Hello,

I'm new to the forums and made an account specifically to ask for some help from veterans

I have an stock 01 c5 with 80k on original engine

belts started slipping and the balancer was wobbling so I figured why not do a cam install with new balancer

I noticed the rear end of the car always seemed sooty (easy to notice cause it's white) but never detected a misfire on the butt dyno.

pulled plugs out, found 2 of them straight up broken when yanking them out, and one of the coils had minor corrosion so there must've been a misfire

decided to do a refresh as well with new belts, pulleys, timing cover etc. cleaned and torqued everything on with new btr stage 2 hardware

engine has new c5r chain, btr stage 2 cam installed correctly and I was in the process of putting it all back together. I did assembly lube for the cam and the dowel rod method so it's in there correctly. did NOT find TDC before buttoning everything up

im a newbie to engine building so wanted to do the compressed air method on springs, but compressed air into spark plugs doesn't actually hold pressure for at least 2 of the cylinders. The air (and a tiny couple of drops of oil) come out of the throttle body- this is what was told to me is a basic leak down test. I don't know how to find TDC through the rope method I heard about and just wanting some help on getting everything fixed. Do I need new heads?

I'm hoping for some input on how to proceed. I just want to get the car running again so I can have a pro at a shop diagnose anything else I could've missed and also do my suspension

engine list:
btr stage 2 cam kit with new hardware and plates
new katech c5r chain
new spark plugs and wires
powerbond race performance balancer


Thanks for your help!

 

My brother is having the same ole' balancer issue on his low mile C5. There's a thread below on spring changes that might be useful to you. You might try the rope method.

 

Can you confirm what you mean when you say you installed the cam correctly? You should have found TDC for installing it correctly.

Obviously the rocker arms are off the head when the compressed air is in the cylinder, right?

Its not uncommon to hear some air leaking past piston rings and swirling around while doing the springs. I use the air method every time I have done springs. If you hear the air through the intake and the valves are supposed to be closed, you might have a bent valve.

 

Right I found TDC, installed the timing chain and cover correctly. put the balancer on with ARP bolt and correct torque.

for the spring change I took all spark plugs out, compressed air into cylinder 2 and did the spring change. currently 1 and 4 are holding 0 pressure at all. air goes in and comes right out the throttle body with a tiny bit of oil

I'm removing the heads to check the valves. I also did not measure my pushrods and I hear those can hold things open unintentionally. the rep at btr just told me to buy 7.450.

 

Pushrods shouldnt matter because you cant change springs with the rocker installed.

 

I just completed the valve spring swap using the rope method and for a C5 it should be way easier to get at the back cylinders. You'll need 2-3 foot of 3/8" nylon rope or parachord, a valve spring compressor tool and I recommend the one from CompCams or the LSM Racing SC-167, a pen magnet and grease for the valve keepers. Also nice to have a bore scope but not a must.

Start by removing all of the spark plugs so you can turn the engine over by hand with a ratchet and socket. I did one cylinder at a time making sure I was on the compression stroke each time. You will know when the cylinder you are working on is coming up on the compression stroke by paying attention to the valve events. When you see the intake valve opening and then going back to closed the piston will be near the bottom of the hole and if you keep turning the crank the piston will be coming up to TDC on the compression stroke. At this point you would start inserting the nylon rope into the cylinder and once you get the rope in there you can turn the motor over by hand bringing it up towards TDC until you feel resistance. From there you can start to remove the valve springs and whatever else is needed to change. If you've done this before with the heads on a table or work bench then you know what to expect when dealing with replacing valve springs..