Recent Topics
Tall Curb
by hotwheels
03/27/15 10:58 PM
Fram Ultra Oil Filter
by crazyoildude
03/27/15 10:35 PM
Check Engine light after replacing PCV valve?
by Hessam
03/27/15 09:58 PM
The truth regarding fungus and bacteria in diesel
by Sawtooth
03/27/15 08:43 PM
Suburban 454 Issues
by BowNisPar
03/27/15 08:40 PM
Nucleate boiling - :doh:
by Shannow
03/27/15 08:29 PM
Buick Roadmaster level ride control
by 10WSmuckers
03/27/15 08:29 PM
What is this, alkyl sulfonate, ester or mineral oi
by Pontual
03/27/15 08:16 PM
Kroger - Pennzoil Platinum score...
by mattwithcats
03/27/15 07:53 PM
Equinox Braking Noise
by wormwood1978
03/27/15 07:46 PM
Automotive Scrap Metal
by cptbarkey
03/27/15 06:14 PM
Any info on the Lincoln 4 .6 L InTech V8-
by clarkflower
03/27/15 05:47 PM
Newest Members
highlifter, MightyAl, Scout706, 02s4audi, JayDaniel
53337 Registered Users
Who's Online
73 registered (72te27, Atlantis, 901Memphis, asiancivicmaniac, 74DartSport, 7 invisible), 1386 Guests and 182 Spiders online.
Key: Admin, Global Mod, Mod
Forum Stats
53337 Members
66 Forums
228780 Topics
3655847 Posts

Max Online: 2862 @ 07/07/14 03:10 PM
Donate to BITOG
Page 1 of 2 1 2 >
Topic Options
#2608935 - 04/24/12 11:08 PM when an engine starts to knock
Dakota1820 Offline
formerly chevyboy14


Registered: 04/28/11
Posts: 3894
Loc: missouri usa
So I've seen it happen where a decent vehicle would be driving along and all of the sudden (usually) while getting on an on ramp or a similar situation would start rattling. Beginning of a thrown rod. But what causes an engine that seems sound and makes no noises all of the sudden to rattle. Whay happens inside to cause this. I had it happen to me once. Shifted from 2nd at high rpm to 3rd and my cavalier started to rattle. What happens to make an engine out of no where start rattling? Just curious. Thanks!
_________________________
2004 Honda civic vp -m1 5w30
1998 Saturn sl2 -mobil super 5000 5w30


Top
#2608937 - 04/24/12 11:13 PM Re: when an engine starts to knock [Re: Dakota1820]
Shannow Online   content


Registered: 12/12/02
Posts: 28280
Loc: a prisoner island
Are you referring to (combustion oriented) knock ?

We live near an intersection, and hear many engines "knock" as they pull away from the give way sign...it's a long way from a thrown rod (leg out of bed in local parlance)

Top
#2608943 - 04/24/12 11:24 PM Re: when an engine starts to knock [Re: Dakota1820]
LeakySeals Offline


Registered: 02/18/11
Posts: 5070
Loc: MA
Oil thats too thick, poor oil flow and sludge blockages will make it rattle at high RPM's.
_________________________
02 Camry XLE 2AZ-FE 305k M1 HM 5w30, 9k OCI.
13 Malibu 9k unknown..

Top
#2608965 - 04/25/12 12:01 AM Re: when an engine starts to knock [Re: Dakota1820]
Dakota1820 Offline
formerly chevyboy14


Registered: 04/28/11
Posts: 3894
Loc: missouri usa
I'm talking about engines that are in good shape and then all the sudden one day when you kick it in passing gear or something and you start to hear the beginning of a thrown rod
(Rod knock) example my cavalier ran great and always had 5w30 its whole life and then one day it just started knocking until 2 weeks later when it threw the rod
I'm not talking about neglected engines or combustion knock I am asking what happens to start rod knock?
_________________________
2004 Honda civic vp -m1 5w30
1998 Saturn sl2 -mobil super 5000 5w30


Top
#2608976 - 04/25/12 12:36 AM Re: when an engine starts to knock [Re: Dakota1820]
JimPghPA Offline


Registered: 08/22/09
Posts: 2879
Loc: Pittsburgh,PA U.S.A.
It use to be that besides octane, it could be valves requiring adjusting. Sometimes it was a worn timing chain, causing the cam to be out of time with the crank.

Now days with hydraulic lifters usually the valves do not require adjusting. The timing chain could still worn to the point of having too much slop.

Some old engines with a worn timing chain were best tuned by tweaking the distributor timing by a few degree followed by a demanding road test using a lot of gas peddle, repeated until the engine ran well, if the funds and or time was not available for replacing the timing chain. Sometimes the tweaking of the distributor was enough to get an engine to run well, and sometimes it was not enough.

Now days with all of the electronics on engines and the emissions requirements, tweaking a ignition timing is not something that is common.
_________________________
Boy will I be happy when ALL vehicles on public roads are autonomous.


JimPghPa


Top
#2608977 - 04/25/12 12:38 AM Re: when an engine starts to knock [Re: Dakota1820]
JimPghPA Offline


Registered: 08/22/09
Posts: 2879
Loc: Pittsburgh,PA U.S.A.
PS cam lobes could be worn down.
_________________________
Boy will I be happy when ALL vehicles on public roads are autonomous.


