87 chevy tranny help

[chevy_power1995]

I blew up my transmission im my 1987 silverado and i swapped it out
with a different transmission and torque converter. and it moves fine
and everything but theres a LOUD knocking coming from the flywheel/
bellhousing/area i dont know what the hell it is any suggestions????
and it has fluid in it and the torque converter bolts are really tight
and i didnt remove the flywheel so its not that and i also inspected
the flywheel for cracks any one know whats going on???

[87 STEPPER]

Welcome to the board!

Sorry about the death of your tranny i am assuming your new trans is also a 700r4 as well.

Is this a rebuilt unit or a used unit? same ? for the converter.

It sound's like it could be the front plantary gears or the pump but it's hard to say for sure.

[old Rusty C10]

ive seen perfectly good flywheels crack when the tranny is replaced sounds to me like the flywheel went youre going to have to drop the trans anyway or at least pull it forward prior to removal so check the flywheel its possible one of the torque converter to flywheel bolts broke or something too if they were put on too tight but ive had several over the years do this it sounds almost like a real bad motor bearing

[chevy_power1995]

They are both used but in good shape yes 700r4 any other suggestions working on droping the tranny as we speak...How do i know if it is a bad pump? of course I have to take it out but how do I tell if it is bad thanks for all the help.

[James McClure]

Chevy. Seeing as your going to pull the old slush box, check this beforehand. Remove the torque converter to flexplate bolts. Try to pry the torque converter towards the rear of the truck. You should be EASLY able to attain 3/8 to 1/2 inch of clearence. If you can't, then the hub on the torque converter didn't properly engage the pump drive gear in the trans when you swapped it out. In this case the front pump is going to be trash. If you can attain the clearence, pull the trans back as far as you can and with a flashlight look up at the end of the crankshaft where the flexplate bolts on. If you see alot of very light powdery rust colored deposits, the flexplate is cracked. If you grab ahold of the flexplate and try to bend it front to back it might make a creaking noise, MIGHT is the key word here. If you rotate the eng 360 degrees a little at a time you might be able to see a shiney spot where the crack is. I have seen flexplates cracked all the way around the crankshaft hub and had it litterly fall out when the converter bolts were removed! Hope this helps, jim

[68K20 x Drill]

Jim is right, and surprisingly, you can still drive with it cracked all the way around if you don't mind the racket.

[chevy_power1995]

i thought about moving the tranny back
myself but i dont have very much free time i think i am going to do
that this weekend though i just wanted to explore all my options
before i went and redrooped the tranny for spark knock or something it
deffinetly sounds like i dropped a bolt in my torque converter or
something..... is that a possibility and also too i forgot to fill the
converter up with fluid before i installed it will that do it???? it
had a little bit in it not much though.... thanks for all the help

[James McClure]

Chevy. haveing the converter empty on install isn't a problem if you fill the trans to mark as soon as you start up. You might have left a converter bolt loose and it fell out. That would certainly make a racket. Bottom line is pull the trans back and look. jim

[Thumpin455]

Did you use the bolts that came out of the old converter, or just some that fit in the holes? Have had people replace transmissions, lose the converter bolts, then find they have a knocking noise. The bolts are short for the converters, if you use a 1" or longer bolt it will bottom out before it holds the flywheel. It makes a noise just like a rod knock when it happens.

If the thing moves, the pump is usually ok. No pump = no pressure = no movement because nothing will apply.

Other than the bolts, a knocking noise is the flexplate cracked or loose. Chevies tend to break flexplates, must be cheaper metal than the BOP flexplates. Still havent broken a Pontiac plate and they have been behind 500-700hp drag engines with high stall converters. Have cracked 3 plates behind 305s with two barrel carbs.

[chevy_power1995]

i moveed the converter fine it definetly was enagaged yes i used the same bolts for the converter its not tthat the only thing i see wrong with the flexplate is like a few teeth are worn on the edges like 4 teeth

[chevy_power1995]

okay i took the transmission out i and started it.... its still making the noise. i took the flywheel completly off no cracks or nothing like that... thrown motor bearing? Get a new flywheel and test it again with a new flywheel???

