Engine Knock

[itlbtu2]

Well, I got a great deal on my SY :tup: but it's at a cost :tdown: . I hear a knocking noise when the truck is in neutral or park and I rev the motor up to 2500 rpm. I've blown up many a natural aspirated engines and this doesn't sound like a typical knock. it's not consistant. I almost wonder if it's the turbo making noise. I'm curious if anyone has any input on this subject. Also, if i'm going to be in need of an engine, does anyone have a good recipe for a mid 12 sec. build up??

Thanks

Dusty

 

[blk00z28]

Re: Engine Knock

Is it a poping sound in N or P and does it go away when you put it in Drive?

 

[itlbtu2]

Re: Engine Knock

well, It's really a knocking sound but it doesn't do it under a load, ie. if i'm driving, i don't hear it.

 

[blk00z28]

Re: Engine Knock

Odd. I have a poping sound when I'm in N or P and it goes away and is as smooth as a babys ass when its loaded.

Got datamaster? or a scan tool? Hook it up and see if its knocking at idle.

 

[cloneman315]

Re: Engine Knock

make sure its not the noisy injectors

 

[itlbtu2]

Re: Engine Knock

No, I don't have a datamaster. I may need to purchase one though......as far as injectors, I'm sure it's not them.

 

[SeattleSy#1255]

Re: Engine Knock

is it a knocking noise or constant ticking noise?

 

[itlbtu2]

Re: Engine Knock

it's a knock, that is not constant. It's weird because my first Sy done close to the same thing. I wish someone that has a lot of knowledge with these trucks was close to me so they could just hear it. The truck runs pretty strong though.

 

[SeattleSy#1255]

Re: Engine Knock

well more info would help, like what side of the engine is it coming from? How loud is it? describe the "knock" sound.

 

[RSpengler]

Re: Engine Knock

I hope its not a spun rod bearing... Less oil pressure at idle could cause the rod to start knocking, then when you get into the Higher RPM's the oil pressure is restored and it goes away?
Rob

 

[NecroWolf]

Re: Engine Knock

you might check the torque convertor bolts or bell housing bolts

 

[AUSyTyIN]

Re: Engine Knock

you might check the torque convertor bolts or bell housing bolts

2nd, or it could be the torque converter itself.

 

[VermontTy]

Re: Engine Knock

I had a 4.0 wrangler do the same thing; ran 100% percent (well, actually ran 83.33%) under load with no knocking or banging; just ran great. At idle or revving, it really knocked like a SOB. I pulled the pan to find one rod completely blown apart in the bottom of the pan and the piston lodged in the cylinder. There was no smoke or stumble, it ran awesome on 5 cyl, but that banging was one rod bearing. Under load, where there was always force crank from the rod, and the knock would go away, but when there was no load at idle, or even when revving the motor, it sounded like it was going to explode.

 

[toolmann]

Re: Engine Knock

i had a knock in my ty...135k...turned out to be the harmonic balanced seperating & banging...had it replaced by a local shop along with the timing chain,noise gone.
on a side note,use caution when choosing a 'mechanic'...
when i picked it up,i asked them what oil they put in,and of coarse,wrong stuff(says F'n Mobil 1 right on the filler cap!!),soo i went to the MB dealer i work at and put Mobil 1 in it...turned out to be 0-40 grade(out of the elect.spickets thingys) and after 1 week a knock was back....that oil was a bit tooooo thin....this time the noise was in the motor....smoked the crank bearings,destoyed the crank.
i know i should have made the shop correct the mistake and put in the right oil,but with all the time it took them,and all the other mistakes they made(incorrect oil,timing not set right,wrong t-stat put back in,hardware for remote oil line not installed,line rubbed x pipe-leaked,ect..) i dident want them touching it agian.soo i unfortunatly, f'd it up myself and got a crash coarse in oil grades and applications.suck.
live & learn
T

 

[Don W.]

Re: Engine Knock

I’d suspect rods as well. If, in neutral, you can “control” the knock with throttle then it’s either rods or possibly a cracked piston skirt. IMO Under no load you won't get fuel knock.:2cents:

 

[itlbtu2]

Re: Engine Knock

yea, that all makes sense, I'm going to take a closer look at it in the morining and hope for the best. Until then does anyone know of a proven recipe to build a low 12 sec. motor?

Thanks to all for your replies. They are appreciated

 

[hideakimura]

Re: Engine Knock

you might check the torque convertor bolts or bell housing bolts

Will this make knock-like sound in N and P or also D in WOT?

 

[itlbtu2]

Re: Engine Knock

no, it seems to only do it in N or P i dont' hear anything in drive or at WOT. I messed with it a little bit yesterday and I believe that it is the flexplate or loose torque converter. But i'm still not 100%

 

[itlbtu2]

Re: Engine Knock

Also, something to think about, the truck runs really strong and will show boost up to 15 psi. Shouldn't the knock sensor detect this sound?? If it does, it should run rich and not boost this high. Right?????