Cool weather start up knock

Hey guys. First time posting but I have spent numerous hours reading through the forums. This place came in handy when I did my 5100's and new rear leafs.....I have an 04 DC with a 3.4L. It has about 125K miles. I park my truck outside over night and on some of the cooler mornings I get a knock when I first start it. It only last a few seconds. I have never heard the knock any other time. I am currently running Mobil1 5w-30 with a Wix filter, but I have tried Valvoline full synthetic in 5w-30 and 10w-30. It doesn't matter what oil I run, I still get the knock when I start it on cold mornings. I am only talking about 50° or colder, so not very cold. I really don't think it is a main or rod bearing. Is there something else it may be?

Any feedback would be appreciated.

 

Hello I get the same problem here in colorado. I take my toyota to a shop that used Mobil oil not synthetic and caused some sludge in the engine. Mine started around 70k . I switched to synthetic oil and use a quart of Lucas synthetic stabilizer and it seems to help. I think mine is a hung up lifter. Got 104k on it now. I just get use to it. Hope it helps.

 

FWIW.....

I owned a 96 many many years ago. I switched to Mobile 1 at 60,000 miles and ran that until I sold the truck 5 years later at 110,000 miles.

I would also get the 'lifter tap' from time to time. From what I understand...the hydraulic lifters lose pressure. At startup, you get the tap until the hydraulic pressure builds up again. The longer the truck sits...the more often it would occur (for me anyway).

 

Try switching to a factory OEM oil filter. They have an anti-drainback check valve that is supposed to prevent this. Not sure if your WIX does.

 

'96 here just turned over 214,000. Has had the cold morning startup tick/knock for the last 100,000 or so. It's just hydraulic lifters draining down and cold oil doesn't pump as fast as warm oil. Clearances increase over time and that's what you're hearing. It can be disconcerting to hear it, if it goes away fairly quick I wouldn't worry about it too much. Keep good quality oil in it and don't switch between brands.

An old fashioned heater magnet on the oil pan bottom will help if it really bothers you.

 

Thanks for the info. I read in another post that someone else had the same problem until they switched back to the factory oil filter. I think you are correct about it being a lifter. I'll keep running full synthetic and switch to Toyota filters. I'll let you know if the new filter helps.

Thanks again.

 

The anti-drainback valve is just a silicone gasket with a wide flange that acts as a flapper. Pretty much every oil filter (including the cheaply built Fram) has it. See:



However, switching to OEM filter is still valid, because the bypass valve setting could be too high on an aftermarket filter, which could potentially mean reduced flow at startup, when the cold oil is really thick.