JimPghPa


Top
#2608986 - 04/25/12 01:00 AM Re: when an engine starts to knock [Re: Dakota1820]
genynnc Offline


Registered: 10/13/08
Posts: 379
Loc: OR
Originally Posted By: chevyboy14

I'm not talking about neglected engines or combustion knock I am asking what happens to start rod knock?


A spun rod and/or main bearing.
_________________________
03 Dodge Ram 1500 5.7= Kendal GT1 5w30, 55 Chevrolet 327/ Muncie= Valvoline VR1 10w30, 67 Chevelle Malibu 283= Quaker State Defy 5w-30

Top
#2608987 - 04/25/12 01:10 AM Re: when an engine starts to knock [Re: Dakota1820]
tommygunn Offline


Registered: 01/27/11
Posts: 3061
Loc: usa
Sounds more like bad fuel causing pinging.

If its actually rod knock, the connecting rod cap on the crankshaft is damaged or the bearing is spun/melted and the bottom of the connrod is literally knocking around as the piston reciprocates.

At any rate actual, serious rod knock is a huge concern and you have three options then.

Rebuild the engine to fix the issues, run a thick nasty oil to mask the problem until it completely kills itself, or do nothing and seize a piston.

So, pray its not actual rod knock.

Edit: Rattling, hard to say, but rod knock comes from abuse and will sound terrifically bad at all times, especially at idle. It sounds like a diesel afterwards.


Edited by tommygunn (04/25/12 01:11 AM)
_________________________
i am a [censored] who hides behind bugmenot.
i also like applying negative pressure to a certain male appendage.

Top
#2609004 - 04/25/12 02:14 AM Re: when an engine starts to knock [Re: genynnc]
Texan4Life Offline


Registered: 01/28/10
Posts: 2213
Loc: Texas
Originally Posted By: genynnc
Originally Posted By: chevyboy14

I'm not talking about neglected engines or combustion knock I am asking what happens to start rod knock?


A spun rod and/or main bearing.


+1


or if it is worn out it will slowly develope knock. like one day you will be like hey did notice that noise before. and then it gets worse exponentially until you got the full on brick bouncing around in the crankcase noise.
_________________________
2005 Dodge Ram 1500, 5.7L
[Current Fill: PP 0w-20][Baldwin B2-HPG]

Top
#2609037 - 04/25/12 05:01 AM Re: when an engine starts to knock [Re: Dakota1820]
NHGUY Offline


Registered: 10/09/11
Posts: 3706
Loc: USA
Worn bearing will not retain its position in rod end,it will spin,blocking the oil hole,bearing and journal will get chewed up,increasing clearance and sending junk through the engine.That clearance will make a knock as the piston is being forced up/down,eventually engine failure will result.

Top
#2609065 - 04/25/12 06:14 AM Re: when an engine starts to knock [Re: Dakota1820]
bullwinkle Offline


Registered: 10/09/04
Posts: 4467
Loc: Cincinnati, OH, USA
I think the rod bearing starts to spin and blocks (at least partially) an oil passage through the bearing & crank. That's when it's time to start looking for another engine or fix it before it throws it. I've only had 1 engine toss a rod on me-an old 2 liter Pinto motor that I ran out of oil-it doesn't seem to happen often on well-maintained engines.
_________________________
06 Ram 3500 CTD 4X4 48RE SRW, 93 GMC C3500 6.2 diesel, 89 F-450 7.3 IDI, 98 Cherokee 4.0, 05 Scion xB, 12 Ford E-250 4.6

Top
#2609103 - 04/25/12 07:14 AM Re: when an engine starts to knock [Re: bullwinkle]
Scott_Tucker Offline


Registered: 12/31/09
Posts: 877
Loc: Santa Cruz, Ca.
If it is indeed rod knock then it is excessive rod bearing clearance due to wear. Rod bearings don't all of the sudden wear, it would have to have started some time before.
_________________________
2012 Honda Civic Si, Dyno Blue Pearl

Top
#2609127 - 04/25/12 07:51 AM Re: when an engine starts to knock [Re: Dakota1820]
KrisZ Offline


Registered: 12/23/06
Posts: 4572
Loc: Toronto, Canada
Hmm, 2nd gear, high RPM and high engine load. Sounds like oil starvation to me or the engine wasn't as healthy as initially thought.
_________________________
2006 Mazda 3 - 127,000 miles
2003 Ford Focus ZX5 - 104,000 miles

Top
#2609144 - 04/25/12 08:18 AM Re: when an engine starts to knock [Re: Dakota1820]
Dakota1820 Offline
formerly chevyboy14


Registered: 04/28/11
Posts: 3894
Loc: missouri usa
Well I can tell you for an ohv 2.2 it was prettt quiet. Lol maybe that's why it broke smile its possible to throw a rod from over revving to. But I dont understand how
_________________________
2004 Honda civic vp -m1 5w30
1998 Saturn sl2 -mobil super 5000 5w30


Top
#2609298 - 04/25/12 11:05 AM Re: when an engine starts to knock [Re: Dakota1820]
rslifkin Offline


Registered: 06/27/10
Posts: 2296
Loc: Stamford, CT / Rochester, NY
If you over-rev and engine, if you don't float the valves into the pistons and kill it that way, you can over-stress bearing caps, etc, and cause them to fail, leading to a thrown rod.
_________________________
1998 Jeep Grand Cherokee 5.9 Limited with Heads/Cam/Headers/Exhaust/Tune/Shift Kit/Suspension Work (182k miles, bought with 100k)
Rotella T6 @ 6k OCI

Top
Page 1 of 2 1 2 >