ayang951

ok guys im going to keep it short and simple this time. got the car back from the shop, the shop said, i dont really know what the problem is, they thought it was a distributor but nope, so they put the stock one back on, and said 7 out of the 8 injectors are bad and the altenator is bad as well. so i am planning on buying all 8 injectors and a new altenator, but the sound its making is weird, itll make this cling sound, but once the car is revv'd a little itll go away, and when im driving it, ill punch it and itll sputter and not really gain anything... so id appreciate some expert help and ideas here. again anything will be appreciated and thank you for your time.

here is a video link i have of what its doing at idle:
http://s92.photobucket.com/albums/l6...t=IMG_0417.mp4


notice the lights are flickering and the volt meter jumps back and forth in the car as well, is this due to the altenator being bad?

again thank you.

also on a side note, how much do the injectors go for? im curious, because the shop i had the car at, told me that it will cost alot to do them, and if i wanted to, he will sell me a 98' swap for $2000 for parts and another $2000 for labor... is this a better route or just get this motor fixed?

oldalaskaman

since you dont work on it yourself, do the swap

87 vette 81 big girl

Your Vette has a heavy engine knock present at idle.

I watched & listened to your Video.

The knock is Concern #1 to me at the moment.

The engine seems to idling smooth.

Rule out injectors & ignition - distributor for now.

Does the engine still carry decent oil pressure HOT ?
How much oil pressure at 600 - 750 RPM at engine idle ?

How much oil pressure at 1,500 & 2,600 RPM's ?

If the engine is healthy,
You should see around 55psi to 70Psi HOT oil pressure @ 2,600RPM's.

The knock is 1 of 2 things ...........

A connecting rod bearing has failed & took the crankshaft journal with it.

Or the Torque Converter to Flexplate ( flywheel ) bolts are loose.
There are 3 torque converter to flexplate bolts.

Or the flexplate is cracked / broken around the rear crankshaft Hub.

Any of those 3 situations would cause the engine knock I heard in Video.

If you are lucky, just the 3 torque converter bolts to flexplate flywheel are loose.
Re-tighten them & you may be OK again.

If the engine is missing badly,
The crankshaft & alternator rotor speeds are fluctuating up down rapidly,
Voltage regulator is trying to keep up by increasing current to the rotating electromagnetic field, but cant keep up for a smooth voltage & current output like Normal.

Brian R.

87 vette 81 big girl

Its never too late to learn how to make repairs on your own C4 Corvette.

Only experts left on them are on here on C4 nationwide & worldwide.

We are scattered around the world.

C4 - Corvette Forum is where WE all are.

BR

ayang951

thanks... ive always worked on my own cars, but since i have never owned a domestic car before, and let along a corvette, i wanted to take extra care of it, so i took it to the shop for a check up... so i dont know, im thinking about that swap, but then again i am also thinking about rebuilding the motor myself too... i mean, i rebuilt some engine before, and this corvette shouldnt be too hard, since now i have this awesome forums advice. but i am still conflicted in this swap or rebuild.

87 vette 81 big girl

You have to decide what is best for YOU.

Its a pushrod V8 underneath the EFI system.

Much easier to work on & less complicated than a SOHC or DOHC engine of Euro or Japanese design.

You can make repairs yourself if YOU have the determination to do so.

Troubleshoot what is wrong with the engine in Your Corvette yourself with help here on C4.

That would be my 1st move.

BR

ayang951

ok i did another video on the oil pressure for you all to see on the gauge cluster... hopefully this will make it easier for you all to make a diagnosis on the cars symptoms..




but yeah, i know i havent been working on the car as much as i normally do on some of the other cars i have owned in the past, but this car, for some reason i just have MORE love for it, and im scared to mess it up, this is my first BIG BOY car and i want to be a BIG BOY now and i just want all the BEST for it... this is my weekend cruiser car, and not my weekend warrior car...

ayang951

thanks... i think im just going to stick to the stock motor and work on it, i love what its doing, just want it to be healthier. So im going to do some homework and lots of question asking before i embark on this journey.. but i am planning onto now, is ripping out the motor and do a rebuild on it, it will let me learn to understand the car alot better as a whole. i should have saved the $100 diagnostic fee and just put the video on this forum for you all in the first place. =D

Churchkey

Your 90 sounds like it has 2 problems however camera sound can be deceiving.

The alternator sounds like it is failing.

The knock sound seems to disappear when the engine rpm is changed/increased. If so what Brian said regarding the toque converter or flex plate is correct however now that we know you have a 6 speed what you have a "dual mass" flywheel. The flywheel will knock if the engine has a misfire at idle or if it is failing.

