coco95z28

95 z 128k miles

i replaced the water pump about 5k miles ago

car has orig. opti spark plugs and wires were changed 40k miles ago by the previous owner's friend of a friend (who knows if he changed all of them)

just did an oil change and have NO metal floating in the oil not even shavings

problem #1....................
car has a bad miss, every gear after 4600 rpm car acts like its hitting the rev limmiter

problem #2..................
im getting an annoying (knock, kind of noise- like a bearing or something) its external like its on the outside of motor... in the front.

we used a mechanic's stethoscope and a 3 foot wood pole to press up against the oil pan, top of motor, both valve covers,

its real, real, real, loud and bad right around the water pump

my question is... what does the water pump attach too called? does it attach right to the cam? are there bearings that can go bad in the pump? if i get an electric pump can i delete that shaft (if it is possible)

my next question is as far as the opti goes, is there any type of gear in them? that mybe goes bad? maybe thats causing the miss and also that noise?

thank you for taking the time to read all this, just want to get a good idea how this stuff works before i get into all this....

z28beast

the opti has a shaft on the end of it which slides into the the cam sprocket.,..if you look at an lt1 timing set youll see that the cam sprocket bolts to the cam and the opti sits in the splined opening of the gear....if you get an electric wp (ewp) then yes you can delete the shaft by removing the timing cover and pulling out the whole shaft /bearing assembly... and no there is no gear inside the opti itself just a roter...if your getting a miss and stumble 8/10 times its the opti....wp's generally dont cause problems unless leaking

coco95z28

does the water pump bearing go bad sometimes? i mean i swear its comming right from the pump...

OBE1 95Z28

I doubt that the waterpump or the opti would cause the noise you are describing. Pump bearings would generate a growl noise not a knock. As stated above, waterpump failures usually exhibit themselves as a leak out the weep hole.

Injuneer

He has a 95. His vented (95-97) Opti is not driven by the shaft, and neither the Opti pilot shaft or the cam sprocket is splined. Vented Opti's are driven by the cam dowel pin. The "shaft" is only a pilot shaft and rests in the deeper hole in the nose of the cam, not in the sprocket. The shaft for the Opti has nothing to do with the water pump, and can never be deleted, unless you delete the Opti.

The water pump is driven by a gear machined into the back of the cam sprocket, which in turn drives the water pump via a gear on a splined shaft that is bolted to the block and supported in the back by the block, and in the middle passes through a seal in the timing cover.

From Shoebox:

http://shbox.com/ci/water_pump.jpg

I believe he is addressing two problems, one being the misfiring, and the other being a knocking noise that the mechanic's stethescope seems to indicate is coming from the water pump.

I would check the weep holes on the water pump, to see if coolant is dripping on the Opti.

coco95z28

ok did some work on the car, i took the water pump off and it seems fine, spins free, no viberatins.

i used a pair of pliers and started wiggling that shaft that comes out of the motor (for the water pump) and it doesnt go in or out, it just wiggles around a little bit like its loose. seal still looks good though.

so is that shaft even suppose to wiggle like that?

and if not, i can pull the opti off, and crank hub off, since the water pumps off, how hard is it to remove that (timing chain cover?) i dont know whats back there?


also how far does the front of the oil pan have to come down? and what is the correct way to do this???

and if i just remove it all together (since its going to be off) i have a welder for the hole, i may just put an electric water pump on to delete that shaft?

coco95z28

update.


its just like a noise coming from right behind the pump, we used a stick and there is no sound coming from the oilpan, valve covers, or top of motor, car is also missing bad after 4500 rpm.


BUT i just took off my orig. opti and it feels rough and you can hear something grinding/hitting in it (when you manualy spin it). plus a bunch of plastic peices fell out when i took it off...


i might have found the problem, but its a $250 guess.

97FormulaWS-6

The opti is 99.9% probably the cause of the miss.

And as for the noise, describe it a little better; a knocking is too generic to even do anything more then generalize at.

coco95z28

ok guys i think im on to something...


i loosend the 3 (cam retainer?) bolts by hand (right behind the opti)

they all backed out, and were hitting the opti. on top of that, they are all stripped out and shiny about 2 mm from the nut? i tried to tighten them but they just kept spinning so i looked down as best i could and the motor part looks good, so i just need them 3 bolts.

sound was a grinding, clunk every now and then, goes away after 1000 rpm
(like something was loose)

i got tired so i left the car till 2maro. also how tight do them bolts have to be? just snug?

Injuneer

Never assume something like "just snug".... that's how you got where you are right now with the bolts coming loose.

Shoebox has a bolt/fastener torque matrix for the LT1:

http://shbox.com/ci/fastener_matrix.html

coco95z28

Camshaft Sprocket Bolt 18 lb. ft. 1/2" 5/16"-18 x 3/4"

guess thats it, heck it even gives me the bolt size lol.

i wonder how them bolts even loosened up?

z28beast

thanks for the info fred...i wasn't talking about the opti shaft i meant the wp shaft/bearing.....so on his camaro that cam pin drives his opti?? hmmm weird

coco95z28

last update.

got it running!

needed 3 new bolts and a new opti. no noises and runs/shifts great!

OBE1 95Z28

sounds like you may need to apply loctite to keep them from backing out again.