2.7L engine knock

Nothing like a quick warm truck,,when it's a bit chilled outside. Your truck will thank you. Your oil should be fine,,for quite a bit colder.

Some of those pad heaters can get damn warm. Just a heads up. My buddy uses one for a coffee cup warmer in his shop, and if you accidentally lean on it,,you immediately know you did .

 

My 2002 2.7 had the knock on cold mornings, and I just discovered my 2011 (which I bought used in August 2015) has it too.

From everything I've read here and elsewhere, it's not uncommon. In fact, I just got back from the Toyota dealer (where they replaced my catalytic converters under a special service campaign) and I asked about this issue. The tech said yes, it's not uncommon and yes it is the piston skirts slapping the cylinder walls. In a nutshell, their answer was "<shrug>, just let it warm up until it goes away". That doesn't change the fact that it's an incredibly alarming noise!

On the plus side, Toyota replaced the frame on my 2002 and now just gave me brand new catalytic converters, for free! So I'm willing to cut them a little slack.

 

Since I went to alky free fuel,,no severe cold knocks the last handful of years. Imagine that.

I can induce it,,if I'm stupid late and get greedy, but we try not to be that way. My windshield has been iced over every morning,,so plenty of warmup. Needle level operating temp as a matter of fact.

 

Check and change the PCV valve. I had the same thing and was changing a few things. Like the injectors seals and the PCV valve and its2not doing it now more. Hope this helps.
Chay

 

This issue is well-documented. These engines knock when cold because of the hypereutectic pistons: https://en.wikipedia.org/wiki/Hypereutectic_piston
Some prefer to deal with it by using a pan heater/coolant warmer, or letting the engine run and warm up a little before driving. Others (like me) don't worry about it and drive away gently when fast idle comes down, but I very rarely see anything below 30*F. Either way, they will happily run many times 100,000 miles with this knock.

Other kinds of knocking (fuel or emissions related, etc) should be investigated pronto.

 

Mine was the same way. It use to know when engine was cold. They changed the pvc valve and injectors O rings because engine light on from code p0440, and after they changed that, the engine sound went away and hasn't sound any more. That knock was also driving me crazy. It started around 40,000 miles and mnow had 60,000 miles. 02 tacoma 4x4. By the way the P440 was the fuel pump gasket.

 

Yall should have heard my engine knocking the other morning...wound up being a raccoon taking a snooze!

 

What?! Yall gun kill that snoozy coon!!! KILL!!!!! lmfao

 

My 01 does this, it has the 2.7L and 193K miles. Temps under 40F this week, and the piston slap in the morning. Quite embarrassing, if parked not at my own house. Sounds like an old jalopy

 

Let them warm up for 5-10 minutes or more,,if you have audible piston slap right after cold startup. Don't try and drive on that noise. Just because the noise suddenly disappears during warmup does not mean take off immediately. Let it run for a few more minutes after that.

 

Appreciate the heads up

I was driving it after the noise goes away
But will give it some more warm up time

 

My 2.7 had 120,000 on it when I bought it. I heard the slap for just a second or less a couple of times. It wasn't cold outside either. Maybe around 65 or 70. Thicker oil can help with piston slap. I've been running 10-30 Amsoil since and haven't heard that noise since. Actually, I did run Mobil 1 for a few changes and then went to the Amsoil. Depending on where one lives thicker oil is an option. It gets well below zero where I live in the winter and the 10-30 hasn't caused a problem. It "is" a full synthetic though and that makes a huge difference. A dino 10-30 wouldn't fare as well at temps like that.

As far as letting it warm up that's very good advice as well. Putting a load on the engine with the pistons slapping is a no-no. I let my engine warm up even in the summer time. I wait until it gets at least to the "cold" mark on the temp gauge before I take off.

 

Interesting. Mine seems to be temp dependant only.

 

Is it OK to drive gently with piston slap? Technically that is still loading the engine, but not much. I've been doing this for years, gentle driving with light piston slap. After the high idle comes down and I roll away, the slap goes on for about 45 seconds and only when the temp is below 40F. I am extra light on the throttle during this period. So really it doesn't happen very often, and I've never had any problems, but I don't want any problems either. 45 seconds is not very long to wait so maybe I will start waiting until the slap stops.

 

Same here. I live on a top of a hill. So usually piston slap will die down in 30 seconds. Reverse. Put it in D2, and essentially coast down for about a 1.5 before getting on the throttle

 

Mine has been knocking now that it's cold.

Hadn't heard it before (bought new in 2013), but didn't cause me any concern.

 

seems to be pretty common with the 2.7L

 

I love you.

 

Get a room.

 

I tried. But he won't tell me his size.