Bad News Knock

[tazgn]

Today, after doing some FAST tuning, I noticed my knock gage going crazy at light throttle cruising. My oil pressure is slightly lower than normal in the past (about 8psi idle and 25psi at 3K RPM). I got it home and noticed that only above idle I have a pretty bad knocking sound that seems to be coming from the top end of the motor. Very much less prevalent in the bottom end. Seems to be from the mid to back of the motor as well. I can't really feel it much either. I'm thinking a rod bearing, but I would think it would be more noticable in the bottom end. I checked the rocker shafts, arms, etc. with nothing wrong there. I HATE the idea of tearing this thing apart AGAIN. There are so many aftermarket parts and hours spent routing things how I like it, it SUCKS tearing it down. Please, anyone have any other suggestions of things to do before I tear it down? I'm going to check the TC bolts and make sure they are still tight. Then I think I'm going to do the bearing swap with the motor in the car to save the hassels of tearing everything apart.

Oh, this also seems to be more pronounced when the car is warm and the oil pressure is lower.

Derrick

 

[Nick Micale]

When you are checking the converter bolts, also check for movement of the crank back and forth, like a bad thrust bearing?

 

[Richard Inglett]

Oil pressure seems a little low. With temperatures getting cooler, should be fairly easy to meet the 37 psig at 2400 rpm minimum requirement. From what you're describing, sounds like a rod is making the noise and could be causing the low oil pressure problems. But, low oil pressure usually indicates a bad main bearing. It's all bad but don't be too discouraged, it can be fixed. Best to determine for sure. A rod can be identified by doing the spark plug wire trick (i.e. remove one wire at a time and listen). Bearing damage usually reveals itself with copper flakes in the oil filter. Whatever the problem, hope it's an easy fix.

Good luck,
Richard

 

[tazgn]

Well, just fixed it. It turns out #1 rod bearing was completely shot. All the rest looked good, but changed them out to be on the safe side. I just got done putting the motor back together and fired her up. NO noise, but unfortuantely I caused some other damage. I removed the oil cooler lines from my remote cooler adapter, and found out when I fired her up that I cracked the damn fitting that goes onto the oil pump. This is from one of the summit oil filter relocation kits. So now I need to find another adapter somewhere (the piece that screws on where the stock oil filter would have gone on the oil pump). DAMN the luck.

Derrick

 

[Bob Avellar]

How did the bearing replacement turn out. Any miles on it? Is it holding up? Did you change them in the car? I am facing a similar problem. I'lll be dropping the pan tomorrow. Hope you were successful.

 

[Richard Inglett]

Originally posted by Bob Avellar
How did the bearing replacement turn out. Any miles on it? Is it holding up? Did you change them in the car? I am facing a similar problem. I'lll be dropping the pan tomorrow. Hope you were successful.

Not sure what TazGN reply will be be in my case every other case I have heard about, wiped out bearing requires turning the shaft at least .010".

 

[bird]

"When you are checking the converter bolts, also check for movement of the crank back and forth, like a bad thrust bearing?"

nick would a bad thrust bearing knock? i thought it sounded more like a growl as you raise the rpm. i have a buddy with a bad thrust bearing, actually it turned out to be a worn rear thrust surface, (looks kike he might have some convertor issues)but it didnt knock. is this common?
bird.

 

[1FASTV6]

Originally posted by tazgn
Today, after doing some FAST tuning, I noticed my knock gage going crazy at light throttle cruising.
Derrick

The knock gage still works with F.A.S.T.?

Artie

Glad you were able to fix the bearings w/o tearing it apart.

 

[tsturbo]

Is this the car that was for sale a while back ?