Well crap.

We did a cam swap (TR 224/224 114LSA cam along with 918 springs, TR 7.400 pushrods, titanium retainers, LS-6 oil pump, and rollmaster double roller timing chain) the other night. Started it up and it was running fine. The next day, after driving it a few miles, we did a fresh oil change (mobil 1 5W-30). Started it up, ran great. We were planning on hooking up the autotap and LS-1 edit to it this weekend for some tuning and maybe a little racing. I also have (ready to install) a techedge wideband O2, that just needs the bung welded in to complete the install. So, we were set, or so we thought.

While doing the warm up on the new oil, a ticking noise started from the engine. Got a little louder as the the engine warmed. Shut it off and let it cool. The noise was definetly coming from the driver's side. After the engine was nice and cool, we pulled the coil pack and valve cover. Checked the torque on all of the rockers, and all were fine. I thought maybe one had come loose. Checked all of the push rods, all were fine. Scraped off the old gasket from the AIR tubes, and resealed. Checked the torque on the headers, and they were fine. Made sure the spark plugs were in tight, and of course, they were. Put it all back together and started it up, no noise at all. I'm thinking "I AM THE MAN!" Not so fast there big fella. After the warm up, here comes the tick. Well, a lifter is all I can think of. I came on here and LS-1.com and read through all of the lifter stuff I could find (yes, the search function works!!). Still sounded like a lifter. The car only has 12,000 miles, and we have an "understanding" dealer, so today, off to the dealer it goes. About a 40 mile trip. I "thought" it would make it. It didn't. After about 5-6 miles, that tick morphed into a knock, then a thud. SES light comes on. I just happened to have the auto tap hooked up (was actually watching the LTs). Threw about 6 codes when it started knocking. P0300 misfire was the first. Checked the history, and #3 showed 26 misfires. DOH! The car wants to die at idle now, and I quite frankly don't blame it. Poor car. I had to have it towed the rest of the way (actually a flat bed). Monday it will be looked at be Mr Goodwrench, but I'm thinking the lifter gave out altogether, and the valve made contact with the piston. So, minimum, new head. Probaly a piston, and maybe a block. I didn't run it very long like that, just enought to get me to a parking lot.

So that's my story. Damn engine mods!!! Actually a friend of mine and I are thinking the lifter was probably bad to start with, and the higher lift cam and comp springs just polished it off. So, a word of caution, if you think you have a bad lifter, it may not be the wisest thing to keep driving the thing. Sorry for the long story, but I had to vent.

 

How old are the springs? That is what happened to mine when I broke a spring....

 

Brand new comp 918 springs.

 

You did not mention any thing about the springs.. You checked them?

 

Well, I have no idea how to check them.They were all seated correctly. All with new titanium retainers, all of them had the keepers installed correctly. I guess one could have been bad, but I didn't check them beyond a visual check.

 

My understanding is that 918's should be heat cycled 3 times before romping. If it's a lifter I'll be suprised. Good luck! Hope it's a simple cheap fast fix.

 

The funny part (well not funny) is it still hasn't been romped on. It was pretty much babied. Very gentle break in. Until today, it maybe saw 50mph and 2800 rpm. The wife and I were trying to break the new cam in gently. The springs weren't really even a thought. It was the cam I was thinking about.

 

I cant believe I am reading this. SAME EXACT **** happened to me, only I got no thud. I hear the knock. I think it is a spun bearing, not sure yet. I dont know how this happened. I have no idea what I am going to do now. Stroker? I dunno. Cool thing is, I am mr. goodwrench, so we shall see what my options are. Bro, I feel your pain. My bird was ready to fly, then this horseshit. Well, I am gonna plug in the tech 2 and see what she says. Just remember, 9 times out of 10 spun bearing are from lack of oil pressure. I dont know what you have exactly, but that could be a culprit. The oil pump might not have been able to keep up, or while your front cover was off something could have clogged it? I dont know. Best of luck to you, and if you need any advice straight from GM free of charge, drop me a line, I'll help ya out.

 

Also, if the crankshaft journal is black, the rod didn't fail first. Broken rods don't spin bearings - spun bearings break rods. A true rod failure will always leave the bearing intact - and it's very rare to see that.

 

I thought that if you messed with the internals of the motor that the dealership wouldn't do any warranty work to it. Because they would say that whatever you had done to it caused the problem????? Another ? is why do so many people say that you have to break in a roller cam shaft??? What is there to break in???

 

Well, since I work for GM, lemme enlighten you. If they know you swaped out any internal engine part, your warranty is void. Can they tell? Yes, but it isn't THAT easy, and depnding on the dealership, they may not even bother. Secondly, the valve springs have the break in period, they are supposed to be heat cycled as well.

 

I also started experiencing tapping after cam/headers/intake install and some head porting. Never any tapping before that. Thought it was a lifter but last weekend I pulled the heads, took a look at the sylinders and... #4 was showing piston slapping signs and was scored pretty bad.

Dunno how's that possible. At the moment I have three theories :

1 ) Due to !EGR and milling the engine did not like that much part throttle timing. #4 was the weakest.

2 ) The porting yielded different A/F ratios to the sylinders, #4 was damaged due to overheating

3 ) The tolerances were not perfect from the factory, modifications took the engine over the edge

The engine is -98 with 29k miles and is not beaten too much.
Next weekend I'm going to assemble the engine anyway and take it easy until rebuild. I'm going to try pulling part throttle timing to see if it helps any.

Tapping sucks.

 

If it makes you feel better I collapsed 2 lifters with only 4k miles on my car(stock motor)My lifters were louder when got hot,sounded normal cold.
A broken spring could make that noise but it would of done it right when you started it the second time,not after it was warmed up for a while.

 

I'd check the springs first.

If you spun a bearing, the oil pressure will fluctuate badly after the car is warmed up. The knocking will go up with rpms. When I spun a bearing several years ago the car had a ton of driveline vibration at 2500, the whole car shook.

 

WE JUST PULLED THE VALVE COVER OFF AND THE ROCKER ARM ON THE EXHAUST SIDE OF #3 CYLINDER HAD ABOUT 2 THREADS HOLDING IT ON. WE CHECKED THE PUSHROD AND SPRING AND SAW NO PROBLEMS, WE INSTALLED THE ROCKER AND CHECKED THE OTHERS, SO WE PUT IT BACK TOGETHER. FIRED UP THE CAR AND HAD NO NOISE, DROVE IT ABOUT 14 MILES AND STILL NO NOISE. SO THE BOTTOM LINE IS EXHAUST VALVE WAS NOT OPENING AND THE EXHAUST WAS POPPING BACK THROUGH INTAKE.

 

Woohoo...Calling you now. That's so weird, though, since I pulled them off and retorqued them. Think it needs some thread lock? Or do I need to have my torque wrench checked? Dangit! I should have had it brought back home I guess and checked that myself.

 

So were the rockers the problem?

 

I guess so. I need to have my torque wrench checked I guess. I know I torqued it, twice. Weird.

 

Wait, so your car is running nice now?

 

I hope they checked to make sure the threads weren't stripped. Hard to believe they were torqued twice and then loose! Maybe like you said, time for a new torque wrench.

Wish I had gotten off that easy!