Alright, so my power steering pump bearing was starting to squeek so I figured I would replace it. Got the car on ramps last Wednesday and started working on it and I messed up the high pressure line that goes into the pump so I ordered a new one. I put the new line on today and bolted everything back up. Go to start the car up and it makes a HORRIBLE noise. The whole thing shakes and vibrates and it sounds like something is loose inside the motor. I have no idea what so ever it could be. The car sat for less then a week and when I put the car up on the ramps it ran perfect. I really need help here guys, I'm afraid to let the car run more than 5 seconds. Sounds awful and I just don't know what to do, I pulled the injector fuses and cranked it up and got oil pressure to make sure the lifters weren't down or anything. Does anyone have any ideas as to what could be wrong with it? Please help, I am totally lost. I have the belt off of it, so I know it's not that.... I really hope I don't need a new motor....

Car is a 94 Z28 with 6-speed, LE1 heads/cam and all the boltons only 90K miles too.

Thanks everyone,

Bill

 

You need to isolate the cause of the noise. Since the only thing you changed before and after was the pump, start with that. Pull off the belt, start it up, and see if the noise goes away.

EDIT: Just saw that you already did that, hahah.

Can you identify where the noise is coming from?

 

Couple be your water pump starting to go. or maybe your opti.

 

Sorry, forgot to mention that I tried that, took the belt off and still did it. I have an electric water pump and the opti has less then 5000 miles on it and ran perfect. The thing is when I parked the car it ran great, when I started it up today after less then a week and this happened. It starts, just hardly runs and makes and weird tapping/clanking/banging noise. I would say it almost sounds like the started isn't disengaging, is that possible?

Thanks....

 

Sure, it is possible. drop the starter down and see if the armature is stuck or if anything is wedged.

 

Alright, going to go try that, then take off valve covers and pull the plugs, ugh I have no idea...

 

Hopefully you didn't spin a bearing upon start up...
If all you did was change the pump and now it makes the noise with the belt off, then your problem is completely unrelated.

What does it sound like?
When I spun a bearing, it sounded like a hammer beating on the inside of my motor. When I took the valve covers off, I ran the engine and I noticed that oil was squirting out of only a few rockers (more than normal) and the rest were getting nothing. Hopefully that's not your problem.

 

It's really hard to describe as I let it run for 5 seconds or less out of fear. The motor and car shake and it doesn't seem like it wants to idle at the usual 800 RPM. It didn't sound like a hammer hitting the inside persay, but something was banging, I was thinking maybe a collapsed lifter. What I don't get is why it would spin or do this on start up. I pulled the plugs and some looked really bad, like totally fouled which didn't make sense because the car ran fine when I parked it. I got new plugs and changed the oil, nothing unusual in the oil.

Also, when you spin a bearing the oil pressure usually goes down right? When I spun the motor over with the injector fuses out I got a good 25 psi, which I thought would be normal for just the start cranking the motor over. I am really stumped as why it would suddenly do this after sitting up on the ramps...

Thanks,
Bill

 

It's pretty easy to knock off a plug wire doing the pump, I had to remove one anyhow....look there.

 

You should try to pinpoint where the banging is happening with a stethoscope. Pull the covers, and go from there. If nothing looks awry, maybe pull the intake...

 

Just be happy it's not the power steering pulley making the noise - only 2 dealerships in the whole country have any remaining power steering pulleys in stock and the only other place you can get a power steering pulley is hawksthirdgen. Otherwise you have to go junkyard diving... haven't found one company that makes aftermarket pulleys. Anyway, sorry, little OT but your power steering reminded me of it.

 

Can you take a video OR record the sound? Unless you dont wanna chance running the engine.

 

I don't really want to chance running the motor, but at this point it's really the only thing I have left to do and just let it go. I replaced the plugs and I know the wires are on there. When I had the plugs out I took off the valve covers and turned it over by hand a few times but I didn't hear/feel anything at all. When I pull the batt/ign fuse and turn it over with the starter I hear nothing either. My mechanic suggested maybe a stuck valve, but they all looked good and it only sat for a week if that. I'm starting to think that it wiped a main bearing on start up, which makes no sense but is the only thing that I can think of that would make it cause such a loud banging noise. I just don't want to ruin my top end if I do need a new bottom end, I can transfer the LE1 package.

 

Sounds more like a rod bearing then a main, since you still have oil pressure.
My rod bearing spun when I turned the car off, I heard a ping and the next morning on the way to work......thump,thump, thump, thump.....etc. Didnt actually happen while racing it was when I got home.

 

Sweet, just what I wanted to hear lol, where is a good place to get a good shortblock cheap? I see new ones listed on Ebay with 4 bolt mains that says they are new GM units for $1200, seems cheap. I want to keep this one cheap bc I will probably forge it and stuff in the next few years.

Thanks guys....

 

Well I would tear down your current block and take it to a reputable machine shop and have them bore and hone the block, cut/polish the stock crank, recondition the rods and install ARP rod bolts, new Mahle 4.030" pistons (forged if you have the money), balance the rotating assembly, install new bearings and rings. Then you'll have a nice short block that can handle a decent amount of power and rpm.

 

Alright, thanks for the idea, I was thinking the same thing, just wondering what the average cost for that would be. And which bearings are the best for the LT1's I know that's a common problem. Thanks for the help guys. Just gotta find a place to do the work as I have no garage to do it in

Thanks again,
Bill

 

you can find used short blocks for cheap all over and just swap it in.

 

https://ls1tech.com/forums/lt1-lt4-m...d-rebuild.html

 

I rebuilt mine myself.. got the parts and saved a lot that way