grinding when eccelerating
Senior User
Joined: Jul 2004
Posts: 116
Likes: 0
From: Corpus Christi,Tx.
I may be mistaken, but if it was the crank/rod/piston wouldnt the knock happen twice a flash with the timing light and if valve train only once per flash ?? spark plug fires every other crank rotation... intake/compression first rotation, power(spark)/exaust second rotation...
and each valve opens once per ... cycle?? ya know ...4 strokes that these beast are.
and each valve opens once per ... cycle?? ya know ...4 strokes that these beast are.
Post Fiend
Joined: Jan 2003
Posts: 8,600
Likes: 4
From: Iowa
You got it Uemf. Valve train is once per timing light flash, bottom end may be twice.
This method is flawed, though, since often bottom end noises only occur on the power stroke, not the intake, compression or exhaust strokes. So they would then only go once per timing light flash. I've seen wrist pins do this.
The big thing here is that it does it more under load. That pretty much removes the valvetrain from consideration, as it's loads on the valvetrain dont change when engine load does. The bottom end, however, does undergo more stresses when the engine is subjected to more load, so that's where I think the problem is. More gas = louder noise, right?
I'd guess, at this point, either:
1. Piston slap, from collapsed piston skirt
2. Wrist pin knock
3. A bearing
4. Loose or cracked flywheel or flexplate
An educated guess from the above would most likely to be the wrist pin. I've seen it happen more than once.
This method is flawed, though, since often bottom end noises only occur on the power stroke, not the intake, compression or exhaust strokes. So they would then only go once per timing light flash. I've seen wrist pins do this.
The big thing here is that it does it more under load. That pretty much removes the valvetrain from consideration, as it's loads on the valvetrain dont change when engine load does. The bottom end, however, does undergo more stresses when the engine is subjected to more load, so that's where I think the problem is. More gas = louder noise, right?
I'd guess, at this point, either:
1. Piston slap, from collapsed piston skirt
2. Wrist pin knock
3. A bearing
4. Loose or cracked flywheel or flexplate
An educated guess from the above would most likely to be the wrist pin. I've seen it happen more than once.
Senior User
Joined: Dec 2004
Posts: 137
Likes: 0
From: washington
After reading through all the posts it sounds like your leaning away from grinding, toward tapping/knocking. Depending frequency, I.E. single tap or double knock, I would lean towards a weak lifter or conrod/collapsed piston. While your'e under the truck though. check crank for execessive endplay. They will rap on startup and certain idle speeds, Especialy if the torque converter is ballooning.
O.K. Rustyf100 beat me to a couple things while typing.
O.K. Rustyf100 beat me to a couple things while typing.
Last edited by oldeiron; Dec 21, 2005 at 11:07 AM.
Posting Guru
Joined: Jul 2003
Posts: 2,232
Likes: 1
From: Colville, Washington
Originally Posted by Icicle
Ouch.......
I guess we'll have to start digging around to try and figure out whats going on
I guess we'll have to start digging around to try and figure out whats going on
Cargo Master
Joined: Apr 2004
Posts: 2,574
Likes: 4
From: Golden, CO
Originally Posted by uemf
if it was the crank/rod/piston wouldnt the knock happen twice a flash with the timing light and if valve train only once per flash ??
Originally Posted by Icicle
I guess we'll have to start digging around to try and figure out whats going on
Keep us posted, Mike
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Postmaster
Joined: Mar 2003
Posts: 4,038
Likes: 2
From: Spokane WA
Any opinions on what may be going on are always appreciated oldeiron. NW chapter folk stick together, no matter how much we know, or how much we learn, its always easy to overlook a possibility occasionally. If you have any input, byall means chime in, Im sure Mark appreciates it!!
Posting Guru
Joined: May 2004
Posts: 2,297
Likes: 0
From: Spokane WA
I have an idea I havent seen on here..............(cant believe i didnt realize this earlier)
Mine was doing this SAME THING. Metalic clicking under load. Yeah. I was sure it was something valvetrain. Then Ivan played with my timing........ALL BETTER!!!
......Till a little while ago, when they started oxygenating (sp?) the fuel for winter. Tweaked the distributor a little, all better. Now I run premium fuel, that way I can keep a little advance on it. I figure that it makes up for the price with making a little more power so I dont need to use quite as much fuel to get moving. I dunno.
In other words, check to see if it's predetonating/pinging. Mine honestly sounded like a bend pushrod, but that's all it was.
Mine was doing this SAME THING. Metalic clicking under load. Yeah. I was sure it was something valvetrain. Then Ivan played with my timing........ALL BETTER!!!
......Till a little while ago, when they started oxygenating (sp?) the fuel for winter. Tweaked the distributor a little, all better. Now I run premium fuel, that way I can keep a little advance on it. I figure that it makes up for the price with making a little more power so I dont need to use quite as much fuel to get moving. I dunno.
In other words, check to see if it's predetonating/pinging. Mine honestly sounded like a bend pushrod, but that's all it was.
Postmaster
Joined: Mar 2003
Posts: 4,038
Likes: 2
From: Spokane WA
Wow, Ill be SHOCKED if thats what it is, its LOUD.....
Come to think of it, Ive never actually HEARD an engine thats pinging before..... but that doesnt jive with it doing it on start up only initially, it does however Jive with it doing it under load, but its a problem thats gotten worse, it didnt start from us playing with the timing.
But it doesnt hurt to back it off a hair and see what happens......
Come to think of it, Ive never actually HEARD an engine thats pinging before..... but that doesnt jive with it doing it on start up only initially, it does however Jive with it doing it under load, but its a problem thats gotten worse, it didnt start from us playing with the timing.
But it doesnt hurt to back it off a hair and see what happens......