Warm up with piston slap?

[DriveHard]

This might be a fun twist on a question we have debated before. I know the general consensus for very cold mornings is to get it, start the car, put on seat belt, adjust HVAC, mirrors, etc...make sure engine is off the initial very high idle, and drive slowly away. I do this in my vehicles, as well as keeping very light throttle and less than 50% max RPM until it hits operating temp.

Ok...now what if you have an engine with cold piston slap? I have had a couple GM vehicles that will rattle when very cold (<0F) for a minute or so. If you get in and drive, even lightly, the knocking sound gets MUCH louder.

Since the sound is from the piston rocking back and forth and smacking the inside of the bore, I would think any increase in force from driving would increase the wear from this motion.

So...do you let it idle for a bit longer until the rattling stops, or do you drive gently away with what sounds like a cold diesel?

Personally...I let it warm up until the rattling stops. I hate the sound of it.

 

[dogememe]

Piston slap was supposed to be super common in early 2000s GM trucks. I've never personally heard it and the 01 Suburban with almost 300K I owned at some point never made any engine noise. But, despite all the complaints online about this "issue", these are some of the longest lasting engines and vehicles ever made IMO. So, it seems it doesn't really matter that much?

If it's super cold out, go ahead and warm the vehicle up for a couple minutes... nothing wrong with that, no matter what type of vehicle it is.

 

[RDY4WAR]

My 2002 Tahoe has had bad piston slap since the day it rolled off the dealer's lot. My procedure for driving off on a cold morning is the same as yours. It'll rattle the whole way out of the neighborhood and out on the main road. It has 288k miles currently. At 250k miles, it still had <5% leakdown in all cylinders and only using ~0.5 qt of oil in 7,500 miles. While piston slap can sound awful, it's relatively harmless.

 

[JavierH19]

I'd let it warm up to. My 5.3 has some slap in the cold but it's not alarming. My 6.0 has none. I let it idle for a few minutes during the cold mornings. I start it and go back in to make my coffee and it's gone by then. Not worried about dilution it's not gdi and in my long drives It'll burn it off. When I drive off I try to keep the rpm's to 1500.

 

[supton]

Interesting. I'm in the camp of "let it warm up" as it can't be good for the engine--but if these mills are turning high miles despite not warming up & slapping until so, then my first thought must be wrong.

Still would hate to be hearing it.

 

[Glenda W.]

I can actually tell you what GM recommended in its engine classes as this was always brought up. The engineers always said it was best to let the engine warm up to 120 degrees before driving off easy. Many years later in my 2013 Subaru Forester with a cold engine light I hooked up my scanner out of curiosity. Sure enough the light turns off at 120 degrees. I had remembered the recommendation from the mid nineties.

 

[cptbarkey]

6.0 LQ4, always knocks, get in and drive.

 

[Kalle.J]

0W-20/30/40 and block heater or preferably inline-coolant heater?

Not much else you can do, If its that cold you usually need to clear the windows so a couple minutes of idling is normal.

 

[Glenda W.]

Another funny story. The GM 3100 series engines had such bad piston slap a TSB was released to replace the pistons. The new pistons had a black coating on the skirts. The engines were dead quiet for about 20k miles until the coating wore off.

 

[Gyro Gearloose]

We had 2 or 3 GM V8 slappers in the early 2000's. Nothing helped or made them worse. Standard drive off procedure was give it 5-10 seconds to get oil pressure up and then drive away easy. By the time we got to the neighborhood entrance 1/2 mile away they would be almost normal. The ones we kept a long time went over 200K with just sparkplugs and waterpumps.

 

[dnewton3]

I had a 2002 Tundra with 4.7L piston slap. It was annoying, but went away as the temps came up. The sooner they came up, the sooner the slap went away.

I did as recommended ... let the high-idle flare die off, and drive away in a sane manner.

 

[carviewsonic]

I was assigned a new 2004 GMC pickup with the 4.8. Piston slap started at 100,000 km’s. I drove the truck until 200,000 km’s, and let it warm up each morning because I didn’t like the piston slap. It was then passed on to one of our crews, where it got really rough use. It was auctioned off at over 400,000 km’s, still running good but with everything else worn out.

 

[parshisa]

cold start piston slap in my pilot since brand new. put it in drive and off I go.

 

[SwampSurvivor]

My very high mileage 5.4 ford has some bad piston slap. It'll piston slap idling all day if you let it. So I try to drive off easy somewhat early to get some heat into it.

 

[JohnnyG]

It's acually a design feature, especially in trucks. Since pistons get hot WAY faster that the block (bore) a little piston slap is MUCH better than a siezed piston.
If it goes away, your good. If it doesn't, you've got a problem.

Ya' gotta have clearance Clarence!

 

[BigCahuna]

I had an old chevy van that would slap when cold. I read around on what really causes it, and can't believe it was meant to do that from the factory. I like to try and cure a problem on the cheap side, so here's my hack. I bought several different brands of oil filters and tested them until I found one where I could barely hear a slap. Then used that one until I got rid of that vehicle. It seems alot or most filters go into bypass mode especially when oil is cold and thick. Which I understand, but some brands are still are too restrictive. This "cure" obviously will only work with spin on filters. I never had a vehicle have the slap issue with a cartridge type filter.,,

 

[tnt_motorsports]

I had a 1991 Mazda B2200 that I missed a shift going from 3rd to 4th and went 3rd to 2nd. The engine screamed for a few seconds and had piston slap ever since that. FWIW the engine went another 150,000KM's after that with no ill effects. Some days I waited, some days I needed to get going, so as far as your question, I don't think it will matter IMO. My advice is to let it warm up some and don't beat the snot out of it until it is warmed up.

Just my $0.02

 

[CBR.worm]

My '06 FX45 had a lot of piston slap when cold. It always bugged me, until I sold it at ~220K miles. If it was below freezing, I'd let it warm up for probably closer to a minute, just because it seemed like the right thing to do. Honestly, it doesn't matter what I'm driving, if it's freezing out (or colder) I'll let it warm up a little bit longer.

 

[FoxProTwisty]

It's acually a design feature, especially in trucks. Since pistons get hot WAY faster that the block (bore) a little piston slap is MUCH better than a siezed piston.
If it goes away, your good. If it doesn't, you've got a problem.

Ya' gotta have clearance Clarence!

Great points. The number of guys trying to 'cure' it with Valvoline R&P is getting comical.

My 6.2L Vortec sounds like a clunky steam locomotive on cold starts - even with running 0W, a block heater and an oil pan pad.

 

[wlk]

10w30/40 helped my piston slap in my 90s GM motors. Never gone but was less with a 10w30 over 5w30, same brand. And yes, I'd let it warm up before driving.