My 99FRC had a CEL and loss of power. I found a po300 code and pulled the valve covers. The intake pushrod on the drivers side rear piston is missing(I dont know the firing order yet). I am sure it broke and fell into the galley I hope.
I am going to replace all of the pushrods with aftermarket versions(u-suggest). At the same time I want to buy a set of nice affordable rocker arms(suggest ratio and brands). Can I stop here assuming there is no valvetrain/engine damage? Or should I replace the stock springs,retainers,ect. Consider that I want new heads in the future. Will the aftermarket rockers and pushrods add strain to the stock springs? I have heard the springs break easy on stock motors is this true? What is the highest spring rate that you can run with a stock cam or does this matter?
I noticed the pushrod hole in the head is now slotted a little, does this hole act as a guide? Are you guys running rod guides and should I add them also? Sorry so many questions here, I guess I could just replace the pushrod and check the others. What would you do?
Last thing, I will have the intake off while looking for the pushrod. I could put on a 2001 at this time. Would you? The BBK looks affordable does it work good? Thanks for your time - Steve

 

I started thinking about the pushrod breaking and I bet I am wrong. It could fall into the galley by bending below the head. Anyway I will find out ASAP. Thanks - Steve

 

The very first thing that I would do is determine why it broke! Did you ZING the engine (shift into second when you should have shifted into fourth )
The P0300 code is normal and should be expected during a cylinder misfire condition.

If anything like that happened or you have a broken spring and the valve touched the piston, you could have a bent valve. Recommend that you do a compresson test and or a cylinder leak down test. If you hear air leaking into the intake during the leak down test, that would indicate a bent valve.

As for the intake, yes I would change it to an LS6 intake. I would just port the OEM throttle body.

1.8 rockers will help BUT it looks like your springs are already having issues controling the valves!

New heads seem like the best money spent in the LONG RUN!

BC

 

I agree with Bill. You need to find out why you lost a pushrod first, and check for a bent valve.............or worst. Have you checked your valve spring to see if it's broke? I have a strong feeling you will be pulling that head off. Good luck and hopefully no expensive damage.

 

Aftermarket rockers will require aftermarket springs. The Crane setup is a good setup.

I can't figure out where that push rod would go. I would get a boroscope and see if you can find it. You need to get out all of the pieces. I have heard of them bending, and breaking, but no disappearing completely.

What was happening when this occurred?

 

If it were my motor I wouldn't do anything until I found the pushrod and/or pieces of it and figured out what happened. It's not normal for a pushrod to be completely missing, something extreme happened inside your engine.

 

That is unless you were driving a C6R at Road Atlanta! (Sorry, couldn't resist).

Good luck, let us know, take some pics as well.

 

Yea, and we all know how that turned out! Seriously though, find that pushrod.

 

How it happened... I did a u turn and ran first up to 5500+ and then shifted to second with my foot off the gas like I always do. No power shifting with the gas on the floor ever. When it got around 4000rpm it started loosing power so I let off at around 5500. I never hit the rev limiter, but I do not know how the car was treated before me. I bought it about 3 months ago and drive it with respect.
After the CEL came on I stayed under 2500 rpm and limped it home 20 miles. No odd engine noises or anything scary sounding. I had oil pressure and the temp was ok, it just felt like a burnt plug wire does. I assumed it was valvetrain problems since I ran up the rpm when it happened. What was weird is the fact that I turned off the traction control just before this happened. It should not have caused anything to go wrong because I was not spinning the tires when I stepped into it.
I had it a small Chevy dealership and the mechanic found problems with cyl 2 and 7 when he did a compresion check. I am pulling the itake tonight and will repost what I find. I am also going to do a comp. check myself soon. Sounds like I might need a set of heads. Strange to me I could not find any thing wrong with the valve springs. Its the first time I have pulled a valve cover off and had a pushrod hiding below the head. Its my first Ls1 so thanks for the help. So far it has been simple to work on. Steve

 

PLEASE post pictures of what you find!!!! Remember, FIND the ROOT CAUSE of the problem.

Good luck and let us know if you need any more help.