My 90 had a flywheel knock @ idle when it had the original multitech fuel injectors. A change to Bosch 3 injectors = a smooth engine idle & zero noise from the dual mass flywheel. Contact Jon @ fuel injection connection here on the forum for a cost effective set of Bosch 3's. There is a sticky in the tech section for FIC. Cost is around 200.00 for 8 flow matched injectors including gaskets, "0" rings & shipping.

Suggest getting a mechanics stethoscope. Check the alternator for noise & also the bellhousing area for noise.

If the alternator is in fact noisy it is an easy swap out & should cure your light flickering problem.

If the engine noise is emanating from the bellhousing area you will need to ohm test the fuel injectors to insure that they are working properly. A digital multi meter will be required & can be purchased at a discount tool house for less than 20.00. First test them on a cold engine. Remove the retaining clip & unplug each injector, test across the 2 injector terminals & record the data for comparison. IIRC the ohm reading should be 16. Next step is to test the injectors when they are hot. If any injectors read low replace the set.

If the compression & ignition system are good & there are no vacuum leaks the flywheel noise should be gone.

Your oil pressure appears to be OK.

ayang951

thanks churchkey... ill look into the bellhousing... well the diagnostic already told me that 7 out of the 8 injectors are bad also the altenator, so im going to replace those, but the bosch i see, 200 for the set.. amazing, im going to look it up right now.. again thanks.

oldalaskaman

I heard and saw something different in your two vid's, something from the old days, probly not relevent, my question, you can do a dignostic on those injectors prior to pulling them , why dont you? also do one on the alternator? the suggestion for a mechanics steth was excellent, also a multimeter. Foriegn and domestic engines may look different but the basic operation is the same, pistons go up and down, valves open and close, less its a rotary. this forum is full of folks throwing parts at problems without taking the time to do good diagnostic. as said before though, there are some really excellent vette mech's on this forum, the two posting ahead of me on your thread represent them well.

ayang951

yupp that is true... and your right... im just doing some research now... im getting prepared to start on it soon... i just want to be 100% sure... but im going to replace the altenator and injectors for sure... and im going to look into the bellhousing... again thanks for your support and time.

Muffin

Since you have some wrench turning experience suggest you spend a few hours with the book "Corvette Fuel Injection" by Probst. Will help you understand the beast. Second lay hands on a copy of the Field Service Manual. The FSM is kinda pricey but you will save the purchase price with your first repair.

Lastly, find a new mechanic, fast.

ayang951

thanks, i have purchased the chilton repair manual, just waiting for it to come in, and i will look into the Fuel Injection book. also yea that mechanic, i dont know him to well, actually this is the first time since i have ever owned a car, where i even took it to a shop, that guy was just a word from a friend, but yeah, im just going to buy some stuff i need, i just went to him because i didnt have a diagnostic reader.. i need to buy one tho, but thank you for your time and knowledge i really appreciate it, again thank you.

oldalaskaman

the chilton and haynes books for vettes are b.s. get the fsm and the probst.

ayang951

i see... ok ill call up the store that i ordered it from and cancel it and get the fsm and probst.... thanks

1963SS

You can usually go to that big auction site and search for "19xx (insert your year) FSM". I've seen them sell for as little as $50.00

ayang951

O.o big auction site... as in ebay? sorry, there are just so many of them now, like the penny ones and etc etc...

Churchkey

Agree.

You want the red cover FSM. There is a white cover FSM for 90's, it is a preliminary manual.

A complete set is 2 volumes, the second FSM is the electrical system supplement.

ayang951

so i went ahead and installed a new alternator today, the car started up with one try and it didnt make that sound, took it for a drive it was AWESOME no sputter and clanking sound, im so happy and pleased... i came home parked it, and ate lunch, decided that i was going to get some gas afterwards so i went to start the car and it happened... it started clanking again FML so i figured id drive it anyways to the gas station, on the way there the sputters started again around 2500-3000 rpms FML... so now im on to ordering some injectors...

oh yeah on a side note, sometimes when the security light and service engine light comes on the car wont start, i usually have to wait like 10-15mins before i can try and itll start? didnt happen now, but i remeber it happened to me 2 times in the past... what could that be? again all advice is highly appreciated, and thank you for your time and wisdom.

ok i just bought some injectors from kragen o'reily and im in the process of installing them right now, but it seems that i dont have the tool to take off the intake body... now do i need to take off the whole unit or just the top and leave the pipes that goes into the head on? well im looking online for a write up, so hopefully i find one, if not maybe someone can send me a link to one or talk me through it, again thank you for your time and advice also your patience as well. once again thank you.