# 5.3L cold start, engine knock



## Squires (Jan 9, 2009)

Truck is a 2010 5.3L
If it has been below -5C the truck sounds like it is knocking on start up.

It goes out of it fairly quickly, but is definitly noticable.

I had a 2007 same body style that never did it in 3 years and over 75,000km's

New truck was a year old the summer and just rolled 17,000km's

Dealers idea was it's not really an issue as i have warranty left.....

I did the first oil change with mineral oil, and the last i went to full synthetic, oil level is good, but cold starts are noisy.
Doesn't have a block heater, but im under the impression that they have a thermostat that only kicks in at like -10, im having this problem at just below 0deg

I just figured out how my phone camera works, so i will video it on cold starts and post when it happens again.


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## White Gardens (Oct 29, 2008)

Are you running the recommended oil for the winter?

GM's are notorious for piston knock and lifter rattle when starting up even when it's warm out. Any mechanic says it's because the modern engines tend to have tighter tolerances. 

My, 4.3 S-10 does it, along with my 8.1.

In the cold it's noticeably louder. For my 8.1 that gets used mostly during extreme cold/snow, I plan on putting in a block heater of some sort to help it to be warmer getting into the truck, and also for better cold starts.

,....


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## Squires (Jan 9, 2009)

Pennzoil Platnum 5-30 full synthetic
was changed at the dealer.

Never in the past have i had the need for winter oil, always just got a drive thru oil change.

Im between a heater magnet, coolant heater, something like that.

Dealer said $180 for the GM block heater plus install at around $100/hour, and with that like i said, im under the understanding that it only comes on at a certain temp.
was looking at this possibly

http://www.canadiantire.ca/AST/brow...03P/ZeroStart+Super+Heat+Magnet.jsp?locale=en


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## Plowtoy (Dec 15, 2001)

White Gardens;1356966 said:


> Are you running the recommended oil for the winter?
> 
> GM's are notorious for piston knock and lifter rattle when starting up even when it's warm out. Any mechanic says it's because the modern engines tend to have tighter tolerances.
> 
> ...


Sounds very much like "piston slap" witch is "normal" for most GM V engines. What you are hearing is the piston skirt is slapping against the side of the cylinder when that piston is fired. This is caused by short piston skirts unlike engines of the 80s and prior. GM has done some fine tuning and found that putting a material (Teflon) on the piston skirts will help reduce the noise. It is not uncommon for the noise to go away shortly after the engine is started, since after just a few minutes the pistons are expanding with the heat produced, however, there are cases where I have heard the noise even after hours of driving. Over all, I wouldn't be concerned about the problem unless your oil pressure gage is not coming up. Piston slap WILL NOT reduce the longevity of your engine.


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## mnglocker (Dec 24, 2008)

Piston Slap or GM Lifter Noise. If it goes away after 30 seconds it's lifter noise. If it takes the engine coming up in temp to make the sound go away it's piston slap. 

There's one thing you also forgot to mention, what kind of oil filter are you using. Not all filters are the same. 


As far as block heaters go, just get the OEM heater and be done. Magnetic heaters won't work for you anyway, the oil pan is aluminum.


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## Squires (Jan 9, 2009)

A dealer standard filter but i brought the oil, so it has the pennzoil synthetic.

the time seems to vary dependant on the temp, the colder the longer the noice on start, oil pressure is fine/instant on start.

what if that magnet could fit on the block someplace?

Like i said the dealer wants $40 for the heater and like $130 for the cord, then no set labor cost, what ever it takes the mechanic, shop rate is between 100 and 120/ hour

what about any one of these things?
In line coolant heater etc etc

http://www.canadiantire.ca/AST/brow...PRD~0303280P/Engine+Hose+Heater.jsp?locale=en

thanks for the info


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## Plowtoy (Dec 15, 2001)

The oil pressure is good, noise lasts a while, I have to believe its piston slap. I don't think I would be overly concerned. Piston slap has little to no effect on an engines performance or longevity. Again, I wouldn't be concerned with the noise. Most likely the last one you had that didn't make any noise was a fluke. Not all engines are alike (but they are very close). Piston slap has been around for a while and these engines are lasting 2-3 hundred thousand before needing replacement with proper care. 
The only other thing I could think of is, Ive heard that the 5.3s that "drop cylinders" at higher speeds are having oil consumption issues and that GM is replacing pistons on those engines, but you didn't mention that you have one of those engines.


