engine knock when cold start

[bass724]

hey guys,
I have a 2005 tundra limited 4 door, 4.7 v-8, 158,000 miles, when i start up the engine has a loud knock 7-8 times, then it stops, only happens 3 or 4 times in a weeks period (only when the engine is cold). i thought about a spark knock, changed gas types still happens, i used fram oil filters, wal-mart high milage oil. cleaned throttle body, replaced timing belt/water pump, service transmission over the summer, was doing the knocking before i did all of this, oil pressure seems to be good.

any ideas?

[perfectlawn]

I have a 2004 tundra that has been having this same noise, and I can't seem to figure it out.

[macmcalexander]

My step-brother's 2005 doublecab, with 140,000 on the odo, also does this horrible knock at start up during the winter months. If he just jumps in it, starts up and just drives off in cold weather, it sounds like the engine is about to lock up. It is that bad. If he starts it and lets it warm before leaving to go anywhere, it sounded normal. Like all sweet 4.7L. He bought some kind of additive (Russian name) added it to his oil change, and so far it has made the cold weather start up knock stay quiet. He had tried our favorite additive, Lucas oil, to the previous oil change and it did not help at all. We have had great luck with that stuff in our old GM's junk and any engine that had leaky valve seals. He was thinking about trading it in but he is not into the new Tundra's, so he was thinking another brand. After he gets back home from Christmas away, I will post what the additive was. I thought, no-way would I have used it in my Tundra. But when it worked in his truck, well, it made me think that if mine sounded as bad as his, maybe I would. His 4.7L sounds like a sewing machine again.

[Tones]

If what you're hearing is piston slap, it is pretty normal for this range of model years. I haven't had this problem on my '01. Perhaps it just doesn't get cold enough here.

[char846]

Make sure you use 5-30 winter time (60 deg. F and under) 10-30 summer time (60 deg. F and up).
Its normal for it to knock first cold start of the day 45 F or colder and let it worm up before you go maybe till the temp gauge start to rise
above the first line.
Don't use high mileage oil it designed for vehicles that leak oil so its thicker you drive a tundra 160,000 mile you are still braking in the engine
and the best oil filter you can use is a Toyota filter go to the dealer and buy a case 10 or 12 then write the mileage on each box that you want to change at 155,000 160,000 165,000,170,000 etc......
Driving down the street when its cold and your oil is like molasses and your doing 2000 + RPM's is not good on your engine.
don't be in such a rat race

[kerryman71]

As was mentioned, it sounds like piston slap. It's pretty common in a lot of vehicles, particularly ours. I run Mobil 1 0W30 year round. The "knock" is more pronounced in the colder weather (it can get into the single digits here), but it isn't anything horrific. Try going with synthetic if you aren't already. If you're comfortable try the 0W30 but if not go with 5W30 and see if that makes a difference.

John