Knocking after new heads

[stacker]

Just finish putting the new heads,injectors and #8 piston in. Now i got a knock that sounds like piston slap. Need some advice. If i had that much wear wouldn't i have had a large ring ridge, which i didn't and loss of oil. but she ran great until i lost a pre cup. any help would be appreciated. Getting real expensive.:confused:

[grancito]

Does it really sound like piston slap, or is it injector knock? They usually knock when new. Pistons slap with some revs on.

[stacker]

I think the mech. put either too small (dumb) or too tall of piston in.
Too used to working of 7.3 not gm .
since it's suppose to be a 40 to 50 k block.

[JD_countryboy]

too small could be seeable. too tall that would be a streach? if t it were too tall id think it would make it crak hard or lock up, on that cylinder. Theres next to no clearance between head and top of stock piston. But if the truck cranks over funny, normal then a knock and hesitation, maybe it is. Anyone know, is a 6.5 an interferance engine? I though i was told it is but i'm not sure. How long have you ran the engine since it was put back together? My first guess would be air in the injector lines. Sometimes it takes a bit for them to clear out. Are the injectors new, or rebuilt? could be a bad injector.

[torque454]

Id guess the injectors too. Somone was saying they will make it knock like it was ready to blow for a while after replacing injectors.

[grancito]

Describe the knock, erratic at idle, or knocks with some revs, no knock revs up, knocks all the revs, heavy or light knock?

[rodgera]

I put in new injectors and instant glow plugs but ocassionaly listen to a knock for a few minutes on start up. I'm starting to think that it may be lack of fuel in a cylinder that does that. Its always on the passenger side of my engine when it knocks but it doesn't stay long. I haven't investigated it enough yet but I'm starting to think it may be low fuel pressure adding to the problem and a cylinder is not getting the proper amount of fuel.
I'm trying one thing at a time, first its an OPS making sure the lift pump is coming on properly and the wiring connections are good. At that point I'll check the pressure to see if its within factory specs. If not then I'll replace the lift pump. After that Its the injection pump I think.
Lets face it, when the truck was new it did't knock so there is a reason somewhere and I intend to find it by process of elimination.

[grancito]

Most probably injector clatter, when very cold, they can make a hell of a noise, but not always everyone of them.