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## Squires (Jan 9, 2009)

It is that displacement on demand engine, no noticable oil or oil pressure loss.

I'll keep an eye on it, more of an annoyance than anything i guess.

thanks for all the replys,
as for the block heater or equilivant, anyone have any luck in any of the after market ones i have posted?


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## mnglocker (Dec 24, 2008)

Squires;1357021 said:


> A dealer standard filter but i brought the oil, so it has the pennzoil synthetic.
> 
> the time seems to vary dependant on the temp, the colder the longer the noice on start, oil pressure is fine/instant on start.
> 
> ...


There's no place on the block that's flat enough for the magnet to stick/make any difference. The block heater heats in the block, not at a distant external point that allows for heat loss. Plain and simple, the frost plug style block heaters just plain work and the others don't cut it.

Drop the dime on the OEM heater, you'll spend more money on coolant and dicking around with the hose heater or on a magnet in the end only to still buy the OEM heater because the others won't cut it.


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## Holland (Aug 18, 2010)

TECHNICAL 

Bulletin No.: 10-06-01-007C

Date: February 09, 2011

Subject: Active Fuel Management (AFM) Engine, Valve Lifter Tick Noise at Start Up When Engine Has Been Off for 2 Hours or More (Evaluate Noise and/or Replace Valve Lifters)

Models: 
2007 Buick Rainier
2009 Buick LaCrosse Super, Allure Super (Canada Only)
2007 Cadillac Escalade
Built Prior to April 1, 2006 with 6.2L Engine RPO L92 (These engines were built with AFM Hardware but the AFM system was disabled)
2010-2011 Cadillac Escalade, Escalade ESV, Escalade EXT 
2007 Chevrolet Monte Carlo
2007-2009 Chevrolet Impala
2007-2011 Chevrolet Avalanche, Silverado, Suburban, Tahoe, TrailBlazer, TrailBlazer EXT
2010-2011 Chevrolet Camaro SS
2007-2011 GMC Envoy, Envoy XL, Sierra, Yukon, Yukon Denali, Yukon XL, Yukon XL Denali
2007-2008 Pontiac Grand Prix
2008-2009 Pontiac G8
2007-2009 Saab 9-7X
Equipped with AFM (Active Fuel Management) and V8 Engine RPO L76, L94, L99, LC9, LFA, LH6, LMG, LS4, LY5 or LZ1

Attention: 
This bulletin only applies to the AFM V8 engines listed above. It DOES NOT apply to Non-AFM Engines. If you are dealing with a Non-AFM engine that is experiencing a similar noise, please refer to Engine Mechanical > Diagnostic Information and Procedures
> Symptoms in SI.

Supercede:
This bulletin is being revised to add models. Please discard Corporate Bulletin Number 10-06-01-007B (Section 06 - Engine/Propulsion System).

Condition 

Some customers may comment on an engine valve lifter tick noise that occurs after the engine has been shut off for at least two hours. The tick noise may last from two seconds to ten minutes.

Cause 

This condition may be caused by any of the following: 

- Aerated oil in the valve lifter body, resulting in the valve lifter being unable to purge the air quickly. 
- A low engine oil level or incorrect oil viscosity. 
- Dirty or contaminated oil. 
- A low internal valve lifter oil reservoir level. 
- Debris in the valve lifter. 
- A high valve lifter leak down rate. 


Correction 

If the SI diagnostics do not isolate the cause of this valve lifter tick noise and normal oil pressure is noted during the concern, perform the following steps:

1. Inspect the engine oil condition and level. Refer to Owner Manual > Service and Appearance Care > Checking Things Under the Hood > Description and Operation > Engine Oil in SI.

