Originally Posted by ChopperDoc

If you have a manual, then line pressure doesn't apply to you. Perhaps the crank was improperly measured/torqued. Maybe the pilot bushing is worn out... not sure in your case. First I would determine if your thrust bearing is even bad. Could be something else.

Originally Posted by ChopperDoc

If you have a manual, then line pressure doesn't apply to you. Perhaps the crank was improperly measured/torqued. Maybe the pilot bushing is worn out... not sure in your case. First I would determine if your thrust bearing is even bad. Could be something else.

Originally Posted by ChopperDoc

If that's the case, I'd tear it down and take it to the machine shop to have the bores checked, as well as the crank journals. I've never heard of a clutch taking out a thrust bearing. Maybe someone that sees this could chime in if they have experience with that. I know that sucks to hear, but to me it sounds internal. I'm not trying to hijack the op either, but try to offer an answer. That doesn't make a lot of sense. Something has to be wrong with the block. Obviously, checking all clearances would be the first step.

Originally Posted by Black2ssrs

Supposedly they checked everything. The crank walked and took piston, crank bearings, cam and everything else. Only thing that was good was the block. They didn't check anything with the transmission. Now they said it has to be with the transmission since the same issue is happening again. I got ripped off and when I brought it up to the shops they blamed machine shop and machine shop blame speed shot. I'm not a auto mechanic but worked helicopters for 15 years so I can recognize when things aren't right. My plan is check the engine for metal and the bearings and might send transmission to get looked at.
I have ls3, BTR custom grind cam, heads shaved down, headers and mecleod RST clutch. The engine rebuilt twice so I have a alot investediin this car. Sucks I havent been able to enjoy it for a few years cause of the issues. Sorry for rant its just stressful.
I just want it fixed right and on the road

Originally Posted by ChopperDoc

It's funny you say you're a helicopter mechanic... I've been doing that on blackhawks for over 12 years, and 5 on hueys. I've been working on cars since I was a kid though... I can understand your frustration with the shops. The only shop I ever deal with is good machine shops. Everything else I do myself. I would also have that trans checked, but I would measure the clearances in the block myself. The crank shouldn't be "walking around" more than .003". This is as simple as the correct sized thrust bearing and proper main bearing clearance, which should be in the .002-.003" range. Check that with plasti-gauge or a micrometer. The only other potential problem could be the bore alignment, as in when the engine was honed or bored over, if this was done, it is possible that they could have got the alignment off, but unlikely. This would cause whichever piston to add a bit of lateral thrust or imbalance on the crank, but again, doubtful.

Rebuilding engines is the bread and butter of auto mechanics, I suggest learning how so you don't get ripped off. It really sounds like someone didn't do thier job and messed up your build. It's really not hard. YouTube has all the info you'll ever need, and you can always come here and ask if you get stuck.

Originally Posted by Black2ssrs

I worked blackhawks, 206, hh-65, 407, and did 412 and hueys over in the desert. Those are piece of cakes.
I've been dealing with some neck and back surgery so I'm only able to do a little at a time so this is my learning experience. I been using 4 or 5 different books to do work and tried the but the videos seem too easy and for me it never goes like that.
I tried to move the crank with a mallet and didn't see any movement. Didn't use dial indicator though. I know that's not very accurate.
Do you mind if I PM you if I have questions?
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Originally Posted by G Atsma

A loose flexplate WILL sound like a rod knock. Have you checked it?

Originally Posted by ccrane0044

Hey guys,

Hoping someone can shed some light on my situation. I am getting a loud knocking sounds from what sounds like the bottom end of my engine. This started when I first installed an '08 LY6 and 6l90e into my Cutlass. This only happens in very cold temperatures, generally below 15F and seems to be worse the colder it is. The noise will occur in all gears. (P,N,R,D etc.)

At first I thought it was engine know since when I'm in the vehicle it sounds like a ping or like someone is tapping on the headers with a wrench or something. Once everything warms up the noise goes away completely until the next time I start things up after it sits for a little while. Anyways, I ended up replacing the Engine (not due to the sound I'm referring to) for an LS3. This engine is spot less and and I have done the tuning and have scanned everything on this engine and am not getting any knock whatsoever and it runs great. For the first week or two I didn't hear the knocking noise at all so I figured it was something internal with the previous engine and was relieved until yesterday when we had another cold day. When I heard the sound I then investigated as best as I could in the driveway and determined the sound is in fact very prominent under the car, almost sounds like a rod knock. Another thing I noticed was that when I cut the engine while the noise was happening I still heard a few more pings after the ignition was cut which everything was rotating to a stop. No drivability issues have been noticed while the noise is present, everything seems to run and drive great. (Also use the recommended Mobil1 5w30 engine oil)

The transmission has low mileage, new/clean fluid and the level has been checked multiple times since the initial swap. Everything also operates properly and even get lockup with the Torque converter.

Everything that I have described is leading me to believe that this is a flexplate issue, or perhaps a Torque converter issue but I'm hoping someone can give their opinion before I drop more cash into the car. I don't mind spending the money regardless how tight things are right now, I just don't want to be spending time or money replacing parts that don't need to be.

I've never experienced a cracked flexplate so figured I would get some opinions.