ok just came back from the shop... so installed a timing chain tensioner.. the big bolt in the back... redid the oil, bam noise gone! let it get to warm state, high idel and yeep sound came back.... sooo valve cover is off... tiny and i mean tiny slack in the timing chain.... start the car (with cover off) can not see anything damaged... now the timing chain is so tight you can even budge it... sooooo we are now at the wtf moment...

soo we are going to pull the timing chain compartments off and check to see if anything on the timing chain is broke... if it is not broke.. it leaves 1 or 2 things... push rod or main rod....

last option.. instead of dropping in 700+ for all the rods, rework etc... junk yard motor for 500 w/ 6 month warranty and keep the blown motor for spare parts.

 

Push rods? Dual Overhead cam engine does not have them.

And main rod?

I don't think we're talking the same Ecotec langauge.

 

There is a procedure to installing the timing chain tensioner. It involves removing the valve cover to pretension the chain tensioner.

The chain should not be super tight with engine not running unless the tensioner was released before install. Witch means it is not installed correctly.

If it was installed with the tensioner released and the engine was running for some time the timing chain guides will be damaged because the chain was so tight.

 

Here is a thread from a cobalt web site where a GM tech explains the new tensioner and the misconception that the new ones don't need to be per tensioned

The GM tech come into the conversation at post 130. The complete thread is an interesting read

http://www.cobaltss.net/forums/how-g...sioner-203071/

 

it was not ran very long after the install of the tensioner bolt. we did just take out the old throw in the new.

sorry i might not know proper terms.. push rods under the rockers. then main rod for the cylinders. still might not be proper terms. sorry.

 

also the new timing chain tensioner bolt was the new style with c-clip holding it all together, no spring like what shot out when the old came out.

 

The new updated tensioner is built different that the old tensioner but still requires the same install proceeder. Here is a picture of the new and old tensioner disassembled

 

Sorry the picture is up side down. Some day I will learn how to fix that.

 

im still reading the other thread, it was 6 pages, plus reading about engine swaping etc. so if its more then just swap engine.. so i need to put it out and redo it... however that still doesnt explain why you can hear the knock/slap with valve cover off and chain at tight state.

 

Ta da

Attachment 15580