BC

 

If your spring isn't broke, and the push rod is on one peice, then the only other explanation I can think of would be a lifter collapsed. How does the Rocker Arm look? I have heard the bearings going out. I don't know if that would give enough slack to cause the pushrod to come out or not. But I would check everything from the cam up to the Valves on that cylinder. I don't think you lost a cam lobe, because you would have heard a lot of noise before that. I have seen a roller lifter fail (Not on a LS1) and it made the roller sieze up and it wore the wheel and the cam lobe down like as if it was on a belt sander.

Did you find the push rod yet?

 

Back from the garage. I found half of a bent push rod in my head bolt oil galley. It is bent and looks to be chopped in half. The rockers all look good and feel good, no needle bearings found. My next step is to pull the valley pan. Is this tricky or do you just pull the coolant tube,ect and unbolt the pan? What does the inside of the block look like? Could the other half of the pushrod make it to the pan? I know the little chunks could have since it was not a clean break. How hard is it to pull the oil pan in the car on a lift?
Has anyone pulled the intake on a car with a real clean engine compartment and found a sandbox under there? I guess on a 99 it should be a little dirty. Well I better get back on it and find the rest of the trouble. I have a few pics , can you browse upload on this site or do you have to have a host? Thanks , Steve

 

Not sure why you are pulling the intake. You can't access the lifters by removing the intake. You unfortunately need to pull the heads. You might want to pick up a tester and check the valve springs. If they lost a lot of stiffness you might have inadvertantely floated the valves. Also, even though the tach says 5,500 it may lag the actual RPM.

 

Unlike the old SBC, the pushrods for each cylinder goes through a galley of their own under the heads through a plastic guide that fits in the galley on top of the lifters. My best guess is that the bigger parts of the missing pushrod will be found at the bottom of the valve guide or possibly they pierced through the guide into the pushrod galley itself. Can't see the pushrod busting through the aluminum to the valley under the intake.

Bent pushrods are most commonly caused by excessive rpm or weak valve springs. Since you didn't hit the rev limiter and you don't appear to have any broken parts except the pushrod, that leaves the spring as the probable culprit.

 

Loss in power huh? My car wouldnt even stay running with a cylinder down. Maybe your's did since the valve was closed

 

Ok,
So should I pull the heads now? Sounds like the best thing to do instead of trying to find the other half of the pushrod with a telescopic magnet. I doubt I could get all the pieces out of the block. How hard is a cam swap? Should I start another thread or check the archives on this? I have ?'s about upgrading the oil pump, new heads and a better cam. I am looking for 425hp at the crank if I do this. At this time does anyone think I can replace a pushrod and check the others and get it running. If I could it sounds like it will happen again until I find the cause of the origional problem. I bought this reliable c5 so I could finish my c3 project HEHEE! Just my luck! Looks like HP upgrade time. Thanks,
Steve

 

Pulling the heads is the best idea. Besides getting the rest of the pushrod out, you can check the lifters for any visable damage.

Hardest part about a cam swap is moving the steering rack out of the way of the crank pulley. Here's all you need to know about a heads & cam swap: http://www.ls1howto.com/index.php?article=1

I would still replace the valve springs and pushrods if you decide against heads and cam at this time. In this case I would at least use '01 LS6 springs and hardened pushrods for a little added strength.

If you swap the cam, the newer '01 up LS1/LS6 oil pump and a LS2 chain are cheap insurance since you're in the neighborhood.

If you have about $800 laying around then you could buy a set of used '02 and newer LS6 heads. You get heads that will give you some added hp and have a lightweight valve train that will spin to 7500 rpm and can handle a .570 lift cam. If you decide on bigger heads later on then you can resell them or use them as a core on some stage 2 LS6 heads

 

Sand Box under the intake!! OHHHHHHH YEA!! When we did Englandgreens cam, there was a lot OF SAND UNDER THERE!! Pull it off carefully and vacuum out the sand/dirt!

If you just want to fix the problem and need a set of springs, rockers and some pushrods, I'M sure still has them laying arounr his garage. You could most likely pick them up for a song!!

Replacing springs, rockers and pushrods is a snap!

BC