway. A flexplate/bolt problem will vanish in drive just above idle. My

 

thanks for the replys...i checked the oil(via dipstick and there is no trace of metal) however I understand that the proper way is to drop the oil pan...also i checked all of the rocker arm studs and they are all at the same height..as well as the nuts, ONe time when i lost a keeper and my valve just dropped a little..i automatically lost oil pressure....however like i stated previously..the oil pressure guage reads that there is plently of pressure and the car does idle..however it is hard to start..as in when it cranks..it almost seems to wind back....THis is a sign of possibly too much advance..i havent touched the timing and the distributor is tight..however the distributor might have skipped a tooth or something internal that is causing this rapid advance like situation....I will pull the distributor tomorow and narrow down the possibilities even more..Thanks for the replys...Keep em coming

 

well i did some more searching and it also could possibly be a cracked flexplate which would completely add up to my findings..however a further inspection will be done tomorow by myself

 

Hmmm im not too sure on the cracked flexplate deal...

My dads old truck had a 305/TH-350 and it had a mysterious vibration @ WOT, we couldnt figure out for the life of us what it was. That is untill the engine finally had the bun and upon swapping in a replacement we found the flexplate had cracked just about 3/4 of the way around and about 1" from the bolt pattern on the crank.

Im not ruling the flexplate out but from personal experience we have had a very badly cracked flexplate and it caused nothing more than some vibration @ WOT.

 

If you wanted to rule out a cracked flexplate you will need to move the transmission out of the way. Not a fun task, but maybe if you planned to put a shift kit in, or just change the fluid and filter on it at the same time then it would seem a little more worth while?

 

well i installed my b&M shifter a few months ago...but i do need to change the trannyfluid and filter....but I have checked off a lot of things already that are not the issue....so ill continue to narrow down my list..thanks for the replys

 

Check the TC bolts and damper bolt before you drop the pan. I had an 81 malibu wagon that did the same thing twice. The first time it was the damper bolt, then it did it again and I checked it and it was tight so I thought I blew it up, then I checked the TC bolts and one was loose. That is where I would start.

 

thanks a bunch..ill definately give it a good check when i have a free second

 

it probably could be that your flex plate cracked around the six bolts that's what happened to me when I thought I blew my motor. It made a loud noise

 

damn...flexplate is fine

 

When I broke the crank in my old 355 TBI, it ran very poorly due to the knock sensor. Funny thing is that in DRIVE above idle, I never knew I had a problem. It wasn't until I tried to start it that I knew I had a problem. You have probably never heard anything that sounded like this engine while it was cranking over. As soon as it fired it sounded like rod knock or a broken flexplate. When you put it into gear, the noise vanished.

 

Drop the pan & pull the rod caps on #3 & #4. Bet you will find a wiped bearing.

 

well i took my engine and tranny out the other day.....today I took the drivers side valve cover off(never suspected sound to be coming from there).........noticed that pushrod was not in lifter bore so after further inspection I noticed that my crappy proform roller tipped rocker was cracked .

wow all that , pistons are fine, heads are fine, just a damaged rocker ..I will post pics
...well whatever really, if i still had it in the car I would just replace the rocker and be on my way....but I will continue with the 383 buildup
ATleast now I can trade my 350 crank and pistons....as they are not damaged at all

 

how are you going to trade in your 350 crank and end up with a 383 or is sleep depravation getting to me again?

 

its the sleep..

 

what do you mean trade in then wow nvm i'll go to sleep and reread tomorow.

 

no i just meant that my local machine shop redid the bottom end last year and I bought new pistons from them for the 350 so they might take my 350crank and my flattops and give me their 383 ready cranks fora lower price as well .......thats what i meant,,,,i really didnt mean for it to be a brain twister...Ill be clearer on my wording next time,,,in the mean time,,,,get some sleep and dream of

 

I just had a proform rocker fail also, well I can't be sure that the rocker failed first or if it was the broken pushrod that cause the rocker body to "egg out". Either way proform=junk IMO, the bearings are rebuildable you'll probably never get the chance to rebuild them though as the rocker body itself will fail long before the bearings do. I replaced the stock pushrods with speedpro stuff and ordered up a single rocker. I wouldn't reccomend doing that fix, it's just a matter of time before one of the other's comes apart! Using proform rockers on anything except a mild build up could be an expensive gamble. I'm probably just stating the obvious to most of you guys, it might save someone trouble though! -Ben

That 383 project sounds like fun! I can't wait to get more inches under my hood.

 

1983 f body...true true and true.....no more screwing around for me ...its screw in studs and crane gold full roller rockers....
its gonna be one fun time with the 383.....I will seriously have to mount a camera underneath facing the diff and shaft.....I suspect some major carnage under there if I hook up