Cold start knock - long term

Ever since I got my truck ('06 RC 5 sp 4x4) in 2011 with 18k miles it has had a knock when cold starting at temps below 45-50°F. It has always gone away after about 15-30 seconds. This winter (currently at 140k miles) seems like it takes longer, maybe a minute or more if less than 30°F. It does not use oil at all. Does anyone know if it's normal for cold start knock to get worse with time? Have there ever been any catastrophic failures due to this issue? Anyone else had the cold knock for the life of his/her truck? Thanks for any feedback!

 

It's probably "piston slap". Especially if it is more of a tick or higher pitched "rattle" than a deep knock. Listen to the noise real close. Higher pitched rattle that goes away within a minute or so? Piston slap. Lower pitched "knock"? You have big problems. Which I doubt you do because a "knock" will stay there and it's a Toyota. Any real mechanic's on this forum can correct me if I'm wrong.

Many of these newer cars/trucks have it. My 2004 did it once or twice at around 70 degrees. A heavier oil fixed it for me. I've been running 10-30 since then. I haven't heard it since. These "water thin" oils in this day and age are for CAFE standards, not engine protection. You should look up what they use in Europe for the same engines. It's thicker than here in the states. The last time I checked anyway.

If it "is" piston slap it won't hurt anything. Believe it or not. It is caused by the new hypertuetectic pistons (I've always had a problem spelling that. I hope I got it right) they started putting in cars and trucks all over the world way back in the 80's when they decided to "save the planet". These pistons have shorter skirts on them and if not fitted perfectly to the bores they slap at start-up until they get warmed up and expand. They actually "rock" in the bores until they expand which doesn't take long and excessive clearance it what causes the noise. That's why the noise goes away rather quickly.

Thicker oil helps and in my case cured the problem all the way down to -20. If you have VVT in your engine be careful changing oil weight. If you don't? Try 10-30 instead of 5-30. 10-30 has fewer VI's (Viscosity Improvers) which make it a better weight anyway. Another reason I use it. It's closer to a single weight but still is thin enough at start up. It won't hurt a thing where you live. Don't waste your time calling Toyota. They'll tell you it is "normal" and it is. Thanks to the EPA.

This newer piston technology seems to have gotten much better over the years. I rarely read or hear about it these days but it does happen. You should have seen the stories on it back in the 90's. It was everywhere from just about every manufacturer. On top of that? To save fuel and "save the planet" they then started putting "low tension" piston rings in engines which is why, General motors, for one, started telling everyone that a quart of oil or two disappearing every oil change was "normal". They weren't the only company to do that either. They pretty much ALL did. The General replaced a lot of engines under warranty back then. Many engines are built with this ridiculous idea to lower drag and "save fuel" to pass ridiculous CAFE standards. Hence, lower tension piston rings.

No, I'm not a mechanic. I just do a lot of reading. I don't know if you use a synthetic oil or not but synthetic is better if it gets cold where you are at and I know it does. I lived in Yorktown/Newport News for 5 years decades ago. You should be fine with a dino in a heavier weight. Especially if you don't have VVT. If you have VVT I'd suggest getting more than just my opinion.

You didn't say what engine you have but it really doesn't make a difference unless a real mechanic sees this and may need to know. All engines whether V-8, 4 cyl., V-6's etc., etc. have been plagued with "piston slap" for decades now.

 

Should have added this:. 2TR-FE engine using Pennzoil Platinum synthetic 5W-30 (this viscosity is what the owners manual calls for). Used Mobil 1 until 90k miles then switched to Pennzoil.

Thanks for the great info @TRVLR500. The knocking is a deeper sound, and like I said, has been there for at least 120k miles, but it's never lasted for more than 30 seconds before going away. Now it still goes away, but will knock for a minute or more when colder. If ambient temps are above 50°F, there is no sound at all. I should probably try to get a video and post it here. Maybe later this week.

 

Had this same knock in my last 2tr upon cold startup and never had an issue

 

You should hear it at -20 lo.. ya it's all good, the 2.7 is a big 4cyl theyvet got some decent piston slap. Unless you're hearing thing when at temp I wouldn't worry about it.

 

Same. Heard it on the coldest days here in VA this winter... probably when it was below 20* in the mornings. Goes away after a short warm-up period. Definitely loud enough to be noticeable.

 

My daily has been doing this for 10 years. Only when it’s cold and for maybe 30 seconds it’s still going and I’m not nice to it so I wouldn’t worry too much.

 

Mine did it to. Since it had 40k miles on it. They didnt have 5w30 at Walmart in the brand I use so I put 10w30 in it this time and it hasn't made a noise all winter. Or I'm going deaf?
I also use pennzoil platinum

 

I was going to start a thread on this same issue. Mine has gotten worse over time and I hear it if it’s below 35. Sounds awful at startup in the morning. Mine might take up to about 2 minutes before it completely goes away.

 

You guys have to remember as the engines age they wear, unless it starts consuming oil, there's really nothing you can do except run a thicker weight oil in the winter months to help compensate for the slap

 

My 2TR-FE has the exact same symptoms as yours. No slapping above 50*F. When it does slap, it takes about 60-90 seconds to go away. By what I have read, this is a common issue and I'd say TRVLR500 is correct. I don't know if mine has gotten worse with time, it just started up about 5 years ago (around 100k) and it sounds about the same now as it did when it started.
As long as it runs good and isn't using any oil, just keep on truckin'...

 

All anyone has to do is look at the difference in the piston skirt length on any engine from the 70's and then look at the skirt length on these new engines. There's the cause of your piston slap if the tolerances aren't just right. Trying to save fuel has cost the average car/truck owner probably billions (collectively) over the last 30 years not to mention what it has done to the economy by costing businesses as well. I'm all for better fuel economy but when it gets downright stupid it's time to say enough is enough.

 

I know what you're TRYING to say, but the way you wrote it is like its costing EACH average owner billions

What you're really trying to say is that its cost ALL (not average) owners billions COMBINED.

I.e., $billions / total number of owners = average cost per owner.

 

You are correct. That is what I meant/was trying to say. If you just look at the increase in fatalities (not widely reported on but reported on here or there over the years) since CAFE standards were put into effect not even counting the cost of ownership while they tried to figure out how to implement the standards I'd say "billions" is accurate. But I could be wrong.

I did auto body repair back in the 80's. and we had a customer who we repaired a car for after he wrecked it. He ended up selling it because the collision did something to the "computer". I don't remember the exact price but it was high enough to where he just sold the car rather than pay the price. That is just one example of "cost of ownership". Then there were the paint delaminations and GM's "water based paint" which may not have anything to do with CAFE standards but it still had to do with "saving the planet". What a decade of nightmares that was for the new car buyer. I could go on and on but won't.

I edited my post. Thanks for pointing that out.