326 Startup.... Bad Knock...

[psfracer]

Yes that could be piston slap in which case the noise will lessen as the engine comes to operating temperature. Have you had it running long enough for the engine to reach operating temp?

 

[Dark_horse]

Yes that could be piston slap in which case the noise will lessen as the engine comes to operating temperature. Have you had it running long enough for the engine to reach operating temp?

Ive had it up to operating temperature twice and both times the Knock went away....

 

[muztangman93]

I had a 98 trans am and it had hideous piston slap. I bought it after the guy had been driving it around and it was warm so you so you couldnt hear it. Next morning sounded like a severe knock. I googled it and I guess they were notorious for it. After a couple minutes of running it would go away.

Wouldnt that be a bad thing if it was piston slap?

 

[GB10]

Do you have any specs on clearances (mainly piston to wall) and what brand pistons? Any moly skirt coating on the pistons? Piston slap at lower temps isn't always necessarily bad, but it can be avoided with most street/strip types of motors.

 

[Dark_horse]

From what I have been hearing/reading it is a notorious 2618 problem and I guess as long as you wait till its nice and warm to drive it I don't see how it could hurt anything....I could be completely wrong though...

I am curious to see if it will go away/lessen over the break in period

 

[aleborjas]

that is not a piston slap noise...

 

[muztangman93]

It sounds more like a tick then a knock to me as well. Something top end

 

[one eyed willy]

that is not a piston slap noise...

I agree...my JE 2618 had a little slap when cold. i would compare it more to the same sound as injector tapping, it was more of a ticking noise than a loud knocking noise.

 

[Dark_horse]

Ok replaced all the lifters and followers.... absolutely no noise what so ever during the first 3-4 seconds then it came back....FUCK!!

Give it a little gas and it goes away...

 

[86GT351]

I have a new set coming and will be priming them before install... showed the video to my engine builder and he replied welcome to 2618 piston problems... he said that piston slap was his guess without actually listening to it in person...he said the motor was set up on the looser side

If you are thinking Pistin Slap, find someone with a video Scope or Boroscope to look into each cylinder. Pull your plugs and go right through that hole. Might be able to see some markings on the pistons!

 

[Dark_horse]

Heres a new video.... 70lbs of oil pressure on startup... new lifters and rockers.. lifter were soaked/primed/pumped up before install....

I just don't know what else to do....

 

[BruceH]

A gap between the head and header could create the same noise and go away when everything warmed up and expanded.

Stock manifolds or headers? If headers did you use any gap be gone (orange high temp rtv) between the header and gasket?

 

[hamish]

Sounds like my Dodge Ram.
Has a loose exhaust manifold, goes away when warm.

 

[GIG4FUN]

wrist pin?

Are they floating with side keepers or pressed?

It's a noise I wouldn't ignore. Can you isolate it to a cylinder by pulling the COP (ignition load).

 

[Dark_horse]

wrist pin?

Are they floating with side keepers or pressed?

It's a noise I wouldn't ignore. Can you isolate it to a cylinder by pulling the COP (ignition load).

I nedd to do that... the wrist pins are floaters... I used rtv on the stock manifolds... I cant isolate the noise from side to side..

It does go away when its warm

 

[JoshK]

You used rtv on the exhaust manifold gaskets? Did you clean/and how the mating surface for the exhaust manifold gaskets?

 

[Dark_horse]

You used rtv on the exhaust manifold gaskets? Did you clean/and how the mating surface for the exhaust manifold gaskets?

I did use copper rtv on the exhaust manifolds

 

[crownaviation]

Once it is warm it does quit knocking completely (all rpm)? When warm and you start it back up does it start knocking again for a few seconds or is it totally quiet always when warm?

IS it REALLY as loud as the video makes it out to be? Sometimes video can be very misleading

Do you have any tolerances on the build? Sorry, does not sound like an exhaust leak to me and I am sure you could locate/diagnose it if it were. Definately sounds metalic to me. No codes?

 

[Dark_horse]

Once it is warm its soo quiet its rediculous... even a warm restart it is really really quiet... its pretty loud in person and it is not an exhaust leak...

 

[psfracer]

Well then I guess it really is the piston slap as a result of the larger tolerance with the 2618 piston.

If there was something mechanically wrong, the noise wouldn't go away when warm, it would remain constant as a function of rpm.

Oil pressure certainly isn't the problem, valve train isn't, more then likely just piston slap on cold startup then.