[James McClure]

Chevy: Flywheel is definately bad and will have to be replaced. Starter clutch (the gear part) or solinoid cause teeth to get "ripped off". Replace them both and try again.
I do, however, doubt they are the source of this noise. Lets do a little digging here. First, the noise wasen't there before the swap, so, obviously you did something. Oddly enough I want you to check the distributor, specificly the cap. When you drop the back of the engine to get the trans out the cap hits the firewall and will get cocked to the front just a bit and will stay cocked after your done. When you start the engine the rotor hits the cap and it makes I racket. If you find this to be true, replace the cap and rotor with GM ones. Aftermarket caps are thin in the coil screw area and the spark will jump to one of these screws and you'll wind up with a skip. If that isn't the problem next place to look is the front of the engine. Quick check is take off the drive belts and start it up for a minute. If the noise is gone, check all the rotating members for something bent, sticking or out of position. Check the fan blades and the fan shroud. I HAVE MADE THESE MISTAKES MYSELF. If you still have the noise, the last place to check is the oil pan. Did you use a floor jack under it when you swapped out the trans? Bottom of the pan HAS TO BE PERFECTLY FLAT!! The oil pump pickup screen is only about 1/2 to 3/4 of an inch away from the pan so if the pan is squashed up it could block off the pickup screen and starve the engine for oil and turn it into a good boat anchor. Let us know, jim

[chevy_power1995]

i took off the cap like you suggested there is a pretty good gash in it i dont know if thats the source of the problem yet or not but i will go to the auto parts store later on today and pick up a cap and rotor and see if it gos away i didnt do anything with the engine it just stayed in place i just put a jack stand and a piece of wood under it to support it just in case but i did not drop the engine at all...... if this cap and rotor idea does not work i will try the belts next thanks for the help james

[Dooley]

You didn't happen to place a jack under the engine's oil pan did you? Sometimes people jack the engine up in this manner to line things up. Bad move! People that have done this sometimes tweak it just enough for the crankshaft to hit the pan in the shallow end. Take a look at it.

[chevy_power1995]

No i didnt place a jack under it to line things up. the transmission is completly out right now so its something motor related obviously i put a new 350 flywheel on it. the cap and rotor are brand new now..... so it wasnt that. i looked in the fan shroud area nothing is knocking in there either.. also too its not the starter i also replaced that.i have yet to try taking the belts off ill go do that now

[Dooley]

Originally Posted by chevy_power1995

No i didnt place a jack under it to line things up. the transmission is completly out right now so its something motor related obviously i put a new 350 flywheel on it. the cap and rotor are brand new now..... so it wasnt that. i looked in the fan shroud area nothing is knocking in there either.. also too its not the starter i also replaced that.i have yet to try taking the belts off ill go do that now

I was referencing your original post. You said you blew the tranny and replaced it. You didn't allude the noise was there before but, after tranny replacement. If the pan got tweaked in your original repair/replacement, it still would be tweaked even if you subsequently remove the tranny. sorry for not being helpful.

[chevy_power1995]

no no no all help is appreciated please if you have any other suggestions i appreciate them all because im still stumped im starting to think its the starter does any one know a good way to test to see if the flywheel is maybe hiting the starter a lil???

[Thumpin455]

witness marks on the starter, meaning there would be a spot where the starter has gouges or scrapes from the flex plate hitting it. Smack steel against aluminum and the aluminum will give every time..

Im beginning to think its a bearing.. hate to say it, but it is possible..

[chevy_power1995]

yeah me too compression test will tell me if it is right?????? i have done everything its not the starter its not the flywheel its not the drivebelts its not the transmission not the oil pan or pump pick up not the cap or rotor not the fan blades i dont want it to be the motor i just put that thing in there not even 2 months ago!!!!!! any body got any other suggestions??? im lost............. (compression test tell me if its engine internal if not what will????) thanks for all the help so far guys......