Piston slap - cold engine noise

[[email protected]]

I recently bought a 2002 variant of the Trailblazer. It has the 4.2l Inline 6 cylinder. 138,000 miles. Looks to have been nicely maintained (the previous owner gave me a STACK of oil change receipts for the 3000 mile OCI's he was doing with full syn).

Common problem on this vintage was piston slap noise and mine is no exception - its VERY noisy when cold.

Right now Im running MSS 5w30 and a Purolator Classic.

Any suggestion with oils that lessen piston slap noise?

 

[ls1mike]

My LS1 in the Trans Am and 6.0 in the truck do it to.

I have not found anything that quiets down the piston slap at the recommended weight.

It isn't really an oil problem. I just live the with the noise it is gone when warm.

 

[UNC017]

Originally Posted By: [email protected]


Any suggestion with oils that lessen piston slap noise?



There's no reason to chase around trying to lessen it. Stick with the recommended grade and ignore the harmless sound. The truth is that engines WITHOUT piston slap all have some amount of introduced friction to hide it- either by piston coatings, offset piston pins, or longer piston skirts, or a combination of methods.

 

[jeepman3071]

The Jeep 4.0 (also an inline-six) is known for being noisy. Piston slap and valve train noise are common issues. Both me and another member on here noticed that Pennzoil conventional seemed to quiet our 4.0 engines quite a bit due to the high moly content. I've also noticed this with 2 other 4.0 engines I maintain. I'd give Pennzoil 5w30 conventional a try and see if it does anything.

 

[Turk]

My 03 Sierra has that some and my previous Sierra had it A LOT.

GM did a "Decarbonization" on it and that helped significantally.

 

[SteveSRT8]

^^^If it quieted then you had carbon knock, also surprisingly common. And quite hard to tell the difference!

We have had a ton of slappers, the worst one was our 04 3500 Savana recently sold with half a million miles! That's right, 500k miles with no leaks, no oil burning, and quieter than ever at time of sale.

A huge non-issue if ever there was one...

 

[CourierDriver]

Originally Posted By: [email protected]
I recently bought a 2002 variant of the Trailblazer. It has the 4.2l Inline 6 cylinder. 138,000 miles. Looks to have been nicely maintained (the previous owner gave me a STACK of oil change receipts for the 3000 mile OCI's he was doing with full syn).

Common problem on this vintage was piston slap noise and mine is no exception - its VERY noisy when cold.

Right now Im running MSS 5w30 and a Purolator Classic.

Any suggestion with oils that lessen piston slap noise?



Piston Noise
Piston slap is a classic symptom of too much clearance between the pistons and cylinder bores. Piston slap is most audible when a cold engine is first started because clearances are greatest then. This doesn’t necessarily mean the pistons are worn, because some new engines will slap a bit when first started. But if the slap doesn’t go away as the engine warms up, it usually means the pistons and/or cylinders are worn. A compression test and/or leakdown test can be used to confirm the diagnosis.

The wrist pins on many pistons are offset slightly so as to load the piston slightly to one side. This reduces piston noise as the piston approaches top dead center (TDC) on its compression stroke, then passes over TDC and starts down on its power stroke.

 

[A_Harman]

My Camaro has had piston slap since it was new. At 199k miles, it hasn't changed a bit over the years. The noise goes away when the engine warms up. I have found that gently revving it up to ~1700 rpm when cold gets rid of the slap noise, and speeds warmup. I have tried a few different and slightly higher viscosity oils (but still 30-weights), but they don't affect piston slap.

 

[nitehawk55]

Originally Posted By: SteveSRT8
^^^If it quieted then you had carbon knock, also surprisingly common. And quite hard to tell the difference!

We have had a ton of slappers, the worst one was our 04 3500 Savana recently sold with half a million miles! That's right, 500k miles with no leaks, no oil burning, and quieter than ever at time of sale.

A huge non-issue if ever there was one...


Carbon knock doesn't go away or become less noticeable when it warms up .

No oil is going to help you with piston slap , just turn up the radio and ignore it .

 

[SteveSRT8]

Originally Posted By: nitehawk55
Originally Posted By: SteveSRT8
^^^If it quieted then you had carbon knock, also surprisingly common. And quite hard to tell the difference!

We have had a ton of slappers, the worst one was our 04 3500 Savana recently sold with half a million miles! That's right, 500k miles with no leaks, no oil burning, and quieter than ever at time of sale.

A huge non-issue if ever there was one...


Carbon knock doesn't go away or become less noticeable when it warms up .

No oil is going to help you with piston slap , just turn up the radio and ignore it .


Sorry, but not IME here with GM V8's. Carbon knock nearly mimics the piston slap, just has a deeper and less metallic sound IMO. May sound very different in other engine designs.

Just a cup or two of Kreen in the gas and gone in 10 minutes

 

[Shannow]

I doubt that this would be a recommendation in Michigan...

http://www.mobiloil.com/USA-English/MotorOil/Car_Care/AskMobil/Viscosity_Cold_Start_Knock.aspx

 

[CATERHAM]

Ask Mobil Ask Mobil
Will Switching to 0W-40 be Better for a Toyota Tacoma in a Hot Climate?