¤ If the engine oil is more than one quart low, an incorrect oil viscosity is being used or if poor quality/contamination is observed, change the oil and filter. 

Note 
Allow at least a two hour soak time between engine OFF and start up when evaluating the tick noise.

2. Start the engine and evaluate the valve lifter tick noise. 

¤ If the valve lifter tick noise is still present, replace all 16 valve lifters. Refer to Valve Lifter Replacement in SI.


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## Squires (Jan 9, 2009)

Thanks for the info.
I'll bring that service bulletin # with me to the dealer.

Does anyone know if anything has to be done with the computer for the factory block heater? If im gonig to pay that much money for the factory heater i might as well do it myself to save the labor.


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## Holland (Aug 18, 2010)

Anytime! Thumbs Up


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## White Gardens (Oct 29, 2008)

Squires;1357197 said:


> Thanks for the info.
> I'll bring that service bulletin # with me to the dealer.
> 
> Does anyone know if anything has to be done with the computer for the factory block heater? If im gonig to pay that much money for the factory heater i might as well do it myself to save the labor.


Personally I would go with a re-circulating heater from KATZ. The problem with a block heater is that it only heats one side of the block well.

I also used to use a magnet on my old f-350 diesel. After the block heater went out, it was a quick fix so could get it started when cold. It worked well, and I would just stick it to the bottom of the oil pan. Luckily Tue truck sat high enough that it wasn't a pain to deal with.


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## gwhalen3 (Jan 15, 2010)

My 2000 2500 ^.0 does tha same thing. I was told it's normal and you can't do much about it and it is doing no harm. 125000 and still going strong so whatever


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## theholycow (Nov 29, 2002)

OP, does it sound like distinct separate knocks/ticks/taps, or does it sound like a smooth but different-than-normal sound (almost like a diesel)?



mnglocker;1356988 said:


> Piston Slap or GM Lifter Noise. If it goes away after 30 seconds it's lifter noise. If it takes the engine coming up in temp to make the sound go away it's piston slap.


That's news to me, and I've been reading about piston slap since 2006. As far as I can tell, piston slap disappears after 30 seconds (less if you drive, more if you wait while it idles).

Is that lifter noise as harmless as piston slap?


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## leolkfrm (Mar 11, 2010)

if you istall a katz, do not start the engine with it plugged in...you will hurt the heater....


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## mnglocker (Dec 24, 2008)

theholycow;1357727 said:


> OP, does it sound like distinct separate knocks/ticks/taps, or does it sound like a smooth but different-than-normal sound (almost like a diesel)?
> 
> That's news to me, and I've been reading about piston slap since 2006. As far as I can tell, piston slap disappears after 30 seconds (less if you drive, more if you wait while it idles).
> 
> Is that lifter noise as harmless as piston slap?


The lifter noise is pretty harmless. I wouldn't go revving the piss out of any motor the moment you start it, the noise is cause by the lack of oil pressure in the lifters. They take a moment to fill up with oil and become pressurized. Hence the extra noise.

Piston slap quiets down when the pistons heat up enough to expand a couple thousands of an inch in the bore, tightening the tolerances. That's a by-product of using non-forged aluminum pistons.


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## Squires (Jan 9, 2009)

mnglocker;1357046 said:


> There's no place on the block that's flat enough for the magnet to stick/make any difference. The block heater heats in the block, not at a distant external point that allows for heat loss. Plain and simple, the frost plug style block heaters just plain work and the others don't cut it.
> 
> Drop the dime on the OEM heater, you'll spend more money on coolant and dicking around with the hose heater or on a magnet in the end only to still buy the OEM heater because the others won't cut it.


Bought a block heater, but there is a thermostat in the cord, doesn't work until 0 deg f, or -18 deg C, whats the use in that?


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## mnglocker (Dec 24, 2008)

get a different cord.


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