Question:
Will Switching to 0W-40 be Better for a Toyota Tacoma in a Hot Climate?
My 2005 Tacoma has a little over 60,000 miles now. It has some "cold start knock" - piston slap, that so many recent engines have. Once warmed up, it only has a faint bit of slap at idle. I have been using Mobil 1 5w30 since about 15,000 miles. Now that the vehicle has some mileage and is out of warranty and since the weather can be very hot for long periods of time in South Carolina, would it be advisable to use 0W-40 now? Thanks!
-- Robert Boudreau, Boiling Springs, SC

Answer:
A 40 grade (0W-40) would provide some relief but your engine does not see this viscosity until it has warmed up. Since it appears to be only an issue during warm-up, you may want to try Mobil 1 15W-50. This will provide an initial viscosity that is higher than the 0W-40. This assumes that the 15W will be adequate low temperature flow for South Carolina mornings.


Sometimes Mobil's answers are not the best if not reveal a questionable understanding of viscosity itself.

Considering that a 5W-20 is also spec'd for the 6 cyl and 0W-20 back spec'd for the 4 cyl 2005 Tacoma I'm not even sure piston slap is the correct diagnosis.

Of course Mobil 1 0W-40 is heavier on start-up than Mobil 1 5w30.
And recommending their 15W-50 is surely a case of the medicine being worse than the affliction.

 

[gregk24]

If it is piston slap then it is harmless. As far as quieting it down I would use Pennzoil Conventional or Pennzoil Platinum, depending if you want to use conventional or synthetic. My Accord 2.4 likes to slap in the mornings, Pennzoil products seemed to help make it quieter. Make sure you use the recommended grade, don't go up a grade to quiet down a harmless noise, you will probably cause more harm than good.

 

[Clevy]

Originally Posted By: gregk24
If it is piston slap then it is harmless. As far as quieting it down I would use Pennzoil Conventional or Pennzoil Platinum, depending if you want to use conventional or synthetic. My Accord 2.4 likes to slap in the mornings, Pennzoil products seemed to help make it quieter. Make sure you use the recommended grade, don't go up a grade to quiet down a harmless noise, you will probably cause more harm than good.


Because going a grade thicker does harm?
I've got a 99 silverado with a 5.3. It still slaps with 270k or so. Doesn't consume any oil and runs great.
Non issue if its piston slap.

 

[KenO]

Originally Posted By: SteveSRT8
^^^If it quieted then you had carbon knock, also surprisingly common. And quite hard to tell the difference!

We have had a ton of slappers, the worst one was our 04 3500 Savana recently sold with half a million miles! That's right, 500k miles with no leaks, no oil burning, and quieter than ever at time of sale.

A huge non-issue if ever there was one...



Agreed. Although, if I ever tore one down, I'm curious whats wearing more over time - the piston skirt (or lack thereof), or the cylinder liners. It's caused by basically the pistons being ever so slightly too small for the bore. GM changed manufacture methods in the 90's to instead of matching pistons to the holes, they make all the pistons the same (within tolerance, of course) and they are 'good' for every cylinder. Not really, but they think so, and refuse to do anything about it.


And yes, some is also carbon knock from built-up carbon on top of the piston physically coming into contact with the cylidner head. Seafoam the [censored] out of it (or use the good stuff you can buy at the GM dealer) and see what happens. Or water works almost as well.

 

[AHC]

With my F150, M1 was noisy, Valvoline is quieter and Amsoil signature was most quiet of all oils I've tried.

 

[72te27]

Like most in it's engine family, the 5.3 liter in my '03 Suburban has some light
piston slap when it's cold. Pennzoil Ultra 5w30 minimizes the slap and it goes away when warm. Try some Ultra if you can find it.

 

[CourierDriver]

some new ford f150s have what you would call valves ticking and they say thats normal,,,new kind of engineering these days. As for piston slap, if one pays 20k or 50k for a ride and the pistons are slapping, not acceptable imho. Do Ferraris have piston slap,,,hmmmm, probably not.

 

[[email protected]]

Thanks guys. The consensus seems to be to live with it, but I *might* find some benefit by using Pennzoil OR Amsoil.

I was thinking of trying Amsoil out for the next OCI anyways. Looks like I might have a reason to now!

 

[Hokiefyd]

Our CR-V's cold engine noises are generally the loudest on Pennzoil synthetics, generally the quietest on Mobil 1, and are in between on Pennzoil conventional. I have tried many different oils in this engine, and the different oils make a noticeable difference in the cold engine noise.

In ours, you can actually hear the noise go away during shifting (when spark is pulled and not under significant load), and it's dead silent at idle. Only during acceleration do you really hear it. And once the engine or oil is FULLY warm, it's gone completely.

A few years ago, I had a sump full of Pennzoil Platinum 0w20, and it was quite tappy when cold. I drained a quart and re-filled with Mobil 1 0W-40 and it made a significant difference in the cold engine noise. Right now, it's got Mobil 1 0W-20 in it and it's not as quiet as I remember with this oil. May have to try the 0W-40 trick again.